Blocking Connection Adapter¶
[!WARNING]
BlockingConnectionis deprecated and will be removed in Pika 2.0. Because the calling thread is the IOLoop, any blocking user code stalls heartbeats unlessprocess_data_events()is called periodically, and the adapter is not thread-safe. UseConnectioninstead, which runs its own IOLoop on a background thread and provides a thread-safe blocking API.
The blocking connection adapter module implements blocking semantics on top of Pika's core AMQP driver. While most of the asynchronous expectations are removed when using the blocking connection adapter, it attempts to remain true to the asynchronous RPC nature of the AMQP protocol, supporting server sent RPC commands.
The user facing classes in the module consist of the
:py:class:~pika.adapters.blocking_connection.BlockingConnection
and the :class:~pika.adapters.blocking_connection.BlockingChannel
classes.
The BlockingChannel implements blocking semantics for most things that
one would use callback-passing-style for with the
:py:class:~pika.channel.Channel class. In addition,
the BlockingChannel class implements a :term:generator that allows
you to :doc:consume messages </examples/blocking_consumer_generator>
without using callbacks.
Example of creating a BlockingChannel::
import pika
# Create our connection object
connection = pika.BlockingConnection()
# The returned object will be a synchronous channel
channel = connection.channel()
Source code in pika/adapters/blocking_connection.py
class BlockingChannel:
"""The BlockingChannel implements blocking semantics for most things that
one would use callback-passing-style for with the
:py:class:`~pika.channel.Channel` class. In addition,
the `BlockingChannel` class implements a :term:`generator` that allows
you to :doc:`consume messages </examples/blocking_consumer_generator>`
without using callbacks.
Example of creating a BlockingChannel::
import pika
# Create our connection object
connection = pika.BlockingConnection()
# The returned object will be a synchronous channel
channel = connection.channel()
"""
class _RxMessageArgs(NamedTuple):
channel: Any
method: Any
properties: Any
body: bytes
class _MethodFrameCallbackResultArgs(NamedTuple):
method_frame: Any
class _OnMessageConfirmationReportArgs(NamedTuple):
method_frame: Any
class _FlowOkCallbackResultArgs(NamedTuple):
active: bool
_CONSUMER_CANCELLED_CB_KEY = 'blocking_channel_consumer_cancelled'
def __init__(self, channel_impl: pika.channel.Channel,
connection: BlockingConnection) -> None:
"""
Create a new instance of the Channel.
:param channel_impl: Channel implementation object as returned from
SelectConnection.channel()
:param connection: The connection object
"""
self._impl = channel_impl
self._connection = connection
# A mapping of consumer tags to _ConsumerInfo for active consumers
self._consumer_infos: dict[Any, Any] = {}
# Queue consumer generator generator info of type
# _QueueConsumerGeneratorInfo created by BlockingChannel.consume
self._queue_consumer_generator: _QueueConsumerGeneratorInfo | None = None
# Whether RabbitMQ delivery confirmation has been enabled
self._delivery_confirmation = False
# Receives message delivery confirmation report (Basic.ack or
# Basic.nack) from broker when delivery confirmations are enabled
self._message_confirmation_result = _CallbackResult(
self._OnMessageConfirmationReportArgs)
# deque of pending events: _ConsumerDeliveryEvt and
# _ConsumerCancellationEvt objects that will be returned by
# `BlockingChannel.get_event()`
self._pending_events: deque[Any] = deque()
# Holds a ReturnedMessage object representing a message received via
# Basic.Return in publisher-acknowledgments mode.
self._puback_return: ReturnedMessage | None = None
# self._on_channel_closed() saves the reason exception here
self._closing_reason = None # type: None | Exception
# Receives Basic.ConsumeOk reply from server
self._basic_consume_ok_result = _CallbackResult()
# Receives args from Basic.GetEmpty response
# https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.get
self._basic_getempty_result = _CallbackResult(
self._MethodFrameCallbackResultArgs)
self._impl.add_on_cancel_callback(self._on_consumer_cancelled_by_broker)
self._impl.add_callback(self._basic_consume_ok_result.signal_once,
replies=[pika.spec.Basic.ConsumeOk],
one_shot=False)
self._impl.add_on_close_callback(self._on_channel_closed)
self._impl.add_callback(self._basic_getempty_result.set_value_once,
replies=[pika.spec.Basic.GetEmpty],
one_shot=False)
LOGGER.info('Created channel=%s', self.channel_number)
def __int__(self) -> int:
"""
Return the channel object as its channel number.
NOTE: inherited from legacy BlockingConnection; might be error-prone;
use `channel_number` property instead.
"""
return self.channel_number
@override
def __repr__(self) -> str:
return f'<{self.__class__.__name__} impl={self._impl!r}>'
def __enter__(self) -> Self:
return self
def __exit__(self, exc_type: type[BaseException] | None,
value: BaseException | None,
traceback: TracebackType | None) -> None:
if self.is_open:
self.close()
def _cleanup(self) -> None:
"""Clean up members that might inhibit garbage collection."""
self._message_confirmation_result.reset()
self._pending_events = deque()
self._consumer_infos = {}
self._queue_consumer_generator = None
@property
def channel_number(self) -> int:
"""Channel number."""
return self._impl.channel_number
@property
def connection(self) -> BlockingConnection:
"""The channel's BlockingConnection instance."""
return self._connection
@property
def is_closed(self) -> bool:
"""Returns True if the channel is closed."""
return self._impl.is_closed
@property
def is_open(self) -> bool:
"""Returns True if the channel is open."""
return self._impl.is_open
@property
def consumer_tags(self) -> list[str]:
"""Property method that returns a list of consumer tags for active consumers."""
return list(self._consumer_infos.keys())
_ALWAYS_READY_WAITERS = ((lambda: True),)
def _flush_output(self, *waiters: Callable[[], bool]) -> None:
"""
Flush output and process input while waiting for any of the given callbacks to return true.
The wait is aborted upon channel-close or connection-close. Otherwise, processing continues
until the output is flushed AND at least one of the callbacks returns true. If there are no
callbacks, then processing ends when all output is flushed.
:param waiters: sequence of zero or more callables taking no args and returning true when
it's time to stop processing. Their results are OR'ed together. An empty sequence is
treated as equivalent to a waiter always returning true.
"""
if self.is_closed:
self._impl._raise_if_not_open()
if not waiters:
waiters = self._ALWAYS_READY_WAITERS
self._connection._flush_output(lambda: self.is_closed, *waiters)
if self.is_closed and isinstance(self._closing_reason,
exceptions.ChannelClosedByBroker):
raise self._closing_reason
def _on_puback_message_returned(self, channel: pika.channel.Channel,
method: pika.spec.Basic.Return,
properties: pika.spec.BasicProperties,
body: bytes) -> None:
"""
Called as the result of Basic.Return from broker in publisher-acknowledgements mode.
Saves the info as a ReturnedMessage instance in self._puback_return.
:param channel: our self._impl channel
:param method:
:param properties: message properties
:param body: returned message body; empty string if no body
"""
assert channel is self._impl, (channel.channel_number,
self.channel_number)
assert isinstance(method, pika.spec.Basic.Return), method
assert isinstance(properties, pika.spec.BasicProperties), (properties)
LOGGER.warning(
'Published message was returned: _delivery_confirmation=%s; '
'channel=%s; method=%r; properties=%r; body_size=%d; '
'body_prefix=%.255r', self._delivery_confirmation,
channel.channel_number, method, properties,
len(body) if body is not None else None, body)
self._puback_return = ReturnedMessage(method, properties, body)
def _add_pending_event(self, evt: _ChannelPendingEvt) -> None:
"""
Append an event to the channel's list of events that are ready for dispatch to user and
signal our connection that this channel is ready for event dispatch.
:param evt: an event derived from _ChannelPendingEvt
"""
self._pending_events.append(evt)
self.connection._request_channel_dispatch(self.channel_number)
def _on_channel_closed(self, _channel: pika.channel.Channel,
reason: Exception) -> None:
"""
Callback from impl notifying us that the channel has been closed.
This may be as the result of user-, broker-, or internal connection clean-up initiated closing or meta-closing of the
channel.
If it resulted from receiving `Channel.Close` from broker, we will
expedite waking up of the event subsystem so that it may respond by
raising `ChannelClosed` from user's context.
NOTE: We can't raise exceptions in callbacks in order to protect
the integrity of the underlying implementation. BlockingConnection's
underlying asynchronous connection adapter (SelectConnection) uses
callbacks to communicate with us. If BlockingConnection leaks exceptions
back into the I/O loop or the asynchronous connection adapter, we
interrupt their normal workflow and introduce a high likelihood of state
inconsistency.
See `pika.Channel.add_on_close_callback()` for additional documentation.
:param _channel: (unused)
:param reason:
"""
LOGGER.debug('_on_channel_closed: %r; %r', reason, self)
self._closing_reason = reason
if isinstance(reason, exceptions.ChannelClosedByBroker):
self.connection._server_channel_closures.append(reason)
self._cleanup()
# Request urgent termination of `process_data_events()`, in case
# it's executing or next time it will execute
self.connection._request_channel_dispatch(-self.channel_number)
def _on_consumer_cancelled_by_broker(
self,
method_frame: pika.frame.Method[pika.spec.Basic.Cancel]) -> None:
"""
Called by impl when broker cancels consumer via Basic.Cancel.
This is a RabbitMQ-specific feature. The circumstances include deletion of queue being
consumed as well as failure of a HA node responsible for the queue being consumed.
:param method_frame: method frame with the `spec.Basic.Cancel` method
"""
evt = _ConsumerCancellationEvt(method_frame)
consumer = self._consumer_infos[method_frame.method.consumer_tag]
# Don't interfere with client-initiated cancellation flow
if not consumer.tearing_down:
consumer.state = _ConsumerInfo.CANCELLED_BY_BROKER
if consumer.alternate_event_sink is not None:
consumer.alternate_event_sink(evt)
else:
self._add_pending_event(evt)
def _on_consumer_message_delivery(self, _channel: pika.channel.Channel,
method: pika.spec.Basic.Deliver,
properties: pika.spec.BasicProperties,
body: bytes) -> None:
"""
Called by impl when a message is delivered for a consumer.
:param _channel: The implementation channel object
:param method:
:param properties: message properties
:param body: delivered message body; empty string if no body
"""
evt = _ConsumerDeliveryEvt(method, properties, body)
consumer = self._consumer_infos[method.consumer_tag]
if consumer.alternate_event_sink is not None:
consumer.alternate_event_sink(evt)
else:
self._add_pending_event(evt)
def _on_consumer_generator_event(self, evt: _ChannelPendingEvt) -> None:
"""
Sink for the queue consumer generator's consumer events; append the event to queue consumer
generator's pending events buffer.
:param evt: an object of type _ConsumerDeliveryEvt or _ConsumerCancellationEvt
"""
assert self._queue_consumer_generator is not None
self._queue_consumer_generator.pending_events.append(evt)
# Schedule termination of connection.process_data_events using a
# negative channel number
self.connection._request_channel_dispatch(-self.channel_number)
def _cancel_all_consumers(self) -> None:
"""
Cancel all consumers.
NOTE: pending non-ackable messages will be lost; pending ackable
messages will be rejected.
"""
if self._consumer_infos:
LOGGER.debug('Cancelling %i consumers', len(self._consumer_infos))
if self._queue_consumer_generator is not None:
# Cancel queue consumer generator
self.cancel()
# Cancel consumers created via basic_consume
for consumer_tag in list(self._consumer_infos.keys()):
self.basic_cancel(consumer_tag)
def _dispatch_events(self) -> None:
"""
Called by BlockingConnection to dispatch pending events.
`BlockingChannel` schedules this callback via `BlockingConnection._request_channel_dispatch`
"""
while self._pending_events:
evt = self._pending_events.popleft()
if type(evt) is _ConsumerDeliveryEvt:
consumer_info = self._consumer_infos[evt.method.consumer_tag]
consumer_info.on_message_callback(self, evt.method,
evt.properties, evt.body)
elif type(evt) is _ConsumerCancellationEvt:
del self._consumer_infos[evt.method_frame.method.consumer_tag]
self._impl.callbacks.process(self.channel_number,
self._CONSUMER_CANCELLED_CB_KEY,
self, evt.method_frame)
else:
evt.dispatch()
def close(self,
reply_code: int = 0,
reply_text: str = 'Normal shutdown') -> None:
"""
Will invoke a clean shutdown of the channel with the AMQP Broker.
:param reply_code: The reply code to close the channel with
:param reply_text: The reply text to close the channel with
"""
LOGGER.debug('Channel.close(%s, %s)', reply_code, reply_text)
self._impl._raise_if_not_open()
try:
# Cancel remaining consumers
self._cancel_all_consumers()
# Close the channel
self._impl.close(reply_code=reply_code, reply_text=reply_text)
self._flush_output(lambda: self.is_closed)
finally:
self._cleanup()
def flow(self, active: bool) -> bool:
"""
Turn Channel flow control off and on.
NOTE: RabbitMQ doesn't support active=False; per
https://www.rabbitmq.com/specification.html: "active=false is not
supported by the server. Limiting prefetch with basic.qos provides much
better control"
For more information, please reference:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#channel.flow
:param active: Turn flow on (True) or off (False)
:returns: True if broker will start or continue sending; False if not
"""
with _CallbackResult(self._FlowOkCallbackResultArgs) as flow_ok_result:
self._impl.flow(active=active,
callback=flow_ok_result.set_value_once)
self._flush_output(flow_ok_result.is_ready)
return flow_ok_result.value.active
def add_on_cancel_callback(
self, callback: Callable[[pika.frame.Method[pika.spec.Basic.Cancel]],
None]
) -> None:
"""
Pass a callback function that will be called when Basic.Cancel is sent by the broker.
The callback function should receive a method frame parameter.
:param callback: a callable for handling broker's Basic.Cancel
notification with the call signature: callback(method_frame)
where method_frame is of type `pika.frame.Method` with method of
type `spec.Basic.Cancel`
"""
self._impl.callbacks.add(self.channel_number,
self._CONSUMER_CANCELLED_CB_KEY,
callback,
one_shot=False)
def add_on_return_callback(
self, callback: Callable[[
BlockingChannel, pika.spec.Basic.Return, pika.spec.
BasicProperties, bytes
], None]
) -> None:
"""
Pass a callback function that will be called when a published message is rejected and
returned by the server via `Basic.Return`.
:param callback: The method to call on callback with the
signature callback(channel, method, properties, body), where
- channel: pika.Channel
- method: pika.spec.Basic.Return
- properties: pika.spec.BasicProperties
- body: bytes
"""
self._impl.add_on_return_callback(
lambda _channel, method, properties, body: (self._add_pending_event(
_ReturnedMessageEvt(callback, self, method, properties, body))))
def basic_consume(self,
queue: str,
on_message_callback: Callable[[
BlockingChannel, pika.spec.Basic.Deliver, pika.spec.
BasicProperties, bytes
], None],
auto_ack: bool = False,
exclusive: bool = False,
consumer_tag: str | None = None,
arguments: dict[str, Any] | None = None) -> str:
"""
Sends the AMQP command Basic.Consume to the broker and binds messages for the consumer_tag
to the consumer callback. If you do not pass in a consumer_tag, one will be automatically
generated for you. Returns the consumer tag.
NOTE: the consumer callbacks are dispatched only in the scope of
specially-designated methods: see
`BlockingConnection.process_data_events` and
`BlockingChannel.start_consuming`.
For more information about Basic.Consume, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume
:param queue: The queue from which to consume
:param on_message_callback: Required function for dispatching messages
to user, having the signature:
on_message_callback(channel, method, properties, body)
- channel: BlockingChannel
- method: spec.Basic.Deliver
- properties: spec.BasicProperties
- body: bytes
:param auto_ack: if set to True, automatic acknowledgement mode will be used
(see https://www.rabbitmq.com/confirms.html). This corresponds
with the 'no_ack' parameter in the basic.consume AMQP 0.9.1
method
:param exclusive: Don't allow other consumers on the queue
:param consumer_tag: You may specify your own consumer tag; if left
empty, a consumer tag will be generated automatically
:param arguments: Custom key/value pair arguments for the consumer
:returns: consumer tag
:raises pika.exceptions.DuplicateConsumerTag: if consumer with given
consumer_tag is already present.
"""
validators.require_string(queue, 'queue')
validators.require_callback(on_message_callback, 'on_message_callback')
return self._basic_consume_impl(queue=queue,
on_message_callback=on_message_callback,
auto_ack=auto_ack,
exclusive=exclusive,
consumer_tag=consumer_tag,
arguments=arguments)
def _basic_consume_impl(
self,
queue: str,
auto_ack: bool,
exclusive: bool,
consumer_tag: str | None,
arguments: dict[str, Any] | None = None,
on_message_callback: Callable[[
BlockingChannel, pika.spec.Basic.Deliver, pika.spec.
BasicProperties, bytes
], None] | None = None,
alternate_event_sink: Callable[[_ChannelPendingEvt], None] | None = None
) -> str:
"""
The low-level implementation used by `basic_consume` and `consume`.
See `basic_consume` docstring for more info.
NOTE: exactly one of on_message_callback/alternate_event_sink musts be
non-None.
This method has one additional parameter alternate_event_sink over the
args described in `basic_consume`.
:param queue: Queue name
:param auto_ack: If True, the broker acknowledges messages automatically
:param exclusive: If True, restrict access to the current connection
:param consumer_tag: if specified, only the consumer with the given tag will be cancelled
:param arguments: Custom key/value pair arguments for the consumer
:param on_message_callback: Callback for delivered messages
:param alternate_event_sink: if specified, _ConsumerDeliveryEvt
and _ConsumerCancellationEvt objects will be diverted to this
callback instead of being deposited in the channel's
`_pending_events` container. Signature:
alternate_event_sink(evt)
:raises pika.exceptions.DuplicateConsumerTag: if consumer with given
consumer_tag is already present.
"""
if (on_message_callback is None) == (alternate_event_sink is None):
raise ValueError(((
'exactly one of on_message_callback/alternate_event_sink must '
'be non-None'), on_message_callback, alternate_event_sink))
if not consumer_tag:
# Need a consumer tag to register consumer info before sending
# request to broker, because I/O might dispatch incoming messages
# immediately following Basic.Consume-ok before _flush_output
# returns
consumer_tag = self._impl._generate_consumer_tag()
if consumer_tag in self._consumer_infos:
raise exceptions.DuplicateConsumerTag(consumer_tag)
# Create new consumer
self._consumer_infos[consumer_tag] = _ConsumerInfo(
consumer_tag,
auto_ack=auto_ack,
on_message_callback=on_message_callback,
alternate_event_sink=alternate_event_sink)
try:
with self._basic_consume_ok_result as ok_result:
tag = self._impl.basic_consume(
on_message_callback=self._on_consumer_message_delivery,
queue=queue,
auto_ack=auto_ack,
exclusive=exclusive,
consumer_tag=consumer_tag,
arguments=arguments)
assert tag == consumer_tag, (tag, consumer_tag)
self._flush_output(ok_result.is_ready)
except Exception:
# If channel was closed, self._consumer_infos will be empty
if consumer_tag in self._consumer_infos:
del self._consumer_infos[consumer_tag]
# Schedule termination of connection.process_data_events using a
# negative channel number
self.connection._request_channel_dispatch(-self.channel_number)
raise
# NOTE: Consumer could get cancelled by broker immediately after opening
# (e.g., queue getting deleted externally)
if self._consumer_infos[consumer_tag].setting_up:
self._consumer_infos[consumer_tag].state = _ConsumerInfo.ACTIVE
return consumer_tag
def basic_cancel(
self, consumer_tag: str
) -> Sequence[tuple[pika.spec.Basic.Deliver, pika.spec.BasicProperties,
bytes]]:
"""
This method cancels a consumer.
This does not affect already delivered messages, but it does mean the server will not send any more
messages for that consumer. The client may receive an arbitrary number
of messages in between sending the cancel method and receiving the
cancel-ok reply.
NOTE: When cancelling an auto_ack=False consumer, this implementation
automatically Nacks and suppresses any incoming messages that have not
yet been dispatched to the consumer's callback. However, when cancelling
a auto_ack=True consumer, this method will return any pending messages
that arrived before broker confirmed the cancellation.
:param consumer_tag: Identifier for the consumer; the result of
passing a consumer_tag that was created on another channel is
undefined (bad things will happen)
:returns: (NEW IN pika 0.10.0) empty sequence for a auto_ack=False
consumer; for a auto_ack=True consumer, returns a (possibly empty)
sequence of pending messages that arrived before broker confirmed
the cancellation (this is done instead of via consumer's callback in
order to prevent reentrancy/recursion. Each message is three-tuple:
(method, properties, body)
- method: spec.Basic.Deliver
- properties: spec.BasicProperties
- body: bytes
"""
try:
consumer_info = self._consumer_infos[consumer_tag]
except KeyError:
LOGGER.warning(
'User is attempting to cancel an unknown consumer=%s; '
'already cancelled by user or broker?', consumer_tag)
return []
try:
# Assertion failure here is most likely due to reentrance
assert consumer_info.active or consumer_info.cancelled_by_broker, (
consumer_info.state)
# Assertion failure here signals disconnect between consumer state
# in BlockingChannel and Channel
assert (consumer_info.cancelled_by_broker or
consumer_tag in self._impl._consumers), consumer_tag
auto_ack = consumer_info.auto_ack
consumer_info.state = _ConsumerInfo.TEARING_DOWN
with _CallbackResult() as cancel_ok_result:
# Nack pending messages for auto_ack=False consumer
if not auto_ack:
pending_messages = self._remove_pending_deliveries(
consumer_tag)
if pending_messages:
# NOTE: we use impl's basic_reject to avoid the
# possibility of redelivery before basic_cancel takes
# control of nacking.
# NOTE: we can't use basic_nack with the multiple option
# to avoid nacking messages already held by our client.
for message in pending_messages:
delivery_tag = message.method.delivery_tag
# The generated spec types delivery_tag as
# optional, but the broker always sets it on a
# delivery.
assert delivery_tag is not None
self._impl.basic_reject(delivery_tag, requeue=True)
# Cancel the consumer; impl takes care of rejecting any
# additional deliveries that arrive for a auto_ack=False
# consumer
self._impl.basic_cancel(consumer_tag=consumer_tag,
callback=cancel_ok_result.signal_once)
# Flush output and wait for Basic.Cancel-ok or
# broker-initiated Basic.Cancel
self._flush_output(
cancel_ok_result.is_ready,
lambda: consumer_tag not in self._impl._consumers)
if auto_ack:
# Return pending messages for auto_ack=True consumer
return [(evt.method, evt.properties, evt.body)
for evt in self._remove_pending_deliveries(consumer_tag)
]
# impl takes care of rejecting any incoming deliveries during
# cancellation
messages = self._remove_pending_deliveries(consumer_tag)
assert not messages, messages
return []
finally:
# NOTE: The entry could be purged if channel or connection closes
if consumer_tag in self._consumer_infos:
del self._consumer_infos[consumer_tag]
# Schedule termination of connection.process_data_events using a
# negative channel number
self.connection._request_channel_dispatch(-self.channel_number)
def _remove_pending_deliveries(
self, consumer_tag: str) -> Sequence[_ConsumerDeliveryEvt]:
"""
Extract _ConsumerDeliveryEvt objects destined for the given consumer from pending events,
discarding the _ConsumerCancellationEvt, if any.
:param consumer_tag:
:returns: a (possibly empty) sequence of _ConsumerDeliveryEvt destined for the given
consumer tag
"""
remaining_events: deque[Any] = deque()
unprocessed_messages: list[Any] = []
while self._pending_events:
evt = self._pending_events.popleft()
if (type(evt) is _ConsumerDeliveryEvt and
evt.method.consumer_tag == consumer_tag):
unprocessed_messages.append(evt)
continue
if (type(evt) is _ConsumerCancellationEvt and
evt.method_frame.method.consumer_tag == consumer_tag):
# A broker-initiated Basic.Cancel must have arrived
# before our cancel request completed
continue
remaining_events.append(evt)
self._pending_events = remaining_events
return unprocessed_messages
def start_consuming(self) -> None:
"""
Processes I/O events and dispatches timers and `basic_consume` callbacks until all consumers
are cancelled.
NOTE: this blocking function may not be called from the scope of a
pika callback, because dispatching `basic_consume` callbacks from this
context would constitute recursion.
:raises pika.exceptions.ReentrancyError: if called from the scope of a
`BlockingConnection` or `BlockingChannel` callback
:raises ChannelClosed: when this channel is closed by broker.
"""
# Check if called from the scope of an event dispatch callback
with self.connection._acquire_event_dispatch() as dispatch_allowed:
if not dispatch_allowed:
raise exceptions.ReentrancyError(
'start_consuming may not be called from the scope of '
'another BlockingConnection or BlockingChannel callback')
self._impl._raise_if_not_open()
# Process events as long as consumers exist on this channel
while self._consumer_infos:
# This will raise ChannelClosed if channel is closed by broker
self._process_data_events(time_limit=None)
def stop_consuming(self, consumer_tag: str | None = None) -> None:
"""
Cancels all consumers, signalling the `start_consuming` loop to exit.
NOTE: pending non-ackable messages will be lost; pending ackable
messages will be rejected.
:param consumer_tag: if specified, only the consumer with the given tag will be cancelled
"""
if consumer_tag:
self.basic_cancel(consumer_tag)
else:
self._cancel_all_consumers()
def consume(
self,
queue: str,
auto_ack: bool = False,
exclusive: bool = False,
arguments: dict[str, Any] | None = None,
inactivity_timeout: float | None = None,
consumer_tag: str | None = None
) -> Generator[tuple[pika.spec.Basic.Deliver | None,
pika.spec.BasicProperties | None, bytes | None]]:
"""
Blocking consumption of a queue instead of via a callback.
This method is a generator that yields each message as a tuple of method,
properties, and body. The active generator iterator terminates when the
consumer is cancelled by client via `BlockingChannel.cancel()` or by
broker.
Example:
::
for method, properties, body in channel.consume('queue'):
print(body)
channel.basic_ack(method.delivery_tag)
You should call `BlockingChannel.cancel()` when you escape out of the
generator loop.
If you don't cancel this consumer, then next call on the same channel
to `consume()` with the exact same (queue, auto_ack, exclusive) parameters
will resume the existing consumer generator; however, calling with
different parameters will result in an exception.
:param queue: The queue name to consume
:param auto_ack: Tell the broker to not expect a ack/nack response
:param exclusive: Don't allow other consumers on the queue
:param arguments: Custom key/value pair arguments for the consumer
:param inactivity_timeout: if a number is given (in
seconds), will cause the method to yield (None, None, None) after the
given period of inactivity; this permits for pseudo-regular maintenance
activities to be carried out by the user while waiting for messages
to arrive. If None is given (default), then the method blocks until
the next event arrives. NOTE that timing granularity is limited by
the timer resolution of the underlying implementation.
NEW in pika 0.10.0.
:param consumer_tag: Specify your own consumer tag
:yields: tuple(spec.Basic.Deliver, spec.BasicProperties, bytes)
:raises ValueError: if consumer-creation parameters don't match those
of the existing queue consumer generator, if any.
NEW in pika 0.10.0
:raises ChannelClosed: when this channel is closed by broker.
"""
self._impl._raise_if_not_open()
params = (queue, auto_ack, exclusive)
if self._queue_consumer_generator is not None:
if params != self._queue_consumer_generator.params:
raise ValueError(
'Consume with different params not allowed on existing '
f'queue consumer generator; previous params: {self._queue_consumer_generator.params!r}; '
f'new params: {(queue, auto_ack, exclusive)!r}')
else:
LOGGER.debug('Creating new queue consumer generator; params: %r',
params)
# Need a consumer tag to register consumer info before sending
# request to broker, because I/O might pick up incoming messages
# in addition to Basic.Consume-ok
if not consumer_tag:
consumer_tag = self._impl._generate_consumer_tag()
self._queue_consumer_generator = _QueueConsumerGeneratorInfo(
params, consumer_tag)
try:
self._basic_consume_impl(
queue=queue,
auto_ack=auto_ack,
exclusive=exclusive,
consumer_tag=consumer_tag,
arguments=arguments,
alternate_event_sink=self._on_consumer_generator_event)
except Exception:
self._queue_consumer_generator = None
raise
LOGGER.info('Created new queue consumer generator %r',
self._queue_consumer_generator)
while self._queue_consumer_generator is not None:
# Process pending events
if self._queue_consumer_generator.pending_events:
evt = self._queue_consumer_generator.pending_events.popleft()
if type(evt) is _ConsumerCancellationEvt:
# Consumer was cancelled by broker
self._queue_consumer_generator = None
break
else:
yield (evt.method, evt.properties, evt.body)
continue
if inactivity_timeout is None:
# Wait indefinitely for a message to arrive, while processing
# I/O events and triggering ChannelClosed exception when the
# channel fails
self._process_data_events(time_limit=None)
continue
# Wait with inactivity timeout
wait_start_time = pika._utils.time_now()
wait_deadline = wait_start_time + inactivity_timeout
delta = inactivity_timeout
while (self._queue_consumer_generator is not None and
not self._queue_consumer_generator.pending_events):
self._process_data_events(time_limit=delta)
if not self._queue_consumer_generator:
# Consumer was cancelled by client
break
if self._queue_consumer_generator.pending_events:
# Got message(s)
break
delta = wait_deadline - pika._utils.time_now()
if delta <= 0.0:
# Signal inactivity timeout
yield (None, None, None)
break
def _process_data_events(self, time_limit: float | None) -> None:
"""
Wrapper for `BlockingConnection.process_data_events()` with common channel-specific logic
that raises ChannelClosed if broker closed this channel.
NOTE: We need to raise an exception in the context of user's call into
our API to protect the integrity of the underlying implementation.
BlockingConnection's underlying asynchronous connection adapter
(SelectConnection) uses callbacks to communicate with us. If
BlockingConnection leaks exceptions back into the I/O loop or the
asynchronous connection adapter, we interrupt their normal workflow and
introduce a high likelihood of state inconsistency.
See `BlockingConnection.process_data_events()` for documentation of args
and behavior.
:param time_limit:
"""
self.connection.process_data_events(time_limit=time_limit)
if self.is_closed and isinstance(self._closing_reason,
exceptions.ChannelClosedByBroker):
LOGGER.debug('Channel close by broker detected, raising %r; %r',
self._closing_reason, self)
raise self._closing_reason
def get_waiting_message_count(self) -> int:
"""
Returns the number of messages that may be retrieved from the current queue consumer
generator via `BlockingChannel.consume` without blocking. NEW in pika 0.10.0.
:returns: The number of waiting messages
"""
if self._queue_consumer_generator is not None:
pending_events = self._queue_consumer_generator.pending_events
count = len(pending_events)
if count and type(pending_events[-1]) is _ConsumerCancellationEvt:
count -= 1
else:
count = 0
return count
def cancel(self) -> int:
"""
Cancel the queue consumer created by `BlockingChannel.consume`, rejecting all pending
ackable messages.
NOTE: If you're looking to cancel a consumer issued with
BlockingChannel.basic_consume then you should call
BlockingChannel.basic_cancel.
:returns: The number of messages requeued by Basic.Nack.
NEW in 0.10.0: returns 0
"""
if self._queue_consumer_generator is None:
LOGGER.warning('cancel: queue consumer generator is inactive '
'(already cancelled by client or broker?)')
return 0
try:
_, auto_ack, _ = self._queue_consumer_generator.params
if not auto_ack:
# Reject messages held by queue consumer generator; NOTE: we
# can't use basic_nack with the multiple option to avoid nacking
# messages already held by our client.
pending_events = self._queue_consumer_generator.pending_events
# NOTE `get_waiting_message_count` adjusts for `Basic.Cancel`
# from the server at the end (if any)
for _ in range(self.get_waiting_message_count()):
evt = pending_events.popleft()
self._impl.basic_reject(evt.method.delivery_tag,
requeue=True)
self.basic_cancel(self._queue_consumer_generator.consumer_tag)
finally:
self._queue_consumer_generator = None
# Return 0 for compatibility with legacy implementation; the number of
# nacked messages is not meaningful since only messages consumed with
# auto_ack=False may be nacked, and those arriving after calling
# basic_cancel will be rejected automatically by impl channel, so we'll
# never know how many of those were nacked.
return 0
def basic_ack(self, delivery_tag: int = 0, multiple: bool = False) -> None:
"""
Acknowledge one or more messages.
When sent by the client, this method acknowledges one or more messages delivered via the
Deliver or Get-Ok methods. When sent by server, this method acknowledges one or more
messages published with the Publish method on a channel in confirm mode. The acknowledgement
can be for a single message or a set of messages up to and including a specific message.
:param delivery_tag: The server-assigned delivery tag
:param multiple: If set to True, the delivery tag is treated as "up to and including", so
that multiple messages can be acknowledged with a single method. If set to False, the
delivery tag refers to a single message. If the multiple field is 1, and the delivery
tag is zero, this indicates acknowledgement of all outstanding messages.
"""
self._impl.basic_ack(delivery_tag=delivery_tag, multiple=multiple)
self._flush_output()
def basic_nack(self,
delivery_tag: int = 0,
multiple: bool = False,
requeue: bool = True) -> None:
"""
This method allows a client to reject one or more incoming messages.
It can be used to interrupt and cancel large incoming messages, or return untreatable
messages to their original queue.
:param delivery_tag: The server-assigned delivery tag
:param multiple: If set to True, the delivery tag is treated as "up to and including", so
that multiple messages can be acknowledged with a single method. If set to False, the
delivery tag refers to a single message. If the multiple field is 1, and the delivery
tag is zero, this indicates acknowledgement of all outstanding messages.
:param requeue: If requeue is true, the server will attempt to requeue the message. If
requeue is false or the requeue attempt fails the messages are discarded or dead-
lettered.
"""
self._impl.basic_nack(delivery_tag=delivery_tag,
multiple=multiple,
requeue=requeue)
self._flush_output()
def basic_get(
self,
queue: str,
auto_ack: bool = False
) -> tuple[pika.spec.Basic.GetOk | None, pika.spec.BasicProperties | None,
bytes | None]:
"""
Get a single message from the AMQP broker.
Returns a sequence with the method frame, message properties, and body.
:param queue: Name of queue from which to get a message
:param auto_ack: Tell the broker to not expect a reply
:returns: a three-tuple; (None, None, None) if the queue was empty; otherwise (method,
properties, body); NOTE: body may be None
"""
assert not self._basic_getempty_result
validators.require_string(queue, 'queue')
with contextlib.ExitStack() as stack:
get_ok_result = stack.enter_context(
_CallbackResult(self._RxMessageArgs))
stack.enter_context(self._basic_getempty_result)
self._impl.basic_get(queue=queue,
auto_ack=auto_ack,
callback=get_ok_result.set_value_once)
self._flush_output(get_ok_result.is_ready,
self._basic_getempty_result.is_ready)
if get_ok_result:
evt = get_ok_result.value
return evt.method, evt.properties, evt.body
assert self._basic_getempty_result, (
'wait completed without GetOk and GetEmpty')
return None, None, None
def basic_publish(self,
exchange: str,
routing_key: str,
body: bytes,
properties: pika.spec.BasicProperties | None = None,
mandatory: bool = False) -> None:
"""
Publish to the channel with the given exchange, routing key, and body.
For more information on basic_publish and what the parameters do, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.publish
NOTE: mandatory may be enabled even without delivery
confirmation, but in the absence of delivery confirmation the
synchronous implementation has no way to know how long to wait for
the Basic.Return.
:param exchange: The exchange to publish to
:param routing_key: The routing key to bind on
:param body: The message body; empty string if no body
:param properties: message properties
:param mandatory: The mandatory flag
:raises UnroutableError: raised when a message published in
publisher-acknowledgments mode (see
`BlockingChannel.confirm_delivery`) is returned via `Basic.Return`
followed by `Basic.Ack`.
:raises NackError: raised when a message published in
publisher-acknowledgements mode is Nack'ed by the broker. See
`BlockingChannel.confirm_delivery`.
"""
if self._delivery_confirmation:
# In publisher-acknowledgments mode
with self._message_confirmation_result:
self._impl.basic_publish(exchange=exchange,
routing_key=routing_key,
body=body,
properties=properties,
mandatory=mandatory)
self._flush_output(self._message_confirmation_result.is_ready)
conf_method = (
self._message_confirmation_result.value.method_frame.method)
if isinstance(conf_method, pika.spec.Basic.Nack):
# Broker was unable to process the message due to internal
# error
LOGGER.warning(
"Message was Nack'ed by broker: nack=%r; channel=%s; "
"exchange=%s; routing_key=%s; mandatory=%r; ",
conf_method, self.channel_number, exchange, routing_key,
mandatory)
if self._puback_return is not None:
returned_messages: list[ReturnedMessage] = [
self._puback_return
]
self._puback_return = None
else:
returned_messages = []
raise exceptions.NackError(returned_messages)
assert isinstance(conf_method,
pika.spec.Basic.Ack), (conf_method)
if self._puback_return is not None:
# Unroutable message was returned
messages = [self._puback_return]
self._puback_return = None
raise exceptions.UnroutableError(messages)
else:
# In non-publisher-acknowledgments mode
self._impl.basic_publish(exchange=exchange,
routing_key=routing_key,
body=body,
properties=properties,
mandatory=mandatory)
self._flush_output()
def basic_qos(self,
prefetch_size: int = 0,
prefetch_count: int = 0,
global_qos: bool = False) -> None:
"""
Specify quality of service.
This method requests a specific quality of service. The QoS can be specified for the current
channel or for all channels on the connection. The client can request that messages be sent
in advance so that when the client finishes processing a message, the following message is
already held locally, rather than needing to be sent down the channel. Prefetching gives a
performance improvement.
:param prefetch_size: This field specifies the prefetch window size. The server will send a
message in advance if it is equal to or smaller in size than the available prefetch size
(and also falls into other prefetch limits). May be set to zero, meaning "no specific
limit", although other prefetch limits may still apply. The prefetch-size is ignored if
the no-ack option is set in the consumer.
:param prefetch_count: Specifies a prefetch window in terms of whole messages. This field
may be used in combination with the prefetch-size field; a message will only be sent in
advance if both prefetch windows (and those at the channel and connection level) allow
it. The prefetch-count is ignored if the no-ack option is set in the consumer.
:param global_qos: Should the QoS apply to all channels on the connection.
"""
with _CallbackResult() as qos_ok_result:
self._impl.basic_qos(callback=qos_ok_result.signal_once,
prefetch_size=prefetch_size,
prefetch_count=prefetch_count,
global_qos=global_qos)
self._flush_output(qos_ok_result.is_ready)
def basic_recover(self, requeue: bool = False) -> None:
"""
This method asks the server to redeliver all unacknowledged messages on a specified channel.
Zero or more messages may be redelivered. This method replaces the asynchronous Recover.
:param requeue: If False, the message will be redelivered to the original recipient. If
True, the server will attempt to requeue the message, potentially then delivering it to
an alternative subscriber.
"""
with _CallbackResult() as recover_ok_result:
self._impl.basic_recover(requeue=requeue,
callback=recover_ok_result.signal_once)
self._flush_output(recover_ok_result.is_ready)
def basic_reject(self, delivery_tag: int = 0, requeue: bool = True) -> None:
"""
Reject an incoming message.
This method allows a client to reject a message. It can be used to interrupt and cancel
large incoming messages, or return untreatable messages to their original queue.
:param delivery_tag: The server-assigned delivery tag
:param requeue: If requeue is true, the server will attempt to requeue the message. If
requeue is false or the requeue attempt fails the messages are discarded or dead-
lettered.
"""
self._impl.basic_reject(delivery_tag=delivery_tag, requeue=requeue)
self._flush_output()
def confirm_delivery(self) -> None:
"""
Turn on RabbitMQ-proprietary Confirm mode in the channel.
For more information see:
https://www.rabbitmq.com/confirms.html
"""
if self._delivery_confirmation:
LOGGER.error(
'confirm_delivery: confirmation was already enabled '
'on channel=%s', self.channel_number)
return
with _CallbackResult() as select_ok_result:
self._impl.confirm_delivery(
ack_nack_callback=self._message_confirmation_result.
set_value_once,
callback=select_ok_result.signal_once)
self._flush_output(select_ok_result.is_ready)
self._delivery_confirmation = True
# Unroutable messages returned after this point will be in the context
# of publisher acknowledgments
self._impl.add_on_return_callback(self._on_puback_message_returned)
def exchange_declare(self,
exchange: str,
exchange_type: (ExchangeType |
str) = ExchangeType.direct,
passive: bool = False,
durable: bool = False,
auto_delete: bool = False,
internal: bool = False,
arguments: dict[str, Any] | None = None) -> None:
"""
This method creates an exchange if it does not already exist, and if the exchange exists,
verifies that it is of the correct and expected class.
If passive set, the server will reply with Declare-Ok if the exchange
already exists with the same name, and raise an error if not and if the
exchange does not already exist, the server MUST raise a channel
exception with reply code 404 (not found).
:param exchange: The exchange name consists of a non-empty sequence of
these characters: letters, digits, hyphen, underscore,
period, or colon.
:param exchange_type: The exchange type to use
:param passive: Perform a declare or just check to see if it exists
:param durable: Survive a reboot of RabbitMQ
:param auto_delete: Remove when no more queues are bound to it
:param internal: Can only be published to by other exchanges
:param arguments: Custom key/value pair arguments for the exchange
:returns: Method frame from the Exchange.Declare-ok response
"""
validators.require_string(exchange, 'exchange')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as declare_ok_result:
self._impl.exchange_declare(
exchange=exchange,
exchange_type=exchange_type,
passive=passive,
durable=durable,
auto_delete=auto_delete,
internal=internal,
arguments=arguments,
callback=declare_ok_result.set_value_once)
self._flush_output(declare_ok_result.is_ready)
return declare_ok_result.value.method_frame
def exchange_delete(self,
exchange: str | None = None,
if_unused: bool = False
) -> pika.frame.Method[pika.spec.Exchange.DeleteOk]:
"""
Delete the exchange.
:param exchange: The exchange name
:param if_unused: only delete if the exchange is unused
:returns: Method frame from the Exchange.Delete-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as delete_ok_result:
self._impl.exchange_delete(exchange=exchange,
if_unused=if_unused,
callback=delete_ok_result.set_value_once)
self._flush_output(delete_ok_result.is_ready)
return delete_ok_result.value.method_frame
def exchange_bind(
self,
destination: str,
source: str,
routing_key: str = '',
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Exchange.BindOk]:
"""
Bind an exchange to another exchange.
:param destination: The destination exchange to bind
:param source: The source exchange to bind to
:param routing_key: The routing key to bind on
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Exchange.Bind-ok response
"""
validators.require_string(destination, 'destination')
validators.require_string(source, 'source')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as bind_ok_result:
self._impl.exchange_bind(destination=destination,
source=source,
routing_key=routing_key,
arguments=arguments,
callback=bind_ok_result.set_value_once)
self._flush_output(bind_ok_result.is_ready)
return bind_ok_result.value.method_frame
def exchange_unbind(
self,
destination: str | None = None,
source: str | None = None,
routing_key: str = '',
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Exchange.UnbindOk]:
"""
Unbind an exchange from another exchange.
:param destination: The destination exchange to unbind
:param source: The source exchange to unbind from
:param routing_key: The routing key to unbind
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Exchange.Unbind-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as unbind_ok_result:
self._impl.exchange_unbind(destination=destination,
source=source,
routing_key=routing_key,
arguments=arguments,
callback=unbind_ok_result.set_value_once)
self._flush_output(unbind_ok_result.is_ready)
return unbind_ok_result.value.method_frame
def queue_declare(
self,
queue: str,
passive: bool = False,
durable: bool = False,
exclusive: bool = False,
auto_delete: bool = False,
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Queue.DeclareOk]:
"""
Declare queue, create if needed.
This method creates or checks a queue. When creating a new queue the client can specify various
properties that control the durability of the queue and its contents,
and the level of sharing for the queue.
Use an empty string as the queue name for the broker to auto-generate
one. Retrieve this auto-generated queue name from the returned
`spec.Queue.DeclareOk` method frame.
:param queue: The queue name; if empty string, the broker will
create a unique queue name
:param passive: Only check to see if the queue exists and raise
`ChannelClosed` if it doesn't
:param durable: Survive reboots of the broker
:param exclusive: Only allow access by the current connection
:param auto_delete: Delete after consumer cancels or disconnects
:param arguments: Custom key/value arguments for the queue
:returns: Method frame from the Queue.Declare-ok response
"""
validators.require_string(queue, 'queue')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as declare_ok_result:
self._impl.queue_declare(queue=queue,
passive=passive,
durable=durable,
exclusive=exclusive,
auto_delete=auto_delete,
arguments=arguments,
callback=declare_ok_result.set_value_once)
self._flush_output(declare_ok_result.is_ready)
return declare_ok_result.value.method_frame
def queue_delete(self,
queue: str,
if_unused: bool = False,
if_empty: bool = False
) -> pika.frame.Method[pika.spec.Queue.DeleteOk]:
"""
Delete a queue from the broker.
:param queue: The queue to delete
:param if_unused: only delete if it's unused
:param if_empty: only delete if the queue is empty
:returns: Method frame from the Queue.Delete-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as delete_ok_result:
self._impl.queue_delete(queue=queue,
if_unused=if_unused,
if_empty=if_empty,
callback=delete_ok_result.set_value_once)
self._flush_output(delete_ok_result.is_ready)
return delete_ok_result.value.method_frame
def queue_purge(self,
queue: str) -> pika.frame.Method[pika.spec.Queue.PurgeOk]:
"""
Purge all of the messages from the specified queue.
:param queue: The queue to purge
:returns: Method frame from the Queue.Purge-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as purge_ok_result:
self._impl.queue_purge(queue=queue,
callback=purge_ok_result.set_value_once)
self._flush_output(purge_ok_result.is_ready)
return purge_ok_result.value.method_frame
def queue_bind(
self,
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Queue.BindOk]:
"""
Bind the queue to the specified exchange.
:param queue: The queue to bind to the exchange
:param exchange: The source exchange to bind to
:param routing_key: The routing key to bind on
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Queue.Bind-ok response
"""
validators.require_string(queue, 'queue')
validators.require_string(exchange, 'exchange')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as bind_ok_result:
self._impl.queue_bind(queue=queue,
exchange=exchange,
routing_key=routing_key,
arguments=arguments,
callback=bind_ok_result.set_value_once)
self._flush_output(bind_ok_result.is_ready)
return bind_ok_result.value.method_frame
def queue_unbind(
self,
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Queue.UnbindOk]:
"""
Unbind a queue from an exchange.
:param queue: The queue to unbind from the exchange
:param exchange: The source exchange to bind from
:param routing_key: The routing key to unbind
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Queue.Unbind-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as unbind_ok_result:
self._impl.queue_unbind(queue=queue,
exchange=exchange,
routing_key=routing_key,
arguments=arguments,
callback=unbind_ok_result.set_value_once)
self._flush_output(unbind_ok_result.is_ready)
return unbind_ok_result.value.method_frame
def tx_select(self) -> pika.frame.Method[pika.spec.Tx.SelectOk]:
"""
Select standard transaction mode.
This method sets the channel to use standard transactions. The client must use this method
at least once on a channel before using the Commit or Rollback methods.
:returns: Method frame from the Tx.Select-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as select_ok_result:
self._impl.tx_select(select_ok_result.set_value_once)
self._flush_output(select_ok_result.is_ready)
return select_ok_result.value.method_frame
def tx_commit(self) -> pika.frame.Method[pika.spec.Tx.CommitOk]:
"""
Commit a transaction.
:returns: Method frame from the Tx.Commit-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as commit_ok_result:
self._impl.tx_commit(commit_ok_result.set_value_once)
self._flush_output(commit_ok_result.is_ready)
return commit_ok_result.value.method_frame
def tx_rollback(self) -> pika.frame.Method[pika.spec.Tx.RollbackOk]:
"""
Rollback a transaction.
:returns: Method frame from the Tx.Rollback-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as rollback_ok_result:
self._impl.tx_rollback(rollback_ok_result.set_value_once)
self._flush_output(rollback_ok_result.is_ready)
return rollback_ok_result.value.method_frame
property
¶
consumer_tags: list[str]
Property method that returns a list of consumer tags for active consumers.
__init__(
channel_impl: Channel, connection: BlockingConnection
) -> None
Create a new instance of the Channel.
| PARAMETER | DESCRIPTION |
|---|---|
channel_impl
|
Channel implementation object as returned from SelectConnection.channel()
TYPE:
|
connection
|
The connection object
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def __init__(self, channel_impl: pika.channel.Channel,
connection: BlockingConnection) -> None:
"""
Create a new instance of the Channel.
:param channel_impl: Channel implementation object as returned from
SelectConnection.channel()
:param connection: The connection object
"""
self._impl = channel_impl
self._connection = connection
# A mapping of consumer tags to _ConsumerInfo for active consumers
self._consumer_infos: dict[Any, Any] = {}
# Queue consumer generator generator info of type
# _QueueConsumerGeneratorInfo created by BlockingChannel.consume
self._queue_consumer_generator: _QueueConsumerGeneratorInfo | None = None
# Whether RabbitMQ delivery confirmation has been enabled
self._delivery_confirmation = False
# Receives message delivery confirmation report (Basic.ack or
# Basic.nack) from broker when delivery confirmations are enabled
self._message_confirmation_result = _CallbackResult(
self._OnMessageConfirmationReportArgs)
# deque of pending events: _ConsumerDeliveryEvt and
# _ConsumerCancellationEvt objects that will be returned by
# `BlockingChannel.get_event()`
self._pending_events: deque[Any] = deque()
# Holds a ReturnedMessage object representing a message received via
# Basic.Return in publisher-acknowledgments mode.
self._puback_return: ReturnedMessage | None = None
# self._on_channel_closed() saves the reason exception here
self._closing_reason = None # type: None | Exception
# Receives Basic.ConsumeOk reply from server
self._basic_consume_ok_result = _CallbackResult()
# Receives args from Basic.GetEmpty response
# https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.get
self._basic_getempty_result = _CallbackResult(
self._MethodFrameCallbackResultArgs)
self._impl.add_on_cancel_callback(self._on_consumer_cancelled_by_broker)
self._impl.add_callback(self._basic_consume_ok_result.signal_once,
replies=[pika.spec.Basic.ConsumeOk],
one_shot=False)
self._impl.add_on_close_callback(self._on_channel_closed)
self._impl.add_callback(self._basic_getempty_result.set_value_once,
replies=[pika.spec.Basic.GetEmpty],
one_shot=False)
LOGGER.info('Created channel=%s', self.channel_number)
__int__() -> int
Return the channel object as its channel number.
NOTE: inherited from legacy BlockingConnection; might be error-prone;
use channel_number property instead.
Source code in pika/adapters/blocking_connection.py
def __int__(self) -> int:
"""
Return the channel object as its channel number.
NOTE: inherited from legacy BlockingConnection; might be error-prone;
use `channel_number` property instead.
"""
return self.channel_number
add_on_cancel_callback(
callback: Callable[[Method[Cancel]], None],
) -> None
Pass a callback function that will be called when Basic.Cancel is sent by the broker.
The callback function should receive a method frame parameter.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
a callable for handling broker's Basic.Cancel
notification with the call signature: callback(method_frame)
where method_frame is of type
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def add_on_cancel_callback(
self, callback: Callable[[pika.frame.Method[pika.spec.Basic.Cancel]],
None]
) -> None:
"""
Pass a callback function that will be called when Basic.Cancel is sent by the broker.
The callback function should receive a method frame parameter.
:param callback: a callable for handling broker's Basic.Cancel
notification with the call signature: callback(method_frame)
where method_frame is of type `pika.frame.Method` with method of
type `spec.Basic.Cancel`
"""
self._impl.callbacks.add(self.channel_number,
self._CONSUMER_CANCELLED_CB_KEY,
callback,
one_shot=False)
add_on_return_callback(
callback: Callable[
[BlockingChannel, Return, BasicProperties, bytes],
None,
],
) -> None
Pass a callback function that will be called when a published message is rejected and
returned by the server via Basic.Return.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The method to call on callback with the signature callback(channel, method, properties, body), where - channel: pika.Channel - method: pika.spec.Basic.Return - properties: pika.spec.BasicProperties - body: bytes
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def add_on_return_callback(
self, callback: Callable[[
BlockingChannel, pika.spec.Basic.Return, pika.spec.
BasicProperties, bytes
], None]
) -> None:
"""
Pass a callback function that will be called when a published message is rejected and
returned by the server via `Basic.Return`.
:param callback: The method to call on callback with the
signature callback(channel, method, properties, body), where
- channel: pika.Channel
- method: pika.spec.Basic.Return
- properties: pika.spec.BasicProperties
- body: bytes
"""
self._impl.add_on_return_callback(
lambda _channel, method, properties, body: (self._add_pending_event(
_ReturnedMessageEvt(callback, self, method, properties, body))))
basic_ack(
delivery_tag: int = 0, multiple: bool = False
) -> None
Acknowledge one or more messages.
When sent by the client, this method acknowledges one or more messages delivered via the Deliver or Get-Ok methods. When sent by server, this method acknowledges one or more messages published with the Publish method on a channel in confirm mode. The acknowledgement can be for a single message or a set of messages up to and including a specific message.
| PARAMETER | DESCRIPTION |
|---|---|
delivery_tag
|
The server-assigned delivery tag
TYPE:
|
multiple
|
If set to True, the delivery tag is treated as "up to and including", so that multiple messages can be acknowledged with a single method. If set to False, the delivery tag refers to a single message. If the multiple field is 1, and the delivery tag is zero, this indicates acknowledgement of all outstanding messages.
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def basic_ack(self, delivery_tag: int = 0, multiple: bool = False) -> None:
"""
Acknowledge one or more messages.
When sent by the client, this method acknowledges one or more messages delivered via the
Deliver or Get-Ok methods. When sent by server, this method acknowledges one or more
messages published with the Publish method on a channel in confirm mode. The acknowledgement
can be for a single message or a set of messages up to and including a specific message.
:param delivery_tag: The server-assigned delivery tag
:param multiple: If set to True, the delivery tag is treated as "up to and including", so
that multiple messages can be acknowledged with a single method. If set to False, the
delivery tag refers to a single message. If the multiple field is 1, and the delivery
tag is zero, this indicates acknowledgement of all outstanding messages.
"""
self._impl.basic_ack(delivery_tag=delivery_tag, multiple=multiple)
self._flush_output()
basic_cancel(
consumer_tag: str,
) -> Sequence[tuple[Deliver, BasicProperties, bytes]]
This method cancels a consumer.
This does not affect already delivered messages, but it does mean the server will not send any more messages for that consumer. The client may receive an arbitrary number of messages in between sending the cancel method and receiving the cancel-ok reply.
NOTE: When cancelling an auto_ack=False consumer, this implementation automatically Nacks and suppresses any incoming messages that have not yet been dispatched to the consumer's callback. However, when cancelling a auto_ack=True consumer, this method will return any pending messages that arrived before broker confirmed the cancellation.
| PARAMETER | DESCRIPTION |
|---|---|
consumer_tag
|
Identifier for the consumer; the result of passing a consumer_tag that was created on another channel is undefined (bad things will happen)
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Sequence[tuple[Deliver, BasicProperties, bytes]]
|
(NEW IN pika 0.10.0) empty sequence for a auto_ack=False consumer; for a auto_ack=True consumer, returns a (possibly empty) sequence of pending messages that arrived before broker confirmed the cancellation (this is done instead of via consumer's callback in order to prevent reentrancy/recursion. Each message is three-tuple: (method, properties, body) - method: spec.Basic.Deliver - properties: spec.BasicProperties - body: bytes |
Source code in pika/adapters/blocking_connection.py
def basic_cancel(
self, consumer_tag: str
) -> Sequence[tuple[pika.spec.Basic.Deliver, pika.spec.BasicProperties,
bytes]]:
"""
This method cancels a consumer.
This does not affect already delivered messages, but it does mean the server will not send any more
messages for that consumer. The client may receive an arbitrary number
of messages in between sending the cancel method and receiving the
cancel-ok reply.
NOTE: When cancelling an auto_ack=False consumer, this implementation
automatically Nacks and suppresses any incoming messages that have not
yet been dispatched to the consumer's callback. However, when cancelling
a auto_ack=True consumer, this method will return any pending messages
that arrived before broker confirmed the cancellation.
:param consumer_tag: Identifier for the consumer; the result of
passing a consumer_tag that was created on another channel is
undefined (bad things will happen)
:returns: (NEW IN pika 0.10.0) empty sequence for a auto_ack=False
consumer; for a auto_ack=True consumer, returns a (possibly empty)
sequence of pending messages that arrived before broker confirmed
the cancellation (this is done instead of via consumer's callback in
order to prevent reentrancy/recursion. Each message is three-tuple:
(method, properties, body)
- method: spec.Basic.Deliver
- properties: spec.BasicProperties
- body: bytes
"""
try:
consumer_info = self._consumer_infos[consumer_tag]
except KeyError:
LOGGER.warning(
'User is attempting to cancel an unknown consumer=%s; '
'already cancelled by user or broker?', consumer_tag)
return []
try:
# Assertion failure here is most likely due to reentrance
assert consumer_info.active or consumer_info.cancelled_by_broker, (
consumer_info.state)
# Assertion failure here signals disconnect between consumer state
# in BlockingChannel and Channel
assert (consumer_info.cancelled_by_broker or
consumer_tag in self._impl._consumers), consumer_tag
auto_ack = consumer_info.auto_ack
consumer_info.state = _ConsumerInfo.TEARING_DOWN
with _CallbackResult() as cancel_ok_result:
# Nack pending messages for auto_ack=False consumer
if not auto_ack:
pending_messages = self._remove_pending_deliveries(
consumer_tag)
if pending_messages:
# NOTE: we use impl's basic_reject to avoid the
# possibility of redelivery before basic_cancel takes
# control of nacking.
# NOTE: we can't use basic_nack with the multiple option
# to avoid nacking messages already held by our client.
for message in pending_messages:
delivery_tag = message.method.delivery_tag
# The generated spec types delivery_tag as
# optional, but the broker always sets it on a
# delivery.
assert delivery_tag is not None
self._impl.basic_reject(delivery_tag, requeue=True)
# Cancel the consumer; impl takes care of rejecting any
# additional deliveries that arrive for a auto_ack=False
# consumer
self._impl.basic_cancel(consumer_tag=consumer_tag,
callback=cancel_ok_result.signal_once)
# Flush output and wait for Basic.Cancel-ok or
# broker-initiated Basic.Cancel
self._flush_output(
cancel_ok_result.is_ready,
lambda: consumer_tag not in self._impl._consumers)
if auto_ack:
# Return pending messages for auto_ack=True consumer
return [(evt.method, evt.properties, evt.body)
for evt in self._remove_pending_deliveries(consumer_tag)
]
# impl takes care of rejecting any incoming deliveries during
# cancellation
messages = self._remove_pending_deliveries(consumer_tag)
assert not messages, messages
return []
finally:
# NOTE: The entry could be purged if channel or connection closes
if consumer_tag in self._consumer_infos:
del self._consumer_infos[consumer_tag]
# Schedule termination of connection.process_data_events using a
# negative channel number
self.connection._request_channel_dispatch(-self.channel_number)
basic_consume(
queue: str,
on_message_callback: Callable[
[BlockingChannel, Deliver, BasicProperties, bytes],
None,
],
auto_ack: bool = False,
exclusive: bool = False,
consumer_tag: str | None = None,
arguments: dict[str, Any] | None = None,
) -> str
Sends the AMQP command Basic.Consume to the broker and binds messages for the consumer_tag to the consumer callback. If you do not pass in a consumer_tag, one will be automatically generated for you. Returns the consumer tag.
NOTE: the consumer callbacks are dispatched only in the scope of
specially-designated methods: see
BlockingConnection.process_data_events and
BlockingChannel.start_consuming.
For more information about Basic.Consume, see: https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue from which to consume
TYPE:
|
on_message_callback
|
Required function for dispatching messages to user, having the signature: on_message_callback(channel, method, properties, body) - channel: BlockingChannel - method: spec.Basic.Deliver - properties: spec.BasicProperties - body: bytes
TYPE:
|
auto_ack
|
if set to True, automatic acknowledgement mode will be used (see https://www.rabbitmq.com/confirms.html). This corresponds with the 'no_ack' parameter in the basic.consume AMQP 0.9.1 method
TYPE:
|
exclusive
|
Don't allow other consumers on the queue
TYPE:
|
consumer_tag
|
You may specify your own consumer tag; if left empty, a consumer tag will be generated automatically
TYPE:
|
arguments
|
Custom key/value pair arguments for the consumer
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
str
|
consumer tag |
| RAISES | DESCRIPTION |
|---|---|
pika.exceptions.DuplicateConsumerTag
|
if consumer with given consumer_tag is already present. |
Source code in pika/adapters/blocking_connection.py
def basic_consume(self,
queue: str,
on_message_callback: Callable[[
BlockingChannel, pika.spec.Basic.Deliver, pika.spec.
BasicProperties, bytes
], None],
auto_ack: bool = False,
exclusive: bool = False,
consumer_tag: str | None = None,
arguments: dict[str, Any] | None = None) -> str:
"""
Sends the AMQP command Basic.Consume to the broker and binds messages for the consumer_tag
to the consumer callback. If you do not pass in a consumer_tag, one will be automatically
generated for you. Returns the consumer tag.
NOTE: the consumer callbacks are dispatched only in the scope of
specially-designated methods: see
`BlockingConnection.process_data_events` and
`BlockingChannel.start_consuming`.
For more information about Basic.Consume, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume
:param queue: The queue from which to consume
:param on_message_callback: Required function for dispatching messages
to user, having the signature:
on_message_callback(channel, method, properties, body)
- channel: BlockingChannel
- method: spec.Basic.Deliver
- properties: spec.BasicProperties
- body: bytes
:param auto_ack: if set to True, automatic acknowledgement mode will be used
(see https://www.rabbitmq.com/confirms.html). This corresponds
with the 'no_ack' parameter in the basic.consume AMQP 0.9.1
method
:param exclusive: Don't allow other consumers on the queue
:param consumer_tag: You may specify your own consumer tag; if left
empty, a consumer tag will be generated automatically
:param arguments: Custom key/value pair arguments for the consumer
:returns: consumer tag
:raises pika.exceptions.DuplicateConsumerTag: if consumer with given
consumer_tag is already present.
"""
validators.require_string(queue, 'queue')
validators.require_callback(on_message_callback, 'on_message_callback')
return self._basic_consume_impl(queue=queue,
on_message_callback=on_message_callback,
auto_ack=auto_ack,
exclusive=exclusive,
consumer_tag=consumer_tag,
arguments=arguments)
basic_get(
queue: str, auto_ack: bool = False
) -> tuple[
GetOk | None, BasicProperties | None, bytes | None
]
Get a single message from the AMQP broker.
Returns a sequence with the method frame, message properties, and body.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
Name of queue from which to get a message
TYPE:
|
auto_ack
|
Tell the broker to not expect a reply
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
tuple[GetOk | None, BasicProperties | None, bytes | None]
|
a three-tuple; (None, None, None) if the queue was empty; otherwise (method, properties, body); NOTE: body may be None |
Source code in pika/adapters/blocking_connection.py
def basic_get(
self,
queue: str,
auto_ack: bool = False
) -> tuple[pika.spec.Basic.GetOk | None, pika.spec.BasicProperties | None,
bytes | None]:
"""
Get a single message from the AMQP broker.
Returns a sequence with the method frame, message properties, and body.
:param queue: Name of queue from which to get a message
:param auto_ack: Tell the broker to not expect a reply
:returns: a three-tuple; (None, None, None) if the queue was empty; otherwise (method,
properties, body); NOTE: body may be None
"""
assert not self._basic_getempty_result
validators.require_string(queue, 'queue')
with contextlib.ExitStack() as stack:
get_ok_result = stack.enter_context(
_CallbackResult(self._RxMessageArgs))
stack.enter_context(self._basic_getempty_result)
self._impl.basic_get(queue=queue,
auto_ack=auto_ack,
callback=get_ok_result.set_value_once)
self._flush_output(get_ok_result.is_ready,
self._basic_getempty_result.is_ready)
if get_ok_result:
evt = get_ok_result.value
return evt.method, evt.properties, evt.body
assert self._basic_getempty_result, (
'wait completed without GetOk and GetEmpty')
return None, None, None
basic_nack(
delivery_tag: int = 0,
multiple: bool = False,
requeue: bool = True,
) -> None
This method allows a client to reject one or more incoming messages.
It can be used to interrupt and cancel large incoming messages, or return untreatable messages to their original queue.
| PARAMETER | DESCRIPTION |
|---|---|
delivery_tag
|
The server-assigned delivery tag
TYPE:
|
multiple
|
If set to True, the delivery tag is treated as "up to and including", so that multiple messages can be acknowledged with a single method. If set to False, the delivery tag refers to a single message. If the multiple field is 1, and the delivery tag is zero, this indicates acknowledgement of all outstanding messages.
TYPE:
|
requeue
|
If requeue is true, the server will attempt to requeue the message. If requeue is false or the requeue attempt fails the messages are discarded or dead- lettered.
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def basic_nack(self,
delivery_tag: int = 0,
multiple: bool = False,
requeue: bool = True) -> None:
"""
This method allows a client to reject one or more incoming messages.
It can be used to interrupt and cancel large incoming messages, or return untreatable
messages to their original queue.
:param delivery_tag: The server-assigned delivery tag
:param multiple: If set to True, the delivery tag is treated as "up to and including", so
that multiple messages can be acknowledged with a single method. If set to False, the
delivery tag refers to a single message. If the multiple field is 1, and the delivery
tag is zero, this indicates acknowledgement of all outstanding messages.
:param requeue: If requeue is true, the server will attempt to requeue the message. If
requeue is false or the requeue attempt fails the messages are discarded or dead-
lettered.
"""
self._impl.basic_nack(delivery_tag=delivery_tag,
multiple=multiple,
requeue=requeue)
self._flush_output()
basic_publish(
exchange: str,
routing_key: str,
body: bytes,
properties: BasicProperties | None = None,
mandatory: bool = False,
) -> None
Publish to the channel with the given exchange, routing key, and body.
For more information on basic_publish and what the parameters do, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.publish
NOTE: mandatory may be enabled even without delivery confirmation, but in the absence of delivery confirmation the synchronous implementation has no way to know how long to wait for the Basic.Return.
| PARAMETER | DESCRIPTION |
|---|---|
exchange
|
The exchange to publish to
TYPE:
|
routing_key
|
The routing key to bind on
TYPE:
|
body
|
The message body; empty string if no body
TYPE:
|
properties
|
message properties
TYPE:
|
mandatory
|
The mandatory flag
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
UnroutableError
|
raised when a message published in
publisher-acknowledgments mode (see
|
NackError
|
raised when a message published in
publisher-acknowledgements mode is Nack'ed by the broker. See
|
Source code in pika/adapters/blocking_connection.py
def basic_publish(self,
exchange: str,
routing_key: str,
body: bytes,
properties: pika.spec.BasicProperties | None = None,
mandatory: bool = False) -> None:
"""
Publish to the channel with the given exchange, routing key, and body.
For more information on basic_publish and what the parameters do, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.publish
NOTE: mandatory may be enabled even without delivery
confirmation, but in the absence of delivery confirmation the
synchronous implementation has no way to know how long to wait for
the Basic.Return.
:param exchange: The exchange to publish to
:param routing_key: The routing key to bind on
:param body: The message body; empty string if no body
:param properties: message properties
:param mandatory: The mandatory flag
:raises UnroutableError: raised when a message published in
publisher-acknowledgments mode (see
`BlockingChannel.confirm_delivery`) is returned via `Basic.Return`
followed by `Basic.Ack`.
:raises NackError: raised when a message published in
publisher-acknowledgements mode is Nack'ed by the broker. See
`BlockingChannel.confirm_delivery`.
"""
if self._delivery_confirmation:
# In publisher-acknowledgments mode
with self._message_confirmation_result:
self._impl.basic_publish(exchange=exchange,
routing_key=routing_key,
body=body,
properties=properties,
mandatory=mandatory)
self._flush_output(self._message_confirmation_result.is_ready)
conf_method = (
self._message_confirmation_result.value.method_frame.method)
if isinstance(conf_method, pika.spec.Basic.Nack):
# Broker was unable to process the message due to internal
# error
LOGGER.warning(
"Message was Nack'ed by broker: nack=%r; channel=%s; "
"exchange=%s; routing_key=%s; mandatory=%r; ",
conf_method, self.channel_number, exchange, routing_key,
mandatory)
if self._puback_return is not None:
returned_messages: list[ReturnedMessage] = [
self._puback_return
]
self._puback_return = None
else:
returned_messages = []
raise exceptions.NackError(returned_messages)
assert isinstance(conf_method,
pika.spec.Basic.Ack), (conf_method)
if self._puback_return is not None:
# Unroutable message was returned
messages = [self._puback_return]
self._puback_return = None
raise exceptions.UnroutableError(messages)
else:
# In non-publisher-acknowledgments mode
self._impl.basic_publish(exchange=exchange,
routing_key=routing_key,
body=body,
properties=properties,
mandatory=mandatory)
self._flush_output()
basic_qos(
prefetch_size: int = 0,
prefetch_count: int = 0,
global_qos: bool = False,
) -> None
Specify quality of service.
This method requests a specific quality of service. The QoS can be specified for the current channel or for all channels on the connection. The client can request that messages be sent in advance so that when the client finishes processing a message, the following message is already held locally, rather than needing to be sent down the channel. Prefetching gives a performance improvement.
| PARAMETER | DESCRIPTION |
|---|---|
prefetch_size
|
This field specifies the prefetch window size. The server will send a message in advance if it is equal to or smaller in size than the available prefetch size (and also falls into other prefetch limits). May be set to zero, meaning "no specific limit", although other prefetch limits may still apply. The prefetch-size is ignored if the no-ack option is set in the consumer.
TYPE:
|
prefetch_count
|
Specifies a prefetch window in terms of whole messages. This field may be used in combination with the prefetch-size field; a message will only be sent in advance if both prefetch windows (and those at the channel and connection level) allow it. The prefetch-count is ignored if the no-ack option is set in the consumer.
TYPE:
|
global_qos
|
Should the QoS apply to all channels on the connection.
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def basic_qos(self,
prefetch_size: int = 0,
prefetch_count: int = 0,
global_qos: bool = False) -> None:
"""
Specify quality of service.
This method requests a specific quality of service. The QoS can be specified for the current
channel or for all channels on the connection. The client can request that messages be sent
in advance so that when the client finishes processing a message, the following message is
already held locally, rather than needing to be sent down the channel. Prefetching gives a
performance improvement.
:param prefetch_size: This field specifies the prefetch window size. The server will send a
message in advance if it is equal to or smaller in size than the available prefetch size
(and also falls into other prefetch limits). May be set to zero, meaning "no specific
limit", although other prefetch limits may still apply. The prefetch-size is ignored if
the no-ack option is set in the consumer.
:param prefetch_count: Specifies a prefetch window in terms of whole messages. This field
may be used in combination with the prefetch-size field; a message will only be sent in
advance if both prefetch windows (and those at the channel and connection level) allow
it. The prefetch-count is ignored if the no-ack option is set in the consumer.
:param global_qos: Should the QoS apply to all channels on the connection.
"""
with _CallbackResult() as qos_ok_result:
self._impl.basic_qos(callback=qos_ok_result.signal_once,
prefetch_size=prefetch_size,
prefetch_count=prefetch_count,
global_qos=global_qos)
self._flush_output(qos_ok_result.is_ready)
basic_recover(requeue: bool = False) -> None
This method asks the server to redeliver all unacknowledged messages on a specified channel. Zero or more messages may be redelivered. This method replaces the asynchronous Recover.
| PARAMETER | DESCRIPTION |
|---|---|
requeue
|
If False, the message will be redelivered to the original recipient. If True, the server will attempt to requeue the message, potentially then delivering it to an alternative subscriber.
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def basic_recover(self, requeue: bool = False) -> None:
"""
This method asks the server to redeliver all unacknowledged messages on a specified channel.
Zero or more messages may be redelivered. This method replaces the asynchronous Recover.
:param requeue: If False, the message will be redelivered to the original recipient. If
True, the server will attempt to requeue the message, potentially then delivering it to
an alternative subscriber.
"""
with _CallbackResult() as recover_ok_result:
self._impl.basic_recover(requeue=requeue,
callback=recover_ok_result.signal_once)
self._flush_output(recover_ok_result.is_ready)
basic_reject(
delivery_tag: int = 0, requeue: bool = True
) -> None
Reject an incoming message.
This method allows a client to reject a message. It can be used to interrupt and cancel large incoming messages, or return untreatable messages to their original queue.
| PARAMETER | DESCRIPTION |
|---|---|
delivery_tag
|
The server-assigned delivery tag
TYPE:
|
requeue
|
If requeue is true, the server will attempt to requeue the message. If requeue is false or the requeue attempt fails the messages are discarded or dead- lettered.
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def basic_reject(self, delivery_tag: int = 0, requeue: bool = True) -> None:
"""
Reject an incoming message.
This method allows a client to reject a message. It can be used to interrupt and cancel
large incoming messages, or return untreatable messages to their original queue.
:param delivery_tag: The server-assigned delivery tag
:param requeue: If requeue is true, the server will attempt to requeue the message. If
requeue is false or the requeue attempt fails the messages are discarded or dead-
lettered.
"""
self._impl.basic_reject(delivery_tag=delivery_tag, requeue=requeue)
self._flush_output()
cancel() -> int
Cancel the queue consumer created by BlockingChannel.consume, rejecting all pending
ackable messages.
NOTE: If you're looking to cancel a consumer issued with BlockingChannel.basic_consume then you should call BlockingChannel.basic_cancel.
| RETURNS | DESCRIPTION |
|---|---|
int
|
The number of messages requeued by Basic.Nack. NEW in 0.10.0: returns 0 |
Source code in pika/adapters/blocking_connection.py
def cancel(self) -> int:
"""
Cancel the queue consumer created by `BlockingChannel.consume`, rejecting all pending
ackable messages.
NOTE: If you're looking to cancel a consumer issued with
BlockingChannel.basic_consume then you should call
BlockingChannel.basic_cancel.
:returns: The number of messages requeued by Basic.Nack.
NEW in 0.10.0: returns 0
"""
if self._queue_consumer_generator is None:
LOGGER.warning('cancel: queue consumer generator is inactive '
'(already cancelled by client or broker?)')
return 0
try:
_, auto_ack, _ = self._queue_consumer_generator.params
if not auto_ack:
# Reject messages held by queue consumer generator; NOTE: we
# can't use basic_nack with the multiple option to avoid nacking
# messages already held by our client.
pending_events = self._queue_consumer_generator.pending_events
# NOTE `get_waiting_message_count` adjusts for `Basic.Cancel`
# from the server at the end (if any)
for _ in range(self.get_waiting_message_count()):
evt = pending_events.popleft()
self._impl.basic_reject(evt.method.delivery_tag,
requeue=True)
self.basic_cancel(self._queue_consumer_generator.consumer_tag)
finally:
self._queue_consumer_generator = None
# Return 0 for compatibility with legacy implementation; the number of
# nacked messages is not meaningful since only messages consumed with
# auto_ack=False may be nacked, and those arriving after calling
# basic_cancel will be rejected automatically by impl channel, so we'll
# never know how many of those were nacked.
return 0
close(
reply_code: int = 0, reply_text: str = 'Normal shutdown'
) -> None
Will invoke a clean shutdown of the channel with the AMQP Broker.
| PARAMETER | DESCRIPTION |
|---|---|
reply_code
|
The reply code to close the channel with
TYPE:
|
reply_text
|
The reply text to close the channel with
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def close(self,
reply_code: int = 0,
reply_text: str = 'Normal shutdown') -> None:
"""
Will invoke a clean shutdown of the channel with the AMQP Broker.
:param reply_code: The reply code to close the channel with
:param reply_text: The reply text to close the channel with
"""
LOGGER.debug('Channel.close(%s, %s)', reply_code, reply_text)
self._impl._raise_if_not_open()
try:
# Cancel remaining consumers
self._cancel_all_consumers()
# Close the channel
self._impl.close(reply_code=reply_code, reply_text=reply_text)
self._flush_output(lambda: self.is_closed)
finally:
self._cleanup()
confirm_delivery() -> None
Turn on RabbitMQ-proprietary Confirm mode in the channel.
For more information see: https://www.rabbitmq.com/confirms.html
Source code in pika/adapters/blocking_connection.py
def confirm_delivery(self) -> None:
"""
Turn on RabbitMQ-proprietary Confirm mode in the channel.
For more information see:
https://www.rabbitmq.com/confirms.html
"""
if self._delivery_confirmation:
LOGGER.error(
'confirm_delivery: confirmation was already enabled '
'on channel=%s', self.channel_number)
return
with _CallbackResult() as select_ok_result:
self._impl.confirm_delivery(
ack_nack_callback=self._message_confirmation_result.
set_value_once,
callback=select_ok_result.signal_once)
self._flush_output(select_ok_result.is_ready)
self._delivery_confirmation = True
# Unroutable messages returned after this point will be in the context
# of publisher acknowledgments
self._impl.add_on_return_callback(self._on_puback_message_returned)
consume(
queue: str,
auto_ack: bool = False,
exclusive: bool = False,
arguments: dict[str, Any] | None = None,
inactivity_timeout: float | None = None,
consumer_tag: str | None = None,
) -> Generator[
tuple[
Deliver | None, BasicProperties | None, bytes | None
]
]
Blocking consumption of a queue instead of via a callback.
This method is a generator that yields each message as a tuple of method,
properties, and body. The active generator iterator terminates when the
consumer is cancelled by client via BlockingChannel.cancel() or by
broker.
Example: :: for method, properties, body in channel.consume('queue'): print(body) channel.basic_ack(method.delivery_tag)
You should call BlockingChannel.cancel() when you escape out of the
generator loop.
If you don't cancel this consumer, then next call on the same channel
to consume() with the exact same (queue, auto_ack, exclusive) parameters
will resume the existing consumer generator; however, calling with
different parameters will result in an exception.
:yields: tuple(spec.Basic.Deliver, spec.BasicProperties, bytes)
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue name to consume
TYPE:
|
auto_ack
|
Tell the broker to not expect a ack/nack response
TYPE:
|
exclusive
|
Don't allow other consumers on the queue
TYPE:
|
arguments
|
Custom key/value pair arguments for the consumer
TYPE:
|
inactivity_timeout
|
if a number is given (in seconds), will cause the method to yield (None, None, None) after the given period of inactivity; this permits for pseudo-regular maintenance activities to be carried out by the user while waiting for messages to arrive. If None is given (default), then the method blocks until the next event arrives. NOTE that timing granularity is limited by the timer resolution of the underlying implementation. NEW in pika 0.10.0.
TYPE:
|
consumer_tag
|
Specify your own consumer tag
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
if consumer-creation parameters don't match those of the existing queue consumer generator, if any. NEW in pika 0.10.0 |
ChannelClosed
|
when this channel is closed by broker. |
Source code in pika/adapters/blocking_connection.py
def consume(
self,
queue: str,
auto_ack: bool = False,
exclusive: bool = False,
arguments: dict[str, Any] | None = None,
inactivity_timeout: float | None = None,
consumer_tag: str | None = None
) -> Generator[tuple[pika.spec.Basic.Deliver | None,
pika.spec.BasicProperties | None, bytes | None]]:
"""
Blocking consumption of a queue instead of via a callback.
This method is a generator that yields each message as a tuple of method,
properties, and body. The active generator iterator terminates when the
consumer is cancelled by client via `BlockingChannel.cancel()` or by
broker.
Example:
::
for method, properties, body in channel.consume('queue'):
print(body)
channel.basic_ack(method.delivery_tag)
You should call `BlockingChannel.cancel()` when you escape out of the
generator loop.
If you don't cancel this consumer, then next call on the same channel
to `consume()` with the exact same (queue, auto_ack, exclusive) parameters
will resume the existing consumer generator; however, calling with
different parameters will result in an exception.
:param queue: The queue name to consume
:param auto_ack: Tell the broker to not expect a ack/nack response
:param exclusive: Don't allow other consumers on the queue
:param arguments: Custom key/value pair arguments for the consumer
:param inactivity_timeout: if a number is given (in
seconds), will cause the method to yield (None, None, None) after the
given period of inactivity; this permits for pseudo-regular maintenance
activities to be carried out by the user while waiting for messages
to arrive. If None is given (default), then the method blocks until
the next event arrives. NOTE that timing granularity is limited by
the timer resolution of the underlying implementation.
NEW in pika 0.10.0.
:param consumer_tag: Specify your own consumer tag
:yields: tuple(spec.Basic.Deliver, spec.BasicProperties, bytes)
:raises ValueError: if consumer-creation parameters don't match those
of the existing queue consumer generator, if any.
NEW in pika 0.10.0
:raises ChannelClosed: when this channel is closed by broker.
"""
self._impl._raise_if_not_open()
params = (queue, auto_ack, exclusive)
if self._queue_consumer_generator is not None:
if params != self._queue_consumer_generator.params:
raise ValueError(
'Consume with different params not allowed on existing '
f'queue consumer generator; previous params: {self._queue_consumer_generator.params!r}; '
f'new params: {(queue, auto_ack, exclusive)!r}')
else:
LOGGER.debug('Creating new queue consumer generator; params: %r',
params)
# Need a consumer tag to register consumer info before sending
# request to broker, because I/O might pick up incoming messages
# in addition to Basic.Consume-ok
if not consumer_tag:
consumer_tag = self._impl._generate_consumer_tag()
self._queue_consumer_generator = _QueueConsumerGeneratorInfo(
params, consumer_tag)
try:
self._basic_consume_impl(
queue=queue,
auto_ack=auto_ack,
exclusive=exclusive,
consumer_tag=consumer_tag,
arguments=arguments,
alternate_event_sink=self._on_consumer_generator_event)
except Exception:
self._queue_consumer_generator = None
raise
LOGGER.info('Created new queue consumer generator %r',
self._queue_consumer_generator)
while self._queue_consumer_generator is not None:
# Process pending events
if self._queue_consumer_generator.pending_events:
evt = self._queue_consumer_generator.pending_events.popleft()
if type(evt) is _ConsumerCancellationEvt:
# Consumer was cancelled by broker
self._queue_consumer_generator = None
break
else:
yield (evt.method, evt.properties, evt.body)
continue
if inactivity_timeout is None:
# Wait indefinitely for a message to arrive, while processing
# I/O events and triggering ChannelClosed exception when the
# channel fails
self._process_data_events(time_limit=None)
continue
# Wait with inactivity timeout
wait_start_time = pika._utils.time_now()
wait_deadline = wait_start_time + inactivity_timeout
delta = inactivity_timeout
while (self._queue_consumer_generator is not None and
not self._queue_consumer_generator.pending_events):
self._process_data_events(time_limit=delta)
if not self._queue_consumer_generator:
# Consumer was cancelled by client
break
if self._queue_consumer_generator.pending_events:
# Got message(s)
break
delta = wait_deadline - pika._utils.time_now()
if delta <= 0.0:
# Signal inactivity timeout
yield (None, None, None)
break
exchange_bind(
destination: str,
source: str,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
) -> Method[BindOk]
Bind an exchange to another exchange.
| PARAMETER | DESCRIPTION |
|---|---|
destination
|
The destination exchange to bind
TYPE:
|
source
|
The source exchange to bind to
TYPE:
|
routing_key
|
The routing key to bind on
TYPE:
|
arguments
|
Custom key/value pair arguments for the binding
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[BindOk]
|
Method frame from the Exchange.Bind-ok response |
Source code in pika/adapters/blocking_connection.py
def exchange_bind(
self,
destination: str,
source: str,
routing_key: str = '',
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Exchange.BindOk]:
"""
Bind an exchange to another exchange.
:param destination: The destination exchange to bind
:param source: The source exchange to bind to
:param routing_key: The routing key to bind on
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Exchange.Bind-ok response
"""
validators.require_string(destination, 'destination')
validators.require_string(source, 'source')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as bind_ok_result:
self._impl.exchange_bind(destination=destination,
source=source,
routing_key=routing_key,
arguments=arguments,
callback=bind_ok_result.set_value_once)
self._flush_output(bind_ok_result.is_ready)
return bind_ok_result.value.method_frame
exchange_declare(
exchange: str,
exchange_type: ExchangeType | str = direct,
passive: bool = False,
durable: bool = False,
auto_delete: bool = False,
internal: bool = False,
arguments: dict[str, Any] | None = None,
) -> None
This method creates an exchange if it does not already exist, and if the exchange exists, verifies that it is of the correct and expected class.
If passive set, the server will reply with Declare-Ok if the exchange already exists with the same name, and raise an error if not and if the exchange does not already exist, the server MUST raise a channel exception with reply code 404 (not found).
| PARAMETER | DESCRIPTION |
|---|---|
exchange
|
The exchange name consists of a non-empty sequence of these characters: letters, digits, hyphen, underscore, period, or colon.
TYPE:
|
exchange_type
|
The exchange type to use
TYPE:
|
passive
|
Perform a declare or just check to see if it exists
TYPE:
|
durable
|
Survive a reboot of RabbitMQ
TYPE:
|
auto_delete
|
Remove when no more queues are bound to it
TYPE:
|
internal
|
Can only be published to by other exchanges
TYPE:
|
arguments
|
Custom key/value pair arguments for the exchange
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
Method frame from the Exchange.Declare-ok response |
Source code in pika/adapters/blocking_connection.py
def exchange_declare(self,
exchange: str,
exchange_type: (ExchangeType |
str) = ExchangeType.direct,
passive: bool = False,
durable: bool = False,
auto_delete: bool = False,
internal: bool = False,
arguments: dict[str, Any] | None = None) -> None:
"""
This method creates an exchange if it does not already exist, and if the exchange exists,
verifies that it is of the correct and expected class.
If passive set, the server will reply with Declare-Ok if the exchange
already exists with the same name, and raise an error if not and if the
exchange does not already exist, the server MUST raise a channel
exception with reply code 404 (not found).
:param exchange: The exchange name consists of a non-empty sequence of
these characters: letters, digits, hyphen, underscore,
period, or colon.
:param exchange_type: The exchange type to use
:param passive: Perform a declare or just check to see if it exists
:param durable: Survive a reboot of RabbitMQ
:param auto_delete: Remove when no more queues are bound to it
:param internal: Can only be published to by other exchanges
:param arguments: Custom key/value pair arguments for the exchange
:returns: Method frame from the Exchange.Declare-ok response
"""
validators.require_string(exchange, 'exchange')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as declare_ok_result:
self._impl.exchange_declare(
exchange=exchange,
exchange_type=exchange_type,
passive=passive,
durable=durable,
auto_delete=auto_delete,
internal=internal,
arguments=arguments,
callback=declare_ok_result.set_value_once)
self._flush_output(declare_ok_result.is_ready)
return declare_ok_result.value.method_frame
exchange_delete(
exchange: str | None = None, if_unused: bool = False
) -> Method[DeleteOk]
Delete the exchange.
| PARAMETER | DESCRIPTION |
|---|---|
exchange
|
The exchange name
TYPE:
|
if_unused
|
only delete if the exchange is unused
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[DeleteOk]
|
Method frame from the Exchange.Delete-ok response |
Source code in pika/adapters/blocking_connection.py
def exchange_delete(self,
exchange: str | None = None,
if_unused: bool = False
) -> pika.frame.Method[pika.spec.Exchange.DeleteOk]:
"""
Delete the exchange.
:param exchange: The exchange name
:param if_unused: only delete if the exchange is unused
:returns: Method frame from the Exchange.Delete-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as delete_ok_result:
self._impl.exchange_delete(exchange=exchange,
if_unused=if_unused,
callback=delete_ok_result.set_value_once)
self._flush_output(delete_ok_result.is_ready)
return delete_ok_result.value.method_frame
exchange_unbind(
destination: str | None = None,
source: str | None = None,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
) -> Method[UnbindOk]
Unbind an exchange from another exchange.
| PARAMETER | DESCRIPTION |
|---|---|
destination
|
The destination exchange to unbind
TYPE:
|
source
|
The source exchange to unbind from
TYPE:
|
routing_key
|
The routing key to unbind
TYPE:
|
arguments
|
Custom key/value pair arguments for the binding
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[UnbindOk]
|
Method frame from the Exchange.Unbind-ok response |
Source code in pika/adapters/blocking_connection.py
def exchange_unbind(
self,
destination: str | None = None,
source: str | None = None,
routing_key: str = '',
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Exchange.UnbindOk]:
"""
Unbind an exchange from another exchange.
:param destination: The destination exchange to unbind
:param source: The source exchange to unbind from
:param routing_key: The routing key to unbind
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Exchange.Unbind-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as unbind_ok_result:
self._impl.exchange_unbind(destination=destination,
source=source,
routing_key=routing_key,
arguments=arguments,
callback=unbind_ok_result.set_value_once)
self._flush_output(unbind_ok_result.is_ready)
return unbind_ok_result.value.method_frame
flow(active: bool) -> bool
Turn Channel flow control off and on.
NOTE: RabbitMQ doesn't support active=False; per https://www.rabbitmq.com/specification.html: "active=false is not supported by the server. Limiting prefetch with basic.qos provides much better control"
For more information, please reference:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#channel.flow
| PARAMETER | DESCRIPTION |
|---|---|
active
|
Turn flow on (True) or off (False)
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
bool
|
True if broker will start or continue sending; False if not |
Source code in pika/adapters/blocking_connection.py
def flow(self, active: bool) -> bool:
"""
Turn Channel flow control off and on.
NOTE: RabbitMQ doesn't support active=False; per
https://www.rabbitmq.com/specification.html: "active=false is not
supported by the server. Limiting prefetch with basic.qos provides much
better control"
For more information, please reference:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#channel.flow
:param active: Turn flow on (True) or off (False)
:returns: True if broker will start or continue sending; False if not
"""
with _CallbackResult(self._FlowOkCallbackResultArgs) as flow_ok_result:
self._impl.flow(active=active,
callback=flow_ok_result.set_value_once)
self._flush_output(flow_ok_result.is_ready)
return flow_ok_result.value.active
get_waiting_message_count() -> int
Returns the number of messages that may be retrieved from the current queue consumer
generator via BlockingChannel.consume without blocking. NEW in pika 0.10.0.
| RETURNS | DESCRIPTION |
|---|---|
int
|
The number of waiting messages |
Source code in pika/adapters/blocking_connection.py
def get_waiting_message_count(self) -> int:
"""
Returns the number of messages that may be retrieved from the current queue consumer
generator via `BlockingChannel.consume` without blocking. NEW in pika 0.10.0.
:returns: The number of waiting messages
"""
if self._queue_consumer_generator is not None:
pending_events = self._queue_consumer_generator.pending_events
count = len(pending_events)
if count and type(pending_events[-1]) is _ConsumerCancellationEvt:
count -= 1
else:
count = 0
return count
queue_bind(
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
) -> Method[BindOk]
Bind the queue to the specified exchange.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue to bind to the exchange
TYPE:
|
exchange
|
The source exchange to bind to
TYPE:
|
routing_key
|
The routing key to bind on
TYPE:
|
arguments
|
Custom key/value pair arguments for the binding
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[BindOk]
|
Method frame from the Queue.Bind-ok response |
Source code in pika/adapters/blocking_connection.py
def queue_bind(
self,
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Queue.BindOk]:
"""
Bind the queue to the specified exchange.
:param queue: The queue to bind to the exchange
:param exchange: The source exchange to bind to
:param routing_key: The routing key to bind on
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Queue.Bind-ok response
"""
validators.require_string(queue, 'queue')
validators.require_string(exchange, 'exchange')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as bind_ok_result:
self._impl.queue_bind(queue=queue,
exchange=exchange,
routing_key=routing_key,
arguments=arguments,
callback=bind_ok_result.set_value_once)
self._flush_output(bind_ok_result.is_ready)
return bind_ok_result.value.method_frame
queue_declare(
queue: str,
passive: bool = False,
durable: bool = False,
exclusive: bool = False,
auto_delete: bool = False,
arguments: dict[str, Any] | None = None,
) -> Method[DeclareOk]
Declare queue, create if needed.
This method creates or checks a queue. When creating a new queue the client can specify various properties that control the durability of the queue and its contents, and the level of sharing for the queue.
Use an empty string as the queue name for the broker to auto-generate
one. Retrieve this auto-generated queue name from the returned
spec.Queue.DeclareOk method frame.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue name; if empty string, the broker will create a unique queue name
TYPE:
|
passive
|
Only check to see if the queue exists and raise
TYPE:
|
durable
|
Survive reboots of the broker
TYPE:
|
exclusive
|
Only allow access by the current connection
TYPE:
|
auto_delete
|
Delete after consumer cancels or disconnects
TYPE:
|
arguments
|
Custom key/value arguments for the queue
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[DeclareOk]
|
Method frame from the Queue.Declare-ok response |
Source code in pika/adapters/blocking_connection.py
def queue_declare(
self,
queue: str,
passive: bool = False,
durable: bool = False,
exclusive: bool = False,
auto_delete: bool = False,
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Queue.DeclareOk]:
"""
Declare queue, create if needed.
This method creates or checks a queue. When creating a new queue the client can specify various
properties that control the durability of the queue and its contents,
and the level of sharing for the queue.
Use an empty string as the queue name for the broker to auto-generate
one. Retrieve this auto-generated queue name from the returned
`spec.Queue.DeclareOk` method frame.
:param queue: The queue name; if empty string, the broker will
create a unique queue name
:param passive: Only check to see if the queue exists and raise
`ChannelClosed` if it doesn't
:param durable: Survive reboots of the broker
:param exclusive: Only allow access by the current connection
:param auto_delete: Delete after consumer cancels or disconnects
:param arguments: Custom key/value arguments for the queue
:returns: Method frame from the Queue.Declare-ok response
"""
validators.require_string(queue, 'queue')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as declare_ok_result:
self._impl.queue_declare(queue=queue,
passive=passive,
durable=durable,
exclusive=exclusive,
auto_delete=auto_delete,
arguments=arguments,
callback=declare_ok_result.set_value_once)
self._flush_output(declare_ok_result.is_ready)
return declare_ok_result.value.method_frame
queue_delete(
queue: str,
if_unused: bool = False,
if_empty: bool = False,
) -> Method[DeleteOk]
Delete a queue from the broker.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue to delete
TYPE:
|
if_unused
|
only delete if it's unused
TYPE:
|
if_empty
|
only delete if the queue is empty
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[DeleteOk]
|
Method frame from the Queue.Delete-ok response |
Source code in pika/adapters/blocking_connection.py
def queue_delete(self,
queue: str,
if_unused: bool = False,
if_empty: bool = False
) -> pika.frame.Method[pika.spec.Queue.DeleteOk]:
"""
Delete a queue from the broker.
:param queue: The queue to delete
:param if_unused: only delete if it's unused
:param if_empty: only delete if the queue is empty
:returns: Method frame from the Queue.Delete-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as delete_ok_result:
self._impl.queue_delete(queue=queue,
if_unused=if_unused,
if_empty=if_empty,
callback=delete_ok_result.set_value_once)
self._flush_output(delete_ok_result.is_ready)
return delete_ok_result.value.method_frame
queue_purge(queue: str) -> Method[PurgeOk]
Purge all of the messages from the specified queue.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue to purge
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[PurgeOk]
|
Method frame from the Queue.Purge-ok response |
Source code in pika/adapters/blocking_connection.py
def queue_purge(self,
queue: str) -> pika.frame.Method[pika.spec.Queue.PurgeOk]:
"""
Purge all of the messages from the specified queue.
:param queue: The queue to purge
:returns: Method frame from the Queue.Purge-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as purge_ok_result:
self._impl.queue_purge(queue=queue,
callback=purge_ok_result.set_value_once)
self._flush_output(purge_ok_result.is_ready)
return purge_ok_result.value.method_frame
queue_unbind(
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
) -> Method[UnbindOk]
Unbind a queue from an exchange.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue to unbind from the exchange
TYPE:
|
exchange
|
The source exchange to bind from
TYPE:
|
routing_key
|
The routing key to unbind
TYPE:
|
arguments
|
Custom key/value pair arguments for the binding
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[UnbindOk]
|
Method frame from the Queue.Unbind-ok response |
Source code in pika/adapters/blocking_connection.py
def queue_unbind(
self,
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Queue.UnbindOk]:
"""
Unbind a queue from an exchange.
:param queue: The queue to unbind from the exchange
:param exchange: The source exchange to bind from
:param routing_key: The routing key to unbind
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Queue.Unbind-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as unbind_ok_result:
self._impl.queue_unbind(queue=queue,
exchange=exchange,
routing_key=routing_key,
arguments=arguments,
callback=unbind_ok_result.set_value_once)
self._flush_output(unbind_ok_result.is_ready)
return unbind_ok_result.value.method_frame
start_consuming() -> None
Processes I/O events and dispatches timers and basic_consume callbacks until all consumers
are cancelled.
NOTE: this blocking function may not be called from the scope of a
pika callback, because dispatching basic_consume callbacks from this
context would constitute recursion.
| RAISES | DESCRIPTION |
|---|---|
pika.exceptions.ReentrancyError
|
if called from the scope of a
|
ChannelClosed
|
when this channel is closed by broker. |
Source code in pika/adapters/blocking_connection.py
def start_consuming(self) -> None:
"""
Processes I/O events and dispatches timers and `basic_consume` callbacks until all consumers
are cancelled.
NOTE: this blocking function may not be called from the scope of a
pika callback, because dispatching `basic_consume` callbacks from this
context would constitute recursion.
:raises pika.exceptions.ReentrancyError: if called from the scope of a
`BlockingConnection` or `BlockingChannel` callback
:raises ChannelClosed: when this channel is closed by broker.
"""
# Check if called from the scope of an event dispatch callback
with self.connection._acquire_event_dispatch() as dispatch_allowed:
if not dispatch_allowed:
raise exceptions.ReentrancyError(
'start_consuming may not be called from the scope of '
'another BlockingConnection or BlockingChannel callback')
self._impl._raise_if_not_open()
# Process events as long as consumers exist on this channel
while self._consumer_infos:
# This will raise ChannelClosed if channel is closed by broker
self._process_data_events(time_limit=None)
stop_consuming(consumer_tag: str | None = None) -> None
Cancels all consumers, signalling the start_consuming loop to exit.
NOTE: pending non-ackable messages will be lost; pending ackable messages will be rejected.
| PARAMETER | DESCRIPTION |
|---|---|
consumer_tag
|
if specified, only the consumer with the given tag will be cancelled
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def stop_consuming(self, consumer_tag: str | None = None) -> None:
"""
Cancels all consumers, signalling the `start_consuming` loop to exit.
NOTE: pending non-ackable messages will be lost; pending ackable
messages will be rejected.
:param consumer_tag: if specified, only the consumer with the given tag will be cancelled
"""
if consumer_tag:
self.basic_cancel(consumer_tag)
else:
self._cancel_all_consumers()
tx_commit() -> Method[CommitOk]
Commit a transaction.
| RETURNS | DESCRIPTION |
|---|---|
Method[CommitOk]
|
Method frame from the Tx.Commit-ok response |
Source code in pika/adapters/blocking_connection.py
def tx_commit(self) -> pika.frame.Method[pika.spec.Tx.CommitOk]:
"""
Commit a transaction.
:returns: Method frame from the Tx.Commit-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as commit_ok_result:
self._impl.tx_commit(commit_ok_result.set_value_once)
self._flush_output(commit_ok_result.is_ready)
return commit_ok_result.value.method_frame
tx_rollback() -> Method[RollbackOk]
Rollback a transaction.
| RETURNS | DESCRIPTION |
|---|---|
Method[RollbackOk]
|
Method frame from the Tx.Rollback-ok response |
Source code in pika/adapters/blocking_connection.py
def tx_rollback(self) -> pika.frame.Method[pika.spec.Tx.RollbackOk]:
"""
Rollback a transaction.
:returns: Method frame from the Tx.Rollback-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as rollback_ok_result:
self._impl.tx_rollback(rollback_ok_result.set_value_once)
self._flush_output(rollback_ok_result.is_ready)
return rollback_ok_result.value.method_frame
tx_select() -> Method[SelectOk]
Select standard transaction mode.
This method sets the channel to use standard transactions. The client must use this method at least once on a channel before using the Commit or Rollback methods.
| RETURNS | DESCRIPTION |
|---|---|
Method[SelectOk]
|
Method frame from the Tx.Select-ok response |
Source code in pika/adapters/blocking_connection.py
def tx_select(self) -> pika.frame.Method[pika.spec.Tx.SelectOk]:
"""
Select standard transaction mode.
This method sets the channel to use standard transactions. The client must use this method
at least once on a channel before using the Commit or Rollback methods.
:returns: Method frame from the Tx.Select-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as select_ok_result:
self._impl.tx_select(select_ok_result.set_value_once)
self._flush_output(select_ok_result.is_ready)
return select_ok_result.value.method_frame
The BlockingConnection creates a layer on top of Pika's asynchronous core
providing methods that will block until their expected response has
returned. Due to the asynchronous nature of the Basic.Deliver and
Basic.Return calls from RabbitMQ to your application, you can still
implement continuation-passing style asynchronous methods if you'd like to
receive messages from RabbitMQ using
:meth:basic_consume <BlockingChannel.basic_consume> or if you want to be
notified of a delivery failure when using
:meth:basic_publish <BlockingChannel.basic_publish>.
For more information about communicating with the blocking_connection
adapter, be sure to check out the
:class:BlockingChannel <BlockingChannel> class which implements the
:class:Channel <pika.channel.Channel> based communication for the
blocking_connection adapter.
To prevent recursion/reentrancy, the blocking connection and channel
implementations queue asynchronously-delivered events received
in nested context (e.g., while waiting for BlockingConnection.channel or
BlockingChannel.queue_declare to complete), dispatching them synchronously
once nesting returns to the desired context. This concerns all callbacks,
such as those registered via BlockingConnection.call_later,
BlockingConnection.add_on_connection_blocked_callback,
BlockingConnection.add_on_connection_unblocked_callback,
BlockingChannel.basic_consume, etc.
Blocked Connection deadlock avoidance: when RabbitMQ becomes low on
resources, it emits Connection.Blocked (AMQP extension) to the client
connection when client makes a resource-consuming request on that connection
or its channel (e.g., Basic.Publish); subsequently, RabbitMQ suspsends
processing requests from that connection until the affected resources are
restored. See https://www.rabbitmq.com/connection-blocked.html. This
may impact BlockingConnection and BlockingChannel operations in a
way that users might not be expecting. For example, if the user dispatches
BlockingChannel.basic_publish in non-publisher-confirmation mode while
RabbitMQ is in this low-resource state followed by a synchronous request
(e.g., BlockingConnection.channel, BlockingChannel.consume,
BlockingChannel.basic_consume, etc.), the synchronous request will block
indefinitely (until Connection.Unblocked) waiting for RabbitMQ to reply. If
the blocked state persists for a long time, the blocking operation will
appear to hang. In this state, BlockingConnection instance and its
channels will not dispatch user callbacks. SOLUTION: To break this potential
deadlock, applications may configure the blocked_connection_timeout
connection parameter when instantiating BlockingConnection. Upon blocked
connection timeout, this adapter will raise ConnectionBlockedTimeout
exception. Seepika.connection.ConnectionParametersdocumentation to
learn more about theblocked_connection_timeout` configuration.
Source code in pika/adapters/blocking_connection.py
class BlockingConnection:
"""The BlockingConnection creates a layer on top of Pika's asynchronous core
providing methods that will block until their expected response has
returned. Due to the asynchronous nature of the `Basic.Deliver` and
`Basic.Return` calls from RabbitMQ to your application, you can still
implement continuation-passing style asynchronous methods if you'd like to
receive messages from RabbitMQ using
:meth:`basic_consume <BlockingChannel.basic_consume>` or if you want to be
notified of a delivery failure when using
:meth:`basic_publish <BlockingChannel.basic_publish>`.
For more information about communicating with the blocking_connection
adapter, be sure to check out the
:class:`BlockingChannel <BlockingChannel>` class which implements the
:class:`Channel <pika.channel.Channel>` based communication for the
blocking_connection adapter.
To prevent recursion/reentrancy, the blocking connection and channel
implementations queue asynchronously-delivered events received
in nested context (e.g., while waiting for `BlockingConnection.channel` or
`BlockingChannel.queue_declare` to complete), dispatching them synchronously
once nesting returns to the desired context. This concerns all callbacks,
such as those registered via `BlockingConnection.call_later`,
`BlockingConnection.add_on_connection_blocked_callback`,
`BlockingConnection.add_on_connection_unblocked_callback`,
`BlockingChannel.basic_consume`, etc.
Blocked Connection deadlock avoidance: when RabbitMQ becomes low on
resources, it emits Connection.Blocked (AMQP extension) to the client
connection when client makes a resource-consuming request on that connection
or its channel (e.g., `Basic.Publish`); subsequently, RabbitMQ suspsends
processing requests from that connection until the affected resources are
restored. See https://www.rabbitmq.com/connection-blocked.html. This
may impact `BlockingConnection` and `BlockingChannel` operations in a
way that users might not be expecting. For example, if the user dispatches
`BlockingChannel.basic_publish` in non-publisher-confirmation mode while
RabbitMQ is in this low-resource state followed by a synchronous request
(e.g., `BlockingConnection.channel`, `BlockingChannel.consume`,
`BlockingChannel.basic_consume`, etc.), the synchronous request will block
indefinitely (until Connection.Unblocked) waiting for RabbitMQ to reply. If
the blocked state persists for a long time, the blocking operation will
appear to hang. In this state, `BlockingConnection` instance and its
channels will not dispatch user callbacks. SOLUTION: To break this potential
deadlock, applications may configure the `blocked_connection_timeout`
connection parameter when instantiating `BlockingConnection`. Upon blocked
connection timeout, this adapter will raise ConnectionBlockedTimeout
exception`. See `pika.connection.ConnectionParameters` documentation to
learn more about the `blocked_connection_timeout` configuration.
"""
class _OnClosedArgs(NamedTuple):
connection: Any
error: Any
class _OnChannelOpenedArgs(NamedTuple):
channel: Any
def __init__(
self,
parameters: pika.connection.Parameters |
Sequence[pika.connection.Parameters] | None = None,
_impl_class: select_connection.SelectConnection | None = None
) -> None:
"""
Create a new instance of the Connection object.
:param parameters:
Connection parameters instance or non-empty sequence of them. If
None, a `pika.connection.Parameters` instance will be created with
default settings. See `pika.AMQPConnectionWorkflow` for more
details about multiple parameter configurations and retries.
Type: `None | pika.connection.Parameters | sequence`.
:param _impl_class: for tests/debugging only; implementation class;
None=default
:raises RuntimeError:
"""
warnings.warn(
'BlockingConnection is deprecated and will be removed in Pika 2.0. '
'Use Connection instead, which runs its own IOLoop on a '
'background thread and provides a thread-safe blocking API that '
'does not stall heartbeats on slow message processing. See '
'https://pika.github.io/pika/latest/modules/adapters/thread_safe/',
DeprecationWarning,
stacklevel=2,
)
# Used for mutual exclusion to avoid race condition between
# BlockingConnection._cleanup() and another thread calling
# BlockingConnection.add_callback_threadsafe() against a closed
# ioloop.
self._cleanup_mutex = threading.Lock()
# Used by the _acquire_event_dispatch decorator; when already greater
# than 0, event dispatch is already acquired higher up the call stack
self._event_dispatch_suspend_depth = 0
# Connection-specific events that are ready for dispatch: _TimerEvt,
# _ConnectionBlockedEvt, _ConnectionUnblockedEvt
self._ready_events: deque[Any] = deque()
# Channel numbers of channels that are requesting a call to their
# BlockingChannel._dispatch_events method; See
# `_request_channel_dispatch`
self._channels_pending_dispatch: set[int] = set()
# Receives on_close_callback args from Connection
self._closed_result = _CallbackResult(self._OnClosedArgs)
# Store exceptions for server-initiated channel closures
self._server_channel_closures: deque[Exception] = deque()
# Declared without a value so that the type stays non-optional for the
# public API, all of which runs only after a successful workflow.
# `_create_connection()` may raise before this is ever assigned, so the
# two members that can run on a half-built instance, `_cleanup()` and
# `__repr__()`, read it with `getattr()`.
self._impl: select_connection.SelectConnection
self._impl = self._create_connection(parameters, _impl_class)
self._impl.add_on_close_callback(self._closed_result.set_value_once)
@override
def __repr__(self) -> str:
# `getattr` because `__repr__` runs on a half-built instance whenever
# `__init__` raises: a traceback or debugger rendering the frame's locals
# must not turn the real error into an `AttributeError`.
impl = getattr(self, '_impl', None)
return f'<{self.__class__.__name__} impl={impl!r}>'
def __enter__(self) -> Self:
# Prepare `with` context
return self
def __exit__(self, exc_type: type[BaseException] | None,
value: BaseException | None,
traceback: TracebackType | None) -> None:
# Close connection after `with` context
if self.is_open:
self.close()
def _cleanup(self) -> None:
"""Clean up members that might inhibit garbage collection."""
with self._cleanup_mutex:
# `getattr` rather than a plain attribute test: `__init__` may have
# raised before `_impl` was assigned.
if getattr(self, '_impl', None) is not None:
self._impl.ioloop.close()
self._ready_events.clear()
self._closed_result.reset()
@contextlib.contextmanager
def _acquire_event_dispatch(self) -> Generator[bool, Any, None]:
"""
Context manager that controls access to event dispatcher for preventing reentrancy.
The "as" value is True if the managed code block owns the event dispatcher and False if
caller higher up in the call stack already owns it. Only managed code that gets ownership
(got True) is permitted to dispatch
"""
try:
# __enter__ part
self._event_dispatch_suspend_depth += 1
yield self._event_dispatch_suspend_depth == 1
finally:
# __exit__ part
self._event_dispatch_suspend_depth -= 1
def _create_connection(
self,
configs: pika.connection.Parameters |
Sequence[pika.connection.Parameters] | None = None,
impl_class: select_connection.SelectConnection | None = None
) -> select_connection.SelectConnection:
"""
Run connection workflow, blocking until it completes.
:param configs: Connection
parameters instance or non-empty sequence of them.
Type: `None | pika.connection.Parameters | sequence`.
:param impl_class: for tests/debugging only; implementation class.
:raises Exception: on failure
"""
if configs is None:
configs = (pika.connection.Parameters(),)
if isinstance(configs, pika.connection.Parameters):
configs = (configs,)
if not configs:
raise ValueError('Expected a non-empty sequence of connection '
f'parameters, but got {configs!r}.')
# Connection workflow completion args
# `result` may be an instance of connection on success or exception on
# failure.
on_cw_done_result = _CallbackResult(
namedtuple('BlockingConnection_OnConnectionWorkflowDoneArgs',
'result'))
resolved_impl_class = impl_class or select_connection.SelectConnection
ioloop = select_connection.IOLoop()
ioloop.activate_poller()
try:
resolved_impl_class.create_connection(
configs,
on_done=on_cw_done_result.set_value_once,
custom_ioloop=ioloop)
while not on_cw_done_result.ready:
ioloop.poll()
ioloop.process_timeouts()
if isinstance(on_cw_done_result.value.result, BaseException):
error = on_cw_done_result.value.result
LOGGER.error('Connection workflow failed: %r', error)
raise self._reap_last_connection_workflow_error(error)
LOGGER.info('Connection workflow succeeded: %r',
on_cw_done_result.value.result)
return on_cw_done_result.value.result
except Exception:
LOGGER.exception('Error in _create_connection().')
ioloop.close()
self._cleanup()
raise
@staticmethod
def _reap_last_connection_workflow_error(
error: BaseException) -> BaseException:
"""
Extract exception value from the last connection attempt.
:param error: error passed by the `AMQPConnectionWorkflow` completion callback.
:returns: Exception value from the last connection attempt
"""
if isinstance(error, connection_workflow.AMQPConnectionWorkflowFailed):
# Extract exception value from the last connection attempt
last = error.exceptions[-1]
if isinstance(last,
connection_workflow.AMQPConnectorSocketConnectError):
error = exceptions.AMQPConnectionError(last,
host=last.host,
port=last.port)
elif isinstance(last,
connection_workflow.AMQPConnectorPhaseErrorBase):
error = last.exception
else:
error = last
return error
def _flush_output(self, *waiters: Callable[[], bool]) -> None:
"""
Flush output and process input while waiting for any of the given callbacks to return true.
The wait is aborted upon connection-close. Otherwise, processing continues until the output
is flushed AND at least one of the callbacks returns true. If there are no callbacks, then
processing ends when all output is flushed.
:param waiters: sequence of zero or more callables taking no args and returning true when
it's time to stop processing. Their results are OR'ed together.
:raises Exception: exceptions passed by impl if opening of connection fails or connection
closes.
"""
if self.is_closed:
raise exceptions.ConnectionWrongStateError()
# Conditions for terminating the processing loop:
# connection closed
# OR
# empty outbound buffer and no waiters
# OR
# empty outbound buffer and any waiter is ready
def is_done() -> bool:
return (self._closed_result.ready or
((not self._impl._transport or
self._impl._get_write_buffer_size() == 0) and
(not waiters or any(ready() for ready in waiters))))
# Process I/O until our completion condition is satisfied
while not is_done():
self._impl.ioloop.poll()
self._impl.ioloop.process_timeouts()
if self._closed_result.ready:
try:
if not isinstance(self._closed_result.value.error,
exceptions.ConnectionClosedByClient):
LOGGER.error('Unexpected connection close detected: %r',
self._closed_result.value.error)
raise self._closed_result.value.error
LOGGER.info('User-initiated close: result=%r',
self._closed_result.value)
finally:
self._cleanup()
def _request_channel_dispatch(self, channel_number: int) -> None:
"""Called by BlockingChannel instances to request a call to their
_dispatch_events method or to terminate `process_data_events`;
BlockingConnection will honor these requests from a safe context.
:param channel_number: positive channel number to request a call
to the channel's `_dispatch_events`; a negative channel number to
request termination of `process_data_events`
"""
self._channels_pending_dispatch.add(channel_number)
def _dispatch_channel_events(self) -> None:
"""Invoke the `_dispatch_events` method on open channels that requested it."""
if not self._channels_pending_dispatch:
return
with self._acquire_event_dispatch() as dispatch_acquired:
if not dispatch_acquired:
# Nested dispatch or dispatch blocked higher in call stack
return
candidates = list(self._channels_pending_dispatch)
self._channels_pending_dispatch.clear()
for channel_number in candidates:
if channel_number < 0:
# This was meant to terminate process_data_events
continue
try:
impl_channel = self._impl._channels[channel_number]
except KeyError:
continue
if impl_channel.is_open:
impl_channel._get_cookie()._dispatch_events()
def _on_timer_ready(self, evt: _TimerEvt) -> None:
"""Handle expiry of a timer that was registered via
`_adapter_call_later()`
:param evt:
"""
self._ready_events.append(evt)
def _on_threadsafe_callback(self, user_callback: Callable[[],
None]) -> None:
"""Handle callback that was registered via
`self._impl._adapter_add_callback_threadsafe`.
:param user_callback: callback passed to our
`add_callback_threadsafe` by the application.
"""
# Turn it into a 0-delay timeout to take advantage of our existing logic
# that deals with reentrancy
self.call_later(0, user_callback)
def _on_connection_blocked(
self, user_callback: Callable[
[pika.frame.Method[pika.spec.Connection.Blocked]],
None], _impl: select_connection.SelectConnection,
method_frame: pika.frame.Method[pika.spec.Connection.Blocked]
) -> None:
"""
Handle Connection.Blocked notification from RabbitMQ broker.
:param user_callback: callback passed to `add_on_connection_blocked_callback`
:param _impl:
:param method_frame: method frame having `method` member of type
`pika.spec.Connection.Blocked`
"""
self._ready_events.append(
_ConnectionBlockedEvt(user_callback, method_frame))
def _on_connection_unblocked(
self, user_callback: Callable[
[pika.frame.Method[pika.spec.Connection.Unblocked]],
None], _impl: select_connection.SelectConnection,
method_frame: pika.frame.Method[pika.spec.Connection.Unblocked]
) -> None:
"""
Handle Connection.Unblocked notification from RabbitMQ broker.
:param user_callback: callback passed to `add_on_connection_unblocked_callback`
:param _impl:
:param method_frame: method frame having `method` member of type
`pika.spec.Connection.Blocked`
"""
self._ready_events.append(
_ConnectionUnblockedEvt(user_callback, method_frame))
def _dispatch_connection_events(self) -> None:
"""Dispatch ready connection events."""
if not self._ready_events:
return
with self._acquire_event_dispatch() as dispatch_acquired:
if not dispatch_acquired:
# Nested dispatch or dispatch blocked higher in call stack
return
# Limit dispatch to the number of currently ready events to avoid
# getting stuck in this loop
for _ in range(len(self._ready_events)):
try:
evt = self._ready_events.popleft()
except IndexError:
# Some events (e.g., timers) must have been cancelled
break
evt.dispatch()
def add_on_connection_blocked_callback(
self, callback: Callable[[
pika.connection.Connection, pika.frame.Method[pika.spec.Connection.
Blocked]
], None]
) -> None:
"""RabbitMQ AMQP extension - Add a callback to be notified when the
connection gets blocked (`Connection.Blocked` received from RabbitMQ)
due to the broker running low on resources (memory or disk). In this
state RabbitMQ suspends processing incoming data until the connection
is unblocked, so it's a good idea for publishers receiving this
notification to suspend publishing until the connection becomes
unblocked.
NOTE: due to the blocking nature of BlockingConnection, if it's sending
outbound data while the connection is/becomes blocked, the call may
remain blocked until the connection becomes unblocked, if ever. You
may use `ConnectionParameters.blocked_connection_timeout` to abort a
BlockingConnection method call with an exception when the connection
remains blocked longer than the given timeout value.
See also `Connection.add_on_connection_unblocked_callback()`
See also `ConnectionParameters.blocked_connection_timeout`.
:param callback: Callback to call on `Connection.Blocked`,
having the signature `callback(connection, pika.frame.Method)`,
where connection is the `BlockingConnection` instance and the method
frame's `method` member is of type `pika.spec.Connection.Blocked`
"""
self._impl.add_on_connection_blocked_callback(
functools.partial(
self._on_connection_blocked,
functools.partial(callback,
cast(pika.connection.Connection, self))))
def add_on_connection_unblocked_callback(
self, callback: Callable[[
pika.connection.Connection, pika.frame.Method[pika.spec.Connection.
Unblocked]
], None]
) -> None:
"""RabbitMQ AMQP extension - Add a callback to be notified when the
connection gets unblocked (`Connection.Unblocked` frame is received from
RabbitMQ) letting publishers know it's ok to start publishing again.
:param callback: Callback to call on Connection.Unblocked`,
having the signature `callback(connection, pika.frame.Method)`,
where connection is the `BlockingConnection` instance and the method
frame's `method` member is of type `pika.spec.Connection.Unblocked`
"""
self._impl.add_on_connection_unblocked_callback(
functools.partial(
self._on_connection_unblocked,
functools.partial(callback,
cast(pika.connection.Connection, self))))
def call_later(self, delay: float, callback: Callable[[], None]) -> int:
"""
Create a single-shot timer to fire after delay seconds.
Do not confuse with Tornado's timeout where you pass in the time you want to
have your callback called. Only pass in the seconds until it's to be
called.
NOTE: the timer callbacks are dispatched only in the scope of
specially-designated methods: see
`BlockingConnection.process_data_events()` and
`BlockingChannel.start_consuming()`.
:param delay: The number of seconds to wait to call callback
:param callback: The callback method with the signature
callback()
:returns: Opaque timer id
"""
validators.require_callback(callback)
evt = _TimerEvt(callback=callback)
timer_id = cast(
int,
self._impl._adapter_call_later(
delay, functools.partial(self._on_timer_ready, evt)))
evt.timer_id = timer_id
return timer_id
def add_callback_threadsafe(self, callback: Callable[..., None]) -> None:
"""
Requests a call to the given function as soon as possible in the context of this
connection's thread.
NOTE: This is the only thread-safe method in `BlockingConnection`. All
other manipulations of `BlockingConnection` must be performed from the
connection's thread.
NOTE: the callbacks are dispatched only in the scope of
specially-designated methods: see
`BlockingConnection.process_data_events()` and
`BlockingChannel.start_consuming()`.
For example, a thread may request a call to the
`BlockingChannel.basic_ack` method of a `BlockingConnection` that is
running in a different thread via::
connection.add_callback_threadsafe(
functools.partial(channel.basic_ack, delivery_tag=...))
NOTE: if you know that the requester is running on the same thread as
the connection it is more efficient to use the
`BlockingConnection.call_later()` method with a delay of 0.
:param callback: The callback method; must be callable
:raises pika.exceptions.ConnectionWrongStateError: if connection is
closed
"""
with self._cleanup_mutex:
# NOTE: keep in mind that we may be called from another thread and
# this mutex only synchronizes us with our connection cleanup logic,
# so a simple check for "is_closed" is pretty much all we're allowed
# to do here besides calling the only thread-safe method
# _adapter_add_callback_threadsafe().
if self.is_closed:
raise exceptions.ConnectionWrongStateError(
'BlockingConnection.add_callback_threadsafe() called on '
'closed or closing connection.')
self._impl._adapter_add_callback_threadsafe(
functools.partial(self._on_threadsafe_callback, callback))
def remove_timeout(self, timeout_id: int) -> None:
"""
Remove a timer if it's still in the timeout stack.
:param timeout_id: The opaque timer id to remove
"""
# Remove from the impl's timeout stack
self._impl._adapter_remove_timeout(timeout_id)
# Remove from ready events, if the timer fired already
for i, evt in enumerate(self._ready_events):
if isinstance(evt, _TimerEvt) and evt.timer_id == timeout_id:
index_to_remove = i
break
else:
# Not found
return
del self._ready_events[index_to_remove]
def update_secret(self, new_secret: str, reason: str) -> None:
"""RabbitMQ AMQP extension - This method updates the secret used to authenticate this connection.
It is used when secrets have an expiration date and need to be renewed, like OAuth 2 tokens.
:param new_secret: The new secret
:param reason: The reason for the secret update
:raises pika.exceptions.ConnectionWrongStateError: if connection is
not open.
"""
result = _CallbackResult()
self._impl.update_secret(new_secret, reason, result.signal_once)
self._flush_output(result.is_ready)
def close(self,
reply_code: int = 200,
reply_text: str = 'Normal shutdown') -> None:
"""
Disconnect from RabbitMQ.
If there are any open channels, it will attempt to close them prior to fully disconnecting.
Channels which have active consumers will attempt to send a Basic.Cancel to RabbitMQ to
cleanly stop the delivery of messages prior to closing the channel.
:param reply_code: The code number for the close
:param reply_text: The text reason for the close
:raises pika.exceptions.ConnectionWrongStateError: if called on a closed connection (NEW in
v1.0.0)
"""
if not self.is_open:
msg = f'{self.__class__.__name__}.close({reply_code}, {reply_text!r}) called on closed connection.'
LOGGER.error(msg)
raise exceptions.ConnectionWrongStateError(msg)
LOGGER.info('Closing connection (%s): %s', reply_code, reply_text)
# Close channels that remain opened
for impl_channel in list(self._impl._channels.values()):
channel = impl_channel._get_cookie()
if channel.is_open:
try:
channel.close(reply_code, reply_text)
except exceptions.ChannelClosed as exc:
# Log and suppress broker-closed channel
LOGGER.warning(
'Got ChannelClosed while closing channel '
'from connection.close: %r', exc)
# Close the connection
self._impl.close(reply_code, reply_text)
self._flush_output(self._closed_result.is_ready)
def process_data_events(self, time_limit: float | None = 0) -> None:
"""
Will make sure that data events are processed.
Dispatches timer and channel callbacks if not called from the scope of BlockingConnection or
BlockingChannel callback. Your app can block on this method. If your application maintains a
long-lived publisher connection, this method should be called periodically in order to
respond to heartbeats and other data events. See `examples/long_running_publisher.py` for an
example.
:param time_limit: suggested upper bound on processing time in seconds. The actual blocking
time depends on the granularity of the underlying ioloop. Zero means return as soon as
possible. None means there is no limit on processing time and the function will block
until I/O produces actionable events. Defaults to 0 for backward compatibility. This
parameter is NEW in pika 0.10.0.
"""
with self._acquire_event_dispatch() as dispatch_acquired:
# Check if we can actually process pending events
def common_terminator() -> bool:
return bool(
dispatch_acquired and
(self._channels_pending_dispatch or self._ready_events))
if time_limit is None:
self._flush_output(common_terminator)
else:
with _IoloopTimerContext(time_limit, self._impl) as timer:
self._flush_output(timer.is_ready, common_terminator)
if self._ready_events:
self._dispatch_connection_events()
if self._channels_pending_dispatch:
self._dispatch_channel_events()
if self._server_channel_closures:
exc = self._server_channel_closures.popleft()
LOGGER.debug('Channel closed by broker: %r', exc)
raise exc
def sleep(self, duration: float) -> None:
"""
A safer way to sleep than calling time.sleep() directly that would keep the adapter from
ignoring frames sent from the broker. The connection will "sleep" or block the number of
seconds specified in duration in small intervals.
:param duration: The time to sleep in seconds
"""
assert duration >= 0, duration
deadline = pika._utils.time_now() + duration
time_limit = duration
# Process events at least once
while True:
self.process_data_events(time_limit)
time_limit = deadline - pika._utils.time_now()
if time_limit <= 0:
break
def channel(self, channel_number: int | None = None) -> BlockingChannel:
"""
Create a new channel with the next available channel number or pass in a channel number to
use. Must be non-zero if you would like to specify but it is recommended that you let Pika
manage the channel numbers.
:param channel_number: optional channel number to use
"""
with _CallbackResult(self._OnChannelOpenedArgs) as opened_args:
impl_channel = self._impl.channel(
channel_number=channel_number,
on_open_callback=opened_args.set_value_once)
# Create our proxy channel
channel = BlockingChannel(impl_channel, self)
# Link implementation channel with our proxy channel
impl_channel._set_cookie(channel)
# Drive I/O until Channel.Open-ok
channel._flush_output(opened_args.is_ready)
return channel
#
# Connections state properties
#
@property
def is_closed(self) -> bool:
"""Returns a boolean reporting the current connection state."""
return self._impl.is_closed
@property
def is_open(self) -> bool:
"""Returns a boolean reporting the current connection state."""
return self._impl.is_open
#
# Properties that reflect server capabilities for the current connection
#
@property
def accept_consumer_cancel_ok_supported(self) -> bool:
"""Specifies if the server accepts a client-sent basic.cancel-ok in reply to a broker-sent
basic.cancel on the active connection.
"""
return self._impl.accept_consumer_cancel_ok
@property
def basic_nack_supported(self) -> bool:
"""Specifies if the server supports basic.nack on the active connection."""
return self._impl.basic_nack
@property
def consumer_cancel_notify_supported(self) -> bool:
"""Specifies if the server supports consumer cancel notification on the active
connection.
"""
return self._impl.consumer_cancel_notify
@property
def exchange_exchange_bindings_supported(self) -> bool:
"""Specifies if the active connection supports exchange to exchange bindings."""
return self._impl.exchange_exchange_bindings
@property
def publisher_confirms_supported(self) -> bool:
"""Specifies if the active connection can use publisher confirmations."""
return self._impl.publisher_confirms
# Legacy property names for backward compatibility
basic_nack = basic_nack_supported
consumer_cancel_notify = consumer_cancel_notify_supported
exchange_exchange_bindings = exchange_exchange_bindings_supported
publisher_confirms = publisher_confirms_supported
property
¶
accept_consumer_cancel_ok_supported: bool
Specifies if the server accepts a client-sent basic.cancel-ok in reply to a broker-sent basic.cancel on the active connection.
property
¶
basic_nack_supported: bool
Specifies if the server supports basic.nack on the active connection.
property
¶
consumer_cancel_notify_supported: bool
Specifies if the server supports consumer cancel notification on the active connection.
property
¶
exchange_exchange_bindings_supported: bool
Specifies if the active connection supports exchange to exchange bindings.
property
¶
publisher_confirms_supported: bool
Specifies if the active connection can use publisher confirmations.
__init__(
parameters: Parameters
| Sequence[Parameters]
| None = None,
_impl_class: SelectConnection | None = None,
) -> None
Create a new instance of the Connection object.
| PARAMETER | DESCRIPTION |
|---|---|
parameters
|
Connection parameters instance or non-empty sequence of them. If
None, a
TYPE:
|
_impl_class
|
for tests/debugging only; implementation class; None=default
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
RuntimeError
|
|
Source code in pika/adapters/blocking_connection.py
def __init__(
self,
parameters: pika.connection.Parameters |
Sequence[pika.connection.Parameters] | None = None,
_impl_class: select_connection.SelectConnection | None = None
) -> None:
"""
Create a new instance of the Connection object.
:param parameters:
Connection parameters instance or non-empty sequence of them. If
None, a `pika.connection.Parameters` instance will be created with
default settings. See `pika.AMQPConnectionWorkflow` for more
details about multiple parameter configurations and retries.
Type: `None | pika.connection.Parameters | sequence`.
:param _impl_class: for tests/debugging only; implementation class;
None=default
:raises RuntimeError:
"""
warnings.warn(
'BlockingConnection is deprecated and will be removed in Pika 2.0. '
'Use Connection instead, which runs its own IOLoop on a '
'background thread and provides a thread-safe blocking API that '
'does not stall heartbeats on slow message processing. See '
'https://pika.github.io/pika/latest/modules/adapters/thread_safe/',
DeprecationWarning,
stacklevel=2,
)
# Used for mutual exclusion to avoid race condition between
# BlockingConnection._cleanup() and another thread calling
# BlockingConnection.add_callback_threadsafe() against a closed
# ioloop.
self._cleanup_mutex = threading.Lock()
# Used by the _acquire_event_dispatch decorator; when already greater
# than 0, event dispatch is already acquired higher up the call stack
self._event_dispatch_suspend_depth = 0
# Connection-specific events that are ready for dispatch: _TimerEvt,
# _ConnectionBlockedEvt, _ConnectionUnblockedEvt
self._ready_events: deque[Any] = deque()
# Channel numbers of channels that are requesting a call to their
# BlockingChannel._dispatch_events method; See
# `_request_channel_dispatch`
self._channels_pending_dispatch: set[int] = set()
# Receives on_close_callback args from Connection
self._closed_result = _CallbackResult(self._OnClosedArgs)
# Store exceptions for server-initiated channel closures
self._server_channel_closures: deque[Exception] = deque()
# Declared without a value so that the type stays non-optional for the
# public API, all of which runs only after a successful workflow.
# `_create_connection()` may raise before this is ever assigned, so the
# two members that can run on a half-built instance, `_cleanup()` and
# `__repr__()`, read it with `getattr()`.
self._impl: select_connection.SelectConnection
self._impl = self._create_connection(parameters, _impl_class)
self._impl.add_on_close_callback(self._closed_result.set_value_once)
add_callback_threadsafe(
callback: Callable[..., None],
) -> None
Requests a call to the given function as soon as possible in the context of this connection's thread.
NOTE: This is the only thread-safe method in BlockingConnection. All
other manipulations of BlockingConnection must be performed from the
connection's thread.
NOTE: the callbacks are dispatched only in the scope of
specially-designated methods: see
BlockingConnection.process_data_events() and
BlockingChannel.start_consuming().
For example, a thread may request a call to the
BlockingChannel.basic_ack method of a BlockingConnection that is
running in a different thread via::
connection.add_callback_threadsafe(
functools.partial(channel.basic_ack, delivery_tag=...))
NOTE: if you know that the requester is running on the same thread as
the connection it is more efficient to use the
BlockingConnection.call_later() method with a delay of 0.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback method; must be callable
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
pika.exceptions.ConnectionWrongStateError
|
if connection is closed |
Source code in pika/adapters/blocking_connection.py
def add_callback_threadsafe(self, callback: Callable[..., None]) -> None:
"""
Requests a call to the given function as soon as possible in the context of this
connection's thread.
NOTE: This is the only thread-safe method in `BlockingConnection`. All
other manipulations of `BlockingConnection` must be performed from the
connection's thread.
NOTE: the callbacks are dispatched only in the scope of
specially-designated methods: see
`BlockingConnection.process_data_events()` and
`BlockingChannel.start_consuming()`.
For example, a thread may request a call to the
`BlockingChannel.basic_ack` method of a `BlockingConnection` that is
running in a different thread via::
connection.add_callback_threadsafe(
functools.partial(channel.basic_ack, delivery_tag=...))
NOTE: if you know that the requester is running on the same thread as
the connection it is more efficient to use the
`BlockingConnection.call_later()` method with a delay of 0.
:param callback: The callback method; must be callable
:raises pika.exceptions.ConnectionWrongStateError: if connection is
closed
"""
with self._cleanup_mutex:
# NOTE: keep in mind that we may be called from another thread and
# this mutex only synchronizes us with our connection cleanup logic,
# so a simple check for "is_closed" is pretty much all we're allowed
# to do here besides calling the only thread-safe method
# _adapter_add_callback_threadsafe().
if self.is_closed:
raise exceptions.ConnectionWrongStateError(
'BlockingConnection.add_callback_threadsafe() called on '
'closed or closing connection.')
self._impl._adapter_add_callback_threadsafe(
functools.partial(self._on_threadsafe_callback, callback))
add_on_connection_blocked_callback(
callback: Callable[[Connection, Method[Blocked]], None],
) -> None
RabbitMQ AMQP extension - Add a callback to be notified when the
connection gets blocked (Connection.Blocked received from RabbitMQ)
due to the broker running low on resources (memory or disk). In this
state RabbitMQ suspends processing incoming data until the connection
is unblocked, so it's a good idea for publishers receiving this
notification to suspend publishing until the connection becomes
unblocked.
NOTE: due to the blocking nature of BlockingConnection, if it's sending
outbound data while the connection is/becomes blocked, the call may
remain blocked until the connection becomes unblocked, if ever. You
may use ConnectionParameters.blocked_connection_timeout to abort a
BlockingConnection method call with an exception when the connection
remains blocked longer than the given timeout value.
See also Connection.add_on_connection_unblocked_callback()
See also ConnectionParameters.blocked_connection_timeout.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
Callback to call on
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def add_on_connection_blocked_callback(
self, callback: Callable[[
pika.connection.Connection, pika.frame.Method[pika.spec.Connection.
Blocked]
], None]
) -> None:
"""RabbitMQ AMQP extension - Add a callback to be notified when the
connection gets blocked (`Connection.Blocked` received from RabbitMQ)
due to the broker running low on resources (memory or disk). In this
state RabbitMQ suspends processing incoming data until the connection
is unblocked, so it's a good idea for publishers receiving this
notification to suspend publishing until the connection becomes
unblocked.
NOTE: due to the blocking nature of BlockingConnection, if it's sending
outbound data while the connection is/becomes blocked, the call may
remain blocked until the connection becomes unblocked, if ever. You
may use `ConnectionParameters.blocked_connection_timeout` to abort a
BlockingConnection method call with an exception when the connection
remains blocked longer than the given timeout value.
See also `Connection.add_on_connection_unblocked_callback()`
See also `ConnectionParameters.blocked_connection_timeout`.
:param callback: Callback to call on `Connection.Blocked`,
having the signature `callback(connection, pika.frame.Method)`,
where connection is the `BlockingConnection` instance and the method
frame's `method` member is of type `pika.spec.Connection.Blocked`
"""
self._impl.add_on_connection_blocked_callback(
functools.partial(
self._on_connection_blocked,
functools.partial(callback,
cast(pika.connection.Connection, self))))
add_on_connection_unblocked_callback(
callback: Callable[
[Connection, Method[Unblocked]], None
],
) -> None
RabbitMQ AMQP extension - Add a callback to be notified when the
connection gets unblocked (Connection.Unblocked frame is received from
RabbitMQ) letting publishers know it's ok to start publishing again.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
Callback to call on Connection.Unblocked
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def add_on_connection_unblocked_callback(
self, callback: Callable[[
pika.connection.Connection, pika.frame.Method[pika.spec.Connection.
Unblocked]
], None]
) -> None:
"""RabbitMQ AMQP extension - Add a callback to be notified when the
connection gets unblocked (`Connection.Unblocked` frame is received from
RabbitMQ) letting publishers know it's ok to start publishing again.
:param callback: Callback to call on Connection.Unblocked`,
having the signature `callback(connection, pika.frame.Method)`,
where connection is the `BlockingConnection` instance and the method
frame's `method` member is of type `pika.spec.Connection.Unblocked`
"""
self._impl.add_on_connection_unblocked_callback(
functools.partial(
self._on_connection_unblocked,
functools.partial(callback,
cast(pika.connection.Connection, self))))
call_later(
delay: float, callback: Callable[[], None]
) -> int
Create a single-shot timer to fire after delay seconds.
Do not confuse with Tornado's timeout where you pass in the time you want to have your callback called. Only pass in the seconds until it's to be called.
NOTE: the timer callbacks are dispatched only in the scope of
specially-designated methods: see
BlockingConnection.process_data_events() and
BlockingChannel.start_consuming().
| PARAMETER | DESCRIPTION |
|---|---|
delay
|
The number of seconds to wait to call callback
TYPE:
|
callback
|
The callback method with the signature callback()
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
int
|
Opaque timer id |
Source code in pika/adapters/blocking_connection.py
def call_later(self, delay: float, callback: Callable[[], None]) -> int:
"""
Create a single-shot timer to fire after delay seconds.
Do not confuse with Tornado's timeout where you pass in the time you want to
have your callback called. Only pass in the seconds until it's to be
called.
NOTE: the timer callbacks are dispatched only in the scope of
specially-designated methods: see
`BlockingConnection.process_data_events()` and
`BlockingChannel.start_consuming()`.
:param delay: The number of seconds to wait to call callback
:param callback: The callback method with the signature
callback()
:returns: Opaque timer id
"""
validators.require_callback(callback)
evt = _TimerEvt(callback=callback)
timer_id = cast(
int,
self._impl._adapter_call_later(
delay, functools.partial(self._on_timer_ready, evt)))
evt.timer_id = timer_id
return timer_id
channel(
channel_number: int | None = None,
) -> BlockingChannel
Create a new channel with the next available channel number or pass in a channel number to use. Must be non-zero if you would like to specify but it is recommended that you let Pika manage the channel numbers.
| PARAMETER | DESCRIPTION |
|---|---|
channel_number
|
optional channel number to use
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def channel(self, channel_number: int | None = None) -> BlockingChannel:
"""
Create a new channel with the next available channel number or pass in a channel number to
use. Must be non-zero if you would like to specify but it is recommended that you let Pika
manage the channel numbers.
:param channel_number: optional channel number to use
"""
with _CallbackResult(self._OnChannelOpenedArgs) as opened_args:
impl_channel = self._impl.channel(
channel_number=channel_number,
on_open_callback=opened_args.set_value_once)
# Create our proxy channel
channel = BlockingChannel(impl_channel, self)
# Link implementation channel with our proxy channel
impl_channel._set_cookie(channel)
# Drive I/O until Channel.Open-ok
channel._flush_output(opened_args.is_ready)
return channel
close(
reply_code: int = 200,
reply_text: str = 'Normal shutdown',
) -> None
Disconnect from RabbitMQ.
If there are any open channels, it will attempt to close them prior to fully disconnecting. Channels which have active consumers will attempt to send a Basic.Cancel to RabbitMQ to cleanly stop the delivery of messages prior to closing the channel.
| PARAMETER | DESCRIPTION |
|---|---|
reply_code
|
The code number for the close
TYPE:
|
reply_text
|
The text reason for the close
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
pika.exceptions.ConnectionWrongStateError
|
if called on a closed connection (NEW in v1.0.0) |
Source code in pika/adapters/blocking_connection.py
def close(self,
reply_code: int = 200,
reply_text: str = 'Normal shutdown') -> None:
"""
Disconnect from RabbitMQ.
If there are any open channels, it will attempt to close them prior to fully disconnecting.
Channels which have active consumers will attempt to send a Basic.Cancel to RabbitMQ to
cleanly stop the delivery of messages prior to closing the channel.
:param reply_code: The code number for the close
:param reply_text: The text reason for the close
:raises pika.exceptions.ConnectionWrongStateError: if called on a closed connection (NEW in
v1.0.0)
"""
if not self.is_open:
msg = f'{self.__class__.__name__}.close({reply_code}, {reply_text!r}) called on closed connection.'
LOGGER.error(msg)
raise exceptions.ConnectionWrongStateError(msg)
LOGGER.info('Closing connection (%s): %s', reply_code, reply_text)
# Close channels that remain opened
for impl_channel in list(self._impl._channels.values()):
channel = impl_channel._get_cookie()
if channel.is_open:
try:
channel.close(reply_code, reply_text)
except exceptions.ChannelClosed as exc:
# Log and suppress broker-closed channel
LOGGER.warning(
'Got ChannelClosed while closing channel '
'from connection.close: %r', exc)
# Close the connection
self._impl.close(reply_code, reply_text)
self._flush_output(self._closed_result.is_ready)
process_data_events(time_limit: float | None = 0) -> None
Will make sure that data events are processed.
Dispatches timer and channel callbacks if not called from the scope of BlockingConnection or
BlockingChannel callback. Your app can block on this method. If your application maintains a
long-lived publisher connection, this method should be called periodically in order to
respond to heartbeats and other data events. See examples/long_running_publisher.py for an
example.
| PARAMETER | DESCRIPTION |
|---|---|
time_limit
|
suggested upper bound on processing time in seconds. The actual blocking time depends on the granularity of the underlying ioloop. Zero means return as soon as possible. None means there is no limit on processing time and the function will block until I/O produces actionable events. Defaults to 0 for backward compatibility. This parameter is NEW in pika 0.10.0.
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def process_data_events(self, time_limit: float | None = 0) -> None:
"""
Will make sure that data events are processed.
Dispatches timer and channel callbacks if not called from the scope of BlockingConnection or
BlockingChannel callback. Your app can block on this method. If your application maintains a
long-lived publisher connection, this method should be called periodically in order to
respond to heartbeats and other data events. See `examples/long_running_publisher.py` for an
example.
:param time_limit: suggested upper bound on processing time in seconds. The actual blocking
time depends on the granularity of the underlying ioloop. Zero means return as soon as
possible. None means there is no limit on processing time and the function will block
until I/O produces actionable events. Defaults to 0 for backward compatibility. This
parameter is NEW in pika 0.10.0.
"""
with self._acquire_event_dispatch() as dispatch_acquired:
# Check if we can actually process pending events
def common_terminator() -> bool:
return bool(
dispatch_acquired and
(self._channels_pending_dispatch or self._ready_events))
if time_limit is None:
self._flush_output(common_terminator)
else:
with _IoloopTimerContext(time_limit, self._impl) as timer:
self._flush_output(timer.is_ready, common_terminator)
if self._ready_events:
self._dispatch_connection_events()
if self._channels_pending_dispatch:
self._dispatch_channel_events()
if self._server_channel_closures:
exc = self._server_channel_closures.popleft()
LOGGER.debug('Channel closed by broker: %r', exc)
raise exc
remove_timeout(timeout_id: int) -> None
Remove a timer if it's still in the timeout stack.
| PARAMETER | DESCRIPTION |
|---|---|
timeout_id
|
The opaque timer id to remove
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def remove_timeout(self, timeout_id: int) -> None:
"""
Remove a timer if it's still in the timeout stack.
:param timeout_id: The opaque timer id to remove
"""
# Remove from the impl's timeout stack
self._impl._adapter_remove_timeout(timeout_id)
# Remove from ready events, if the timer fired already
for i, evt in enumerate(self._ready_events):
if isinstance(evt, _TimerEvt) and evt.timer_id == timeout_id:
index_to_remove = i
break
else:
# Not found
return
del self._ready_events[index_to_remove]
sleep(duration: float) -> None
A safer way to sleep than calling time.sleep() directly that would keep the adapter from ignoring frames sent from the broker. The connection will "sleep" or block the number of seconds specified in duration in small intervals.
| PARAMETER | DESCRIPTION |
|---|---|
duration
|
The time to sleep in seconds
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def sleep(self, duration: float) -> None:
"""
A safer way to sleep than calling time.sleep() directly that would keep the adapter from
ignoring frames sent from the broker. The connection will "sleep" or block the number of
seconds specified in duration in small intervals.
:param duration: The time to sleep in seconds
"""
assert duration >= 0, duration
deadline = pika._utils.time_now() + duration
time_limit = duration
# Process events at least once
while True:
self.process_data_events(time_limit)
time_limit = deadline - pika._utils.time_now()
if time_limit <= 0:
break
update_secret(new_secret: str, reason: str) -> None
RabbitMQ AMQP extension - This method updates the secret used to authenticate this connection. It is used when secrets have an expiration date and need to be renewed, like OAuth 2 tokens.
| PARAMETER | DESCRIPTION |
|---|---|
new_secret
|
The new secret
TYPE:
|
reason
|
The reason for the secret update
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
pika.exceptions.ConnectionWrongStateError
|
if connection is not open. |
Source code in pika/adapters/blocking_connection.py
def update_secret(self, new_secret: str, reason: str) -> None:
"""RabbitMQ AMQP extension - This method updates the secret used to authenticate this connection.
It is used when secrets have an expiration date and need to be renewed, like OAuth 2 tokens.
:param new_secret: The new secret
:param reason: The reason for the secret update
:raises pika.exceptions.ConnectionWrongStateError: if connection is
not open.
"""
result = _CallbackResult()
self._impl.update_secret(new_secret, reason, result.signal_once)
self._flush_output(result.is_ready)
Represents a message returned via Basic.Return in publish-acknowledgments mode.
Source code in pika/adapters/blocking_connection.py
class ReturnedMessage:
"""Represents a message returned via Basic.Return in publish-acknowledgments mode."""
__slots__ = ('body', 'method', 'properties')
def __init__(self, method: pika.spec.Basic.Return,
properties: pika.spec.BasicProperties, body: bytes) -> None:
"""
:param method:
:param properties: message properties
:param body: message body; empty string if no body
"""
self.method = method
self.properties = properties
self.body = body
__init__(
method: Return, properties: BasicProperties, body: bytes
) -> None
| PARAMETER | DESCRIPTION |
|---|---|
method
|
TYPE:
|
properties
|
message properties
TYPE:
|
body
|
message body; empty string if no body
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def __init__(self, method: pika.spec.Basic.Return,
properties: pika.spec.BasicProperties, body: bytes) -> None:
"""
:param method:
:param properties: message properties
:param body: message body; empty string if no body
"""
self.method = method
self.properties = properties
self.body = body
Be sure to check out examples in examples.
Interacting with Pika from another thread¶
pika.BlockingConnection abstracts its I/O loop from the application and thus exposes pika.BlockingConnection.add_callback_threadsafe() to allow interacting with Pika from another thread.
Class Reference¶
The BlockingConnection creates a layer on top of Pika's asynchronous core
providing methods that will block until their expected response has
returned. Due to the asynchronous nature of the Basic.Deliver and
Basic.Return calls from RabbitMQ to your application, you can still
implement continuation-passing style asynchronous methods if you'd like to
receive messages from RabbitMQ using
:meth:basic_consume <BlockingChannel.basic_consume> or if you want to be
notified of a delivery failure when using
:meth:basic_publish <BlockingChannel.basic_publish>.
For more information about communicating with the blocking_connection
adapter, be sure to check out the
:class:BlockingChannel <BlockingChannel> class which implements the
:class:Channel <pika.channel.Channel> based communication for the
blocking_connection adapter.
To prevent recursion/reentrancy, the blocking connection and channel
implementations queue asynchronously-delivered events received
in nested context (e.g., while waiting for BlockingConnection.channel or
BlockingChannel.queue_declare to complete), dispatching them synchronously
once nesting returns to the desired context. This concerns all callbacks,
such as those registered via BlockingConnection.call_later,
BlockingConnection.add_on_connection_blocked_callback,
BlockingConnection.add_on_connection_unblocked_callback,
BlockingChannel.basic_consume, etc.
Blocked Connection deadlock avoidance: when RabbitMQ becomes low on
resources, it emits Connection.Blocked (AMQP extension) to the client
connection when client makes a resource-consuming request on that connection
or its channel (e.g., Basic.Publish); subsequently, RabbitMQ suspsends
processing requests from that connection until the affected resources are
restored. See https://www.rabbitmq.com/connection-blocked.html. This
may impact BlockingConnection and BlockingChannel operations in a
way that users might not be expecting. For example, if the user dispatches
BlockingChannel.basic_publish in non-publisher-confirmation mode while
RabbitMQ is in this low-resource state followed by a synchronous request
(e.g., BlockingConnection.channel, BlockingChannel.consume,
BlockingChannel.basic_consume, etc.), the synchronous request will block
indefinitely (until Connection.Unblocked) waiting for RabbitMQ to reply. If
the blocked state persists for a long time, the blocking operation will
appear to hang. In this state, BlockingConnection instance and its
channels will not dispatch user callbacks. SOLUTION: To break this potential
deadlock, applications may configure the blocked_connection_timeout
connection parameter when instantiating BlockingConnection. Upon blocked
connection timeout, this adapter will raise ConnectionBlockedTimeout
exception. Seepika.connection.ConnectionParametersdocumentation to
learn more about theblocked_connection_timeout` configuration.
Source code in pika/adapters/blocking_connection.py
class BlockingConnection:
"""The BlockingConnection creates a layer on top of Pika's asynchronous core
providing methods that will block until their expected response has
returned. Due to the asynchronous nature of the `Basic.Deliver` and
`Basic.Return` calls from RabbitMQ to your application, you can still
implement continuation-passing style asynchronous methods if you'd like to
receive messages from RabbitMQ using
:meth:`basic_consume <BlockingChannel.basic_consume>` or if you want to be
notified of a delivery failure when using
:meth:`basic_publish <BlockingChannel.basic_publish>`.
For more information about communicating with the blocking_connection
adapter, be sure to check out the
:class:`BlockingChannel <BlockingChannel>` class which implements the
:class:`Channel <pika.channel.Channel>` based communication for the
blocking_connection adapter.
To prevent recursion/reentrancy, the blocking connection and channel
implementations queue asynchronously-delivered events received
in nested context (e.g., while waiting for `BlockingConnection.channel` or
`BlockingChannel.queue_declare` to complete), dispatching them synchronously
once nesting returns to the desired context. This concerns all callbacks,
such as those registered via `BlockingConnection.call_later`,
`BlockingConnection.add_on_connection_blocked_callback`,
`BlockingConnection.add_on_connection_unblocked_callback`,
`BlockingChannel.basic_consume`, etc.
Blocked Connection deadlock avoidance: when RabbitMQ becomes low on
resources, it emits Connection.Blocked (AMQP extension) to the client
connection when client makes a resource-consuming request on that connection
or its channel (e.g., `Basic.Publish`); subsequently, RabbitMQ suspsends
processing requests from that connection until the affected resources are
restored. See https://www.rabbitmq.com/connection-blocked.html. This
may impact `BlockingConnection` and `BlockingChannel` operations in a
way that users might not be expecting. For example, if the user dispatches
`BlockingChannel.basic_publish` in non-publisher-confirmation mode while
RabbitMQ is in this low-resource state followed by a synchronous request
(e.g., `BlockingConnection.channel`, `BlockingChannel.consume`,
`BlockingChannel.basic_consume`, etc.), the synchronous request will block
indefinitely (until Connection.Unblocked) waiting for RabbitMQ to reply. If
the blocked state persists for a long time, the blocking operation will
appear to hang. In this state, `BlockingConnection` instance and its
channels will not dispatch user callbacks. SOLUTION: To break this potential
deadlock, applications may configure the `blocked_connection_timeout`
connection parameter when instantiating `BlockingConnection`. Upon blocked
connection timeout, this adapter will raise ConnectionBlockedTimeout
exception`. See `pika.connection.ConnectionParameters` documentation to
learn more about the `blocked_connection_timeout` configuration.
"""
class _OnClosedArgs(NamedTuple):
connection: Any
error: Any
class _OnChannelOpenedArgs(NamedTuple):
channel: Any
def __init__(
self,
parameters: pika.connection.Parameters |
Sequence[pika.connection.Parameters] | None = None,
_impl_class: select_connection.SelectConnection | None = None
) -> None:
"""
Create a new instance of the Connection object.
:param parameters:
Connection parameters instance or non-empty sequence of them. If
None, a `pika.connection.Parameters` instance will be created with
default settings. See `pika.AMQPConnectionWorkflow` for more
details about multiple parameter configurations and retries.
Type: `None | pika.connection.Parameters | sequence`.
:param _impl_class: for tests/debugging only; implementation class;
None=default
:raises RuntimeError:
"""
warnings.warn(
'BlockingConnection is deprecated and will be removed in Pika 2.0. '
'Use Connection instead, which runs its own IOLoop on a '
'background thread and provides a thread-safe blocking API that '
'does not stall heartbeats on slow message processing. See '
'https://pika.github.io/pika/latest/modules/adapters/thread_safe/',
DeprecationWarning,
stacklevel=2,
)
# Used for mutual exclusion to avoid race condition between
# BlockingConnection._cleanup() and another thread calling
# BlockingConnection.add_callback_threadsafe() against a closed
# ioloop.
self._cleanup_mutex = threading.Lock()
# Used by the _acquire_event_dispatch decorator; when already greater
# than 0, event dispatch is already acquired higher up the call stack
self._event_dispatch_suspend_depth = 0
# Connection-specific events that are ready for dispatch: _TimerEvt,
# _ConnectionBlockedEvt, _ConnectionUnblockedEvt
self._ready_events: deque[Any] = deque()
# Channel numbers of channels that are requesting a call to their
# BlockingChannel._dispatch_events method; See
# `_request_channel_dispatch`
self._channels_pending_dispatch: set[int] = set()
# Receives on_close_callback args from Connection
self._closed_result = _CallbackResult(self._OnClosedArgs)
# Store exceptions for server-initiated channel closures
self._server_channel_closures: deque[Exception] = deque()
# Declared without a value so that the type stays non-optional for the
# public API, all of which runs only after a successful workflow.
# `_create_connection()` may raise before this is ever assigned, so the
# two members that can run on a half-built instance, `_cleanup()` and
# `__repr__()`, read it with `getattr()`.
self._impl: select_connection.SelectConnection
self._impl = self._create_connection(parameters, _impl_class)
self._impl.add_on_close_callback(self._closed_result.set_value_once)
@override
def __repr__(self) -> str:
# `getattr` because `__repr__` runs on a half-built instance whenever
# `__init__` raises: a traceback or debugger rendering the frame's locals
# must not turn the real error into an `AttributeError`.
impl = getattr(self, '_impl', None)
return f'<{self.__class__.__name__} impl={impl!r}>'
def __enter__(self) -> Self:
# Prepare `with` context
return self
def __exit__(self, exc_type: type[BaseException] | None,
value: BaseException | None,
traceback: TracebackType | None) -> None:
# Close connection after `with` context
if self.is_open:
self.close()
def _cleanup(self) -> None:
"""Clean up members that might inhibit garbage collection."""
with self._cleanup_mutex:
# `getattr` rather than a plain attribute test: `__init__` may have
# raised before `_impl` was assigned.
if getattr(self, '_impl', None) is not None:
self._impl.ioloop.close()
self._ready_events.clear()
self._closed_result.reset()
@contextlib.contextmanager
def _acquire_event_dispatch(self) -> Generator[bool, Any, None]:
"""
Context manager that controls access to event dispatcher for preventing reentrancy.
The "as" value is True if the managed code block owns the event dispatcher and False if
caller higher up in the call stack already owns it. Only managed code that gets ownership
(got True) is permitted to dispatch
"""
try:
# __enter__ part
self._event_dispatch_suspend_depth += 1
yield self._event_dispatch_suspend_depth == 1
finally:
# __exit__ part
self._event_dispatch_suspend_depth -= 1
def _create_connection(
self,
configs: pika.connection.Parameters |
Sequence[pika.connection.Parameters] | None = None,
impl_class: select_connection.SelectConnection | None = None
) -> select_connection.SelectConnection:
"""
Run connection workflow, blocking until it completes.
:param configs: Connection
parameters instance or non-empty sequence of them.
Type: `None | pika.connection.Parameters | sequence`.
:param impl_class: for tests/debugging only; implementation class.
:raises Exception: on failure
"""
if configs is None:
configs = (pika.connection.Parameters(),)
if isinstance(configs, pika.connection.Parameters):
configs = (configs,)
if not configs:
raise ValueError('Expected a non-empty sequence of connection '
f'parameters, but got {configs!r}.')
# Connection workflow completion args
# `result` may be an instance of connection on success or exception on
# failure.
on_cw_done_result = _CallbackResult(
namedtuple('BlockingConnection_OnConnectionWorkflowDoneArgs',
'result'))
resolved_impl_class = impl_class or select_connection.SelectConnection
ioloop = select_connection.IOLoop()
ioloop.activate_poller()
try:
resolved_impl_class.create_connection(
configs,
on_done=on_cw_done_result.set_value_once,
custom_ioloop=ioloop)
while not on_cw_done_result.ready:
ioloop.poll()
ioloop.process_timeouts()
if isinstance(on_cw_done_result.value.result, BaseException):
error = on_cw_done_result.value.result
LOGGER.error('Connection workflow failed: %r', error)
raise self._reap_last_connection_workflow_error(error)
LOGGER.info('Connection workflow succeeded: %r',
on_cw_done_result.value.result)
return on_cw_done_result.value.result
except Exception:
LOGGER.exception('Error in _create_connection().')
ioloop.close()
self._cleanup()
raise
@staticmethod
def _reap_last_connection_workflow_error(
error: BaseException) -> BaseException:
"""
Extract exception value from the last connection attempt.
:param error: error passed by the `AMQPConnectionWorkflow` completion callback.
:returns: Exception value from the last connection attempt
"""
if isinstance(error, connection_workflow.AMQPConnectionWorkflowFailed):
# Extract exception value from the last connection attempt
last = error.exceptions[-1]
if isinstance(last,
connection_workflow.AMQPConnectorSocketConnectError):
error = exceptions.AMQPConnectionError(last,
host=last.host,
port=last.port)
elif isinstance(last,
connection_workflow.AMQPConnectorPhaseErrorBase):
error = last.exception
else:
error = last
return error
def _flush_output(self, *waiters: Callable[[], bool]) -> None:
"""
Flush output and process input while waiting for any of the given callbacks to return true.
The wait is aborted upon connection-close. Otherwise, processing continues until the output
is flushed AND at least one of the callbacks returns true. If there are no callbacks, then
processing ends when all output is flushed.
:param waiters: sequence of zero or more callables taking no args and returning true when
it's time to stop processing. Their results are OR'ed together.
:raises Exception: exceptions passed by impl if opening of connection fails or connection
closes.
"""
if self.is_closed:
raise exceptions.ConnectionWrongStateError()
# Conditions for terminating the processing loop:
# connection closed
# OR
# empty outbound buffer and no waiters
# OR
# empty outbound buffer and any waiter is ready
def is_done() -> bool:
return (self._closed_result.ready or
((not self._impl._transport or
self._impl._get_write_buffer_size() == 0) and
(not waiters or any(ready() for ready in waiters))))
# Process I/O until our completion condition is satisfied
while not is_done():
self._impl.ioloop.poll()
self._impl.ioloop.process_timeouts()
if self._closed_result.ready:
try:
if not isinstance(self._closed_result.value.error,
exceptions.ConnectionClosedByClient):
LOGGER.error('Unexpected connection close detected: %r',
self._closed_result.value.error)
raise self._closed_result.value.error
LOGGER.info('User-initiated close: result=%r',
self._closed_result.value)
finally:
self._cleanup()
def _request_channel_dispatch(self, channel_number: int) -> None:
"""Called by BlockingChannel instances to request a call to their
_dispatch_events method or to terminate `process_data_events`;
BlockingConnection will honor these requests from a safe context.
:param channel_number: positive channel number to request a call
to the channel's `_dispatch_events`; a negative channel number to
request termination of `process_data_events`
"""
self._channels_pending_dispatch.add(channel_number)
def _dispatch_channel_events(self) -> None:
"""Invoke the `_dispatch_events` method on open channels that requested it."""
if not self._channels_pending_dispatch:
return
with self._acquire_event_dispatch() as dispatch_acquired:
if not dispatch_acquired:
# Nested dispatch or dispatch blocked higher in call stack
return
candidates = list(self._channels_pending_dispatch)
self._channels_pending_dispatch.clear()
for channel_number in candidates:
if channel_number < 0:
# This was meant to terminate process_data_events
continue
try:
impl_channel = self._impl._channels[channel_number]
except KeyError:
continue
if impl_channel.is_open:
impl_channel._get_cookie()._dispatch_events()
def _on_timer_ready(self, evt: _TimerEvt) -> None:
"""Handle expiry of a timer that was registered via
`_adapter_call_later()`
:param evt:
"""
self._ready_events.append(evt)
def _on_threadsafe_callback(self, user_callback: Callable[[],
None]) -> None:
"""Handle callback that was registered via
`self._impl._adapter_add_callback_threadsafe`.
:param user_callback: callback passed to our
`add_callback_threadsafe` by the application.
"""
# Turn it into a 0-delay timeout to take advantage of our existing logic
# that deals with reentrancy
self.call_later(0, user_callback)
def _on_connection_blocked(
self, user_callback: Callable[
[pika.frame.Method[pika.spec.Connection.Blocked]],
None], _impl: select_connection.SelectConnection,
method_frame: pika.frame.Method[pika.spec.Connection.Blocked]
) -> None:
"""
Handle Connection.Blocked notification from RabbitMQ broker.
:param user_callback: callback passed to `add_on_connection_blocked_callback`
:param _impl:
:param method_frame: method frame having `method` member of type
`pika.spec.Connection.Blocked`
"""
self._ready_events.append(
_ConnectionBlockedEvt(user_callback, method_frame))
def _on_connection_unblocked(
self, user_callback: Callable[
[pika.frame.Method[pika.spec.Connection.Unblocked]],
None], _impl: select_connection.SelectConnection,
method_frame: pika.frame.Method[pika.spec.Connection.Unblocked]
) -> None:
"""
Handle Connection.Unblocked notification from RabbitMQ broker.
:param user_callback: callback passed to `add_on_connection_unblocked_callback`
:param _impl:
:param method_frame: method frame having `method` member of type
`pika.spec.Connection.Blocked`
"""
self._ready_events.append(
_ConnectionUnblockedEvt(user_callback, method_frame))
def _dispatch_connection_events(self) -> None:
"""Dispatch ready connection events."""
if not self._ready_events:
return
with self._acquire_event_dispatch() as dispatch_acquired:
if not dispatch_acquired:
# Nested dispatch or dispatch blocked higher in call stack
return
# Limit dispatch to the number of currently ready events to avoid
# getting stuck in this loop
for _ in range(len(self._ready_events)):
try:
evt = self._ready_events.popleft()
except IndexError:
# Some events (e.g., timers) must have been cancelled
break
evt.dispatch()
def add_on_connection_blocked_callback(
self, callback: Callable[[
pika.connection.Connection, pika.frame.Method[pika.spec.Connection.
Blocked]
], None]
) -> None:
"""RabbitMQ AMQP extension - Add a callback to be notified when the
connection gets blocked (`Connection.Blocked` received from RabbitMQ)
due to the broker running low on resources (memory or disk). In this
state RabbitMQ suspends processing incoming data until the connection
is unblocked, so it's a good idea for publishers receiving this
notification to suspend publishing until the connection becomes
unblocked.
NOTE: due to the blocking nature of BlockingConnection, if it's sending
outbound data while the connection is/becomes blocked, the call may
remain blocked until the connection becomes unblocked, if ever. You
may use `ConnectionParameters.blocked_connection_timeout` to abort a
BlockingConnection method call with an exception when the connection
remains blocked longer than the given timeout value.
See also `Connection.add_on_connection_unblocked_callback()`
See also `ConnectionParameters.blocked_connection_timeout`.
:param callback: Callback to call on `Connection.Blocked`,
having the signature `callback(connection, pika.frame.Method)`,
where connection is the `BlockingConnection` instance and the method
frame's `method` member is of type `pika.spec.Connection.Blocked`
"""
self._impl.add_on_connection_blocked_callback(
functools.partial(
self._on_connection_blocked,
functools.partial(callback,
cast(pika.connection.Connection, self))))
def add_on_connection_unblocked_callback(
self, callback: Callable[[
pika.connection.Connection, pika.frame.Method[pika.spec.Connection.
Unblocked]
], None]
) -> None:
"""RabbitMQ AMQP extension - Add a callback to be notified when the
connection gets unblocked (`Connection.Unblocked` frame is received from
RabbitMQ) letting publishers know it's ok to start publishing again.
:param callback: Callback to call on Connection.Unblocked`,
having the signature `callback(connection, pika.frame.Method)`,
where connection is the `BlockingConnection` instance and the method
frame's `method` member is of type `pika.spec.Connection.Unblocked`
"""
self._impl.add_on_connection_unblocked_callback(
functools.partial(
self._on_connection_unblocked,
functools.partial(callback,
cast(pika.connection.Connection, self))))
def call_later(self, delay: float, callback: Callable[[], None]) -> int:
"""
Create a single-shot timer to fire after delay seconds.
Do not confuse with Tornado's timeout where you pass in the time you want to
have your callback called. Only pass in the seconds until it's to be
called.
NOTE: the timer callbacks are dispatched only in the scope of
specially-designated methods: see
`BlockingConnection.process_data_events()` and
`BlockingChannel.start_consuming()`.
:param delay: The number of seconds to wait to call callback
:param callback: The callback method with the signature
callback()
:returns: Opaque timer id
"""
validators.require_callback(callback)
evt = _TimerEvt(callback=callback)
timer_id = cast(
int,
self._impl._adapter_call_later(
delay, functools.partial(self._on_timer_ready, evt)))
evt.timer_id = timer_id
return timer_id
def add_callback_threadsafe(self, callback: Callable[..., None]) -> None:
"""
Requests a call to the given function as soon as possible in the context of this
connection's thread.
NOTE: This is the only thread-safe method in `BlockingConnection`. All
other manipulations of `BlockingConnection` must be performed from the
connection's thread.
NOTE: the callbacks are dispatched only in the scope of
specially-designated methods: see
`BlockingConnection.process_data_events()` and
`BlockingChannel.start_consuming()`.
For example, a thread may request a call to the
`BlockingChannel.basic_ack` method of a `BlockingConnection` that is
running in a different thread via::
connection.add_callback_threadsafe(
functools.partial(channel.basic_ack, delivery_tag=...))
NOTE: if you know that the requester is running on the same thread as
the connection it is more efficient to use the
`BlockingConnection.call_later()` method with a delay of 0.
:param callback: The callback method; must be callable
:raises pika.exceptions.ConnectionWrongStateError: if connection is
closed
"""
with self._cleanup_mutex:
# NOTE: keep in mind that we may be called from another thread and
# this mutex only synchronizes us with our connection cleanup logic,
# so a simple check for "is_closed" is pretty much all we're allowed
# to do here besides calling the only thread-safe method
# _adapter_add_callback_threadsafe().
if self.is_closed:
raise exceptions.ConnectionWrongStateError(
'BlockingConnection.add_callback_threadsafe() called on '
'closed or closing connection.')
self._impl._adapter_add_callback_threadsafe(
functools.partial(self._on_threadsafe_callback, callback))
def remove_timeout(self, timeout_id: int) -> None:
"""
Remove a timer if it's still in the timeout stack.
:param timeout_id: The opaque timer id to remove
"""
# Remove from the impl's timeout stack
self._impl._adapter_remove_timeout(timeout_id)
# Remove from ready events, if the timer fired already
for i, evt in enumerate(self._ready_events):
if isinstance(evt, _TimerEvt) and evt.timer_id == timeout_id:
index_to_remove = i
break
else:
# Not found
return
del self._ready_events[index_to_remove]
def update_secret(self, new_secret: str, reason: str) -> None:
"""RabbitMQ AMQP extension - This method updates the secret used to authenticate this connection.
It is used when secrets have an expiration date and need to be renewed, like OAuth 2 tokens.
:param new_secret: The new secret
:param reason: The reason for the secret update
:raises pika.exceptions.ConnectionWrongStateError: if connection is
not open.
"""
result = _CallbackResult()
self._impl.update_secret(new_secret, reason, result.signal_once)
self._flush_output(result.is_ready)
def close(self,
reply_code: int = 200,
reply_text: str = 'Normal shutdown') -> None:
"""
Disconnect from RabbitMQ.
If there are any open channels, it will attempt to close them prior to fully disconnecting.
Channels which have active consumers will attempt to send a Basic.Cancel to RabbitMQ to
cleanly stop the delivery of messages prior to closing the channel.
:param reply_code: The code number for the close
:param reply_text: The text reason for the close
:raises pika.exceptions.ConnectionWrongStateError: if called on a closed connection (NEW in
v1.0.0)
"""
if not self.is_open:
msg = f'{self.__class__.__name__}.close({reply_code}, {reply_text!r}) called on closed connection.'
LOGGER.error(msg)
raise exceptions.ConnectionWrongStateError(msg)
LOGGER.info('Closing connection (%s): %s', reply_code, reply_text)
# Close channels that remain opened
for impl_channel in list(self._impl._channels.values()):
channel = impl_channel._get_cookie()
if channel.is_open:
try:
channel.close(reply_code, reply_text)
except exceptions.ChannelClosed as exc:
# Log and suppress broker-closed channel
LOGGER.warning(
'Got ChannelClosed while closing channel '
'from connection.close: %r', exc)
# Close the connection
self._impl.close(reply_code, reply_text)
self._flush_output(self._closed_result.is_ready)
def process_data_events(self, time_limit: float | None = 0) -> None:
"""
Will make sure that data events are processed.
Dispatches timer and channel callbacks if not called from the scope of BlockingConnection or
BlockingChannel callback. Your app can block on this method. If your application maintains a
long-lived publisher connection, this method should be called periodically in order to
respond to heartbeats and other data events. See `examples/long_running_publisher.py` for an
example.
:param time_limit: suggested upper bound on processing time in seconds. The actual blocking
time depends on the granularity of the underlying ioloop. Zero means return as soon as
possible. None means there is no limit on processing time and the function will block
until I/O produces actionable events. Defaults to 0 for backward compatibility. This
parameter is NEW in pika 0.10.0.
"""
with self._acquire_event_dispatch() as dispatch_acquired:
# Check if we can actually process pending events
def common_terminator() -> bool:
return bool(
dispatch_acquired and
(self._channels_pending_dispatch or self._ready_events))
if time_limit is None:
self._flush_output(common_terminator)
else:
with _IoloopTimerContext(time_limit, self._impl) as timer:
self._flush_output(timer.is_ready, common_terminator)
if self._ready_events:
self._dispatch_connection_events()
if self._channels_pending_dispatch:
self._dispatch_channel_events()
if self._server_channel_closures:
exc = self._server_channel_closures.popleft()
LOGGER.debug('Channel closed by broker: %r', exc)
raise exc
def sleep(self, duration: float) -> None:
"""
A safer way to sleep than calling time.sleep() directly that would keep the adapter from
ignoring frames sent from the broker. The connection will "sleep" or block the number of
seconds specified in duration in small intervals.
:param duration: The time to sleep in seconds
"""
assert duration >= 0, duration
deadline = pika._utils.time_now() + duration
time_limit = duration
# Process events at least once
while True:
self.process_data_events(time_limit)
time_limit = deadline - pika._utils.time_now()
if time_limit <= 0:
break
def channel(self, channel_number: int | None = None) -> BlockingChannel:
"""
Create a new channel with the next available channel number or pass in a channel number to
use. Must be non-zero if you would like to specify but it is recommended that you let Pika
manage the channel numbers.
:param channel_number: optional channel number to use
"""
with _CallbackResult(self._OnChannelOpenedArgs) as opened_args:
impl_channel = self._impl.channel(
channel_number=channel_number,
on_open_callback=opened_args.set_value_once)
# Create our proxy channel
channel = BlockingChannel(impl_channel, self)
# Link implementation channel with our proxy channel
impl_channel._set_cookie(channel)
# Drive I/O until Channel.Open-ok
channel._flush_output(opened_args.is_ready)
return channel
#
# Connections state properties
#
@property
def is_closed(self) -> bool:
"""Returns a boolean reporting the current connection state."""
return self._impl.is_closed
@property
def is_open(self) -> bool:
"""Returns a boolean reporting the current connection state."""
return self._impl.is_open
#
# Properties that reflect server capabilities for the current connection
#
@property
def accept_consumer_cancel_ok_supported(self) -> bool:
"""Specifies if the server accepts a client-sent basic.cancel-ok in reply to a broker-sent
basic.cancel on the active connection.
"""
return self._impl.accept_consumer_cancel_ok
@property
def basic_nack_supported(self) -> bool:
"""Specifies if the server supports basic.nack on the active connection."""
return self._impl.basic_nack
@property
def consumer_cancel_notify_supported(self) -> bool:
"""Specifies if the server supports consumer cancel notification on the active
connection.
"""
return self._impl.consumer_cancel_notify
@property
def exchange_exchange_bindings_supported(self) -> bool:
"""Specifies if the active connection supports exchange to exchange bindings."""
return self._impl.exchange_exchange_bindings
@property
def publisher_confirms_supported(self) -> bool:
"""Specifies if the active connection can use publisher confirmations."""
return self._impl.publisher_confirms
# Legacy property names for backward compatibility
basic_nack = basic_nack_supported
consumer_cancel_notify = consumer_cancel_notify_supported
exchange_exchange_bindings = exchange_exchange_bindings_supported
publisher_confirms = publisher_confirms_supported
instance-attribute
¶
_impl: SelectConnection = self._create_connection(
parameters, _impl_class
)
property
¶
accept_consumer_cancel_ok_supported: bool
Specifies if the server accepts a client-sent basic.cancel-ok in reply to a broker-sent basic.cancel on the active connection.
property
¶
basic_nack_supported: bool
Specifies if the server supports basic.nack on the active connection.
class-attribute
instance-attribute
¶
consumer_cancel_notify = consumer_cancel_notify_supported
property
¶
consumer_cancel_notify_supported: bool
Specifies if the server supports consumer cancel notification on the active connection.
class-attribute
instance-attribute
¶
exchange_exchange_bindings = (
exchange_exchange_bindings_supported
)
property
¶
exchange_exchange_bindings_supported: bool
Specifies if the active connection supports exchange to exchange bindings.
class-attribute
instance-attribute
¶
publisher_confirms = publisher_confirms_supported
property
¶
publisher_confirms_supported: bool
Specifies if the active connection can use publisher confirmations.
Bases: NamedTuple
Source code in pika/adapters/blocking_connection.py
class _OnChannelOpenedArgs(NamedTuple):
channel: Any
Bases: NamedTuple
Source code in pika/adapters/blocking_connection.py
class _OnClosedArgs(NamedTuple):
connection: Any
error: Any
__enter__() -> Self
Source code in pika/adapters/blocking_connection.py
def __enter__(self) -> Self:
# Prepare `with` context
return self
__exit__(
exc_type: type[BaseException] | None,
value: BaseException | None,
traceback: TracebackType | None,
) -> None
Source code in pika/adapters/blocking_connection.py
def __exit__(self, exc_type: type[BaseException] | None,
value: BaseException | None,
traceback: TracebackType | None) -> None:
# Close connection after `with` context
if self.is_open:
self.close()
__init__(
parameters: Parameters
| Sequence[Parameters]
| None = None,
_impl_class: SelectConnection | None = None,
) -> None
Create a new instance of the Connection object.
| PARAMETER | DESCRIPTION |
|---|---|
parameters
|
Connection parameters instance or non-empty sequence of them. If
None, a
TYPE:
|
_impl_class
|
for tests/debugging only; implementation class; None=default
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
RuntimeError
|
|
Source code in pika/adapters/blocking_connection.py
def __init__(
self,
parameters: pika.connection.Parameters |
Sequence[pika.connection.Parameters] | None = None,
_impl_class: select_connection.SelectConnection | None = None
) -> None:
"""
Create a new instance of the Connection object.
:param parameters:
Connection parameters instance or non-empty sequence of them. If
None, a `pika.connection.Parameters` instance will be created with
default settings. See `pika.AMQPConnectionWorkflow` for more
details about multiple parameter configurations and retries.
Type: `None | pika.connection.Parameters | sequence`.
:param _impl_class: for tests/debugging only; implementation class;
None=default
:raises RuntimeError:
"""
warnings.warn(
'BlockingConnection is deprecated and will be removed in Pika 2.0. '
'Use Connection instead, which runs its own IOLoop on a '
'background thread and provides a thread-safe blocking API that '
'does not stall heartbeats on slow message processing. See '
'https://pika.github.io/pika/latest/modules/adapters/thread_safe/',
DeprecationWarning,
stacklevel=2,
)
# Used for mutual exclusion to avoid race condition between
# BlockingConnection._cleanup() and another thread calling
# BlockingConnection.add_callback_threadsafe() against a closed
# ioloop.
self._cleanup_mutex = threading.Lock()
# Used by the _acquire_event_dispatch decorator; when already greater
# than 0, event dispatch is already acquired higher up the call stack
self._event_dispatch_suspend_depth = 0
# Connection-specific events that are ready for dispatch: _TimerEvt,
# _ConnectionBlockedEvt, _ConnectionUnblockedEvt
self._ready_events: deque[Any] = deque()
# Channel numbers of channels that are requesting a call to their
# BlockingChannel._dispatch_events method; See
# `_request_channel_dispatch`
self._channels_pending_dispatch: set[int] = set()
# Receives on_close_callback args from Connection
self._closed_result = _CallbackResult(self._OnClosedArgs)
# Store exceptions for server-initiated channel closures
self._server_channel_closures: deque[Exception] = deque()
# Declared without a value so that the type stays non-optional for the
# public API, all of which runs only after a successful workflow.
# `_create_connection()` may raise before this is ever assigned, so the
# two members that can run on a half-built instance, `_cleanup()` and
# `__repr__()`, read it with `getattr()`.
self._impl: select_connection.SelectConnection
self._impl = self._create_connection(parameters, _impl_class)
self._impl.add_on_close_callback(self._closed_result.set_value_once)
__repr__() -> str
Source code in pika/adapters/blocking_connection.py
@override
def __repr__(self) -> str:
# `getattr` because `__repr__` runs on a half-built instance whenever
# `__init__` raises: a traceback or debugger rendering the frame's locals
# must not turn the real error into an `AttributeError`.
impl = getattr(self, '_impl', None)
return f'<{self.__class__.__name__} impl={impl!r}>'
_acquire_event_dispatch() -> Generator[bool, Any, None]
Context manager that controls access to event dispatcher for preventing reentrancy.
The "as" value is True if the managed code block owns the event dispatcher and False if caller higher up in the call stack already owns it. Only managed code that gets ownership (got True) is permitted to dispatch
Source code in pika/adapters/blocking_connection.py
@contextlib.contextmanager
def _acquire_event_dispatch(self) -> Generator[bool, Any, None]:
"""
Context manager that controls access to event dispatcher for preventing reentrancy.
The "as" value is True if the managed code block owns the event dispatcher and False if
caller higher up in the call stack already owns it. Only managed code that gets ownership
(got True) is permitted to dispatch
"""
try:
# __enter__ part
self._event_dispatch_suspend_depth += 1
yield self._event_dispatch_suspend_depth == 1
finally:
# __exit__ part
self._event_dispatch_suspend_depth -= 1
_cleanup() -> None
Clean up members that might inhibit garbage collection.
Source code in pika/adapters/blocking_connection.py
def _cleanup(self) -> None:
"""Clean up members that might inhibit garbage collection."""
with self._cleanup_mutex:
# `getattr` rather than a plain attribute test: `__init__` may have
# raised before `_impl` was assigned.
if getattr(self, '_impl', None) is not None:
self._impl.ioloop.close()
self._ready_events.clear()
self._closed_result.reset()
_create_connection(
configs: Parameters
| Sequence[Parameters]
| None = None,
impl_class: SelectConnection | None = None,
) -> SelectConnection
Run connection workflow, blocking until it completes.
| PARAMETER | DESCRIPTION |
|---|---|
configs
|
Connection
parameters instance or non-empty sequence of them.
Type:
TYPE:
|
impl_class
|
for tests/debugging only; implementation class.
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
Exception
|
on failure |
Source code in pika/adapters/blocking_connection.py
def _create_connection(
self,
configs: pika.connection.Parameters |
Sequence[pika.connection.Parameters] | None = None,
impl_class: select_connection.SelectConnection | None = None
) -> select_connection.SelectConnection:
"""
Run connection workflow, blocking until it completes.
:param configs: Connection
parameters instance or non-empty sequence of them.
Type: `None | pika.connection.Parameters | sequence`.
:param impl_class: for tests/debugging only; implementation class.
:raises Exception: on failure
"""
if configs is None:
configs = (pika.connection.Parameters(),)
if isinstance(configs, pika.connection.Parameters):
configs = (configs,)
if not configs:
raise ValueError('Expected a non-empty sequence of connection '
f'parameters, but got {configs!r}.')
# Connection workflow completion args
# `result` may be an instance of connection on success or exception on
# failure.
on_cw_done_result = _CallbackResult(
namedtuple('BlockingConnection_OnConnectionWorkflowDoneArgs',
'result'))
resolved_impl_class = impl_class or select_connection.SelectConnection
ioloop = select_connection.IOLoop()
ioloop.activate_poller()
try:
resolved_impl_class.create_connection(
configs,
on_done=on_cw_done_result.set_value_once,
custom_ioloop=ioloop)
while not on_cw_done_result.ready:
ioloop.poll()
ioloop.process_timeouts()
if isinstance(on_cw_done_result.value.result, BaseException):
error = on_cw_done_result.value.result
LOGGER.error('Connection workflow failed: %r', error)
raise self._reap_last_connection_workflow_error(error)
LOGGER.info('Connection workflow succeeded: %r',
on_cw_done_result.value.result)
return on_cw_done_result.value.result
except Exception:
LOGGER.exception('Error in _create_connection().')
ioloop.close()
self._cleanup()
raise
_dispatch_channel_events() -> None
Invoke the _dispatch_events method on open channels that requested it.
Source code in pika/adapters/blocking_connection.py
def _dispatch_channel_events(self) -> None:
"""Invoke the `_dispatch_events` method on open channels that requested it."""
if not self._channels_pending_dispatch:
return
with self._acquire_event_dispatch() as dispatch_acquired:
if not dispatch_acquired:
# Nested dispatch or dispatch blocked higher in call stack
return
candidates = list(self._channels_pending_dispatch)
self._channels_pending_dispatch.clear()
for channel_number in candidates:
if channel_number < 0:
# This was meant to terminate process_data_events
continue
try:
impl_channel = self._impl._channels[channel_number]
except KeyError:
continue
if impl_channel.is_open:
impl_channel._get_cookie()._dispatch_events()
_dispatch_connection_events() -> None
Dispatch ready connection events.
Source code in pika/adapters/blocking_connection.py
def _dispatch_connection_events(self) -> None:
"""Dispatch ready connection events."""
if not self._ready_events:
return
with self._acquire_event_dispatch() as dispatch_acquired:
if not dispatch_acquired:
# Nested dispatch or dispatch blocked higher in call stack
return
# Limit dispatch to the number of currently ready events to avoid
# getting stuck in this loop
for _ in range(len(self._ready_events)):
try:
evt = self._ready_events.popleft()
except IndexError:
# Some events (e.g., timers) must have been cancelled
break
evt.dispatch()
_flush_output(*waiters: Callable[[], bool]) -> None
Flush output and process input while waiting for any of the given callbacks to return true. The wait is aborted upon connection-close. Otherwise, processing continues until the output is flushed AND at least one of the callbacks returns true. If there are no callbacks, then processing ends when all output is flushed.
| PARAMETER | DESCRIPTION |
|---|---|
waiters
|
sequence of zero or more callables taking no args and returning true when it's time to stop processing. Their results are OR'ed together.
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
Exception
|
exceptions passed by impl if opening of connection fails or connection closes. |
Source code in pika/adapters/blocking_connection.py
def _flush_output(self, *waiters: Callable[[], bool]) -> None:
"""
Flush output and process input while waiting for any of the given callbacks to return true.
The wait is aborted upon connection-close. Otherwise, processing continues until the output
is flushed AND at least one of the callbacks returns true. If there are no callbacks, then
processing ends when all output is flushed.
:param waiters: sequence of zero or more callables taking no args and returning true when
it's time to stop processing. Their results are OR'ed together.
:raises Exception: exceptions passed by impl if opening of connection fails or connection
closes.
"""
if self.is_closed:
raise exceptions.ConnectionWrongStateError()
# Conditions for terminating the processing loop:
# connection closed
# OR
# empty outbound buffer and no waiters
# OR
# empty outbound buffer and any waiter is ready
def is_done() -> bool:
return (self._closed_result.ready or
((not self._impl._transport or
self._impl._get_write_buffer_size() == 0) and
(not waiters or any(ready() for ready in waiters))))
# Process I/O until our completion condition is satisfied
while not is_done():
self._impl.ioloop.poll()
self._impl.ioloop.process_timeouts()
if self._closed_result.ready:
try:
if not isinstance(self._closed_result.value.error,
exceptions.ConnectionClosedByClient):
LOGGER.error('Unexpected connection close detected: %r',
self._closed_result.value.error)
raise self._closed_result.value.error
LOGGER.info('User-initiated close: result=%r',
self._closed_result.value)
finally:
self._cleanup()
_on_connection_blocked(
user_callback: Callable[[Method[Blocked]], None],
_impl: SelectConnection,
method_frame: Method[Blocked],
) -> None
Handle Connection.Blocked notification from RabbitMQ broker.
| PARAMETER | DESCRIPTION |
|---|---|
user_callback
|
callback passed to
TYPE:
|
_impl
|
TYPE:
|
method_frame
|
method frame having
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def _on_connection_blocked(
self, user_callback: Callable[
[pika.frame.Method[pika.spec.Connection.Blocked]],
None], _impl: select_connection.SelectConnection,
method_frame: pika.frame.Method[pika.spec.Connection.Blocked]
) -> None:
"""
Handle Connection.Blocked notification from RabbitMQ broker.
:param user_callback: callback passed to `add_on_connection_blocked_callback`
:param _impl:
:param method_frame: method frame having `method` member of type
`pika.spec.Connection.Blocked`
"""
self._ready_events.append(
_ConnectionBlockedEvt(user_callback, method_frame))
_on_connection_unblocked(
user_callback: Callable[[Method[Unblocked]], None],
_impl: SelectConnection,
method_frame: Method[Unblocked],
) -> None
Handle Connection.Unblocked notification from RabbitMQ broker.
| PARAMETER | DESCRIPTION |
|---|---|
user_callback
|
callback passed to
TYPE:
|
_impl
|
TYPE:
|
method_frame
|
method frame having
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def _on_connection_unblocked(
self, user_callback: Callable[
[pika.frame.Method[pika.spec.Connection.Unblocked]],
None], _impl: select_connection.SelectConnection,
method_frame: pika.frame.Method[pika.spec.Connection.Unblocked]
) -> None:
"""
Handle Connection.Unblocked notification from RabbitMQ broker.
:param user_callback: callback passed to `add_on_connection_unblocked_callback`
:param _impl:
:param method_frame: method frame having `method` member of type
`pika.spec.Connection.Blocked`
"""
self._ready_events.append(
_ConnectionUnblockedEvt(user_callback, method_frame))
_on_threadsafe_callback(
user_callback: Callable[[], None],
) -> None
Handle callback that was registered via
self._impl._adapter_add_callback_threadsafe.
| PARAMETER | DESCRIPTION |
|---|---|
user_callback
|
callback passed to our
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def _on_threadsafe_callback(self, user_callback: Callable[[],
None]) -> None:
"""Handle callback that was registered via
`self._impl._adapter_add_callback_threadsafe`.
:param user_callback: callback passed to our
`add_callback_threadsafe` by the application.
"""
# Turn it into a 0-delay timeout to take advantage of our existing logic
# that deals with reentrancy
self.call_later(0, user_callback)
_on_timer_ready(evt: _TimerEvt) -> None
Handle expiry of a timer that was registered via
_adapter_call_later()
| PARAMETER | DESCRIPTION |
|---|---|
evt
|
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def _on_timer_ready(self, evt: _TimerEvt) -> None:
"""Handle expiry of a timer that was registered via
`_adapter_call_later()`
:param evt:
"""
self._ready_events.append(evt)
staticmethod
¶
_reap_last_connection_workflow_error(
error: BaseException,
) -> BaseException
Extract exception value from the last connection attempt.
| PARAMETER | DESCRIPTION |
|---|---|
error
|
error passed by the
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
BaseException
|
Exception value from the last connection attempt |
Source code in pika/adapters/blocking_connection.py
@staticmethod
def _reap_last_connection_workflow_error(
error: BaseException) -> BaseException:
"""
Extract exception value from the last connection attempt.
:param error: error passed by the `AMQPConnectionWorkflow` completion callback.
:returns: Exception value from the last connection attempt
"""
if isinstance(error, connection_workflow.AMQPConnectionWorkflowFailed):
# Extract exception value from the last connection attempt
last = error.exceptions[-1]
if isinstance(last,
connection_workflow.AMQPConnectorSocketConnectError):
error = exceptions.AMQPConnectionError(last,
host=last.host,
port=last.port)
elif isinstance(last,
connection_workflow.AMQPConnectorPhaseErrorBase):
error = last.exception
else:
error = last
return error
_request_channel_dispatch(channel_number: int) -> None
Called by BlockingChannel instances to request a call to their
_dispatch_events method or to terminate process_data_events;
BlockingConnection will honor these requests from a safe context.
| PARAMETER | DESCRIPTION |
|---|---|
channel_number
|
positive channel number to request a call
to the channel's
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def _request_channel_dispatch(self, channel_number: int) -> None:
"""Called by BlockingChannel instances to request a call to their
_dispatch_events method or to terminate `process_data_events`;
BlockingConnection will honor these requests from a safe context.
:param channel_number: positive channel number to request a call
to the channel's `_dispatch_events`; a negative channel number to
request termination of `process_data_events`
"""
self._channels_pending_dispatch.add(channel_number)
add_callback_threadsafe(
callback: Callable[..., None],
) -> None
Requests a call to the given function as soon as possible in the context of this connection's thread.
NOTE: This is the only thread-safe method in BlockingConnection. All
other manipulations of BlockingConnection must be performed from the
connection's thread.
NOTE: the callbacks are dispatched only in the scope of
specially-designated methods: see
BlockingConnection.process_data_events() and
BlockingChannel.start_consuming().
For example, a thread may request a call to the
BlockingChannel.basic_ack method of a BlockingConnection that is
running in a different thread via::
connection.add_callback_threadsafe(
functools.partial(channel.basic_ack, delivery_tag=...))
NOTE: if you know that the requester is running on the same thread as
the connection it is more efficient to use the
BlockingConnection.call_later() method with a delay of 0.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback method; must be callable
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
pika.exceptions.ConnectionWrongStateError
|
if connection is closed |
Source code in pika/adapters/blocking_connection.py
def add_callback_threadsafe(self, callback: Callable[..., None]) -> None:
"""
Requests a call to the given function as soon as possible in the context of this
connection's thread.
NOTE: This is the only thread-safe method in `BlockingConnection`. All
other manipulations of `BlockingConnection` must be performed from the
connection's thread.
NOTE: the callbacks are dispatched only in the scope of
specially-designated methods: see
`BlockingConnection.process_data_events()` and
`BlockingChannel.start_consuming()`.
For example, a thread may request a call to the
`BlockingChannel.basic_ack` method of a `BlockingConnection` that is
running in a different thread via::
connection.add_callback_threadsafe(
functools.partial(channel.basic_ack, delivery_tag=...))
NOTE: if you know that the requester is running on the same thread as
the connection it is more efficient to use the
`BlockingConnection.call_later()` method with a delay of 0.
:param callback: The callback method; must be callable
:raises pika.exceptions.ConnectionWrongStateError: if connection is
closed
"""
with self._cleanup_mutex:
# NOTE: keep in mind that we may be called from another thread and
# this mutex only synchronizes us with our connection cleanup logic,
# so a simple check for "is_closed" is pretty much all we're allowed
# to do here besides calling the only thread-safe method
# _adapter_add_callback_threadsafe().
if self.is_closed:
raise exceptions.ConnectionWrongStateError(
'BlockingConnection.add_callback_threadsafe() called on '
'closed or closing connection.')
self._impl._adapter_add_callback_threadsafe(
functools.partial(self._on_threadsafe_callback, callback))
add_on_connection_blocked_callback(
callback: Callable[[Connection, Method[Blocked]], None],
) -> None
RabbitMQ AMQP extension - Add a callback to be notified when the
connection gets blocked (Connection.Blocked received from RabbitMQ)
due to the broker running low on resources (memory or disk). In this
state RabbitMQ suspends processing incoming data until the connection
is unblocked, so it's a good idea for publishers receiving this
notification to suspend publishing until the connection becomes
unblocked.
NOTE: due to the blocking nature of BlockingConnection, if it's sending
outbound data while the connection is/becomes blocked, the call may
remain blocked until the connection becomes unblocked, if ever. You
may use ConnectionParameters.blocked_connection_timeout to abort a
BlockingConnection method call with an exception when the connection
remains blocked longer than the given timeout value.
See also Connection.add_on_connection_unblocked_callback()
See also ConnectionParameters.blocked_connection_timeout.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
Callback to call on
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def add_on_connection_blocked_callback(
self, callback: Callable[[
pika.connection.Connection, pika.frame.Method[pika.spec.Connection.
Blocked]
], None]
) -> None:
"""RabbitMQ AMQP extension - Add a callback to be notified when the
connection gets blocked (`Connection.Blocked` received from RabbitMQ)
due to the broker running low on resources (memory or disk). In this
state RabbitMQ suspends processing incoming data until the connection
is unblocked, so it's a good idea for publishers receiving this
notification to suspend publishing until the connection becomes
unblocked.
NOTE: due to the blocking nature of BlockingConnection, if it's sending
outbound data while the connection is/becomes blocked, the call may
remain blocked until the connection becomes unblocked, if ever. You
may use `ConnectionParameters.blocked_connection_timeout` to abort a
BlockingConnection method call with an exception when the connection
remains blocked longer than the given timeout value.
See also `Connection.add_on_connection_unblocked_callback()`
See also `ConnectionParameters.blocked_connection_timeout`.
:param callback: Callback to call on `Connection.Blocked`,
having the signature `callback(connection, pika.frame.Method)`,
where connection is the `BlockingConnection` instance and the method
frame's `method` member is of type `pika.spec.Connection.Blocked`
"""
self._impl.add_on_connection_blocked_callback(
functools.partial(
self._on_connection_blocked,
functools.partial(callback,
cast(pika.connection.Connection, self))))
add_on_connection_unblocked_callback(
callback: Callable[
[Connection, Method[Unblocked]], None
],
) -> None
RabbitMQ AMQP extension - Add a callback to be notified when the
connection gets unblocked (Connection.Unblocked frame is received from
RabbitMQ) letting publishers know it's ok to start publishing again.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
Callback to call on Connection.Unblocked
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def add_on_connection_unblocked_callback(
self, callback: Callable[[
pika.connection.Connection, pika.frame.Method[pika.spec.Connection.
Unblocked]
], None]
) -> None:
"""RabbitMQ AMQP extension - Add a callback to be notified when the
connection gets unblocked (`Connection.Unblocked` frame is received from
RabbitMQ) letting publishers know it's ok to start publishing again.
:param callback: Callback to call on Connection.Unblocked`,
having the signature `callback(connection, pika.frame.Method)`,
where connection is the `BlockingConnection` instance and the method
frame's `method` member is of type `pika.spec.Connection.Unblocked`
"""
self._impl.add_on_connection_unblocked_callback(
functools.partial(
self._on_connection_unblocked,
functools.partial(callback,
cast(pika.connection.Connection, self))))
call_later(
delay: float, callback: Callable[[], None]
) -> int
Create a single-shot timer to fire after delay seconds.
Do not confuse with Tornado's timeout where you pass in the time you want to have your callback called. Only pass in the seconds until it's to be called.
NOTE: the timer callbacks are dispatched only in the scope of
specially-designated methods: see
BlockingConnection.process_data_events() and
BlockingChannel.start_consuming().
| PARAMETER | DESCRIPTION |
|---|---|
delay
|
The number of seconds to wait to call callback
TYPE:
|
callback
|
The callback method with the signature callback()
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
int
|
Opaque timer id |
Source code in pika/adapters/blocking_connection.py
def call_later(self, delay: float, callback: Callable[[], None]) -> int:
"""
Create a single-shot timer to fire after delay seconds.
Do not confuse with Tornado's timeout where you pass in the time you want to
have your callback called. Only pass in the seconds until it's to be
called.
NOTE: the timer callbacks are dispatched only in the scope of
specially-designated methods: see
`BlockingConnection.process_data_events()` and
`BlockingChannel.start_consuming()`.
:param delay: The number of seconds to wait to call callback
:param callback: The callback method with the signature
callback()
:returns: Opaque timer id
"""
validators.require_callback(callback)
evt = _TimerEvt(callback=callback)
timer_id = cast(
int,
self._impl._adapter_call_later(
delay, functools.partial(self._on_timer_ready, evt)))
evt.timer_id = timer_id
return timer_id
channel(
channel_number: int | None = None,
) -> BlockingChannel
Create a new channel with the next available channel number or pass in a channel number to use. Must be non-zero if you would like to specify but it is recommended that you let Pika manage the channel numbers.
| PARAMETER | DESCRIPTION |
|---|---|
channel_number
|
optional channel number to use
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def channel(self, channel_number: int | None = None) -> BlockingChannel:
"""
Create a new channel with the next available channel number or pass in a channel number to
use. Must be non-zero if you would like to specify but it is recommended that you let Pika
manage the channel numbers.
:param channel_number: optional channel number to use
"""
with _CallbackResult(self._OnChannelOpenedArgs) as opened_args:
impl_channel = self._impl.channel(
channel_number=channel_number,
on_open_callback=opened_args.set_value_once)
# Create our proxy channel
channel = BlockingChannel(impl_channel, self)
# Link implementation channel with our proxy channel
impl_channel._set_cookie(channel)
# Drive I/O until Channel.Open-ok
channel._flush_output(opened_args.is_ready)
return channel
close(
reply_code: int = 200,
reply_text: str = 'Normal shutdown',
) -> None
Disconnect from RabbitMQ.
If there are any open channels, it will attempt to close them prior to fully disconnecting. Channels which have active consumers will attempt to send a Basic.Cancel to RabbitMQ to cleanly stop the delivery of messages prior to closing the channel.
| PARAMETER | DESCRIPTION |
|---|---|
reply_code
|
The code number for the close
TYPE:
|
reply_text
|
The text reason for the close
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
pika.exceptions.ConnectionWrongStateError
|
if called on a closed connection (NEW in v1.0.0) |
Source code in pika/adapters/blocking_connection.py
def close(self,
reply_code: int = 200,
reply_text: str = 'Normal shutdown') -> None:
"""
Disconnect from RabbitMQ.
If there are any open channels, it will attempt to close them prior to fully disconnecting.
Channels which have active consumers will attempt to send a Basic.Cancel to RabbitMQ to
cleanly stop the delivery of messages prior to closing the channel.
:param reply_code: The code number for the close
:param reply_text: The text reason for the close
:raises pika.exceptions.ConnectionWrongStateError: if called on a closed connection (NEW in
v1.0.0)
"""
if not self.is_open:
msg = f'{self.__class__.__name__}.close({reply_code}, {reply_text!r}) called on closed connection.'
LOGGER.error(msg)
raise exceptions.ConnectionWrongStateError(msg)
LOGGER.info('Closing connection (%s): %s', reply_code, reply_text)
# Close channels that remain opened
for impl_channel in list(self._impl._channels.values()):
channel = impl_channel._get_cookie()
if channel.is_open:
try:
channel.close(reply_code, reply_text)
except exceptions.ChannelClosed as exc:
# Log and suppress broker-closed channel
LOGGER.warning(
'Got ChannelClosed while closing channel '
'from connection.close: %r', exc)
# Close the connection
self._impl.close(reply_code, reply_text)
self._flush_output(self._closed_result.is_ready)
process_data_events(time_limit: float | None = 0) -> None
Will make sure that data events are processed.
Dispatches timer and channel callbacks if not called from the scope of BlockingConnection or
BlockingChannel callback. Your app can block on this method. If your application maintains a
long-lived publisher connection, this method should be called periodically in order to
respond to heartbeats and other data events. See examples/long_running_publisher.py for an
example.
| PARAMETER | DESCRIPTION |
|---|---|
time_limit
|
suggested upper bound on processing time in seconds. The actual blocking time depends on the granularity of the underlying ioloop. Zero means return as soon as possible. None means there is no limit on processing time and the function will block until I/O produces actionable events. Defaults to 0 for backward compatibility. This parameter is NEW in pika 0.10.0.
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def process_data_events(self, time_limit: float | None = 0) -> None:
"""
Will make sure that data events are processed.
Dispatches timer and channel callbacks if not called from the scope of BlockingConnection or
BlockingChannel callback. Your app can block on this method. If your application maintains a
long-lived publisher connection, this method should be called periodically in order to
respond to heartbeats and other data events. See `examples/long_running_publisher.py` for an
example.
:param time_limit: suggested upper bound on processing time in seconds. The actual blocking
time depends on the granularity of the underlying ioloop. Zero means return as soon as
possible. None means there is no limit on processing time and the function will block
until I/O produces actionable events. Defaults to 0 for backward compatibility. This
parameter is NEW in pika 0.10.0.
"""
with self._acquire_event_dispatch() as dispatch_acquired:
# Check if we can actually process pending events
def common_terminator() -> bool:
return bool(
dispatch_acquired and
(self._channels_pending_dispatch or self._ready_events))
if time_limit is None:
self._flush_output(common_terminator)
else:
with _IoloopTimerContext(time_limit, self._impl) as timer:
self._flush_output(timer.is_ready, common_terminator)
if self._ready_events:
self._dispatch_connection_events()
if self._channels_pending_dispatch:
self._dispatch_channel_events()
if self._server_channel_closures:
exc = self._server_channel_closures.popleft()
LOGGER.debug('Channel closed by broker: %r', exc)
raise exc
remove_timeout(timeout_id: int) -> None
Remove a timer if it's still in the timeout stack.
| PARAMETER | DESCRIPTION |
|---|---|
timeout_id
|
The opaque timer id to remove
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def remove_timeout(self, timeout_id: int) -> None:
"""
Remove a timer if it's still in the timeout stack.
:param timeout_id: The opaque timer id to remove
"""
# Remove from the impl's timeout stack
self._impl._adapter_remove_timeout(timeout_id)
# Remove from ready events, if the timer fired already
for i, evt in enumerate(self._ready_events):
if isinstance(evt, _TimerEvt) and evt.timer_id == timeout_id:
index_to_remove = i
break
else:
# Not found
return
del self._ready_events[index_to_remove]
sleep(duration: float) -> None
A safer way to sleep than calling time.sleep() directly that would keep the adapter from ignoring frames sent from the broker. The connection will "sleep" or block the number of seconds specified in duration in small intervals.
| PARAMETER | DESCRIPTION |
|---|---|
duration
|
The time to sleep in seconds
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def sleep(self, duration: float) -> None:
"""
A safer way to sleep than calling time.sleep() directly that would keep the adapter from
ignoring frames sent from the broker. The connection will "sleep" or block the number of
seconds specified in duration in small intervals.
:param duration: The time to sleep in seconds
"""
assert duration >= 0, duration
deadline = pika._utils.time_now() + duration
time_limit = duration
# Process events at least once
while True:
self.process_data_events(time_limit)
time_limit = deadline - pika._utils.time_now()
if time_limit <= 0:
break
update_secret(new_secret: str, reason: str) -> None
RabbitMQ AMQP extension - This method updates the secret used to authenticate this connection. It is used when secrets have an expiration date and need to be renewed, like OAuth 2 tokens.
| PARAMETER | DESCRIPTION |
|---|---|
new_secret
|
The new secret
TYPE:
|
reason
|
The reason for the secret update
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
pika.exceptions.ConnectionWrongStateError
|
if connection is not open. |
Source code in pika/adapters/blocking_connection.py
def update_secret(self, new_secret: str, reason: str) -> None:
"""RabbitMQ AMQP extension - This method updates the secret used to authenticate this connection.
It is used when secrets have an expiration date and need to be renewed, like OAuth 2 tokens.
:param new_secret: The new secret
:param reason: The reason for the secret update
:raises pika.exceptions.ConnectionWrongStateError: if connection is
not open.
"""
result = _CallbackResult()
self._impl.update_secret(new_secret, reason, result.signal_once)
self._flush_output(result.is_ready)
The BlockingChannel implements blocking semantics for most things that
one would use callback-passing-style for with the
:py:class:~pika.channel.Channel class. In addition,
the BlockingChannel class implements a :term:generator that allows
you to :doc:consume messages </examples/blocking_consumer_generator>
without using callbacks.
Example of creating a BlockingChannel::
import pika
# Create our connection object
connection = pika.BlockingConnection()
# The returned object will be a synchronous channel
channel = connection.channel()
Source code in pika/adapters/blocking_connection.py
class BlockingChannel:
"""The BlockingChannel implements blocking semantics for most things that
one would use callback-passing-style for with the
:py:class:`~pika.channel.Channel` class. In addition,
the `BlockingChannel` class implements a :term:`generator` that allows
you to :doc:`consume messages </examples/blocking_consumer_generator>`
without using callbacks.
Example of creating a BlockingChannel::
import pika
# Create our connection object
connection = pika.BlockingConnection()
# The returned object will be a synchronous channel
channel = connection.channel()
"""
class _RxMessageArgs(NamedTuple):
channel: Any
method: Any
properties: Any
body: bytes
class _MethodFrameCallbackResultArgs(NamedTuple):
method_frame: Any
class _OnMessageConfirmationReportArgs(NamedTuple):
method_frame: Any
class _FlowOkCallbackResultArgs(NamedTuple):
active: bool
_CONSUMER_CANCELLED_CB_KEY = 'blocking_channel_consumer_cancelled'
def __init__(self, channel_impl: pika.channel.Channel,
connection: BlockingConnection) -> None:
"""
Create a new instance of the Channel.
:param channel_impl: Channel implementation object as returned from
SelectConnection.channel()
:param connection: The connection object
"""
self._impl = channel_impl
self._connection = connection
# A mapping of consumer tags to _ConsumerInfo for active consumers
self._consumer_infos: dict[Any, Any] = {}
# Queue consumer generator generator info of type
# _QueueConsumerGeneratorInfo created by BlockingChannel.consume
self._queue_consumer_generator: _QueueConsumerGeneratorInfo | None = None
# Whether RabbitMQ delivery confirmation has been enabled
self._delivery_confirmation = False
# Receives message delivery confirmation report (Basic.ack or
# Basic.nack) from broker when delivery confirmations are enabled
self._message_confirmation_result = _CallbackResult(
self._OnMessageConfirmationReportArgs)
# deque of pending events: _ConsumerDeliveryEvt and
# _ConsumerCancellationEvt objects that will be returned by
# `BlockingChannel.get_event()`
self._pending_events: deque[Any] = deque()
# Holds a ReturnedMessage object representing a message received via
# Basic.Return in publisher-acknowledgments mode.
self._puback_return: ReturnedMessage | None = None
# self._on_channel_closed() saves the reason exception here
self._closing_reason = None # type: None | Exception
# Receives Basic.ConsumeOk reply from server
self._basic_consume_ok_result = _CallbackResult()
# Receives args from Basic.GetEmpty response
# https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.get
self._basic_getempty_result = _CallbackResult(
self._MethodFrameCallbackResultArgs)
self._impl.add_on_cancel_callback(self._on_consumer_cancelled_by_broker)
self._impl.add_callback(self._basic_consume_ok_result.signal_once,
replies=[pika.spec.Basic.ConsumeOk],
one_shot=False)
self._impl.add_on_close_callback(self._on_channel_closed)
self._impl.add_callback(self._basic_getempty_result.set_value_once,
replies=[pika.spec.Basic.GetEmpty],
one_shot=False)
LOGGER.info('Created channel=%s', self.channel_number)
def __int__(self) -> int:
"""
Return the channel object as its channel number.
NOTE: inherited from legacy BlockingConnection; might be error-prone;
use `channel_number` property instead.
"""
return self.channel_number
@override
def __repr__(self) -> str:
return f'<{self.__class__.__name__} impl={self._impl!r}>'
def __enter__(self) -> Self:
return self
def __exit__(self, exc_type: type[BaseException] | None,
value: BaseException | None,
traceback: TracebackType | None) -> None:
if self.is_open:
self.close()
def _cleanup(self) -> None:
"""Clean up members that might inhibit garbage collection."""
self._message_confirmation_result.reset()
self._pending_events = deque()
self._consumer_infos = {}
self._queue_consumer_generator = None
@property
def channel_number(self) -> int:
"""Channel number."""
return self._impl.channel_number
@property
def connection(self) -> BlockingConnection:
"""The channel's BlockingConnection instance."""
return self._connection
@property
def is_closed(self) -> bool:
"""Returns True if the channel is closed."""
return self._impl.is_closed
@property
def is_open(self) -> bool:
"""Returns True if the channel is open."""
return self._impl.is_open
@property
def consumer_tags(self) -> list[str]:
"""Property method that returns a list of consumer tags for active consumers."""
return list(self._consumer_infos.keys())
_ALWAYS_READY_WAITERS = ((lambda: True),)
def _flush_output(self, *waiters: Callable[[], bool]) -> None:
"""
Flush output and process input while waiting for any of the given callbacks to return true.
The wait is aborted upon channel-close or connection-close. Otherwise, processing continues
until the output is flushed AND at least one of the callbacks returns true. If there are no
callbacks, then processing ends when all output is flushed.
:param waiters: sequence of zero or more callables taking no args and returning true when
it's time to stop processing. Their results are OR'ed together. An empty sequence is
treated as equivalent to a waiter always returning true.
"""
if self.is_closed:
self._impl._raise_if_not_open()
if not waiters:
waiters = self._ALWAYS_READY_WAITERS
self._connection._flush_output(lambda: self.is_closed, *waiters)
if self.is_closed and isinstance(self._closing_reason,
exceptions.ChannelClosedByBroker):
raise self._closing_reason
def _on_puback_message_returned(self, channel: pika.channel.Channel,
method: pika.spec.Basic.Return,
properties: pika.spec.BasicProperties,
body: bytes) -> None:
"""
Called as the result of Basic.Return from broker in publisher-acknowledgements mode.
Saves the info as a ReturnedMessage instance in self._puback_return.
:param channel: our self._impl channel
:param method:
:param properties: message properties
:param body: returned message body; empty string if no body
"""
assert channel is self._impl, (channel.channel_number,
self.channel_number)
assert isinstance(method, pika.spec.Basic.Return), method
assert isinstance(properties, pika.spec.BasicProperties), (properties)
LOGGER.warning(
'Published message was returned: _delivery_confirmation=%s; '
'channel=%s; method=%r; properties=%r; body_size=%d; '
'body_prefix=%.255r', self._delivery_confirmation,
channel.channel_number, method, properties,
len(body) if body is not None else None, body)
self._puback_return = ReturnedMessage(method, properties, body)
def _add_pending_event(self, evt: _ChannelPendingEvt) -> None:
"""
Append an event to the channel's list of events that are ready for dispatch to user and
signal our connection that this channel is ready for event dispatch.
:param evt: an event derived from _ChannelPendingEvt
"""
self._pending_events.append(evt)
self.connection._request_channel_dispatch(self.channel_number)
def _on_channel_closed(self, _channel: pika.channel.Channel,
reason: Exception) -> None:
"""
Callback from impl notifying us that the channel has been closed.
This may be as the result of user-, broker-, or internal connection clean-up initiated closing or meta-closing of the
channel.
If it resulted from receiving `Channel.Close` from broker, we will
expedite waking up of the event subsystem so that it may respond by
raising `ChannelClosed` from user's context.
NOTE: We can't raise exceptions in callbacks in order to protect
the integrity of the underlying implementation. BlockingConnection's
underlying asynchronous connection adapter (SelectConnection) uses
callbacks to communicate with us. If BlockingConnection leaks exceptions
back into the I/O loop or the asynchronous connection adapter, we
interrupt their normal workflow and introduce a high likelihood of state
inconsistency.
See `pika.Channel.add_on_close_callback()` for additional documentation.
:param _channel: (unused)
:param reason:
"""
LOGGER.debug('_on_channel_closed: %r; %r', reason, self)
self._closing_reason = reason
if isinstance(reason, exceptions.ChannelClosedByBroker):
self.connection._server_channel_closures.append(reason)
self._cleanup()
# Request urgent termination of `process_data_events()`, in case
# it's executing or next time it will execute
self.connection._request_channel_dispatch(-self.channel_number)
def _on_consumer_cancelled_by_broker(
self,
method_frame: pika.frame.Method[pika.spec.Basic.Cancel]) -> None:
"""
Called by impl when broker cancels consumer via Basic.Cancel.
This is a RabbitMQ-specific feature. The circumstances include deletion of queue being
consumed as well as failure of a HA node responsible for the queue being consumed.
:param method_frame: method frame with the `spec.Basic.Cancel` method
"""
evt = _ConsumerCancellationEvt(method_frame)
consumer = self._consumer_infos[method_frame.method.consumer_tag]
# Don't interfere with client-initiated cancellation flow
if not consumer.tearing_down:
consumer.state = _ConsumerInfo.CANCELLED_BY_BROKER
if consumer.alternate_event_sink is not None:
consumer.alternate_event_sink(evt)
else:
self._add_pending_event(evt)
def _on_consumer_message_delivery(self, _channel: pika.channel.Channel,
method: pika.spec.Basic.Deliver,
properties: pika.spec.BasicProperties,
body: bytes) -> None:
"""
Called by impl when a message is delivered for a consumer.
:param _channel: The implementation channel object
:param method:
:param properties: message properties
:param body: delivered message body; empty string if no body
"""
evt = _ConsumerDeliveryEvt(method, properties, body)
consumer = self._consumer_infos[method.consumer_tag]
if consumer.alternate_event_sink is not None:
consumer.alternate_event_sink(evt)
else:
self._add_pending_event(evt)
def _on_consumer_generator_event(self, evt: _ChannelPendingEvt) -> None:
"""
Sink for the queue consumer generator's consumer events; append the event to queue consumer
generator's pending events buffer.
:param evt: an object of type _ConsumerDeliveryEvt or _ConsumerCancellationEvt
"""
assert self._queue_consumer_generator is not None
self._queue_consumer_generator.pending_events.append(evt)
# Schedule termination of connection.process_data_events using a
# negative channel number
self.connection._request_channel_dispatch(-self.channel_number)
def _cancel_all_consumers(self) -> None:
"""
Cancel all consumers.
NOTE: pending non-ackable messages will be lost; pending ackable
messages will be rejected.
"""
if self._consumer_infos:
LOGGER.debug('Cancelling %i consumers', len(self._consumer_infos))
if self._queue_consumer_generator is not None:
# Cancel queue consumer generator
self.cancel()
# Cancel consumers created via basic_consume
for consumer_tag in list(self._consumer_infos.keys()):
self.basic_cancel(consumer_tag)
def _dispatch_events(self) -> None:
"""
Called by BlockingConnection to dispatch pending events.
`BlockingChannel` schedules this callback via `BlockingConnection._request_channel_dispatch`
"""
while self._pending_events:
evt = self._pending_events.popleft()
if type(evt) is _ConsumerDeliveryEvt:
consumer_info = self._consumer_infos[evt.method.consumer_tag]
consumer_info.on_message_callback(self, evt.method,
evt.properties, evt.body)
elif type(evt) is _ConsumerCancellationEvt:
del self._consumer_infos[evt.method_frame.method.consumer_tag]
self._impl.callbacks.process(self.channel_number,
self._CONSUMER_CANCELLED_CB_KEY,
self, evt.method_frame)
else:
evt.dispatch()
def close(self,
reply_code: int = 0,
reply_text: str = 'Normal shutdown') -> None:
"""
Will invoke a clean shutdown of the channel with the AMQP Broker.
:param reply_code: The reply code to close the channel with
:param reply_text: The reply text to close the channel with
"""
LOGGER.debug('Channel.close(%s, %s)', reply_code, reply_text)
self._impl._raise_if_not_open()
try:
# Cancel remaining consumers
self._cancel_all_consumers()
# Close the channel
self._impl.close(reply_code=reply_code, reply_text=reply_text)
self._flush_output(lambda: self.is_closed)
finally:
self._cleanup()
def flow(self, active: bool) -> bool:
"""
Turn Channel flow control off and on.
NOTE: RabbitMQ doesn't support active=False; per
https://www.rabbitmq.com/specification.html: "active=false is not
supported by the server. Limiting prefetch with basic.qos provides much
better control"
For more information, please reference:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#channel.flow
:param active: Turn flow on (True) or off (False)
:returns: True if broker will start or continue sending; False if not
"""
with _CallbackResult(self._FlowOkCallbackResultArgs) as flow_ok_result:
self._impl.flow(active=active,
callback=flow_ok_result.set_value_once)
self._flush_output(flow_ok_result.is_ready)
return flow_ok_result.value.active
def add_on_cancel_callback(
self, callback: Callable[[pika.frame.Method[pika.spec.Basic.Cancel]],
None]
) -> None:
"""
Pass a callback function that will be called when Basic.Cancel is sent by the broker.
The callback function should receive a method frame parameter.
:param callback: a callable for handling broker's Basic.Cancel
notification with the call signature: callback(method_frame)
where method_frame is of type `pika.frame.Method` with method of
type `spec.Basic.Cancel`
"""
self._impl.callbacks.add(self.channel_number,
self._CONSUMER_CANCELLED_CB_KEY,
callback,
one_shot=False)
def add_on_return_callback(
self, callback: Callable[[
BlockingChannel, pika.spec.Basic.Return, pika.spec.
BasicProperties, bytes
], None]
) -> None:
"""
Pass a callback function that will be called when a published message is rejected and
returned by the server via `Basic.Return`.
:param callback: The method to call on callback with the
signature callback(channel, method, properties, body), where
- channel: pika.Channel
- method: pika.spec.Basic.Return
- properties: pika.spec.BasicProperties
- body: bytes
"""
self._impl.add_on_return_callback(
lambda _channel, method, properties, body: (self._add_pending_event(
_ReturnedMessageEvt(callback, self, method, properties, body))))
def basic_consume(self,
queue: str,
on_message_callback: Callable[[
BlockingChannel, pika.spec.Basic.Deliver, pika.spec.
BasicProperties, bytes
], None],
auto_ack: bool = False,
exclusive: bool = False,
consumer_tag: str | None = None,
arguments: dict[str, Any] | None = None) -> str:
"""
Sends the AMQP command Basic.Consume to the broker and binds messages for the consumer_tag
to the consumer callback. If you do not pass in a consumer_tag, one will be automatically
generated for you. Returns the consumer tag.
NOTE: the consumer callbacks are dispatched only in the scope of
specially-designated methods: see
`BlockingConnection.process_data_events` and
`BlockingChannel.start_consuming`.
For more information about Basic.Consume, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume
:param queue: The queue from which to consume
:param on_message_callback: Required function for dispatching messages
to user, having the signature:
on_message_callback(channel, method, properties, body)
- channel: BlockingChannel
- method: spec.Basic.Deliver
- properties: spec.BasicProperties
- body: bytes
:param auto_ack: if set to True, automatic acknowledgement mode will be used
(see https://www.rabbitmq.com/confirms.html). This corresponds
with the 'no_ack' parameter in the basic.consume AMQP 0.9.1
method
:param exclusive: Don't allow other consumers on the queue
:param consumer_tag: You may specify your own consumer tag; if left
empty, a consumer tag will be generated automatically
:param arguments: Custom key/value pair arguments for the consumer
:returns: consumer tag
:raises pika.exceptions.DuplicateConsumerTag: if consumer with given
consumer_tag is already present.
"""
validators.require_string(queue, 'queue')
validators.require_callback(on_message_callback, 'on_message_callback')
return self._basic_consume_impl(queue=queue,
on_message_callback=on_message_callback,
auto_ack=auto_ack,
exclusive=exclusive,
consumer_tag=consumer_tag,
arguments=arguments)
def _basic_consume_impl(
self,
queue: str,
auto_ack: bool,
exclusive: bool,
consumer_tag: str | None,
arguments: dict[str, Any] | None = None,
on_message_callback: Callable[[
BlockingChannel, pika.spec.Basic.Deliver, pika.spec.
BasicProperties, bytes
], None] | None = None,
alternate_event_sink: Callable[[_ChannelPendingEvt], None] | None = None
) -> str:
"""
The low-level implementation used by `basic_consume` and `consume`.
See `basic_consume` docstring for more info.
NOTE: exactly one of on_message_callback/alternate_event_sink musts be
non-None.
This method has one additional parameter alternate_event_sink over the
args described in `basic_consume`.
:param queue: Queue name
:param auto_ack: If True, the broker acknowledges messages automatically
:param exclusive: If True, restrict access to the current connection
:param consumer_tag: if specified, only the consumer with the given tag will be cancelled
:param arguments: Custom key/value pair arguments for the consumer
:param on_message_callback: Callback for delivered messages
:param alternate_event_sink: if specified, _ConsumerDeliveryEvt
and _ConsumerCancellationEvt objects will be diverted to this
callback instead of being deposited in the channel's
`_pending_events` container. Signature:
alternate_event_sink(evt)
:raises pika.exceptions.DuplicateConsumerTag: if consumer with given
consumer_tag is already present.
"""
if (on_message_callback is None) == (alternate_event_sink is None):
raise ValueError(((
'exactly one of on_message_callback/alternate_event_sink must '
'be non-None'), on_message_callback, alternate_event_sink))
if not consumer_tag:
# Need a consumer tag to register consumer info before sending
# request to broker, because I/O might dispatch incoming messages
# immediately following Basic.Consume-ok before _flush_output
# returns
consumer_tag = self._impl._generate_consumer_tag()
if consumer_tag in self._consumer_infos:
raise exceptions.DuplicateConsumerTag(consumer_tag)
# Create new consumer
self._consumer_infos[consumer_tag] = _ConsumerInfo(
consumer_tag,
auto_ack=auto_ack,
on_message_callback=on_message_callback,
alternate_event_sink=alternate_event_sink)
try:
with self._basic_consume_ok_result as ok_result:
tag = self._impl.basic_consume(
on_message_callback=self._on_consumer_message_delivery,
queue=queue,
auto_ack=auto_ack,
exclusive=exclusive,
consumer_tag=consumer_tag,
arguments=arguments)
assert tag == consumer_tag, (tag, consumer_tag)
self._flush_output(ok_result.is_ready)
except Exception:
# If channel was closed, self._consumer_infos will be empty
if consumer_tag in self._consumer_infos:
del self._consumer_infos[consumer_tag]
# Schedule termination of connection.process_data_events using a
# negative channel number
self.connection._request_channel_dispatch(-self.channel_number)
raise
# NOTE: Consumer could get cancelled by broker immediately after opening
# (e.g., queue getting deleted externally)
if self._consumer_infos[consumer_tag].setting_up:
self._consumer_infos[consumer_tag].state = _ConsumerInfo.ACTIVE
return consumer_tag
def basic_cancel(
self, consumer_tag: str
) -> Sequence[tuple[pika.spec.Basic.Deliver, pika.spec.BasicProperties,
bytes]]:
"""
This method cancels a consumer.
This does not affect already delivered messages, but it does mean the server will not send any more
messages for that consumer. The client may receive an arbitrary number
of messages in between sending the cancel method and receiving the
cancel-ok reply.
NOTE: When cancelling an auto_ack=False consumer, this implementation
automatically Nacks and suppresses any incoming messages that have not
yet been dispatched to the consumer's callback. However, when cancelling
a auto_ack=True consumer, this method will return any pending messages
that arrived before broker confirmed the cancellation.
:param consumer_tag: Identifier for the consumer; the result of
passing a consumer_tag that was created on another channel is
undefined (bad things will happen)
:returns: (NEW IN pika 0.10.0) empty sequence for a auto_ack=False
consumer; for a auto_ack=True consumer, returns a (possibly empty)
sequence of pending messages that arrived before broker confirmed
the cancellation (this is done instead of via consumer's callback in
order to prevent reentrancy/recursion. Each message is three-tuple:
(method, properties, body)
- method: spec.Basic.Deliver
- properties: spec.BasicProperties
- body: bytes
"""
try:
consumer_info = self._consumer_infos[consumer_tag]
except KeyError:
LOGGER.warning(
'User is attempting to cancel an unknown consumer=%s; '
'already cancelled by user or broker?', consumer_tag)
return []
try:
# Assertion failure here is most likely due to reentrance
assert consumer_info.active or consumer_info.cancelled_by_broker, (
consumer_info.state)
# Assertion failure here signals disconnect between consumer state
# in BlockingChannel and Channel
assert (consumer_info.cancelled_by_broker or
consumer_tag in self._impl._consumers), consumer_tag
auto_ack = consumer_info.auto_ack
consumer_info.state = _ConsumerInfo.TEARING_DOWN
with _CallbackResult() as cancel_ok_result:
# Nack pending messages for auto_ack=False consumer
if not auto_ack:
pending_messages = self._remove_pending_deliveries(
consumer_tag)
if pending_messages:
# NOTE: we use impl's basic_reject to avoid the
# possibility of redelivery before basic_cancel takes
# control of nacking.
# NOTE: we can't use basic_nack with the multiple option
# to avoid nacking messages already held by our client.
for message in pending_messages:
delivery_tag = message.method.delivery_tag
# The generated spec types delivery_tag as
# optional, but the broker always sets it on a
# delivery.
assert delivery_tag is not None
self._impl.basic_reject(delivery_tag, requeue=True)
# Cancel the consumer; impl takes care of rejecting any
# additional deliveries that arrive for a auto_ack=False
# consumer
self._impl.basic_cancel(consumer_tag=consumer_tag,
callback=cancel_ok_result.signal_once)
# Flush output and wait for Basic.Cancel-ok or
# broker-initiated Basic.Cancel
self._flush_output(
cancel_ok_result.is_ready,
lambda: consumer_tag not in self._impl._consumers)
if auto_ack:
# Return pending messages for auto_ack=True consumer
return [(evt.method, evt.properties, evt.body)
for evt in self._remove_pending_deliveries(consumer_tag)
]
# impl takes care of rejecting any incoming deliveries during
# cancellation
messages = self._remove_pending_deliveries(consumer_tag)
assert not messages, messages
return []
finally:
# NOTE: The entry could be purged if channel or connection closes
if consumer_tag in self._consumer_infos:
del self._consumer_infos[consumer_tag]
# Schedule termination of connection.process_data_events using a
# negative channel number
self.connection._request_channel_dispatch(-self.channel_number)
def _remove_pending_deliveries(
self, consumer_tag: str) -> Sequence[_ConsumerDeliveryEvt]:
"""
Extract _ConsumerDeliveryEvt objects destined for the given consumer from pending events,
discarding the _ConsumerCancellationEvt, if any.
:param consumer_tag:
:returns: a (possibly empty) sequence of _ConsumerDeliveryEvt destined for the given
consumer tag
"""
remaining_events: deque[Any] = deque()
unprocessed_messages: list[Any] = []
while self._pending_events:
evt = self._pending_events.popleft()
if (type(evt) is _ConsumerDeliveryEvt and
evt.method.consumer_tag == consumer_tag):
unprocessed_messages.append(evt)
continue
if (type(evt) is _ConsumerCancellationEvt and
evt.method_frame.method.consumer_tag == consumer_tag):
# A broker-initiated Basic.Cancel must have arrived
# before our cancel request completed
continue
remaining_events.append(evt)
self._pending_events = remaining_events
return unprocessed_messages
def start_consuming(self) -> None:
"""
Processes I/O events and dispatches timers and `basic_consume` callbacks until all consumers
are cancelled.
NOTE: this blocking function may not be called from the scope of a
pika callback, because dispatching `basic_consume` callbacks from this
context would constitute recursion.
:raises pika.exceptions.ReentrancyError: if called from the scope of a
`BlockingConnection` or `BlockingChannel` callback
:raises ChannelClosed: when this channel is closed by broker.
"""
# Check if called from the scope of an event dispatch callback
with self.connection._acquire_event_dispatch() as dispatch_allowed:
if not dispatch_allowed:
raise exceptions.ReentrancyError(
'start_consuming may not be called from the scope of '
'another BlockingConnection or BlockingChannel callback')
self._impl._raise_if_not_open()
# Process events as long as consumers exist on this channel
while self._consumer_infos:
# This will raise ChannelClosed if channel is closed by broker
self._process_data_events(time_limit=None)
def stop_consuming(self, consumer_tag: str | None = None) -> None:
"""
Cancels all consumers, signalling the `start_consuming` loop to exit.
NOTE: pending non-ackable messages will be lost; pending ackable
messages will be rejected.
:param consumer_tag: if specified, only the consumer with the given tag will be cancelled
"""
if consumer_tag:
self.basic_cancel(consumer_tag)
else:
self._cancel_all_consumers()
def consume(
self,
queue: str,
auto_ack: bool = False,
exclusive: bool = False,
arguments: dict[str, Any] | None = None,
inactivity_timeout: float | None = None,
consumer_tag: str | None = None
) -> Generator[tuple[pika.spec.Basic.Deliver | None,
pika.spec.BasicProperties | None, bytes | None]]:
"""
Blocking consumption of a queue instead of via a callback.
This method is a generator that yields each message as a tuple of method,
properties, and body. The active generator iterator terminates when the
consumer is cancelled by client via `BlockingChannel.cancel()` or by
broker.
Example:
::
for method, properties, body in channel.consume('queue'):
print(body)
channel.basic_ack(method.delivery_tag)
You should call `BlockingChannel.cancel()` when you escape out of the
generator loop.
If you don't cancel this consumer, then next call on the same channel
to `consume()` with the exact same (queue, auto_ack, exclusive) parameters
will resume the existing consumer generator; however, calling with
different parameters will result in an exception.
:param queue: The queue name to consume
:param auto_ack: Tell the broker to not expect a ack/nack response
:param exclusive: Don't allow other consumers on the queue
:param arguments: Custom key/value pair arguments for the consumer
:param inactivity_timeout: if a number is given (in
seconds), will cause the method to yield (None, None, None) after the
given period of inactivity; this permits for pseudo-regular maintenance
activities to be carried out by the user while waiting for messages
to arrive. If None is given (default), then the method blocks until
the next event arrives. NOTE that timing granularity is limited by
the timer resolution of the underlying implementation.
NEW in pika 0.10.0.
:param consumer_tag: Specify your own consumer tag
:yields: tuple(spec.Basic.Deliver, spec.BasicProperties, bytes)
:raises ValueError: if consumer-creation parameters don't match those
of the existing queue consumer generator, if any.
NEW in pika 0.10.0
:raises ChannelClosed: when this channel is closed by broker.
"""
self._impl._raise_if_not_open()
params = (queue, auto_ack, exclusive)
if self._queue_consumer_generator is not None:
if params != self._queue_consumer_generator.params:
raise ValueError(
'Consume with different params not allowed on existing '
f'queue consumer generator; previous params: {self._queue_consumer_generator.params!r}; '
f'new params: {(queue, auto_ack, exclusive)!r}')
else:
LOGGER.debug('Creating new queue consumer generator; params: %r',
params)
# Need a consumer tag to register consumer info before sending
# request to broker, because I/O might pick up incoming messages
# in addition to Basic.Consume-ok
if not consumer_tag:
consumer_tag = self._impl._generate_consumer_tag()
self._queue_consumer_generator = _QueueConsumerGeneratorInfo(
params, consumer_tag)
try:
self._basic_consume_impl(
queue=queue,
auto_ack=auto_ack,
exclusive=exclusive,
consumer_tag=consumer_tag,
arguments=arguments,
alternate_event_sink=self._on_consumer_generator_event)
except Exception:
self._queue_consumer_generator = None
raise
LOGGER.info('Created new queue consumer generator %r',
self._queue_consumer_generator)
while self._queue_consumer_generator is not None:
# Process pending events
if self._queue_consumer_generator.pending_events:
evt = self._queue_consumer_generator.pending_events.popleft()
if type(evt) is _ConsumerCancellationEvt:
# Consumer was cancelled by broker
self._queue_consumer_generator = None
break
else:
yield (evt.method, evt.properties, evt.body)
continue
if inactivity_timeout is None:
# Wait indefinitely for a message to arrive, while processing
# I/O events and triggering ChannelClosed exception when the
# channel fails
self._process_data_events(time_limit=None)
continue
# Wait with inactivity timeout
wait_start_time = pika._utils.time_now()
wait_deadline = wait_start_time + inactivity_timeout
delta = inactivity_timeout
while (self._queue_consumer_generator is not None and
not self._queue_consumer_generator.pending_events):
self._process_data_events(time_limit=delta)
if not self._queue_consumer_generator:
# Consumer was cancelled by client
break
if self._queue_consumer_generator.pending_events:
# Got message(s)
break
delta = wait_deadline - pika._utils.time_now()
if delta <= 0.0:
# Signal inactivity timeout
yield (None, None, None)
break
def _process_data_events(self, time_limit: float | None) -> None:
"""
Wrapper for `BlockingConnection.process_data_events()` with common channel-specific logic
that raises ChannelClosed if broker closed this channel.
NOTE: We need to raise an exception in the context of user's call into
our API to protect the integrity of the underlying implementation.
BlockingConnection's underlying asynchronous connection adapter
(SelectConnection) uses callbacks to communicate with us. If
BlockingConnection leaks exceptions back into the I/O loop or the
asynchronous connection adapter, we interrupt their normal workflow and
introduce a high likelihood of state inconsistency.
See `BlockingConnection.process_data_events()` for documentation of args
and behavior.
:param time_limit:
"""
self.connection.process_data_events(time_limit=time_limit)
if self.is_closed and isinstance(self._closing_reason,
exceptions.ChannelClosedByBroker):
LOGGER.debug('Channel close by broker detected, raising %r; %r',
self._closing_reason, self)
raise self._closing_reason
def get_waiting_message_count(self) -> int:
"""
Returns the number of messages that may be retrieved from the current queue consumer
generator via `BlockingChannel.consume` without blocking. NEW in pika 0.10.0.
:returns: The number of waiting messages
"""
if self._queue_consumer_generator is not None:
pending_events = self._queue_consumer_generator.pending_events
count = len(pending_events)
if count and type(pending_events[-1]) is _ConsumerCancellationEvt:
count -= 1
else:
count = 0
return count
def cancel(self) -> int:
"""
Cancel the queue consumer created by `BlockingChannel.consume`, rejecting all pending
ackable messages.
NOTE: If you're looking to cancel a consumer issued with
BlockingChannel.basic_consume then you should call
BlockingChannel.basic_cancel.
:returns: The number of messages requeued by Basic.Nack.
NEW in 0.10.0: returns 0
"""
if self._queue_consumer_generator is None:
LOGGER.warning('cancel: queue consumer generator is inactive '
'(already cancelled by client or broker?)')
return 0
try:
_, auto_ack, _ = self._queue_consumer_generator.params
if not auto_ack:
# Reject messages held by queue consumer generator; NOTE: we
# can't use basic_nack with the multiple option to avoid nacking
# messages already held by our client.
pending_events = self._queue_consumer_generator.pending_events
# NOTE `get_waiting_message_count` adjusts for `Basic.Cancel`
# from the server at the end (if any)
for _ in range(self.get_waiting_message_count()):
evt = pending_events.popleft()
self._impl.basic_reject(evt.method.delivery_tag,
requeue=True)
self.basic_cancel(self._queue_consumer_generator.consumer_tag)
finally:
self._queue_consumer_generator = None
# Return 0 for compatibility with legacy implementation; the number of
# nacked messages is not meaningful since only messages consumed with
# auto_ack=False may be nacked, and those arriving after calling
# basic_cancel will be rejected automatically by impl channel, so we'll
# never know how many of those were nacked.
return 0
def basic_ack(self, delivery_tag: int = 0, multiple: bool = False) -> None:
"""
Acknowledge one or more messages.
When sent by the client, this method acknowledges one or more messages delivered via the
Deliver or Get-Ok methods. When sent by server, this method acknowledges one or more
messages published with the Publish method on a channel in confirm mode. The acknowledgement
can be for a single message or a set of messages up to and including a specific message.
:param delivery_tag: The server-assigned delivery tag
:param multiple: If set to True, the delivery tag is treated as "up to and including", so
that multiple messages can be acknowledged with a single method. If set to False, the
delivery tag refers to a single message. If the multiple field is 1, and the delivery
tag is zero, this indicates acknowledgement of all outstanding messages.
"""
self._impl.basic_ack(delivery_tag=delivery_tag, multiple=multiple)
self._flush_output()
def basic_nack(self,
delivery_tag: int = 0,
multiple: bool = False,
requeue: bool = True) -> None:
"""
This method allows a client to reject one or more incoming messages.
It can be used to interrupt and cancel large incoming messages, or return untreatable
messages to their original queue.
:param delivery_tag: The server-assigned delivery tag
:param multiple: If set to True, the delivery tag is treated as "up to and including", so
that multiple messages can be acknowledged with a single method. If set to False, the
delivery tag refers to a single message. If the multiple field is 1, and the delivery
tag is zero, this indicates acknowledgement of all outstanding messages.
:param requeue: If requeue is true, the server will attempt to requeue the message. If
requeue is false or the requeue attempt fails the messages are discarded or dead-
lettered.
"""
self._impl.basic_nack(delivery_tag=delivery_tag,
multiple=multiple,
requeue=requeue)
self._flush_output()
def basic_get(
self,
queue: str,
auto_ack: bool = False
) -> tuple[pika.spec.Basic.GetOk | None, pika.spec.BasicProperties | None,
bytes | None]:
"""
Get a single message from the AMQP broker.
Returns a sequence with the method frame, message properties, and body.
:param queue: Name of queue from which to get a message
:param auto_ack: Tell the broker to not expect a reply
:returns: a three-tuple; (None, None, None) if the queue was empty; otherwise (method,
properties, body); NOTE: body may be None
"""
assert not self._basic_getempty_result
validators.require_string(queue, 'queue')
with contextlib.ExitStack() as stack:
get_ok_result = stack.enter_context(
_CallbackResult(self._RxMessageArgs))
stack.enter_context(self._basic_getempty_result)
self._impl.basic_get(queue=queue,
auto_ack=auto_ack,
callback=get_ok_result.set_value_once)
self._flush_output(get_ok_result.is_ready,
self._basic_getempty_result.is_ready)
if get_ok_result:
evt = get_ok_result.value
return evt.method, evt.properties, evt.body
assert self._basic_getempty_result, (
'wait completed without GetOk and GetEmpty')
return None, None, None
def basic_publish(self,
exchange: str,
routing_key: str,
body: bytes,
properties: pika.spec.BasicProperties | None = None,
mandatory: bool = False) -> None:
"""
Publish to the channel with the given exchange, routing key, and body.
For more information on basic_publish and what the parameters do, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.publish
NOTE: mandatory may be enabled even without delivery
confirmation, but in the absence of delivery confirmation the
synchronous implementation has no way to know how long to wait for
the Basic.Return.
:param exchange: The exchange to publish to
:param routing_key: The routing key to bind on
:param body: The message body; empty string if no body
:param properties: message properties
:param mandatory: The mandatory flag
:raises UnroutableError: raised when a message published in
publisher-acknowledgments mode (see
`BlockingChannel.confirm_delivery`) is returned via `Basic.Return`
followed by `Basic.Ack`.
:raises NackError: raised when a message published in
publisher-acknowledgements mode is Nack'ed by the broker. See
`BlockingChannel.confirm_delivery`.
"""
if self._delivery_confirmation:
# In publisher-acknowledgments mode
with self._message_confirmation_result:
self._impl.basic_publish(exchange=exchange,
routing_key=routing_key,
body=body,
properties=properties,
mandatory=mandatory)
self._flush_output(self._message_confirmation_result.is_ready)
conf_method = (
self._message_confirmation_result.value.method_frame.method)
if isinstance(conf_method, pika.spec.Basic.Nack):
# Broker was unable to process the message due to internal
# error
LOGGER.warning(
"Message was Nack'ed by broker: nack=%r; channel=%s; "
"exchange=%s; routing_key=%s; mandatory=%r; ",
conf_method, self.channel_number, exchange, routing_key,
mandatory)
if self._puback_return is not None:
returned_messages: list[ReturnedMessage] = [
self._puback_return
]
self._puback_return = None
else:
returned_messages = []
raise exceptions.NackError(returned_messages)
assert isinstance(conf_method,
pika.spec.Basic.Ack), (conf_method)
if self._puback_return is not None:
# Unroutable message was returned
messages = [self._puback_return]
self._puback_return = None
raise exceptions.UnroutableError(messages)
else:
# In non-publisher-acknowledgments mode
self._impl.basic_publish(exchange=exchange,
routing_key=routing_key,
body=body,
properties=properties,
mandatory=mandatory)
self._flush_output()
def basic_qos(self,
prefetch_size: int = 0,
prefetch_count: int = 0,
global_qos: bool = False) -> None:
"""
Specify quality of service.
This method requests a specific quality of service. The QoS can be specified for the current
channel or for all channels on the connection. The client can request that messages be sent
in advance so that when the client finishes processing a message, the following message is
already held locally, rather than needing to be sent down the channel. Prefetching gives a
performance improvement.
:param prefetch_size: This field specifies the prefetch window size. The server will send a
message in advance if it is equal to or smaller in size than the available prefetch size
(and also falls into other prefetch limits). May be set to zero, meaning "no specific
limit", although other prefetch limits may still apply. The prefetch-size is ignored if
the no-ack option is set in the consumer.
:param prefetch_count: Specifies a prefetch window in terms of whole messages. This field
may be used in combination with the prefetch-size field; a message will only be sent in
advance if both prefetch windows (and those at the channel and connection level) allow
it. The prefetch-count is ignored if the no-ack option is set in the consumer.
:param global_qos: Should the QoS apply to all channels on the connection.
"""
with _CallbackResult() as qos_ok_result:
self._impl.basic_qos(callback=qos_ok_result.signal_once,
prefetch_size=prefetch_size,
prefetch_count=prefetch_count,
global_qos=global_qos)
self._flush_output(qos_ok_result.is_ready)
def basic_recover(self, requeue: bool = False) -> None:
"""
This method asks the server to redeliver all unacknowledged messages on a specified channel.
Zero or more messages may be redelivered. This method replaces the asynchronous Recover.
:param requeue: If False, the message will be redelivered to the original recipient. If
True, the server will attempt to requeue the message, potentially then delivering it to
an alternative subscriber.
"""
with _CallbackResult() as recover_ok_result:
self._impl.basic_recover(requeue=requeue,
callback=recover_ok_result.signal_once)
self._flush_output(recover_ok_result.is_ready)
def basic_reject(self, delivery_tag: int = 0, requeue: bool = True) -> None:
"""
Reject an incoming message.
This method allows a client to reject a message. It can be used to interrupt and cancel
large incoming messages, or return untreatable messages to their original queue.
:param delivery_tag: The server-assigned delivery tag
:param requeue: If requeue is true, the server will attempt to requeue the message. If
requeue is false or the requeue attempt fails the messages are discarded or dead-
lettered.
"""
self._impl.basic_reject(delivery_tag=delivery_tag, requeue=requeue)
self._flush_output()
def confirm_delivery(self) -> None:
"""
Turn on RabbitMQ-proprietary Confirm mode in the channel.
For more information see:
https://www.rabbitmq.com/confirms.html
"""
if self._delivery_confirmation:
LOGGER.error(
'confirm_delivery: confirmation was already enabled '
'on channel=%s', self.channel_number)
return
with _CallbackResult() as select_ok_result:
self._impl.confirm_delivery(
ack_nack_callback=self._message_confirmation_result.
set_value_once,
callback=select_ok_result.signal_once)
self._flush_output(select_ok_result.is_ready)
self._delivery_confirmation = True
# Unroutable messages returned after this point will be in the context
# of publisher acknowledgments
self._impl.add_on_return_callback(self._on_puback_message_returned)
def exchange_declare(self,
exchange: str,
exchange_type: (ExchangeType |
str) = ExchangeType.direct,
passive: bool = False,
durable: bool = False,
auto_delete: bool = False,
internal: bool = False,
arguments: dict[str, Any] | None = None) -> None:
"""
This method creates an exchange if it does not already exist, and if the exchange exists,
verifies that it is of the correct and expected class.
If passive set, the server will reply with Declare-Ok if the exchange
already exists with the same name, and raise an error if not and if the
exchange does not already exist, the server MUST raise a channel
exception with reply code 404 (not found).
:param exchange: The exchange name consists of a non-empty sequence of
these characters: letters, digits, hyphen, underscore,
period, or colon.
:param exchange_type: The exchange type to use
:param passive: Perform a declare or just check to see if it exists
:param durable: Survive a reboot of RabbitMQ
:param auto_delete: Remove when no more queues are bound to it
:param internal: Can only be published to by other exchanges
:param arguments: Custom key/value pair arguments for the exchange
:returns: Method frame from the Exchange.Declare-ok response
"""
validators.require_string(exchange, 'exchange')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as declare_ok_result:
self._impl.exchange_declare(
exchange=exchange,
exchange_type=exchange_type,
passive=passive,
durable=durable,
auto_delete=auto_delete,
internal=internal,
arguments=arguments,
callback=declare_ok_result.set_value_once)
self._flush_output(declare_ok_result.is_ready)
return declare_ok_result.value.method_frame
def exchange_delete(self,
exchange: str | None = None,
if_unused: bool = False
) -> pika.frame.Method[pika.spec.Exchange.DeleteOk]:
"""
Delete the exchange.
:param exchange: The exchange name
:param if_unused: only delete if the exchange is unused
:returns: Method frame from the Exchange.Delete-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as delete_ok_result:
self._impl.exchange_delete(exchange=exchange,
if_unused=if_unused,
callback=delete_ok_result.set_value_once)
self._flush_output(delete_ok_result.is_ready)
return delete_ok_result.value.method_frame
def exchange_bind(
self,
destination: str,
source: str,
routing_key: str = '',
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Exchange.BindOk]:
"""
Bind an exchange to another exchange.
:param destination: The destination exchange to bind
:param source: The source exchange to bind to
:param routing_key: The routing key to bind on
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Exchange.Bind-ok response
"""
validators.require_string(destination, 'destination')
validators.require_string(source, 'source')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as bind_ok_result:
self._impl.exchange_bind(destination=destination,
source=source,
routing_key=routing_key,
arguments=arguments,
callback=bind_ok_result.set_value_once)
self._flush_output(bind_ok_result.is_ready)
return bind_ok_result.value.method_frame
def exchange_unbind(
self,
destination: str | None = None,
source: str | None = None,
routing_key: str = '',
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Exchange.UnbindOk]:
"""
Unbind an exchange from another exchange.
:param destination: The destination exchange to unbind
:param source: The source exchange to unbind from
:param routing_key: The routing key to unbind
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Exchange.Unbind-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as unbind_ok_result:
self._impl.exchange_unbind(destination=destination,
source=source,
routing_key=routing_key,
arguments=arguments,
callback=unbind_ok_result.set_value_once)
self._flush_output(unbind_ok_result.is_ready)
return unbind_ok_result.value.method_frame
def queue_declare(
self,
queue: str,
passive: bool = False,
durable: bool = False,
exclusive: bool = False,
auto_delete: bool = False,
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Queue.DeclareOk]:
"""
Declare queue, create if needed.
This method creates or checks a queue. When creating a new queue the client can specify various
properties that control the durability of the queue and its contents,
and the level of sharing for the queue.
Use an empty string as the queue name for the broker to auto-generate
one. Retrieve this auto-generated queue name from the returned
`spec.Queue.DeclareOk` method frame.
:param queue: The queue name; if empty string, the broker will
create a unique queue name
:param passive: Only check to see if the queue exists and raise
`ChannelClosed` if it doesn't
:param durable: Survive reboots of the broker
:param exclusive: Only allow access by the current connection
:param auto_delete: Delete after consumer cancels or disconnects
:param arguments: Custom key/value arguments for the queue
:returns: Method frame from the Queue.Declare-ok response
"""
validators.require_string(queue, 'queue')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as declare_ok_result:
self._impl.queue_declare(queue=queue,
passive=passive,
durable=durable,
exclusive=exclusive,
auto_delete=auto_delete,
arguments=arguments,
callback=declare_ok_result.set_value_once)
self._flush_output(declare_ok_result.is_ready)
return declare_ok_result.value.method_frame
def queue_delete(self,
queue: str,
if_unused: bool = False,
if_empty: bool = False
) -> pika.frame.Method[pika.spec.Queue.DeleteOk]:
"""
Delete a queue from the broker.
:param queue: The queue to delete
:param if_unused: only delete if it's unused
:param if_empty: only delete if the queue is empty
:returns: Method frame from the Queue.Delete-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as delete_ok_result:
self._impl.queue_delete(queue=queue,
if_unused=if_unused,
if_empty=if_empty,
callback=delete_ok_result.set_value_once)
self._flush_output(delete_ok_result.is_ready)
return delete_ok_result.value.method_frame
def queue_purge(self,
queue: str) -> pika.frame.Method[pika.spec.Queue.PurgeOk]:
"""
Purge all of the messages from the specified queue.
:param queue: The queue to purge
:returns: Method frame from the Queue.Purge-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as purge_ok_result:
self._impl.queue_purge(queue=queue,
callback=purge_ok_result.set_value_once)
self._flush_output(purge_ok_result.is_ready)
return purge_ok_result.value.method_frame
def queue_bind(
self,
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Queue.BindOk]:
"""
Bind the queue to the specified exchange.
:param queue: The queue to bind to the exchange
:param exchange: The source exchange to bind to
:param routing_key: The routing key to bind on
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Queue.Bind-ok response
"""
validators.require_string(queue, 'queue')
validators.require_string(exchange, 'exchange')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as bind_ok_result:
self._impl.queue_bind(queue=queue,
exchange=exchange,
routing_key=routing_key,
arguments=arguments,
callback=bind_ok_result.set_value_once)
self._flush_output(bind_ok_result.is_ready)
return bind_ok_result.value.method_frame
def queue_unbind(
self,
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Queue.UnbindOk]:
"""
Unbind a queue from an exchange.
:param queue: The queue to unbind from the exchange
:param exchange: The source exchange to bind from
:param routing_key: The routing key to unbind
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Queue.Unbind-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as unbind_ok_result:
self._impl.queue_unbind(queue=queue,
exchange=exchange,
routing_key=routing_key,
arguments=arguments,
callback=unbind_ok_result.set_value_once)
self._flush_output(unbind_ok_result.is_ready)
return unbind_ok_result.value.method_frame
def tx_select(self) -> pika.frame.Method[pika.spec.Tx.SelectOk]:
"""
Select standard transaction mode.
This method sets the channel to use standard transactions. The client must use this method
at least once on a channel before using the Commit or Rollback methods.
:returns: Method frame from the Tx.Select-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as select_ok_result:
self._impl.tx_select(select_ok_result.set_value_once)
self._flush_output(select_ok_result.is_ready)
return select_ok_result.value.method_frame
def tx_commit(self) -> pika.frame.Method[pika.spec.Tx.CommitOk]:
"""
Commit a transaction.
:returns: Method frame from the Tx.Commit-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as commit_ok_result:
self._impl.tx_commit(commit_ok_result.set_value_once)
self._flush_output(commit_ok_result.is_ready)
return commit_ok_result.value.method_frame
def tx_rollback(self) -> pika.frame.Method[pika.spec.Tx.RollbackOk]:
"""
Rollback a transaction.
:returns: Method frame from the Tx.Rollback-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as rollback_ok_result:
self._impl.tx_rollback(rollback_ok_result.set_value_once)
self._flush_output(rollback_ok_result.is_ready)
return rollback_ok_result.value.method_frame
class-attribute
instance-attribute
¶
_CONSUMER_CANCELLED_CB_KEY = (
'blocking_channel_consumer_cancelled'
)
instance-attribute
¶
_basic_getempty_result = _CallbackResult(
self._MethodFrameCallbackResultArgs
)
instance-attribute
¶
_message_confirmation_result = _CallbackResult(
self._OnMessageConfirmationReportArgs
)
instance-attribute
¶
_queue_consumer_generator: (
_QueueConsumerGeneratorInfo | None
) = None
property
¶
consumer_tags: list[str]
Property method that returns a list of consumer tags for active consumers.
Bases: NamedTuple
Source code in pika/adapters/blocking_connection.py
class _FlowOkCallbackResultArgs(NamedTuple):
active: bool
Bases: NamedTuple
Source code in pika/adapters/blocking_connection.py
class _MethodFrameCallbackResultArgs(NamedTuple):
method_frame: Any
Bases: NamedTuple
Source code in pika/adapters/blocking_connection.py
class _OnMessageConfirmationReportArgs(NamedTuple):
method_frame: Any
Bases: NamedTuple
Source code in pika/adapters/blocking_connection.py
class _RxMessageArgs(NamedTuple):
channel: Any
method: Any
properties: Any
body: bytes
__enter__() -> Self
Source code in pika/adapters/blocking_connection.py
def __enter__(self) -> Self:
return self
__exit__(
exc_type: type[BaseException] | None,
value: BaseException | None,
traceback: TracebackType | None,
) -> None
Source code in pika/adapters/blocking_connection.py
def __exit__(self, exc_type: type[BaseException] | None,
value: BaseException | None,
traceback: TracebackType | None) -> None:
if self.is_open:
self.close()
__init__(
channel_impl: Channel, connection: BlockingConnection
) -> None
Create a new instance of the Channel.
| PARAMETER | DESCRIPTION |
|---|---|
channel_impl
|
Channel implementation object as returned from SelectConnection.channel()
TYPE:
|
connection
|
The connection object
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def __init__(self, channel_impl: pika.channel.Channel,
connection: BlockingConnection) -> None:
"""
Create a new instance of the Channel.
:param channel_impl: Channel implementation object as returned from
SelectConnection.channel()
:param connection: The connection object
"""
self._impl = channel_impl
self._connection = connection
# A mapping of consumer tags to _ConsumerInfo for active consumers
self._consumer_infos: dict[Any, Any] = {}
# Queue consumer generator generator info of type
# _QueueConsumerGeneratorInfo created by BlockingChannel.consume
self._queue_consumer_generator: _QueueConsumerGeneratorInfo | None = None
# Whether RabbitMQ delivery confirmation has been enabled
self._delivery_confirmation = False
# Receives message delivery confirmation report (Basic.ack or
# Basic.nack) from broker when delivery confirmations are enabled
self._message_confirmation_result = _CallbackResult(
self._OnMessageConfirmationReportArgs)
# deque of pending events: _ConsumerDeliveryEvt and
# _ConsumerCancellationEvt objects that will be returned by
# `BlockingChannel.get_event()`
self._pending_events: deque[Any] = deque()
# Holds a ReturnedMessage object representing a message received via
# Basic.Return in publisher-acknowledgments mode.
self._puback_return: ReturnedMessage | None = None
# self._on_channel_closed() saves the reason exception here
self._closing_reason = None # type: None | Exception
# Receives Basic.ConsumeOk reply from server
self._basic_consume_ok_result = _CallbackResult()
# Receives args from Basic.GetEmpty response
# https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.get
self._basic_getempty_result = _CallbackResult(
self._MethodFrameCallbackResultArgs)
self._impl.add_on_cancel_callback(self._on_consumer_cancelled_by_broker)
self._impl.add_callback(self._basic_consume_ok_result.signal_once,
replies=[pika.spec.Basic.ConsumeOk],
one_shot=False)
self._impl.add_on_close_callback(self._on_channel_closed)
self._impl.add_callback(self._basic_getempty_result.set_value_once,
replies=[pika.spec.Basic.GetEmpty],
one_shot=False)
LOGGER.info('Created channel=%s', self.channel_number)
__int__() -> int
Return the channel object as its channel number.
NOTE: inherited from legacy BlockingConnection; might be error-prone;
use channel_number property instead.
Source code in pika/adapters/blocking_connection.py
def __int__(self) -> int:
"""
Return the channel object as its channel number.
NOTE: inherited from legacy BlockingConnection; might be error-prone;
use `channel_number` property instead.
"""
return self.channel_number
__repr__() -> str
Source code in pika/adapters/blocking_connection.py
@override
def __repr__(self) -> str:
return f'<{self.__class__.__name__} impl={self._impl!r}>'
_add_pending_event(evt: _ChannelPendingEvt) -> None
Append an event to the channel's list of events that are ready for dispatch to user and signal our connection that this channel is ready for event dispatch.
| PARAMETER | DESCRIPTION |
|---|---|
evt
|
an event derived from _ChannelPendingEvt
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def _add_pending_event(self, evt: _ChannelPendingEvt) -> None:
"""
Append an event to the channel's list of events that are ready for dispatch to user and
signal our connection that this channel is ready for event dispatch.
:param evt: an event derived from _ChannelPendingEvt
"""
self._pending_events.append(evt)
self.connection._request_channel_dispatch(self.channel_number)
_basic_consume_impl(
queue: str,
auto_ack: bool,
exclusive: bool,
consumer_tag: str | None,
arguments: dict[str, Any] | None = None,
on_message_callback: Callable[
[BlockingChannel, Deliver, BasicProperties, bytes],
None,
]
| None = None,
alternate_event_sink: Callable[
[_ChannelPendingEvt], None
]
| None = None,
) -> str
The low-level implementation used by basic_consume and consume.
See basic_consume docstring for more info.
NOTE: exactly one of on_message_callback/alternate_event_sink musts be non-None.
This method has one additional parameter alternate_event_sink over the
args described in basic_consume.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
Queue name
TYPE:
|
auto_ack
|
If True, the broker acknowledges messages automatically
TYPE:
|
exclusive
|
If True, restrict access to the current connection
TYPE:
|
consumer_tag
|
if specified, only the consumer with the given tag will be cancelled
TYPE:
|
arguments
|
Custom key/value pair arguments for the consumer
TYPE:
|
on_message_callback
|
Callback for delivered messages
TYPE:
|
alternate_event_sink
|
if specified, _ConsumerDeliveryEvt
and _ConsumerCancellationEvt objects will be diverted to this
callback instead of being deposited in the channel's
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
pika.exceptions.DuplicateConsumerTag
|
if consumer with given consumer_tag is already present. |
Source code in pika/adapters/blocking_connection.py
def _basic_consume_impl(
self,
queue: str,
auto_ack: bool,
exclusive: bool,
consumer_tag: str | None,
arguments: dict[str, Any] | None = None,
on_message_callback: Callable[[
BlockingChannel, pika.spec.Basic.Deliver, pika.spec.
BasicProperties, bytes
], None] | None = None,
alternate_event_sink: Callable[[_ChannelPendingEvt], None] | None = None
) -> str:
"""
The low-level implementation used by `basic_consume` and `consume`.
See `basic_consume` docstring for more info.
NOTE: exactly one of on_message_callback/alternate_event_sink musts be
non-None.
This method has one additional parameter alternate_event_sink over the
args described in `basic_consume`.
:param queue: Queue name
:param auto_ack: If True, the broker acknowledges messages automatically
:param exclusive: If True, restrict access to the current connection
:param consumer_tag: if specified, only the consumer with the given tag will be cancelled
:param arguments: Custom key/value pair arguments for the consumer
:param on_message_callback: Callback for delivered messages
:param alternate_event_sink: if specified, _ConsumerDeliveryEvt
and _ConsumerCancellationEvt objects will be diverted to this
callback instead of being deposited in the channel's
`_pending_events` container. Signature:
alternate_event_sink(evt)
:raises pika.exceptions.DuplicateConsumerTag: if consumer with given
consumer_tag is already present.
"""
if (on_message_callback is None) == (alternate_event_sink is None):
raise ValueError(((
'exactly one of on_message_callback/alternate_event_sink must '
'be non-None'), on_message_callback, alternate_event_sink))
if not consumer_tag:
# Need a consumer tag to register consumer info before sending
# request to broker, because I/O might dispatch incoming messages
# immediately following Basic.Consume-ok before _flush_output
# returns
consumer_tag = self._impl._generate_consumer_tag()
if consumer_tag in self._consumer_infos:
raise exceptions.DuplicateConsumerTag(consumer_tag)
# Create new consumer
self._consumer_infos[consumer_tag] = _ConsumerInfo(
consumer_tag,
auto_ack=auto_ack,
on_message_callback=on_message_callback,
alternate_event_sink=alternate_event_sink)
try:
with self._basic_consume_ok_result as ok_result:
tag = self._impl.basic_consume(
on_message_callback=self._on_consumer_message_delivery,
queue=queue,
auto_ack=auto_ack,
exclusive=exclusive,
consumer_tag=consumer_tag,
arguments=arguments)
assert tag == consumer_tag, (tag, consumer_tag)
self._flush_output(ok_result.is_ready)
except Exception:
# If channel was closed, self._consumer_infos will be empty
if consumer_tag in self._consumer_infos:
del self._consumer_infos[consumer_tag]
# Schedule termination of connection.process_data_events using a
# negative channel number
self.connection._request_channel_dispatch(-self.channel_number)
raise
# NOTE: Consumer could get cancelled by broker immediately after opening
# (e.g., queue getting deleted externally)
if self._consumer_infos[consumer_tag].setting_up:
self._consumer_infos[consumer_tag].state = _ConsumerInfo.ACTIVE
return consumer_tag
_cancel_all_consumers() -> None
Cancel all consumers.
NOTE: pending non-ackable messages will be lost; pending ackable messages will be rejected.
Source code in pika/adapters/blocking_connection.py
def _cancel_all_consumers(self) -> None:
"""
Cancel all consumers.
NOTE: pending non-ackable messages will be lost; pending ackable
messages will be rejected.
"""
if self._consumer_infos:
LOGGER.debug('Cancelling %i consumers', len(self._consumer_infos))
if self._queue_consumer_generator is not None:
# Cancel queue consumer generator
self.cancel()
# Cancel consumers created via basic_consume
for consumer_tag in list(self._consumer_infos.keys()):
self.basic_cancel(consumer_tag)
_cleanup() -> None
Clean up members that might inhibit garbage collection.
Source code in pika/adapters/blocking_connection.py
def _cleanup(self) -> None:
"""Clean up members that might inhibit garbage collection."""
self._message_confirmation_result.reset()
self._pending_events = deque()
self._consumer_infos = {}
self._queue_consumer_generator = None
_dispatch_events() -> None
Called by BlockingConnection to dispatch pending events.
BlockingChannel schedules this callback via BlockingConnection._request_channel_dispatch
Source code in pika/adapters/blocking_connection.py
def _dispatch_events(self) -> None:
"""
Called by BlockingConnection to dispatch pending events.
`BlockingChannel` schedules this callback via `BlockingConnection._request_channel_dispatch`
"""
while self._pending_events:
evt = self._pending_events.popleft()
if type(evt) is _ConsumerDeliveryEvt:
consumer_info = self._consumer_infos[evt.method.consumer_tag]
consumer_info.on_message_callback(self, evt.method,
evt.properties, evt.body)
elif type(evt) is _ConsumerCancellationEvt:
del self._consumer_infos[evt.method_frame.method.consumer_tag]
self._impl.callbacks.process(self.channel_number,
self._CONSUMER_CANCELLED_CB_KEY,
self, evt.method_frame)
else:
evt.dispatch()
_flush_output(*waiters: Callable[[], bool]) -> None
Flush output and process input while waiting for any of the given callbacks to return true. The wait is aborted upon channel-close or connection-close. Otherwise, processing continues until the output is flushed AND at least one of the callbacks returns true. If there are no callbacks, then processing ends when all output is flushed.
| PARAMETER | DESCRIPTION |
|---|---|
waiters
|
sequence of zero or more callables taking no args and returning true when it's time to stop processing. Their results are OR'ed together. An empty sequence is treated as equivalent to a waiter always returning true.
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def _flush_output(self, *waiters: Callable[[], bool]) -> None:
"""
Flush output and process input while waiting for any of the given callbacks to return true.
The wait is aborted upon channel-close or connection-close. Otherwise, processing continues
until the output is flushed AND at least one of the callbacks returns true. If there are no
callbacks, then processing ends when all output is flushed.
:param waiters: sequence of zero or more callables taking no args and returning true when
it's time to stop processing. Their results are OR'ed together. An empty sequence is
treated as equivalent to a waiter always returning true.
"""
if self.is_closed:
self._impl._raise_if_not_open()
if not waiters:
waiters = self._ALWAYS_READY_WAITERS
self._connection._flush_output(lambda: self.is_closed, *waiters)
if self.is_closed and isinstance(self._closing_reason,
exceptions.ChannelClosedByBroker):
raise self._closing_reason
_on_channel_closed(
_channel: Channel, reason: Exception
) -> None
Callback from impl notifying us that the channel has been closed.
This may be as the result of user-, broker-, or internal connection clean-up initiated closing or meta-closing of the channel.
If it resulted from receiving Channel.Close from broker, we will
expedite waking up of the event subsystem so that it may respond by
raising ChannelClosed from user's context.
NOTE: We can't raise exceptions in callbacks in order to protect the integrity of the underlying implementation. BlockingConnection's underlying asynchronous connection adapter (SelectConnection) uses callbacks to communicate with us. If BlockingConnection leaks exceptions back into the I/O loop or the asynchronous connection adapter, we interrupt their normal workflow and introduce a high likelihood of state inconsistency.
See pika.Channel.add_on_close_callback() for additional documentation.
| PARAMETER | DESCRIPTION |
|---|---|
_channel
|
(unused)
TYPE:
|
reason
|
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def _on_channel_closed(self, _channel: pika.channel.Channel,
reason: Exception) -> None:
"""
Callback from impl notifying us that the channel has been closed.
This may be as the result of user-, broker-, or internal connection clean-up initiated closing or meta-closing of the
channel.
If it resulted from receiving `Channel.Close` from broker, we will
expedite waking up of the event subsystem so that it may respond by
raising `ChannelClosed` from user's context.
NOTE: We can't raise exceptions in callbacks in order to protect
the integrity of the underlying implementation. BlockingConnection's
underlying asynchronous connection adapter (SelectConnection) uses
callbacks to communicate with us. If BlockingConnection leaks exceptions
back into the I/O loop or the asynchronous connection adapter, we
interrupt their normal workflow and introduce a high likelihood of state
inconsistency.
See `pika.Channel.add_on_close_callback()` for additional documentation.
:param _channel: (unused)
:param reason:
"""
LOGGER.debug('_on_channel_closed: %r; %r', reason, self)
self._closing_reason = reason
if isinstance(reason, exceptions.ChannelClosedByBroker):
self.connection._server_channel_closures.append(reason)
self._cleanup()
# Request urgent termination of `process_data_events()`, in case
# it's executing or next time it will execute
self.connection._request_channel_dispatch(-self.channel_number)
_on_consumer_cancelled_by_broker(
method_frame: Method[Cancel],
) -> None
Called by impl when broker cancels consumer via Basic.Cancel.
This is a RabbitMQ-specific feature. The circumstances include deletion of queue being consumed as well as failure of a HA node responsible for the queue being consumed.
| PARAMETER | DESCRIPTION |
|---|---|
method_frame
|
method frame with the
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def _on_consumer_cancelled_by_broker(
self,
method_frame: pika.frame.Method[pika.spec.Basic.Cancel]) -> None:
"""
Called by impl when broker cancels consumer via Basic.Cancel.
This is a RabbitMQ-specific feature. The circumstances include deletion of queue being
consumed as well as failure of a HA node responsible for the queue being consumed.
:param method_frame: method frame with the `spec.Basic.Cancel` method
"""
evt = _ConsumerCancellationEvt(method_frame)
consumer = self._consumer_infos[method_frame.method.consumer_tag]
# Don't interfere with client-initiated cancellation flow
if not consumer.tearing_down:
consumer.state = _ConsumerInfo.CANCELLED_BY_BROKER
if consumer.alternate_event_sink is not None:
consumer.alternate_event_sink(evt)
else:
self._add_pending_event(evt)
_on_consumer_generator_event(
evt: _ChannelPendingEvt,
) -> None
Sink for the queue consumer generator's consumer events; append the event to queue consumer generator's pending events buffer.
| PARAMETER | DESCRIPTION |
|---|---|
evt
|
an object of type _ConsumerDeliveryEvt or _ConsumerCancellationEvt
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def _on_consumer_generator_event(self, evt: _ChannelPendingEvt) -> None:
"""
Sink for the queue consumer generator's consumer events; append the event to queue consumer
generator's pending events buffer.
:param evt: an object of type _ConsumerDeliveryEvt or _ConsumerCancellationEvt
"""
assert self._queue_consumer_generator is not None
self._queue_consumer_generator.pending_events.append(evt)
# Schedule termination of connection.process_data_events using a
# negative channel number
self.connection._request_channel_dispatch(-self.channel_number)
_on_consumer_message_delivery(
_channel: Channel,
method: Deliver,
properties: BasicProperties,
body: bytes,
) -> None
Called by impl when a message is delivered for a consumer.
| PARAMETER | DESCRIPTION |
|---|---|
_channel
|
The implementation channel object
TYPE:
|
method
|
TYPE:
|
properties
|
message properties
TYPE:
|
body
|
delivered message body; empty string if no body
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def _on_consumer_message_delivery(self, _channel: pika.channel.Channel,
method: pika.spec.Basic.Deliver,
properties: pika.spec.BasicProperties,
body: bytes) -> None:
"""
Called by impl when a message is delivered for a consumer.
:param _channel: The implementation channel object
:param method:
:param properties: message properties
:param body: delivered message body; empty string if no body
"""
evt = _ConsumerDeliveryEvt(method, properties, body)
consumer = self._consumer_infos[method.consumer_tag]
if consumer.alternate_event_sink is not None:
consumer.alternate_event_sink(evt)
else:
self._add_pending_event(evt)
_on_puback_message_returned(
channel: Channel,
method: Return,
properties: BasicProperties,
body: bytes,
) -> None
Called as the result of Basic.Return from broker in publisher-acknowledgements mode.
Saves the info as a ReturnedMessage instance in self._puback_return.
| PARAMETER | DESCRIPTION |
|---|---|
channel
|
our self._impl channel
TYPE:
|
method
|
TYPE:
|
properties
|
message properties
TYPE:
|
body
|
returned message body; empty string if no body
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def _on_puback_message_returned(self, channel: pika.channel.Channel,
method: pika.spec.Basic.Return,
properties: pika.spec.BasicProperties,
body: bytes) -> None:
"""
Called as the result of Basic.Return from broker in publisher-acknowledgements mode.
Saves the info as a ReturnedMessage instance in self._puback_return.
:param channel: our self._impl channel
:param method:
:param properties: message properties
:param body: returned message body; empty string if no body
"""
assert channel is self._impl, (channel.channel_number,
self.channel_number)
assert isinstance(method, pika.spec.Basic.Return), method
assert isinstance(properties, pika.spec.BasicProperties), (properties)
LOGGER.warning(
'Published message was returned: _delivery_confirmation=%s; '
'channel=%s; method=%r; properties=%r; body_size=%d; '
'body_prefix=%.255r', self._delivery_confirmation,
channel.channel_number, method, properties,
len(body) if body is not None else None, body)
self._puback_return = ReturnedMessage(method, properties, body)
_process_data_events(time_limit: float | None) -> None
Wrapper for BlockingConnection.process_data_events() with common channel-specific logic
that raises ChannelClosed if broker closed this channel.
NOTE: We need to raise an exception in the context of user's call into our API to protect the integrity of the underlying implementation. BlockingConnection's underlying asynchronous connection adapter (SelectConnection) uses callbacks to communicate with us. If BlockingConnection leaks exceptions back into the I/O loop or the asynchronous connection adapter, we interrupt their normal workflow and introduce a high likelihood of state inconsistency.
See BlockingConnection.process_data_events() for documentation of args
and behavior.
| PARAMETER | DESCRIPTION |
|---|---|
time_limit
|
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def _process_data_events(self, time_limit: float | None) -> None:
"""
Wrapper for `BlockingConnection.process_data_events()` with common channel-specific logic
that raises ChannelClosed if broker closed this channel.
NOTE: We need to raise an exception in the context of user's call into
our API to protect the integrity of the underlying implementation.
BlockingConnection's underlying asynchronous connection adapter
(SelectConnection) uses callbacks to communicate with us. If
BlockingConnection leaks exceptions back into the I/O loop or the
asynchronous connection adapter, we interrupt their normal workflow and
introduce a high likelihood of state inconsistency.
See `BlockingConnection.process_data_events()` for documentation of args
and behavior.
:param time_limit:
"""
self.connection.process_data_events(time_limit=time_limit)
if self.is_closed and isinstance(self._closing_reason,
exceptions.ChannelClosedByBroker):
LOGGER.debug('Channel close by broker detected, raising %r; %r',
self._closing_reason, self)
raise self._closing_reason
_remove_pending_deliveries(
consumer_tag: str,
) -> Sequence[_ConsumerDeliveryEvt]
Extract _ConsumerDeliveryEvt objects destined for the given consumer from pending events, discarding the _ConsumerCancellationEvt, if any.
| PARAMETER | DESCRIPTION |
|---|---|
consumer_tag
|
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Sequence[_ConsumerDeliveryEvt]
|
a (possibly empty) sequence of _ConsumerDeliveryEvt destined for the given consumer tag |
Source code in pika/adapters/blocking_connection.py
def _remove_pending_deliveries(
self, consumer_tag: str) -> Sequence[_ConsumerDeliveryEvt]:
"""
Extract _ConsumerDeliveryEvt objects destined for the given consumer from pending events,
discarding the _ConsumerCancellationEvt, if any.
:param consumer_tag:
:returns: a (possibly empty) sequence of _ConsumerDeliveryEvt destined for the given
consumer tag
"""
remaining_events: deque[Any] = deque()
unprocessed_messages: list[Any] = []
while self._pending_events:
evt = self._pending_events.popleft()
if (type(evt) is _ConsumerDeliveryEvt and
evt.method.consumer_tag == consumer_tag):
unprocessed_messages.append(evt)
continue
if (type(evt) is _ConsumerCancellationEvt and
evt.method_frame.method.consumer_tag == consumer_tag):
# A broker-initiated Basic.Cancel must have arrived
# before our cancel request completed
continue
remaining_events.append(evt)
self._pending_events = remaining_events
return unprocessed_messages
add_on_cancel_callback(
callback: Callable[[Method[Cancel]], None],
) -> None
Pass a callback function that will be called when Basic.Cancel is sent by the broker.
The callback function should receive a method frame parameter.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
a callable for handling broker's Basic.Cancel
notification with the call signature: callback(method_frame)
where method_frame is of type
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def add_on_cancel_callback(
self, callback: Callable[[pika.frame.Method[pika.spec.Basic.Cancel]],
None]
) -> None:
"""
Pass a callback function that will be called when Basic.Cancel is sent by the broker.
The callback function should receive a method frame parameter.
:param callback: a callable for handling broker's Basic.Cancel
notification with the call signature: callback(method_frame)
where method_frame is of type `pika.frame.Method` with method of
type `spec.Basic.Cancel`
"""
self._impl.callbacks.add(self.channel_number,
self._CONSUMER_CANCELLED_CB_KEY,
callback,
one_shot=False)
add_on_return_callback(
callback: Callable[
[BlockingChannel, Return, BasicProperties, bytes],
None,
],
) -> None
Pass a callback function that will be called when a published message is rejected and
returned by the server via Basic.Return.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The method to call on callback with the signature callback(channel, method, properties, body), where - channel: pika.Channel - method: pika.spec.Basic.Return - properties: pika.spec.BasicProperties - body: bytes
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def add_on_return_callback(
self, callback: Callable[[
BlockingChannel, pika.spec.Basic.Return, pika.spec.
BasicProperties, bytes
], None]
) -> None:
"""
Pass a callback function that will be called when a published message is rejected and
returned by the server via `Basic.Return`.
:param callback: The method to call on callback with the
signature callback(channel, method, properties, body), where
- channel: pika.Channel
- method: pika.spec.Basic.Return
- properties: pika.spec.BasicProperties
- body: bytes
"""
self._impl.add_on_return_callback(
lambda _channel, method, properties, body: (self._add_pending_event(
_ReturnedMessageEvt(callback, self, method, properties, body))))
basic_ack(
delivery_tag: int = 0, multiple: bool = False
) -> None
Acknowledge one or more messages.
When sent by the client, this method acknowledges one or more messages delivered via the Deliver or Get-Ok methods. When sent by server, this method acknowledges one or more messages published with the Publish method on a channel in confirm mode. The acknowledgement can be for a single message or a set of messages up to and including a specific message.
| PARAMETER | DESCRIPTION |
|---|---|
delivery_tag
|
The server-assigned delivery tag
TYPE:
|
multiple
|
If set to True, the delivery tag is treated as "up to and including", so that multiple messages can be acknowledged with a single method. If set to False, the delivery tag refers to a single message. If the multiple field is 1, and the delivery tag is zero, this indicates acknowledgement of all outstanding messages.
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def basic_ack(self, delivery_tag: int = 0, multiple: bool = False) -> None:
"""
Acknowledge one or more messages.
When sent by the client, this method acknowledges one or more messages delivered via the
Deliver or Get-Ok methods. When sent by server, this method acknowledges one or more
messages published with the Publish method on a channel in confirm mode. The acknowledgement
can be for a single message or a set of messages up to and including a specific message.
:param delivery_tag: The server-assigned delivery tag
:param multiple: If set to True, the delivery tag is treated as "up to and including", so
that multiple messages can be acknowledged with a single method. If set to False, the
delivery tag refers to a single message. If the multiple field is 1, and the delivery
tag is zero, this indicates acknowledgement of all outstanding messages.
"""
self._impl.basic_ack(delivery_tag=delivery_tag, multiple=multiple)
self._flush_output()
basic_cancel(
consumer_tag: str,
) -> Sequence[tuple[Deliver, BasicProperties, bytes]]
This method cancels a consumer.
This does not affect already delivered messages, but it does mean the server will not send any more messages for that consumer. The client may receive an arbitrary number of messages in between sending the cancel method and receiving the cancel-ok reply.
NOTE: When cancelling an auto_ack=False consumer, this implementation automatically Nacks and suppresses any incoming messages that have not yet been dispatched to the consumer's callback. However, when cancelling a auto_ack=True consumer, this method will return any pending messages that arrived before broker confirmed the cancellation.
| PARAMETER | DESCRIPTION |
|---|---|
consumer_tag
|
Identifier for the consumer; the result of passing a consumer_tag that was created on another channel is undefined (bad things will happen)
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Sequence[tuple[Deliver, BasicProperties, bytes]]
|
(NEW IN pika 0.10.0) empty sequence for a auto_ack=False consumer; for a auto_ack=True consumer, returns a (possibly empty) sequence of pending messages that arrived before broker confirmed the cancellation (this is done instead of via consumer's callback in order to prevent reentrancy/recursion. Each message is three-tuple: (method, properties, body) - method: spec.Basic.Deliver - properties: spec.BasicProperties - body: bytes |
Source code in pika/adapters/blocking_connection.py
def basic_cancel(
self, consumer_tag: str
) -> Sequence[tuple[pika.spec.Basic.Deliver, pika.spec.BasicProperties,
bytes]]:
"""
This method cancels a consumer.
This does not affect already delivered messages, but it does mean the server will not send any more
messages for that consumer. The client may receive an arbitrary number
of messages in between sending the cancel method and receiving the
cancel-ok reply.
NOTE: When cancelling an auto_ack=False consumer, this implementation
automatically Nacks and suppresses any incoming messages that have not
yet been dispatched to the consumer's callback. However, when cancelling
a auto_ack=True consumer, this method will return any pending messages
that arrived before broker confirmed the cancellation.
:param consumer_tag: Identifier for the consumer; the result of
passing a consumer_tag that was created on another channel is
undefined (bad things will happen)
:returns: (NEW IN pika 0.10.0) empty sequence for a auto_ack=False
consumer; for a auto_ack=True consumer, returns a (possibly empty)
sequence of pending messages that arrived before broker confirmed
the cancellation (this is done instead of via consumer's callback in
order to prevent reentrancy/recursion. Each message is three-tuple:
(method, properties, body)
- method: spec.Basic.Deliver
- properties: spec.BasicProperties
- body: bytes
"""
try:
consumer_info = self._consumer_infos[consumer_tag]
except KeyError:
LOGGER.warning(
'User is attempting to cancel an unknown consumer=%s; '
'already cancelled by user or broker?', consumer_tag)
return []
try:
# Assertion failure here is most likely due to reentrance
assert consumer_info.active or consumer_info.cancelled_by_broker, (
consumer_info.state)
# Assertion failure here signals disconnect between consumer state
# in BlockingChannel and Channel
assert (consumer_info.cancelled_by_broker or
consumer_tag in self._impl._consumers), consumer_tag
auto_ack = consumer_info.auto_ack
consumer_info.state = _ConsumerInfo.TEARING_DOWN
with _CallbackResult() as cancel_ok_result:
# Nack pending messages for auto_ack=False consumer
if not auto_ack:
pending_messages = self._remove_pending_deliveries(
consumer_tag)
if pending_messages:
# NOTE: we use impl's basic_reject to avoid the
# possibility of redelivery before basic_cancel takes
# control of nacking.
# NOTE: we can't use basic_nack with the multiple option
# to avoid nacking messages already held by our client.
for message in pending_messages:
delivery_tag = message.method.delivery_tag
# The generated spec types delivery_tag as
# optional, but the broker always sets it on a
# delivery.
assert delivery_tag is not None
self._impl.basic_reject(delivery_tag, requeue=True)
# Cancel the consumer; impl takes care of rejecting any
# additional deliveries that arrive for a auto_ack=False
# consumer
self._impl.basic_cancel(consumer_tag=consumer_tag,
callback=cancel_ok_result.signal_once)
# Flush output and wait for Basic.Cancel-ok or
# broker-initiated Basic.Cancel
self._flush_output(
cancel_ok_result.is_ready,
lambda: consumer_tag not in self._impl._consumers)
if auto_ack:
# Return pending messages for auto_ack=True consumer
return [(evt.method, evt.properties, evt.body)
for evt in self._remove_pending_deliveries(consumer_tag)
]
# impl takes care of rejecting any incoming deliveries during
# cancellation
messages = self._remove_pending_deliveries(consumer_tag)
assert not messages, messages
return []
finally:
# NOTE: The entry could be purged if channel or connection closes
if consumer_tag in self._consumer_infos:
del self._consumer_infos[consumer_tag]
# Schedule termination of connection.process_data_events using a
# negative channel number
self.connection._request_channel_dispatch(-self.channel_number)
basic_consume(
queue: str,
on_message_callback: Callable[
[BlockingChannel, Deliver, BasicProperties, bytes],
None,
],
auto_ack: bool = False,
exclusive: bool = False,
consumer_tag: str | None = None,
arguments: dict[str, Any] | None = None,
) -> str
Sends the AMQP command Basic.Consume to the broker and binds messages for the consumer_tag to the consumer callback. If you do not pass in a consumer_tag, one will be automatically generated for you. Returns the consumer tag.
NOTE: the consumer callbacks are dispatched only in the scope of
specially-designated methods: see
BlockingConnection.process_data_events and
BlockingChannel.start_consuming.
For more information about Basic.Consume, see: https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue from which to consume
TYPE:
|
on_message_callback
|
Required function for dispatching messages to user, having the signature: on_message_callback(channel, method, properties, body) - channel: BlockingChannel - method: spec.Basic.Deliver - properties: spec.BasicProperties - body: bytes
TYPE:
|
auto_ack
|
if set to True, automatic acknowledgement mode will be used (see https://www.rabbitmq.com/confirms.html). This corresponds with the 'no_ack' parameter in the basic.consume AMQP 0.9.1 method
TYPE:
|
exclusive
|
Don't allow other consumers on the queue
TYPE:
|
consumer_tag
|
You may specify your own consumer tag; if left empty, a consumer tag will be generated automatically
TYPE:
|
arguments
|
Custom key/value pair arguments for the consumer
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
str
|
consumer tag |
| RAISES | DESCRIPTION |
|---|---|
pika.exceptions.DuplicateConsumerTag
|
if consumer with given consumer_tag is already present. |
Source code in pika/adapters/blocking_connection.py
def basic_consume(self,
queue: str,
on_message_callback: Callable[[
BlockingChannel, pika.spec.Basic.Deliver, pika.spec.
BasicProperties, bytes
], None],
auto_ack: bool = False,
exclusive: bool = False,
consumer_tag: str | None = None,
arguments: dict[str, Any] | None = None) -> str:
"""
Sends the AMQP command Basic.Consume to the broker and binds messages for the consumer_tag
to the consumer callback. If you do not pass in a consumer_tag, one will be automatically
generated for you. Returns the consumer tag.
NOTE: the consumer callbacks are dispatched only in the scope of
specially-designated methods: see
`BlockingConnection.process_data_events` and
`BlockingChannel.start_consuming`.
For more information about Basic.Consume, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume
:param queue: The queue from which to consume
:param on_message_callback: Required function for dispatching messages
to user, having the signature:
on_message_callback(channel, method, properties, body)
- channel: BlockingChannel
- method: spec.Basic.Deliver
- properties: spec.BasicProperties
- body: bytes
:param auto_ack: if set to True, automatic acknowledgement mode will be used
(see https://www.rabbitmq.com/confirms.html). This corresponds
with the 'no_ack' parameter in the basic.consume AMQP 0.9.1
method
:param exclusive: Don't allow other consumers on the queue
:param consumer_tag: You may specify your own consumer tag; if left
empty, a consumer tag will be generated automatically
:param arguments: Custom key/value pair arguments for the consumer
:returns: consumer tag
:raises pika.exceptions.DuplicateConsumerTag: if consumer with given
consumer_tag is already present.
"""
validators.require_string(queue, 'queue')
validators.require_callback(on_message_callback, 'on_message_callback')
return self._basic_consume_impl(queue=queue,
on_message_callback=on_message_callback,
auto_ack=auto_ack,
exclusive=exclusive,
consumer_tag=consumer_tag,
arguments=arguments)
basic_get(
queue: str, auto_ack: bool = False
) -> tuple[
GetOk | None, BasicProperties | None, bytes | None
]
Get a single message from the AMQP broker.
Returns a sequence with the method frame, message properties, and body.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
Name of queue from which to get a message
TYPE:
|
auto_ack
|
Tell the broker to not expect a reply
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
tuple[GetOk | None, BasicProperties | None, bytes | None]
|
a three-tuple; (None, None, None) if the queue was empty; otherwise (method, properties, body); NOTE: body may be None |
Source code in pika/adapters/blocking_connection.py
def basic_get(
self,
queue: str,
auto_ack: bool = False
) -> tuple[pika.spec.Basic.GetOk | None, pika.spec.BasicProperties | None,
bytes | None]:
"""
Get a single message from the AMQP broker.
Returns a sequence with the method frame, message properties, and body.
:param queue: Name of queue from which to get a message
:param auto_ack: Tell the broker to not expect a reply
:returns: a three-tuple; (None, None, None) if the queue was empty; otherwise (method,
properties, body); NOTE: body may be None
"""
assert not self._basic_getempty_result
validators.require_string(queue, 'queue')
with contextlib.ExitStack() as stack:
get_ok_result = stack.enter_context(
_CallbackResult(self._RxMessageArgs))
stack.enter_context(self._basic_getempty_result)
self._impl.basic_get(queue=queue,
auto_ack=auto_ack,
callback=get_ok_result.set_value_once)
self._flush_output(get_ok_result.is_ready,
self._basic_getempty_result.is_ready)
if get_ok_result:
evt = get_ok_result.value
return evt.method, evt.properties, evt.body
assert self._basic_getempty_result, (
'wait completed without GetOk and GetEmpty')
return None, None, None
basic_nack(
delivery_tag: int = 0,
multiple: bool = False,
requeue: bool = True,
) -> None
This method allows a client to reject one or more incoming messages.
It can be used to interrupt and cancel large incoming messages, or return untreatable messages to their original queue.
| PARAMETER | DESCRIPTION |
|---|---|
delivery_tag
|
The server-assigned delivery tag
TYPE:
|
multiple
|
If set to True, the delivery tag is treated as "up to and including", so that multiple messages can be acknowledged with a single method. If set to False, the delivery tag refers to a single message. If the multiple field is 1, and the delivery tag is zero, this indicates acknowledgement of all outstanding messages.
TYPE:
|
requeue
|
If requeue is true, the server will attempt to requeue the message. If requeue is false or the requeue attempt fails the messages are discarded or dead- lettered.
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def basic_nack(self,
delivery_tag: int = 0,
multiple: bool = False,
requeue: bool = True) -> None:
"""
This method allows a client to reject one or more incoming messages.
It can be used to interrupt and cancel large incoming messages, or return untreatable
messages to their original queue.
:param delivery_tag: The server-assigned delivery tag
:param multiple: If set to True, the delivery tag is treated as "up to and including", so
that multiple messages can be acknowledged with a single method. If set to False, the
delivery tag refers to a single message. If the multiple field is 1, and the delivery
tag is zero, this indicates acknowledgement of all outstanding messages.
:param requeue: If requeue is true, the server will attempt to requeue the message. If
requeue is false or the requeue attempt fails the messages are discarded or dead-
lettered.
"""
self._impl.basic_nack(delivery_tag=delivery_tag,
multiple=multiple,
requeue=requeue)
self._flush_output()
basic_publish(
exchange: str,
routing_key: str,
body: bytes,
properties: BasicProperties | None = None,
mandatory: bool = False,
) -> None
Publish to the channel with the given exchange, routing key, and body.
For more information on basic_publish and what the parameters do, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.publish
NOTE: mandatory may be enabled even without delivery confirmation, but in the absence of delivery confirmation the synchronous implementation has no way to know how long to wait for the Basic.Return.
| PARAMETER | DESCRIPTION |
|---|---|
exchange
|
The exchange to publish to
TYPE:
|
routing_key
|
The routing key to bind on
TYPE:
|
body
|
The message body; empty string if no body
TYPE:
|
properties
|
message properties
TYPE:
|
mandatory
|
The mandatory flag
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
UnroutableError
|
raised when a message published in
publisher-acknowledgments mode (see
|
NackError
|
raised when a message published in
publisher-acknowledgements mode is Nack'ed by the broker. See
|
Source code in pika/adapters/blocking_connection.py
def basic_publish(self,
exchange: str,
routing_key: str,
body: bytes,
properties: pika.spec.BasicProperties | None = None,
mandatory: bool = False) -> None:
"""
Publish to the channel with the given exchange, routing key, and body.
For more information on basic_publish and what the parameters do, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.publish
NOTE: mandatory may be enabled even without delivery
confirmation, but in the absence of delivery confirmation the
synchronous implementation has no way to know how long to wait for
the Basic.Return.
:param exchange: The exchange to publish to
:param routing_key: The routing key to bind on
:param body: The message body; empty string if no body
:param properties: message properties
:param mandatory: The mandatory flag
:raises UnroutableError: raised when a message published in
publisher-acknowledgments mode (see
`BlockingChannel.confirm_delivery`) is returned via `Basic.Return`
followed by `Basic.Ack`.
:raises NackError: raised when a message published in
publisher-acknowledgements mode is Nack'ed by the broker. See
`BlockingChannel.confirm_delivery`.
"""
if self._delivery_confirmation:
# In publisher-acknowledgments mode
with self._message_confirmation_result:
self._impl.basic_publish(exchange=exchange,
routing_key=routing_key,
body=body,
properties=properties,
mandatory=mandatory)
self._flush_output(self._message_confirmation_result.is_ready)
conf_method = (
self._message_confirmation_result.value.method_frame.method)
if isinstance(conf_method, pika.spec.Basic.Nack):
# Broker was unable to process the message due to internal
# error
LOGGER.warning(
"Message was Nack'ed by broker: nack=%r; channel=%s; "
"exchange=%s; routing_key=%s; mandatory=%r; ",
conf_method, self.channel_number, exchange, routing_key,
mandatory)
if self._puback_return is not None:
returned_messages: list[ReturnedMessage] = [
self._puback_return
]
self._puback_return = None
else:
returned_messages = []
raise exceptions.NackError(returned_messages)
assert isinstance(conf_method,
pika.spec.Basic.Ack), (conf_method)
if self._puback_return is not None:
# Unroutable message was returned
messages = [self._puback_return]
self._puback_return = None
raise exceptions.UnroutableError(messages)
else:
# In non-publisher-acknowledgments mode
self._impl.basic_publish(exchange=exchange,
routing_key=routing_key,
body=body,
properties=properties,
mandatory=mandatory)
self._flush_output()
basic_qos(
prefetch_size: int = 0,
prefetch_count: int = 0,
global_qos: bool = False,
) -> None
Specify quality of service.
This method requests a specific quality of service. The QoS can be specified for the current channel or for all channels on the connection. The client can request that messages be sent in advance so that when the client finishes processing a message, the following message is already held locally, rather than needing to be sent down the channel. Prefetching gives a performance improvement.
| PARAMETER | DESCRIPTION |
|---|---|
prefetch_size
|
This field specifies the prefetch window size. The server will send a message in advance if it is equal to or smaller in size than the available prefetch size (and also falls into other prefetch limits). May be set to zero, meaning "no specific limit", although other prefetch limits may still apply. The prefetch-size is ignored if the no-ack option is set in the consumer.
TYPE:
|
prefetch_count
|
Specifies a prefetch window in terms of whole messages. This field may be used in combination with the prefetch-size field; a message will only be sent in advance if both prefetch windows (and those at the channel and connection level) allow it. The prefetch-count is ignored if the no-ack option is set in the consumer.
TYPE:
|
global_qos
|
Should the QoS apply to all channels on the connection.
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def basic_qos(self,
prefetch_size: int = 0,
prefetch_count: int = 0,
global_qos: bool = False) -> None:
"""
Specify quality of service.
This method requests a specific quality of service. The QoS can be specified for the current
channel or for all channels on the connection. The client can request that messages be sent
in advance so that when the client finishes processing a message, the following message is
already held locally, rather than needing to be sent down the channel. Prefetching gives a
performance improvement.
:param prefetch_size: This field specifies the prefetch window size. The server will send a
message in advance if it is equal to or smaller in size than the available prefetch size
(and also falls into other prefetch limits). May be set to zero, meaning "no specific
limit", although other prefetch limits may still apply. The prefetch-size is ignored if
the no-ack option is set in the consumer.
:param prefetch_count: Specifies a prefetch window in terms of whole messages. This field
may be used in combination with the prefetch-size field; a message will only be sent in
advance if both prefetch windows (and those at the channel and connection level) allow
it. The prefetch-count is ignored if the no-ack option is set in the consumer.
:param global_qos: Should the QoS apply to all channels on the connection.
"""
with _CallbackResult() as qos_ok_result:
self._impl.basic_qos(callback=qos_ok_result.signal_once,
prefetch_size=prefetch_size,
prefetch_count=prefetch_count,
global_qos=global_qos)
self._flush_output(qos_ok_result.is_ready)
basic_recover(requeue: bool = False) -> None
This method asks the server to redeliver all unacknowledged messages on a specified channel. Zero or more messages may be redelivered. This method replaces the asynchronous Recover.
| PARAMETER | DESCRIPTION |
|---|---|
requeue
|
If False, the message will be redelivered to the original recipient. If True, the server will attempt to requeue the message, potentially then delivering it to an alternative subscriber.
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def basic_recover(self, requeue: bool = False) -> None:
"""
This method asks the server to redeliver all unacknowledged messages on a specified channel.
Zero or more messages may be redelivered. This method replaces the asynchronous Recover.
:param requeue: If False, the message will be redelivered to the original recipient. If
True, the server will attempt to requeue the message, potentially then delivering it to
an alternative subscriber.
"""
with _CallbackResult() as recover_ok_result:
self._impl.basic_recover(requeue=requeue,
callback=recover_ok_result.signal_once)
self._flush_output(recover_ok_result.is_ready)
basic_reject(
delivery_tag: int = 0, requeue: bool = True
) -> None
Reject an incoming message.
This method allows a client to reject a message. It can be used to interrupt and cancel large incoming messages, or return untreatable messages to their original queue.
| PARAMETER | DESCRIPTION |
|---|---|
delivery_tag
|
The server-assigned delivery tag
TYPE:
|
requeue
|
If requeue is true, the server will attempt to requeue the message. If requeue is false or the requeue attempt fails the messages are discarded or dead- lettered.
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def basic_reject(self, delivery_tag: int = 0, requeue: bool = True) -> None:
"""
Reject an incoming message.
This method allows a client to reject a message. It can be used to interrupt and cancel
large incoming messages, or return untreatable messages to their original queue.
:param delivery_tag: The server-assigned delivery tag
:param requeue: If requeue is true, the server will attempt to requeue the message. If
requeue is false or the requeue attempt fails the messages are discarded or dead-
lettered.
"""
self._impl.basic_reject(delivery_tag=delivery_tag, requeue=requeue)
self._flush_output()
cancel() -> int
Cancel the queue consumer created by BlockingChannel.consume, rejecting all pending
ackable messages.
NOTE: If you're looking to cancel a consumer issued with BlockingChannel.basic_consume then you should call BlockingChannel.basic_cancel.
| RETURNS | DESCRIPTION |
|---|---|
int
|
The number of messages requeued by Basic.Nack. NEW in 0.10.0: returns 0 |
Source code in pika/adapters/blocking_connection.py
def cancel(self) -> int:
"""
Cancel the queue consumer created by `BlockingChannel.consume`, rejecting all pending
ackable messages.
NOTE: If you're looking to cancel a consumer issued with
BlockingChannel.basic_consume then you should call
BlockingChannel.basic_cancel.
:returns: The number of messages requeued by Basic.Nack.
NEW in 0.10.0: returns 0
"""
if self._queue_consumer_generator is None:
LOGGER.warning('cancel: queue consumer generator is inactive '
'(already cancelled by client or broker?)')
return 0
try:
_, auto_ack, _ = self._queue_consumer_generator.params
if not auto_ack:
# Reject messages held by queue consumer generator; NOTE: we
# can't use basic_nack with the multiple option to avoid nacking
# messages already held by our client.
pending_events = self._queue_consumer_generator.pending_events
# NOTE `get_waiting_message_count` adjusts for `Basic.Cancel`
# from the server at the end (if any)
for _ in range(self.get_waiting_message_count()):
evt = pending_events.popleft()
self._impl.basic_reject(evt.method.delivery_tag,
requeue=True)
self.basic_cancel(self._queue_consumer_generator.consumer_tag)
finally:
self._queue_consumer_generator = None
# Return 0 for compatibility with legacy implementation; the number of
# nacked messages is not meaningful since only messages consumed with
# auto_ack=False may be nacked, and those arriving after calling
# basic_cancel will be rejected automatically by impl channel, so we'll
# never know how many of those were nacked.
return 0
close(
reply_code: int = 0, reply_text: str = 'Normal shutdown'
) -> None
Will invoke a clean shutdown of the channel with the AMQP Broker.
| PARAMETER | DESCRIPTION |
|---|---|
reply_code
|
The reply code to close the channel with
TYPE:
|
reply_text
|
The reply text to close the channel with
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def close(self,
reply_code: int = 0,
reply_text: str = 'Normal shutdown') -> None:
"""
Will invoke a clean shutdown of the channel with the AMQP Broker.
:param reply_code: The reply code to close the channel with
:param reply_text: The reply text to close the channel with
"""
LOGGER.debug('Channel.close(%s, %s)', reply_code, reply_text)
self._impl._raise_if_not_open()
try:
# Cancel remaining consumers
self._cancel_all_consumers()
# Close the channel
self._impl.close(reply_code=reply_code, reply_text=reply_text)
self._flush_output(lambda: self.is_closed)
finally:
self._cleanup()
confirm_delivery() -> None
Turn on RabbitMQ-proprietary Confirm mode in the channel.
For more information see: https://www.rabbitmq.com/confirms.html
Source code in pika/adapters/blocking_connection.py
def confirm_delivery(self) -> None:
"""
Turn on RabbitMQ-proprietary Confirm mode in the channel.
For more information see:
https://www.rabbitmq.com/confirms.html
"""
if self._delivery_confirmation:
LOGGER.error(
'confirm_delivery: confirmation was already enabled '
'on channel=%s', self.channel_number)
return
with _CallbackResult() as select_ok_result:
self._impl.confirm_delivery(
ack_nack_callback=self._message_confirmation_result.
set_value_once,
callback=select_ok_result.signal_once)
self._flush_output(select_ok_result.is_ready)
self._delivery_confirmation = True
# Unroutable messages returned after this point will be in the context
# of publisher acknowledgments
self._impl.add_on_return_callback(self._on_puback_message_returned)
consume(
queue: str,
auto_ack: bool = False,
exclusive: bool = False,
arguments: dict[str, Any] | None = None,
inactivity_timeout: float | None = None,
consumer_tag: str | None = None,
) -> Generator[
tuple[
Deliver | None, BasicProperties | None, bytes | None
]
]
Blocking consumption of a queue instead of via a callback.
This method is a generator that yields each message as a tuple of method,
properties, and body. The active generator iterator terminates when the
consumer is cancelled by client via BlockingChannel.cancel() or by
broker.
Example: :: for method, properties, body in channel.consume('queue'): print(body) channel.basic_ack(method.delivery_tag)
You should call BlockingChannel.cancel() when you escape out of the
generator loop.
If you don't cancel this consumer, then next call on the same channel
to consume() with the exact same (queue, auto_ack, exclusive) parameters
will resume the existing consumer generator; however, calling with
different parameters will result in an exception.
:yields: tuple(spec.Basic.Deliver, spec.BasicProperties, bytes)
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue name to consume
TYPE:
|
auto_ack
|
Tell the broker to not expect a ack/nack response
TYPE:
|
exclusive
|
Don't allow other consumers on the queue
TYPE:
|
arguments
|
Custom key/value pair arguments for the consumer
TYPE:
|
inactivity_timeout
|
if a number is given (in seconds), will cause the method to yield (None, None, None) after the given period of inactivity; this permits for pseudo-regular maintenance activities to be carried out by the user while waiting for messages to arrive. If None is given (default), then the method blocks until the next event arrives. NOTE that timing granularity is limited by the timer resolution of the underlying implementation. NEW in pika 0.10.0.
TYPE:
|
consumer_tag
|
Specify your own consumer tag
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
if consumer-creation parameters don't match those of the existing queue consumer generator, if any. NEW in pika 0.10.0 |
ChannelClosed
|
when this channel is closed by broker. |
Source code in pika/adapters/blocking_connection.py
def consume(
self,
queue: str,
auto_ack: bool = False,
exclusive: bool = False,
arguments: dict[str, Any] | None = None,
inactivity_timeout: float | None = None,
consumer_tag: str | None = None
) -> Generator[tuple[pika.spec.Basic.Deliver | None,
pika.spec.BasicProperties | None, bytes | None]]:
"""
Blocking consumption of a queue instead of via a callback.
This method is a generator that yields each message as a tuple of method,
properties, and body. The active generator iterator terminates when the
consumer is cancelled by client via `BlockingChannel.cancel()` or by
broker.
Example:
::
for method, properties, body in channel.consume('queue'):
print(body)
channel.basic_ack(method.delivery_tag)
You should call `BlockingChannel.cancel()` when you escape out of the
generator loop.
If you don't cancel this consumer, then next call on the same channel
to `consume()` with the exact same (queue, auto_ack, exclusive) parameters
will resume the existing consumer generator; however, calling with
different parameters will result in an exception.
:param queue: The queue name to consume
:param auto_ack: Tell the broker to not expect a ack/nack response
:param exclusive: Don't allow other consumers on the queue
:param arguments: Custom key/value pair arguments for the consumer
:param inactivity_timeout: if a number is given (in
seconds), will cause the method to yield (None, None, None) after the
given period of inactivity; this permits for pseudo-regular maintenance
activities to be carried out by the user while waiting for messages
to arrive. If None is given (default), then the method blocks until
the next event arrives. NOTE that timing granularity is limited by
the timer resolution of the underlying implementation.
NEW in pika 0.10.0.
:param consumer_tag: Specify your own consumer tag
:yields: tuple(spec.Basic.Deliver, spec.BasicProperties, bytes)
:raises ValueError: if consumer-creation parameters don't match those
of the existing queue consumer generator, if any.
NEW in pika 0.10.0
:raises ChannelClosed: when this channel is closed by broker.
"""
self._impl._raise_if_not_open()
params = (queue, auto_ack, exclusive)
if self._queue_consumer_generator is not None:
if params != self._queue_consumer_generator.params:
raise ValueError(
'Consume with different params not allowed on existing '
f'queue consumer generator; previous params: {self._queue_consumer_generator.params!r}; '
f'new params: {(queue, auto_ack, exclusive)!r}')
else:
LOGGER.debug('Creating new queue consumer generator; params: %r',
params)
# Need a consumer tag to register consumer info before sending
# request to broker, because I/O might pick up incoming messages
# in addition to Basic.Consume-ok
if not consumer_tag:
consumer_tag = self._impl._generate_consumer_tag()
self._queue_consumer_generator = _QueueConsumerGeneratorInfo(
params, consumer_tag)
try:
self._basic_consume_impl(
queue=queue,
auto_ack=auto_ack,
exclusive=exclusive,
consumer_tag=consumer_tag,
arguments=arguments,
alternate_event_sink=self._on_consumer_generator_event)
except Exception:
self._queue_consumer_generator = None
raise
LOGGER.info('Created new queue consumer generator %r',
self._queue_consumer_generator)
while self._queue_consumer_generator is not None:
# Process pending events
if self._queue_consumer_generator.pending_events:
evt = self._queue_consumer_generator.pending_events.popleft()
if type(evt) is _ConsumerCancellationEvt:
# Consumer was cancelled by broker
self._queue_consumer_generator = None
break
else:
yield (evt.method, evt.properties, evt.body)
continue
if inactivity_timeout is None:
# Wait indefinitely for a message to arrive, while processing
# I/O events and triggering ChannelClosed exception when the
# channel fails
self._process_data_events(time_limit=None)
continue
# Wait with inactivity timeout
wait_start_time = pika._utils.time_now()
wait_deadline = wait_start_time + inactivity_timeout
delta = inactivity_timeout
while (self._queue_consumer_generator is not None and
not self._queue_consumer_generator.pending_events):
self._process_data_events(time_limit=delta)
if not self._queue_consumer_generator:
# Consumer was cancelled by client
break
if self._queue_consumer_generator.pending_events:
# Got message(s)
break
delta = wait_deadline - pika._utils.time_now()
if delta <= 0.0:
# Signal inactivity timeout
yield (None, None, None)
break
exchange_bind(
destination: str,
source: str,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
) -> Method[BindOk]
Bind an exchange to another exchange.
| PARAMETER | DESCRIPTION |
|---|---|
destination
|
The destination exchange to bind
TYPE:
|
source
|
The source exchange to bind to
TYPE:
|
routing_key
|
The routing key to bind on
TYPE:
|
arguments
|
Custom key/value pair arguments for the binding
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[BindOk]
|
Method frame from the Exchange.Bind-ok response |
Source code in pika/adapters/blocking_connection.py
def exchange_bind(
self,
destination: str,
source: str,
routing_key: str = '',
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Exchange.BindOk]:
"""
Bind an exchange to another exchange.
:param destination: The destination exchange to bind
:param source: The source exchange to bind to
:param routing_key: The routing key to bind on
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Exchange.Bind-ok response
"""
validators.require_string(destination, 'destination')
validators.require_string(source, 'source')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as bind_ok_result:
self._impl.exchange_bind(destination=destination,
source=source,
routing_key=routing_key,
arguments=arguments,
callback=bind_ok_result.set_value_once)
self._flush_output(bind_ok_result.is_ready)
return bind_ok_result.value.method_frame
exchange_declare(
exchange: str,
exchange_type: ExchangeType | str = direct,
passive: bool = False,
durable: bool = False,
auto_delete: bool = False,
internal: bool = False,
arguments: dict[str, Any] | None = None,
) -> None
This method creates an exchange if it does not already exist, and if the exchange exists, verifies that it is of the correct and expected class.
If passive set, the server will reply with Declare-Ok if the exchange already exists with the same name, and raise an error if not and if the exchange does not already exist, the server MUST raise a channel exception with reply code 404 (not found).
| PARAMETER | DESCRIPTION |
|---|---|
exchange
|
The exchange name consists of a non-empty sequence of these characters: letters, digits, hyphen, underscore, period, or colon.
TYPE:
|
exchange_type
|
The exchange type to use
TYPE:
|
passive
|
Perform a declare or just check to see if it exists
TYPE:
|
durable
|
Survive a reboot of RabbitMQ
TYPE:
|
auto_delete
|
Remove when no more queues are bound to it
TYPE:
|
internal
|
Can only be published to by other exchanges
TYPE:
|
arguments
|
Custom key/value pair arguments for the exchange
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
Method frame from the Exchange.Declare-ok response |
Source code in pika/adapters/blocking_connection.py
def exchange_declare(self,
exchange: str,
exchange_type: (ExchangeType |
str) = ExchangeType.direct,
passive: bool = False,
durable: bool = False,
auto_delete: bool = False,
internal: bool = False,
arguments: dict[str, Any] | None = None) -> None:
"""
This method creates an exchange if it does not already exist, and if the exchange exists,
verifies that it is of the correct and expected class.
If passive set, the server will reply with Declare-Ok if the exchange
already exists with the same name, and raise an error if not and if the
exchange does not already exist, the server MUST raise a channel
exception with reply code 404 (not found).
:param exchange: The exchange name consists of a non-empty sequence of
these characters: letters, digits, hyphen, underscore,
period, or colon.
:param exchange_type: The exchange type to use
:param passive: Perform a declare or just check to see if it exists
:param durable: Survive a reboot of RabbitMQ
:param auto_delete: Remove when no more queues are bound to it
:param internal: Can only be published to by other exchanges
:param arguments: Custom key/value pair arguments for the exchange
:returns: Method frame from the Exchange.Declare-ok response
"""
validators.require_string(exchange, 'exchange')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as declare_ok_result:
self._impl.exchange_declare(
exchange=exchange,
exchange_type=exchange_type,
passive=passive,
durable=durable,
auto_delete=auto_delete,
internal=internal,
arguments=arguments,
callback=declare_ok_result.set_value_once)
self._flush_output(declare_ok_result.is_ready)
return declare_ok_result.value.method_frame
exchange_delete(
exchange: str | None = None, if_unused: bool = False
) -> Method[DeleteOk]
Delete the exchange.
| PARAMETER | DESCRIPTION |
|---|---|
exchange
|
The exchange name
TYPE:
|
if_unused
|
only delete if the exchange is unused
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[DeleteOk]
|
Method frame from the Exchange.Delete-ok response |
Source code in pika/adapters/blocking_connection.py
def exchange_delete(self,
exchange: str | None = None,
if_unused: bool = False
) -> pika.frame.Method[pika.spec.Exchange.DeleteOk]:
"""
Delete the exchange.
:param exchange: The exchange name
:param if_unused: only delete if the exchange is unused
:returns: Method frame from the Exchange.Delete-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as delete_ok_result:
self._impl.exchange_delete(exchange=exchange,
if_unused=if_unused,
callback=delete_ok_result.set_value_once)
self._flush_output(delete_ok_result.is_ready)
return delete_ok_result.value.method_frame
exchange_unbind(
destination: str | None = None,
source: str | None = None,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
) -> Method[UnbindOk]
Unbind an exchange from another exchange.
| PARAMETER | DESCRIPTION |
|---|---|
destination
|
The destination exchange to unbind
TYPE:
|
source
|
The source exchange to unbind from
TYPE:
|
routing_key
|
The routing key to unbind
TYPE:
|
arguments
|
Custom key/value pair arguments for the binding
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[UnbindOk]
|
Method frame from the Exchange.Unbind-ok response |
Source code in pika/adapters/blocking_connection.py
def exchange_unbind(
self,
destination: str | None = None,
source: str | None = None,
routing_key: str = '',
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Exchange.UnbindOk]:
"""
Unbind an exchange from another exchange.
:param destination: The destination exchange to unbind
:param source: The source exchange to unbind from
:param routing_key: The routing key to unbind
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Exchange.Unbind-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as unbind_ok_result:
self._impl.exchange_unbind(destination=destination,
source=source,
routing_key=routing_key,
arguments=arguments,
callback=unbind_ok_result.set_value_once)
self._flush_output(unbind_ok_result.is_ready)
return unbind_ok_result.value.method_frame
flow(active: bool) -> bool
Turn Channel flow control off and on.
NOTE: RabbitMQ doesn't support active=False; per https://www.rabbitmq.com/specification.html: "active=false is not supported by the server. Limiting prefetch with basic.qos provides much better control"
For more information, please reference:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#channel.flow
| PARAMETER | DESCRIPTION |
|---|---|
active
|
Turn flow on (True) or off (False)
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
bool
|
True if broker will start or continue sending; False if not |
Source code in pika/adapters/blocking_connection.py
def flow(self, active: bool) -> bool:
"""
Turn Channel flow control off and on.
NOTE: RabbitMQ doesn't support active=False; per
https://www.rabbitmq.com/specification.html: "active=false is not
supported by the server. Limiting prefetch with basic.qos provides much
better control"
For more information, please reference:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#channel.flow
:param active: Turn flow on (True) or off (False)
:returns: True if broker will start or continue sending; False if not
"""
with _CallbackResult(self._FlowOkCallbackResultArgs) as flow_ok_result:
self._impl.flow(active=active,
callback=flow_ok_result.set_value_once)
self._flush_output(flow_ok_result.is_ready)
return flow_ok_result.value.active
get_waiting_message_count() -> int
Returns the number of messages that may be retrieved from the current queue consumer
generator via BlockingChannel.consume without blocking. NEW in pika 0.10.0.
| RETURNS | DESCRIPTION |
|---|---|
int
|
The number of waiting messages |
Source code in pika/adapters/blocking_connection.py
def get_waiting_message_count(self) -> int:
"""
Returns the number of messages that may be retrieved from the current queue consumer
generator via `BlockingChannel.consume` without blocking. NEW in pika 0.10.0.
:returns: The number of waiting messages
"""
if self._queue_consumer_generator is not None:
pending_events = self._queue_consumer_generator.pending_events
count = len(pending_events)
if count and type(pending_events[-1]) is _ConsumerCancellationEvt:
count -= 1
else:
count = 0
return count
queue_bind(
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
) -> Method[BindOk]
Bind the queue to the specified exchange.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue to bind to the exchange
TYPE:
|
exchange
|
The source exchange to bind to
TYPE:
|
routing_key
|
The routing key to bind on
TYPE:
|
arguments
|
Custom key/value pair arguments for the binding
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[BindOk]
|
Method frame from the Queue.Bind-ok response |
Source code in pika/adapters/blocking_connection.py
def queue_bind(
self,
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Queue.BindOk]:
"""
Bind the queue to the specified exchange.
:param queue: The queue to bind to the exchange
:param exchange: The source exchange to bind to
:param routing_key: The routing key to bind on
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Queue.Bind-ok response
"""
validators.require_string(queue, 'queue')
validators.require_string(exchange, 'exchange')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as bind_ok_result:
self._impl.queue_bind(queue=queue,
exchange=exchange,
routing_key=routing_key,
arguments=arguments,
callback=bind_ok_result.set_value_once)
self._flush_output(bind_ok_result.is_ready)
return bind_ok_result.value.method_frame
queue_declare(
queue: str,
passive: bool = False,
durable: bool = False,
exclusive: bool = False,
auto_delete: bool = False,
arguments: dict[str, Any] | None = None,
) -> Method[DeclareOk]
Declare queue, create if needed.
This method creates or checks a queue. When creating a new queue the client can specify various properties that control the durability of the queue and its contents, and the level of sharing for the queue.
Use an empty string as the queue name for the broker to auto-generate
one. Retrieve this auto-generated queue name from the returned
spec.Queue.DeclareOk method frame.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue name; if empty string, the broker will create a unique queue name
TYPE:
|
passive
|
Only check to see if the queue exists and raise
TYPE:
|
durable
|
Survive reboots of the broker
TYPE:
|
exclusive
|
Only allow access by the current connection
TYPE:
|
auto_delete
|
Delete after consumer cancels or disconnects
TYPE:
|
arguments
|
Custom key/value arguments for the queue
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[DeclareOk]
|
Method frame from the Queue.Declare-ok response |
Source code in pika/adapters/blocking_connection.py
def queue_declare(
self,
queue: str,
passive: bool = False,
durable: bool = False,
exclusive: bool = False,
auto_delete: bool = False,
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Queue.DeclareOk]:
"""
Declare queue, create if needed.
This method creates or checks a queue. When creating a new queue the client can specify various
properties that control the durability of the queue and its contents,
and the level of sharing for the queue.
Use an empty string as the queue name for the broker to auto-generate
one. Retrieve this auto-generated queue name from the returned
`spec.Queue.DeclareOk` method frame.
:param queue: The queue name; if empty string, the broker will
create a unique queue name
:param passive: Only check to see if the queue exists and raise
`ChannelClosed` if it doesn't
:param durable: Survive reboots of the broker
:param exclusive: Only allow access by the current connection
:param auto_delete: Delete after consumer cancels or disconnects
:param arguments: Custom key/value arguments for the queue
:returns: Method frame from the Queue.Declare-ok response
"""
validators.require_string(queue, 'queue')
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as declare_ok_result:
self._impl.queue_declare(queue=queue,
passive=passive,
durable=durable,
exclusive=exclusive,
auto_delete=auto_delete,
arguments=arguments,
callback=declare_ok_result.set_value_once)
self._flush_output(declare_ok_result.is_ready)
return declare_ok_result.value.method_frame
queue_delete(
queue: str,
if_unused: bool = False,
if_empty: bool = False,
) -> Method[DeleteOk]
Delete a queue from the broker.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue to delete
TYPE:
|
if_unused
|
only delete if it's unused
TYPE:
|
if_empty
|
only delete if the queue is empty
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[DeleteOk]
|
Method frame from the Queue.Delete-ok response |
Source code in pika/adapters/blocking_connection.py
def queue_delete(self,
queue: str,
if_unused: bool = False,
if_empty: bool = False
) -> pika.frame.Method[pika.spec.Queue.DeleteOk]:
"""
Delete a queue from the broker.
:param queue: The queue to delete
:param if_unused: only delete if it's unused
:param if_empty: only delete if the queue is empty
:returns: Method frame from the Queue.Delete-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as delete_ok_result:
self._impl.queue_delete(queue=queue,
if_unused=if_unused,
if_empty=if_empty,
callback=delete_ok_result.set_value_once)
self._flush_output(delete_ok_result.is_ready)
return delete_ok_result.value.method_frame
queue_purge(queue: str) -> Method[PurgeOk]
Purge all of the messages from the specified queue.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue to purge
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[PurgeOk]
|
Method frame from the Queue.Purge-ok response |
Source code in pika/adapters/blocking_connection.py
def queue_purge(self,
queue: str) -> pika.frame.Method[pika.spec.Queue.PurgeOk]:
"""
Purge all of the messages from the specified queue.
:param queue: The queue to purge
:returns: Method frame from the Queue.Purge-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as purge_ok_result:
self._impl.queue_purge(queue=queue,
callback=purge_ok_result.set_value_once)
self._flush_output(purge_ok_result.is_ready)
return purge_ok_result.value.method_frame
queue_unbind(
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
) -> Method[UnbindOk]
Unbind a queue from an exchange.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue to unbind from the exchange
TYPE:
|
exchange
|
The source exchange to bind from
TYPE:
|
routing_key
|
The routing key to unbind
TYPE:
|
arguments
|
Custom key/value pair arguments for the binding
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
Method[UnbindOk]
|
Method frame from the Queue.Unbind-ok response |
Source code in pika/adapters/blocking_connection.py
def queue_unbind(
self,
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None
) -> pika.frame.Method[pika.spec.Queue.UnbindOk]:
"""
Unbind a queue from an exchange.
:param queue: The queue to unbind from the exchange
:param exchange: The source exchange to bind from
:param routing_key: The routing key to unbind
:param arguments: Custom key/value pair arguments for the binding
:returns: Method frame from the Queue.Unbind-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as unbind_ok_result:
self._impl.queue_unbind(queue=queue,
exchange=exchange,
routing_key=routing_key,
arguments=arguments,
callback=unbind_ok_result.set_value_once)
self._flush_output(unbind_ok_result.is_ready)
return unbind_ok_result.value.method_frame
start_consuming() -> None
Processes I/O events and dispatches timers and basic_consume callbacks until all consumers
are cancelled.
NOTE: this blocking function may not be called from the scope of a
pika callback, because dispatching basic_consume callbacks from this
context would constitute recursion.
| RAISES | DESCRIPTION |
|---|---|
pika.exceptions.ReentrancyError
|
if called from the scope of a
|
ChannelClosed
|
when this channel is closed by broker. |
Source code in pika/adapters/blocking_connection.py
def start_consuming(self) -> None:
"""
Processes I/O events and dispatches timers and `basic_consume` callbacks until all consumers
are cancelled.
NOTE: this blocking function may not be called from the scope of a
pika callback, because dispatching `basic_consume` callbacks from this
context would constitute recursion.
:raises pika.exceptions.ReentrancyError: if called from the scope of a
`BlockingConnection` or `BlockingChannel` callback
:raises ChannelClosed: when this channel is closed by broker.
"""
# Check if called from the scope of an event dispatch callback
with self.connection._acquire_event_dispatch() as dispatch_allowed:
if not dispatch_allowed:
raise exceptions.ReentrancyError(
'start_consuming may not be called from the scope of '
'another BlockingConnection or BlockingChannel callback')
self._impl._raise_if_not_open()
# Process events as long as consumers exist on this channel
while self._consumer_infos:
# This will raise ChannelClosed if channel is closed by broker
self._process_data_events(time_limit=None)
stop_consuming(consumer_tag: str | None = None) -> None
Cancels all consumers, signalling the start_consuming loop to exit.
NOTE: pending non-ackable messages will be lost; pending ackable messages will be rejected.
| PARAMETER | DESCRIPTION |
|---|---|
consumer_tag
|
if specified, only the consumer with the given tag will be cancelled
TYPE:
|
Source code in pika/adapters/blocking_connection.py
def stop_consuming(self, consumer_tag: str | None = None) -> None:
"""
Cancels all consumers, signalling the `start_consuming` loop to exit.
NOTE: pending non-ackable messages will be lost; pending ackable
messages will be rejected.
:param consumer_tag: if specified, only the consumer with the given tag will be cancelled
"""
if consumer_tag:
self.basic_cancel(consumer_tag)
else:
self._cancel_all_consumers()
tx_commit() -> Method[CommitOk]
Commit a transaction.
| RETURNS | DESCRIPTION |
|---|---|
Method[CommitOk]
|
Method frame from the Tx.Commit-ok response |
Source code in pika/adapters/blocking_connection.py
def tx_commit(self) -> pika.frame.Method[pika.spec.Tx.CommitOk]:
"""
Commit a transaction.
:returns: Method frame from the Tx.Commit-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as commit_ok_result:
self._impl.tx_commit(commit_ok_result.set_value_once)
self._flush_output(commit_ok_result.is_ready)
return commit_ok_result.value.method_frame
tx_rollback() -> Method[RollbackOk]
Rollback a transaction.
| RETURNS | DESCRIPTION |
|---|---|
Method[RollbackOk]
|
Method frame from the Tx.Rollback-ok response |
Source code in pika/adapters/blocking_connection.py
def tx_rollback(self) -> pika.frame.Method[pika.spec.Tx.RollbackOk]:
"""
Rollback a transaction.
:returns: Method frame from the Tx.Rollback-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as rollback_ok_result:
self._impl.tx_rollback(rollback_ok_result.set_value_once)
self._flush_output(rollback_ok_result.is_ready)
return rollback_ok_result.value.method_frame
tx_select() -> Method[SelectOk]
Select standard transaction mode.
This method sets the channel to use standard transactions. The client must use this method at least once on a channel before using the Commit or Rollback methods.
| RETURNS | DESCRIPTION |
|---|---|
Method[SelectOk]
|
Method frame from the Tx.Select-ok response |
Source code in pika/adapters/blocking_connection.py
def tx_select(self) -> pika.frame.Method[pika.spec.Tx.SelectOk]:
"""
Select standard transaction mode.
This method sets the channel to use standard transactions. The client must use this method
at least once on a channel before using the Commit or Rollback methods.
:returns: Method frame from the Tx.Select-ok response
"""
with _CallbackResult(
self._MethodFrameCallbackResultArgs) as select_ok_result:
self._impl.tx_select(select_ok_result.set_value_once)
self._flush_output(select_ok_result.is_ready)
return select_ok_result.value.method_frame