Channel¶
The Channel class provides a wrapper for interacting with RabbitMQ implementing the methods and behaviors for an AMQP Channel.
A Channel is the primary communication method for interacting with RabbitMQ.
It is recommended that you do not directly invoke the creation of a channel object in your application code but rather construct a channel by calling the active connection's channel() method.
Source code in pika/channel.py
class Channel:
"""
A Channel is the primary communication method for interacting with RabbitMQ.
It is recommended that you do not directly invoke the creation of a channel object in your
application code but rather construct a channel by calling the active connection's channel()
method.
"""
CLOSED = 0
OPENING = 1
OPEN = 2
CLOSING = 3 # client-initiated close in progress
_STATE_NAMES: ClassVar[dict[int, str]] = {
CLOSED: 'CLOSED',
OPENING: 'OPENING',
OPEN: 'OPEN',
CLOSING: 'CLOSING'
}
_ON_CHANNEL_CLEANUP_CB_KEY = '_on_channel_cleanup'
# Upper bound on the number of nowait-cancelled consumer tags retained in
# `_cancelled`; see `_retain_cancelled_tag`.
_MAX_RETAINED_CANCELLED_TAGS = 1024
def __init__(self, connection: Connection, channel_number: int,
on_open_callback: _OnOpenCallback | None) -> None:
"""
Create a new instance of the Channel.
:param connection: The connection
:param channel_number: The channel number for this instance
:param on_open_callback: The callback to call on channel open. The callback will be invoked
with the `Channel` instance as its only argument.
"""
if not isinstance(channel_number, int):
raise exceptions.InvalidChannelNumber(channel_number)
validators.rpc_completion_callback(on_open_callback)
self.channel_number = channel_number
self.callbacks = connection.callbacks
self.connection = connection
# Initially, flow is assumed to be active
self.flow_active = True
self._content_assembler = ContentFrameAssembler()
self._blocked: deque = deque()
self._blocking: Any | None = None
self._has_on_flow_callback: bool = False
self._cancelled: set = set()
# Nowait-cancelled tags in cancellation order, bounding how many of
# them `_cancelled` retains; see `_retain_cancelled_tag`.
self._nowait_cancelled: deque = deque()
self._consumers: dict = {}
self._consumers_with_noack: set = set()
self._on_flowok_callback: Callable[..., Any] | None = None
self._on_getok_callback: Callable[..., Any] | None = None
self._on_ack_nack_callback: _OnAckNackCallback | None = None
self._on_openok_callback: Callable[..., Any] | None = on_open_callback
self._state: int = self.CLOSED
# We save the closing reason exception to be passed to on-channel-close
# callback at closing of the channel. Exception representing the closing
# reason; ChannelClosedByClient or ChannelClosedByBroker on controlled
# close; otherwise another exception describing the reason for failure
# (most likely connection failure).
self._closing_reason = None # type: None | Exception
# opaque cookie value set by wrapper layer (e.g., BlockingConnection)
# via _set_cookie
self._cookie: object = None
def __int__(self) -> int:
"""Return the channel object as its channel number."""
return self.channel_number
@override
def __repr__(self) -> str:
return f'<{self.__class__.__name__} number={self.channel_number} {self._STATE_NAMES[self._state]} conn={self.connection!r}>'
def add_callback(self,
callback: Callable[..., Any],
replies: Sequence[type[amqp_object.Method]],
one_shot: bool = True) -> None:
"""
Pass in a callback handler and a list replies from the RabbitMQ broker which you'd like the
callback notified of. Callbacks should allow for the frame parameter to be passed in.
:param callback: The callback to call
:param replies: The replies to get a callback for
:param one_shot: Only handle the first type callback
"""
for reply in replies:
self.callbacks.add(self.channel_number, reply, callback, one_shot)
def add_on_cancel_callback(self, callback: _OnCancelCallback) -> None:
"""
Pass a callback function that will be called when the basic_cancel is sent by the server.
The callback function should receive a frame parameter.
:param callback: The callback to call on Basic.Cancel from broker
"""
self.callbacks.add(self.channel_number, spec.Basic.Cancel, callback,
False)
def add_on_close_callback(self, callback: _OnCloseCallback) -> None:
"""
Pass a callback function that will be called when the channel is closed.
The callback function will receive the channel and an exception describing why the channel
was closed.
If the channel is closed by broker via Channel.Close, the callback will receive
`ChannelClosedByBroker` as the reason.
If graceful user-initiated channel closing completes successfully ( either directly of
indirectly by closing a connection containing the channel) and closing concludes gracefully
without Channel.Close from the broker and without loss of connection, the callback will
receive `ChannelClosedByClient` exception as reason.
If channel was closed due to loss of connection, the callback will receive another exception
type describing the failure.
:param callback: The callback, having the signature: callback(Channel, Exception reason)
"""
self.callbacks.add(self.channel_number, '_on_channel_close', callback,
False, self)
def add_on_flow_callback(self, callback: _OnFlowCallback) -> None:
"""
Pass a callback function that will be called when Channel.Flow is called by the remote
server. Note that newer versions of RabbitMQ will not issue this but instead use TCP
backpressure.
:param callback: The callback function
"""
self._has_on_flow_callback = True
self.callbacks.add(self.channel_number, spec.Channel.Flow, callback,
False)
def add_on_return_callback(self, callback: _OnReturnCallback) -> None:
"""
Pass a callback function that will be called when basic_publish is sent a message that has
been rejected and returned by the server.
:param callback: The function to call, having the signature
callback(channel, method, properties, body)
where
- channel: pika.channel.Channel
- method: pika.spec.Basic.Return
- properties: pika.spec.BasicProperties
- body: bytes
"""
self.callbacks.add(self.channel_number, '_on_return', callback, False)
def remove_callback(
self,
callback: Callable[..., Any],
replies: Sequence[type[amqp_object.Method]] | None = None) -> bool:
"""
Remove a callback previously registered via :meth:`add_callback`.
Mirrors :meth:`add_callback`: the callback is matched by identity and removed
from each reply key it is registered under. If ``replies`` is ``None``, the
callback is removed from every reply key it is currently registered under.
:param callback: The callback to remove
:param replies: The replies to remove the callback from, or ``None`` to
remove it from every reply key it is registered under
:returns: ``True`` if at least one matching callback was removed
"""
reply_keys = (self.callbacks.keys(self.channel_number)
if replies is None else replies)
removed = False
for reply in reply_keys:
if self.callbacks.remove_matching(self.channel_number, reply,
lambda cb: cb == callback):
removed = True
return removed
def remove_on_cancel_callback(self, callback: _OnCancelCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_cancel_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number,
spec.Basic.Cancel,
lambda cb: cb == callback)
def remove_on_close_callback(self, callback: _OnCloseCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_close_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number,
'_on_channel_close',
lambda cb: cb == callback)
def remove_on_flow_callback(self, callback: _OnFlowCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_flow_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number,
spec.Channel.Flow,
lambda cb: cb == callback)
def remove_on_return_callback(self, callback: _OnReturnCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_return_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number, '_on_return',
lambda cb: cb == callback)
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: int/long 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._raise_if_not_open()
return self._send_method(spec.Basic.Ack(delivery_tag, multiple))
def basic_cancel(self,
consumer_tag: str = '',
callback: _OnBasicCancelCallback | None = None) -> None:
"""
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. It may also be sent
from the server to the client in the event of the consumer being unexpectedly cancelled
(i.e. cancelled for any reason other than the server receiving the corresponding
basic.cancel from the client). This allows clients to be notified of the loss of consumers
due to events such as queue deletion.
A cancelled consumer's tag is retained so that a delivery already in flight when the cancel
was sent is rejected rather than left unacknowledged. A cancel that expects a Basic.CancelOk
retires its own entry on arrival; a nowait cancel has no reply to retire it, so its tag is
kept only until `_MAX_RETAINED_CANCELLED_TAGS` later nowait cancels displace it (see
`_retain_cancelled_tag`). Past that point its retention lapses: a straggling delivery for it
is logged as unexpected and left unacknowledged rather than rejected, and the tag may be
reused by `basic_consume`, so reusing the same explicit consumer_tag risks a delivery for
the old consumer reaching the new one. The cap is a generous approximation of the broker's
in-flight window, so this only bites under extreme nowait-cancel churn.
:param consumer_tag: Identifier for the consumer
:param callback: callback(pika.frame.Method) for method Basic.CancelOk. If None, do not
expect a Basic.CancelOk response, otherwise, callback must be callable
:raises ValueError:
"""
validators.require_string(consumer_tag, 'consumer_tag')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if consumer_tag in self._cancelled:
# We check for cancelled first, because basic_cancel removes
# consumers closed with nowait from self._consumers
LOGGER.warning('basic_cancel - consumer is already cancelling: %s',
consumer_tag)
return
if consumer_tag not in self._consumers:
# Could be cancelled by user or broker earlier
LOGGER.warning('basic_cancel - consumer not found: %s',
consumer_tag)
return
LOGGER.debug('Cancelling consumer: %s (nowait=%s)', consumer_tag,
nowait)
if nowait:
# This is our last opportunity while the channel is open to remove
# this consumer callback and help gc.
del self._consumers[consumer_tag]
if callback is not None:
self.callbacks.add(self.channel_number, spec.Basic.CancelOk,
callback)
self._cancelled.add(consumer_tag)
if nowait:
self._retain_cancelled_tag(consumer_tag)
self._rpc(spec.Basic.Cancel(consumer_tag=consumer_tag, nowait=nowait),
self._on_cancelok if not nowait else None,
[(spec.Basic.CancelOk, {
'consumer_tag': consumer_tag
})] if not nowait else [])
def basic_consume(self,
queue: str,
on_message_callback: _OnMessageCallback,
auto_ack: bool = False,
exclusive: bool = False,
consumer_tag: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnBasicConsumeCallback | None = None) -> str:
"""
Sends the AMQP 0-9-1 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.
For more information on basic_consume, see:
Tutorial 2 at https://www.rabbitmq.com/getstarted.html
https://www.rabbitmq.com/confirms.html
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume
:param queue: The queue to consume from. Use the empty string to
specify the most recent server-named queue for this channel
:param on_message_callback: The function to call when
consuming with the signature
on_message_callback(channel, method, properties, body), where
- channel: pika.channel.Channel
- method: pika.spec.Basic.Deliver
- properties: pika.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: Specify your own consumer tag
:param arguments: Custom key/value pair arguments for the consumer
:param callback: callback(pika.frame.Method) for method
Basic.ConsumeOk.
:returns: Consumer tag which may be used to cancel the consumer.
:raises ValueError:
"""
validators.require_string(queue, 'queue')
validators.require_callback(on_message_callback)
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
# If a consumer tag was not passed, create one
if not consumer_tag:
consumer_tag = self._generate_consumer_tag()
if consumer_tag in self._consumers or consumer_tag in self._cancelled:
raise exceptions.DuplicateConsumerTag(consumer_tag)
if auto_ack:
self._consumers_with_noack.add(consumer_tag)
self._consumers[consumer_tag] = on_message_callback
rpc_callback: Callable[
...,
Any] | None = self._on_eventok if callback is None else callback
self._rpc(
spec.Basic.Consume(queue=queue,
consumer_tag=consumer_tag,
no_ack=auto_ack,
exclusive=exclusive,
arguments=arguments or {}), rpc_callback,
[(spec.Basic.ConsumeOk, {
'consumer_tag': consumer_tag
})])
return consumer_tag
def _generate_consumer_tag(self) -> str:
"""
Generate a consumer tag.
NOTE: this protected method may be called by derived classes
:returns: consumer tag
"""
return f'ctag{self.channel_number}.{uuid.uuid4().hex}'
def basic_get(self,
queue: str,
callback: _OnBasicGetCallback,
auto_ack: bool = False) -> None:
"""
Get a single message from the AMQP broker.
If you want to be notified of Basic.GetEmpty, use the Channel.add_callback method
adding your Basic.GetEmpty callback which should expect only one
parameter, frame. Due to implementation details, this cannot be called
a second time until the callback is executed. For more information on
basic_get and its parameters, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.get
:param queue: The queue from which to get a message. Use the empty
string to specify the most recent server-named queue for this
channel
:param callback: The callback to call with a message that has
the signature callback(channel, method, properties, body), where:
- channel: pika.channel.Channel
- method: pika.spec.Basic.GetOk
- properties: pika.spec.BasicProperties
- body: bytes
:param auto_ack: Tell the broker to not expect a reply
:raises ValueError:
"""
validators.require_string(queue, 'queue')
validators.require_callback(callback)
if self._on_getok_callback is not None:
raise exceptions.DuplicateGetOkCallback()
self._on_getok_callback = callback
# TODO Strangely, not using _rpc for the synchronous Basic.Get. Would
# need to extend _rpc to handle Basic.GetOk method, header, and body
# frames (or similar)
self._send_method(spec.Basic.Get(queue=queue, no_ack=auto_ack))
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: int/long 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._raise_if_not_open()
return self._send_method(
spec.Basic.Nack(delivery_tag, multiple, requeue))
def basic_publish(self,
exchange: str,
routing_key: str,
body: bytes,
properties: 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
:param exchange: The exchange to publish to
:param routing_key: The routing key to bind on
:param body: The message body
:param properties: Basic.properties
:param mandatory: The mandatory flag
"""
self._raise_if_not_open()
body = as_bytes(body)
properties = properties or spec.BasicProperties()
self._send_method(
spec.Basic.Publish(exchange=exchange,
routing_key=routing_key,
mandatory=mandatory), (properties, body))
def basic_qos(self,
prefetch_size: int = 0,
prefetch_count: int = 0,
global_qos: bool = False,
callback: _OnBasicQosCallback | None = None) -> None:
"""
Specify quality of service.
This method requests a specific quality of service. 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. The QoS can be
applied separately to each new consumer on channel or shared across all consumers on 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 by
consumers who have enabled the no-ack option.
: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 by consumers who have enabled the no-ack option.
:param global_qos: Should the QoS be shared across all consumers on the channel.
:param callback: The callback to call for Basic.QosOk response
:returns:``None``. Method frame from the Basic.Qos-ok response is delivered to ``callback``
when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
validators.zero_or_greater('prefetch_size', prefetch_size)
validators.zero_or_greater('prefetch_count', prefetch_count)
return self._rpc(
spec.Basic.Qos(prefetch_size, prefetch_count, global_qos), callback,
[spec.Basic.QosOk])
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: int/long 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.
:raises TypeError:
"""
self._raise_if_not_open()
if not isinstance(delivery_tag, int):
raise TypeError('delivery_tag must be an integer')
return self._send_method(spec.Basic.Reject(delivery_tag, requeue))
def basic_recover(self,
requeue: bool = False,
callback: _OnBasicRecoverCallback | None = None) -> 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.
:param callback: callback(pika.frame.Method) for method Basic.RecoverOk
:returns:``None``. Method frame from the Basic.Recover-ok response is delivered to
``callback`` when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Basic.Recover(requeue), callback,
[spec.Basic.RecoverOk])
def close(self,
reply_code: int = 0,
reply_text: str = 'Normal shutdown') -> None:
"""
Invoke a graceful shutdown of the channel with the AMQP Broker.
If channel is OPENING, transition to CLOSING and suppress the incoming Channel.OpenOk, if
any.
:param reply_code: The reason code to send to broker
:param reply_text: The reason text to send to broker
:raises ChannelWrongStateError: if channel is closed or closing
"""
if self.is_closed or self.is_closing:
# Whoever is calling `close` might expect the on-channel-close-cb
# to be called, which won't happen when it's already closed.
self._raise_if_not_open()
# If channel is OPENING, we will transition it to CLOSING state,
# causing the _on_openok method to suppress the OPEN state transition
# and the on-channel-open-callback
LOGGER.info('Closing channel (%s): %r on %s', reply_code, reply_text,
self)
# Save the reason info so that we may use it in the '_on_channel_close'
# callback processing
self._closing_reason = exceptions.ChannelClosedByClient(
reply_code, reply_text)
for consumer_tag in list(self._consumers.keys()):
if consumer_tag not in self._cancelled:
self.basic_cancel(consumer_tag=consumer_tag)
# Change state after cancelling consumers to avoid
# ChannelWrongStateError exception from basic_cancel
self._set_state(self.CLOSING)
self._rpc(spec.Channel.Close(reply_code, reply_text, 0, 0),
self._on_closeok, [spec.Channel.CloseOk])
def confirm_delivery(
self,
ack_nack_callback: _OnAckNackCallback,
callback: _OnConfirmDeliveryCallback | None = None) -> None:
"""
Turn on Confirm mode in the channel.
Pass in a callback to be notified by the Broker when a message has been confirmed as received or
rejected (Basic.Ack, Basic.Nack) from the broker to the publisher.
For more information see:
https://www.rabbitmq.com/confirms.html
:param ack_nack_callback: Required callback for delivery
confirmations that has the following signature:
callback(pika.frame.Method), where method_frame contains
either method `spec.Basic.Ack` or `spec.Basic.Nack`.
:param callback: callback(pika.frame.Method) for method
Confirm.SelectOk
:raises TypeError: if `ack_nack_callback` is not callable
.. note::
Calling this method more than once on the same channel replaces
the previously registered ``ack_nack_callback`` rather than adding
an additional one. Only the most recently registered callback
receives ``Basic.Ack``/``Basic.Nack`` notifications.
"""
if not callable(ack_nack_callback):
# confirm_deliver requires a callback; it's meaningless
# without a user callback to receive Basic.Ack/Basic.Nack notifications
raise TypeError('confirm_delivery requires a callback '
'to receive Basic.Ack/Basic.Nack notifications')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if not (self.connection.publisher_confirms and
self.connection.basic_nack):
raise exceptions.MethodNotImplemented(
'Confirm.Select not Supported by Server')
# Replace any previously registered ack/nack callback so repeated
# calls don't stack listeners and fire stale callbacks (see #1602).
if self._on_ack_nack_callback is not None:
self.callbacks.remove(self.channel_number, spec.Basic.Ack,
self._on_ack_nack_callback)
self.callbacks.remove(self.channel_number, spec.Basic.Nack,
self._on_ack_nack_callback)
# Add the ack and nack callback
self.callbacks.add(self.channel_number, spec.Basic.Ack,
ack_nack_callback, False)
self.callbacks.add(self.channel_number, spec.Basic.Nack,
ack_nack_callback, False)
self._on_ack_nack_callback = ack_nack_callback
self._rpc(spec.Confirm.Select(nowait), callback,
[spec.Confirm.SelectOk] if not nowait else [])
@property
def consumer_tags(self) -> list[str]:
"""Property method that returns a list of currently active consumers."""
return list(self._consumers.keys())
def exchange_bind(self,
destination: str,
source: str,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
callback: _OnExchangeBindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Exchange.BindOk
:returns:``None``. Method frame from the Exchange.Bind-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(destination, 'destination')
validators.require_string(source, 'source')
nowait = validators.rpc_completion_callback(callback)
return self._rpc(
spec.Exchange.Bind(0, destination, source, routing_key, nowait,
arguments or {}), callback,
[spec.Exchange.BindOk] if not nowait else [])
def exchange_declare(
self,
exchange: str,
exchange_type: str = ExchangeType.direct,
passive: bool = False,
durable: bool = False,
auto_delete: bool = False,
internal: bool = False,
arguments: dict[str, Any] | None = None,
callback: _OnExchangeDeclareCallback | 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
:param callback: callback(pika.frame.Method) for method Exchange.DeclareOk
:returns: ``None``. Method frame from the Exchange.Declare-ok response is
delivered to ``callback`` when synchronous (no ok frame in nowait
mode).
:raises ValueError:
"""
validators.require_string(exchange, 'exchange')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if isinstance(exchange_type, Enum):
exchange_type = exchange_type.value
return self._rpc(
spec.Exchange.Declare(0, exchange, exchange_type, passive, durable,
auto_delete, internal, nowait, arguments or
{}), callback,
[spec.Exchange.DeclareOk] if not nowait else [])
def exchange_delete(
self,
exchange: str | None = None,
if_unused: bool = False,
callback: _OnExchangeDeleteCallback | None = None) -> None:
"""
Delete the exchange.
:param exchange: The exchange name
:param if_unused: only delete if the exchange is unused
:param callback: callback(pika.frame.Method) for method Exchange.DeleteOk
:returns:``None``. Method frame from the Exchange.Delete-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
return self._rpc(spec.Exchange.Delete(0, exchange, if_unused,
nowait), callback,
[spec.Exchange.DeleteOk] if not nowait else [])
def exchange_unbind(
self,
destination: str | None = None,
source: str | None = None,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
callback: _OnExchangeUnbindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Exchange.UnbindOk
:returns:``None``. Method frame from the Exchange.Unbind-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
return self._rpc(
spec.Exchange.Unbind(0, destination, source, routing_key, nowait,
arguments), callback,
[spec.Exchange.UnbindOk] if not nowait else [])
def flow(self,
active: bool,
callback: _OnFlowCallback | None = None) -> None:
"""
Turn Channel flow control off and on.
Pass a callback to be notified of the response from the server. active is a bool. Callback
should expect a bool in response indicating channel flow state. For more information, please
reference:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#channel.flow
:param active: Turn flow on or off
:param callback: callback(bool) upon completion
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
self._on_flowok_callback = callback
self._rpc(spec.Channel.Flow(active), self._on_flowok,
[spec.Channel.FlowOk])
@property
def is_closed(self) -> bool:
"""Returns True if the channel is closed."""
return self._state == self.CLOSED
@property
def is_closing(self) -> bool:
"""Returns True if client-initiated closing of the channel is in progress."""
return self._state == self.CLOSING
@property
def is_open(self) -> bool:
"""Returns True if the channel is open."""
return self._state == self.OPEN
@property
def is_opening(self) -> bool:
"""Returns True if the channel is opening."""
return self._state == self.OPENING
def open(self) -> None:
"""Open the channel."""
self._set_state(self.OPENING)
self._add_callbacks()
self._rpc(spec.Channel.Open(), self._on_openok, [spec.Channel.OpenOk])
def queue_bind(self,
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnQueueBindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Queue.BindOk
:returns:``None``. Method frame from the Queue.Bind-ok response is delivered to ``callback``
when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
validators.require_string(queue, 'queue')
validators.require_string(exchange, 'exchange')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if routing_key is None:
routing_key = queue
return self._rpc(
spec.Queue.Bind(0, queue, exchange, routing_key, nowait,
arguments or {}), callback,
[spec.Queue.BindOk] if not nowait else [])
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,
callback: _OnQueueDeclareCallback | None = None) -> None:
"""
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
: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
: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
:param callback: callback(pika.frame.Method) for method Queue.DeclareOk
:returns: ``None``. Method frame from the Queue.Declare-ok response is
delivered to ``callback`` when synchronous (no ok frame in nowait
mode).
:raises ValueError:
"""
validators.require_string(queue, 'queue')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
condition: Any
if queue:
condition = (spec.Queue.DeclareOk, {'queue': queue})
else:
condition = spec.Queue.DeclareOk
replies = [condition] if not nowait else []
return self._rpc(
spec.Queue.Declare(0, queue, passive, durable, exclusive,
auto_delete, nowait, arguments or {}), callback,
replies)
def queue_delete(self,
queue: str,
if_unused: bool = False,
if_empty: bool = False,
callback: _OnQueueDeleteCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Queue.DeleteOk
:returns:``None``. Method frame from the Queue.Delete-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(queue, 'queue')
nowait = validators.rpc_completion_callback(callback)
replies = [spec.Queue.DeleteOk] if not nowait else []
return self._rpc(
spec.Queue.Delete(0, queue, if_unused, if_empty, nowait), callback,
replies)
def queue_purge(self,
queue: str,
callback: _OnQueuePurgeCallback | None = None) -> None:
"""
Purge all of the messages from the specified queue.
:param queue: The queue to purge
:param callback: callback(pika.frame.Method) for method Queue.PurgeOk
:returns:``None``. Method frame from the Queue.Purge-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(queue, 'queue')
nowait = validators.rpc_completion_callback(callback)
replies = [spec.Queue.PurgeOk] if not nowait else []
return self._rpc(spec.Queue.Purge(0, queue, nowait), callback, replies)
def queue_unbind(self,
queue: str,
exchange: str | None = None,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnQueueUnbindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Queue.UnbindOk
:returns:``None``. Method frame from the Queue.Unbind-ok response is delivered to
``callback`` when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(queue, 'queue')
validators.rpc_completion_callback(callback)
if routing_key is None:
routing_key = queue
return self._rpc(
spec.Queue.Unbind(0, queue, exchange, routing_key, arguments or {}),
callback, [spec.Queue.UnbindOk])
def tx_commit(self, callback: _OnTxCommitCallback | None = None) -> None:
"""
Commit a transaction.
:param callback: callback(pika.frame.Method) for method Tx.CommitOk
:returns:``None``. Method frame from the Tx.Commit-ok response is delivered to ``callback``
when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Tx.Commit(), callback, [spec.Tx.CommitOk])
def tx_rollback(self,
callback: _OnTxRollbackCallback | None = None) -> None:
"""
Rollback a transaction.
:param callback: callback(pika.frame.Method) for method Tx.RollbackOk
:returns:``None``. Method frame from the Tx.Rollback-ok response is delivered to
``callback`` when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Tx.Rollback(), callback, [spec.Tx.RollbackOk])
def tx_select(self, callback: _OnTxSelectCallback | None = None) -> None:
"""
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.
:param callback: callback(pika.frame.Method) for method Tx.SelectOk
:returns:``None``. Method frame from the Tx.Select-ok response is delivered to ``callback``
when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Tx.Select(), callback, [spec.Tx.SelectOk])
# Internal methods
def _add_callbacks(self) -> None:
"""Callbacks that add the required behavior for a channel when connecting and connected to a
server.
"""
# Add a callback for Basic.GetEmpty
self.callbacks.add(self.channel_number, spec.Basic.GetEmpty,
self._on_getempty, False)
# Add a callback for Basic.Cancel
self.callbacks.add(self.channel_number, spec.Basic.Cancel,
self._on_cancel, False)
# Deprecated in newer versions of RabbitMQ but still register for it
self.callbacks.add(self.channel_number, spec.Channel.Flow,
self._on_flow, False)
# Add a callback for when the server closes our channel
self.callbacks.add(self.channel_number, spec.Channel.Close,
self._on_close_from_broker, True)
def _add_on_cleanup_callback(self, callback: Callable[..., Any]) -> None:
"""
For internal use only (e.g., Connection needs to remove closed channels from its channel
container). Pass a callback function that will be called when the channel is being cleaned
up after all channel-close callbacks callbacks.
:param callback: The callback to call, having the
signature: callback(channel)
"""
self.callbacks.add(self.channel_number,
self._ON_CHANNEL_CLEANUP_CB_KEY,
callback,
one_shot=True,
only_caller=self)
def _cleanup(self) -> None:
"""Remove all consumers and any callbacks for the channel."""
self.callbacks.process(self.channel_number,
self._ON_CHANNEL_CLEANUP_CB_KEY, self, self)
self._consumers = {}
self._cancelled = set()
self._nowait_cancelled = deque()
self._consumers_with_noack = set()
self.callbacks.cleanup(str(self.channel_number))
self._cookie = None
def _cleanup_consumer_ref(self, consumer_tag: str) -> None:
"""
Remove any references to the consumer tag in internal structures for consumer state.
:param consumer_tag: The consumer tag to cleanup
"""
self._consumers_with_noack.discard(consumer_tag)
self._consumers.pop(consumer_tag, None)
self._cancelled.discard(consumer_tag)
def _retain_cancelled_tag(self, consumer_tag: str) -> None:
"""
Retain a nowait-cancelled consumer tag, evicting the oldest once the cap is reached.
A cancelled tag stays in `_cancelled` (and `_consumers_with_noack`) so that a delivery the
broker had already dispatched when `Basic.Cancel` was sent is rejected rather than left
unacknowledged; see `_on_deliver`. A cancel that expects a `Basic.CancelOk` retires its own
entry in `_on_cancelok`, but a nowait cancel asks the broker for no reply, so nothing
retires it and the entries would otherwise accumulate for the life of the channel.
Bound them here instead. The number of deliveries that can still be in flight for a
cancelled consumer is bounded by what the broker had already dispatched, so a cap on
retained nowait-cancelled tags approximates that window: evicting in cancellation order past
`_MAX_RETAINED_CANCELLED_TAGS` keeps retention constant in the number of cancels. The cap
is not the true window, though, since it is measured in cancels rather than deliveries, so
once a tag is evicted its reject-and-reserve behaviour lapses: a straggling delivery for it
is logged as unexpected and left unacknowledged (see `_on_deliver`), and `basic_consume`
will accept the tag again. The default is large enough that this only occurs under extreme
nowait-cancel churn.
A tag cannot be queued twice: `basic_consume` refuses a tag that is still in `_cancelled`,
and on the nowait path only eviction takes it back out again.
:param consumer_tag: The consumer tag just cancelled with nowait
"""
self._nowait_cancelled.append(consumer_tag)
while len(self._nowait_cancelled) > self._MAX_RETAINED_CANCELLED_TAGS:
self._cleanup_consumer_ref(self._nowait_cancelled.popleft())
def _get_cookie(self) -> Any:
"""
Used by the wrapper implementation (e.g., `BlockingChannel`) to retrieve the cookie that it
set via `_set_cookie`
:returns: opaque cookie value that was set via `_set_cookie`
"""
return self._cookie
def _handle_content_frame(self, frame_value: frame.Frame) -> None:
"""
This is invoked by the connection when frames that are not registered with the
CallbackManager have been found. This should only be the case when the frames are related to
content delivery.
The _content_assembler will be invoked which will return the fully formed message in three
parts when all of the body frames have been received.
:param frame_value: The frame to deliver
"""
try:
response = self._content_assembler.process(frame_value)
except exceptions.UnexpectedFrameError:
self._on_unexpected_frame(frame_value)
return
if response:
method_index = response[0].method.INDEX
if method_index == spec.Basic.Deliver.INDEX:
self._on_deliver(*response)
elif method_index == spec.Basic.GetOk.INDEX:
self._on_getok(*response)
elif method_index == spec.Basic.Return.INDEX:
self._on_return(*response)
def _on_cancel(self, method_frame: frame.Method) -> None:
"""
When the broker cancels a consumer, delete it from our internal dictionary.
Reply with `Basic.CancelOk` if the broker advertises the `accept_consumer_cancel_ok`
capability.
:param method_frame: The method frame received
"""
consumer_tag = method_frame.method.consumer_tag
# Sent before the `_cancelled` check below, so a user-initiated cancel
# racing a broker-sent one still gets a reply. That is safe in both
# orders, which is not obvious from here. A broker advertising the
# capability answers a `Basic.CancelOk` for a tag it is not waiting on
# with `{noreply, State}`, so a late or duplicate reply is ignored
# rather than treated as a protocol error. And if this reply reaches the
# broker first, it releases the consumer without replying, leaving the
# user's in-flight `Basic.Cancel` to arrive for a tag the broker no
# longer tracks - which `cancel_consumer` answers with a `Basic.CancelOk`
# anyway ("Spec requires we ignore this situation"), so the pending RPC
# still completes instead of hanging.
if self.is_open and self.connection.accept_consumer_cancel_ok:
self._send_method(spec.Basic.CancelOk(consumer_tag=consumer_tag))
if consumer_tag in self._cancelled:
# User-initiated cancel is waiting for Cancel-ok
return
self._cleanup_consumer_ref(consumer_tag)
def _on_cancelok(self, method_frame: frame.Method) -> None:
"""
Called in response to a frame from the Broker when the client sends Basic.Cancel.
:param method_frame: The method frame received
"""
self._cleanup_consumer_ref(method_frame.method.consumer_tag)
def _transition_to_closed(self) -> None:
"""Common logic for transitioning the channel to the CLOSED state:
Set state to CLOSED, dispatch callbacks registered via
`Channel.add_on_close_callback()`, and mop up.
Assumes that the channel is not in CLOSED state and that
`self._closing_reason` has been set up
"""
assert not self.is_closed
assert self._closing_reason is not None
self._set_state(self.CLOSED)
try:
self.callbacks.process(self.channel_number, '_on_channel_close',
self, self, self._closing_reason)
finally:
self._cleanup()
def _on_close_from_broker(self, method_frame: frame.Method) -> None:
"""
Handle `Channel.Close` from broker.
:param method_frame: Method frame with Channel.Close method
"""
LOGGER.warning('Received remote Channel.Close (%s): %r on %s',
method_frame.method.reply_code,
method_frame.method.reply_text, self)
# Note, we should not be called when channel is already closed
assert not self.is_closed
# AMQP 0.9.1 requires CloseOk response to Channel.Close;
self._send_method(spec.Channel.CloseOk())
# Save the details, possibly overriding user-provided values if
# user-initiated close is pending (in which case they will be provided
# to user callback when CloseOk arrives).
self._closing_reason = exceptions.ChannelClosedByBroker(
method_frame.method.reply_code, method_frame.method.reply_text)
if self.is_closing:
# Since we may have already put Channel.Close on the wire, we need
# to wait for CloseOk before cleaning up to avoid a race condition
# whereby our channel number might get reused before our CloseOk
# arrives
#
# NOTE: if our Channel.Close destined for the broker was blocked by
# an earlier synchronous method, this call will drop it and perform
# a meta-close (see `_on_close_meta()` which fakes receipt of
# `Channel.CloseOk` and dispatches the `'_on_channel_close'`
# callbacks.
self._drain_blocked_methods_on_remote_close()
else:
self._transition_to_closed()
def _on_close_meta(self, reason: Exception | None) -> None:
"""
Handle meta-close request from either a remote Channel.Close from the broker (when a pending
Channel.Close method is queued for execution) or a Connection's cleanup logic after sudden
connection loss. We use this opportunity to transition to CLOSED state, clean up the
channel, and dispatch the on-channel-closed callbacks.
:param reason: Exception describing the reason for closing.
"""
LOGGER.debug('Handling meta-close on %s: %r', self, reason)
if not self.is_closed:
self._closing_reason = reason
self._transition_to_closed()
def _on_closeok(self, method_frame: frame.Method) -> None:
"""
Invoked when RabbitMQ replies to a Channel.Close method.
:param method_frame: Method frame with Channel.CloseOk method
"""
LOGGER.info('Received %s on %s', method_frame.method, self)
self._transition_to_closed()
def _on_deliver(self, method_frame: frame.Method,
header_frame: frame.Header, body: bytes) -> None:
"""
Cope with reentrancy.
If a particular consumer is still active when another delivery appears for it, queue the
deliveries up until it finally exits.
:param method_frame: The method frame received
:param header_frame: The header frame received
:param body: The body received
"""
consumer_tag = method_frame.method.consumer_tag
if consumer_tag in self._cancelled:
if self.is_open and consumer_tag not in self._consumers_with_noack:
self.basic_reject(method_frame.method.delivery_tag)
return
if consumer_tag not in self._consumers:
LOGGER.error('Unexpected delivery: %r', method_frame)
return
self._consumers[consumer_tag](self, method_frame.method,
header_frame.properties, body)
def _on_eventok(self, method_frame: frame.Method) -> None:
"""
Generic events that returned ok that may have internal callbacks.
We keep a list of what we've yet to implement so that we don't silently drain events that we
don't support.
:param method_frame: The method frame received
"""
LOGGER.debug('Discarding frame %r', method_frame)
def _on_flow(self, _method_frame_unused: frame.Method) -> None:
"""
Called if the server sends a Channel.Flow frame.
:param _method_frame_unused: The Channel.Flow frame
"""
if self._has_on_flow_callback is False:
LOGGER.warning('Channel.Flow received from server')
def _on_flowok(self, method_frame: frame.Method) -> None:
"""
Called in response to us asking the server to toggle on Channel.Flow.
:param method_frame: The method frame received
"""
self.flow_active = method_frame.method.active
if self._on_flowok_callback:
self._on_flowok_callback(method_frame.method.active)
self._on_flowok_callback = None
else:
LOGGER.warning('Channel.FlowOk received with no active callbacks')
def _on_getempty(self, method_frame: frame.Method) -> None:
"""
When we receive an empty reply do nothing but log it.
:param method_frame: The method frame received
"""
LOGGER.debug('Received Basic.GetEmpty: %r', method_frame)
if self._on_getok_callback is not None:
self._on_getok_callback = None
def _on_getok(self, method_frame: frame.Method, header_frame: frame.Header,
body: bytes) -> None:
"""
Called in reply to a Basic.Get when there is a message.
:param method_frame: The method frame received
:param header_frame: The header frame received
:param body: The body received
"""
if self._on_getok_callback is not None:
callback = self._on_getok_callback
self._on_getok_callback = None
callback(self, method_frame.method, header_frame.properties, body)
else:
LOGGER.error('Basic.GetOk received with no active callback')
def _on_openok(self, method_frame: frame.Method) -> None:
"""
Called by our callback handler when we receive a Channel.OpenOk and subsequently calls our
_on_openok_callback which was passed into the Channel constructor. The reason we do this is
because we want to make sure that the on_open_callback parameter passed into the Channel
constructor is not the first callback we make.
Suppress the state transition and callback if channel is already in CLOSING state.
:param method_frame: Channel.OpenOk frame
"""
# Suppress OpenOk if the user or Connection.Close started closing it
# before open completed.
if self.is_closing:
LOGGER.debug('Suppressing while in closing state: %s', method_frame)
else:
self._set_state(self.OPEN)
if self._on_openok_callback is not None:
self._on_openok_callback(self)
def _on_return(self, method_frame: frame.Method, header_frame: frame.Header,
body: bytes) -> None:
"""
Called if the server sends a Basic.Return frame.
:param method_frame: The Basic.Return frame
:param header_frame: The content header frame
:param body: The message body
"""
if not self.callbacks.process(self.channel_number, '_on_return', self,
self, method_frame.method,
header_frame.properties, body):
LOGGER.debug('Basic.Return received from server (%r, %r)',
method_frame.method, header_frame.properties)
def _on_selectok(self, method_frame: frame.Method) -> None:
"""
Called when the broker sends a Confirm.SelectOk frame.
:param method_frame: The method frame received
"""
LOGGER.debug('Confirm.SelectOk Received: %r', method_frame)
def _on_synchronous_complete(self,
_method_frame_unused: frame.Method) -> None:
"""
This is called when a synchronous command is completed.
It will undo the blocking state and send all the frames that stacked up while we were in the
blocking state.
:param _method_frame_unused: The method frame received
"""
LOGGER.debug('%i blocked frames', len(self._blocked))
self._blocking = None
# self._blocking must be checked here as a callback could
# potentially change the state of that variable during an
# iteration of the while loop
while self._blocked and self._blocking is None:
self._rpc(*self._blocked.popleft())
def _drain_blocked_methods_on_remote_close(self) -> None:
"""
This is called when the broker sends a Channel.Close while the client is in CLOSING state.
This method checks the blocked method queue for a pending client-initiated Channel.Close
method and ensures its callbacks are processed, but does not send the method to the broker.
The broker may close the channel before responding to outstanding in-transit synchronous
methods, or even before these methods have been sent to the broker. AMQP 0.9.1 obliges the
server to drop all methods arriving on a closed channel other than Channel.CloseOk and
Channel.Close. Since the response to a synchronous method that blocked the channel never
arrives, the channel never becomes unblocked, and the Channel.Close, if any, in the blocked
queue has no opportunity to be sent, and thus its completion callback would never be called.
"""
LOGGER.debug(
'Draining %i blocked frames due to broker-requested Channel.Close',
len(self._blocked))
while self._blocked:
method = self._blocked.popleft()[0]
if isinstance(method, spec.Channel.Close):
# The desired reason is already in self._closing_reason
self._on_close_meta(self._closing_reason)
else:
LOGGER.debug('Ignoring drained blocked method: %s', method)
def _rpc(
self,
method: amqp_object.Method,
callback: Callable[..., Any] | None = None,
acceptable_replies: Sequence[type[amqp_object.Method] |
tuple[type[amqp_object.Method],
dict[str, Any]]] | None = None
) -> None:
"""
Make a synchronous channel RPC call for a synchronous method frame.
If the channel is already in the blocking state, then enqueue the request,
but don't send it at this time; it will be eventually sent by
`_on_synchronous_complete` after the prior blocking request receives a
response. If the channel is not in the blocking state and
`acceptable_replies` is not empty, transition the channel to the
blocking state and register for `_on_synchronous_complete` before
sending the request.
NOTE: A callback must be accompanied by non-empty acceptable_replies.
:param method: The AMQP method to invoke
:param callback: The callback for the RPC response
:param acceptable_replies: A (possibly empty) sequence of
replies this RPC call expects or None
"""
assert method.synchronous, (
f'Only synchronous-capable methods may be used with _rpc: {method!r}'
)
# Validate we got None or a list of acceptable_replies
if not isinstance(acceptable_replies, (type(None), list)):
raise TypeError('acceptable_replies should be list or None')
if callback is not None:
# Validate the callback is callable
if not callable(callback):
raise TypeError('callback should be None or a callable')
# Make sure that callback is accompanied by acceptable replies
if not acceptable_replies:
raise ValueError(
'Unexpected callback for asynchronous (nowait) operation.')
# Make sure the channel is not closed yet
if self.is_closed:
self._raise_if_not_open()
# If the channel is blocking, add subsequent commands to our stack
if self._blocking:
LOGGER.debug(
'Already in blocking state, so enqueueing method %s; '
'acceptable_replies=%r', method, acceptable_replies)
self._blocked.append([method, callback, acceptable_replies])
return
# Note: _send_method can throw exceptions if there are framing errors
# or invalid data passed in. Call it here to prevent self._blocking
# from being set if an exception is thrown. This also prevents
# acceptable_replies registering callbacks when exceptions are thrown
self._send_method(method)
# If acceptable replies are set, add callbacks
if acceptable_replies:
# Block until a response frame is received for synchronous frames
self._blocking = method.NAME
LOGGER.debug(
'Entering blocking state on frame %s; acceptable_replies=%r',
method, acceptable_replies)
for reply in acceptable_replies:
if isinstance(reply, tuple):
reply, arguments = reply
else:
arguments = None
LOGGER.debug('Adding on_synchronous_complete callback')
self.callbacks.add(self.channel_number,
reply,
self._on_synchronous_complete,
arguments=arguments)
if callback is not None:
LOGGER.debug('Adding passed-in RPC response callback')
self.callbacks.add(self.channel_number,
reply,
callback,
arguments=arguments)
def _raise_if_not_open(self) -> None:
"""
If channel is not in the OPEN state, raises ChannelWrongStateError with `reply_code` and
`reply_text` corresponding to current state.
:raises exceptions.ChannelWrongStateError: if channel is not in OPEN state.
"""
if self._state == self.OPEN:
return
if self._state == self.OPENING:
raise exceptions.ChannelWrongStateError(
'Channel is opening, but is not usable yet.')
if self._state == self.CLOSING:
raise exceptions.ChannelWrongStateError('Channel is closing.')
# Assumed self.CLOSED
assert self._state == self.CLOSED
raise exceptions.ChannelWrongStateError('Channel is closed.')
def _send_method(
self,
method: amqp_object.Method,
content: tuple[spec.BasicProperties, bytes] | None = None) -> None:
"""
Shortcut wrapper to send a method through our connection, passing in the channel number.
:param method: The method to send
:param content: If set, is a content frame, is tuple of properties and body.
"""
self.connection._send_method(self.channel_number, method, content)
def _set_cookie(self, cookie: object) -> None:
"""
Used by wrapper layer (e.g., `BlockingConnection`) to link the channel implementation back
to the proxy. See `_get_cookie`.
:param cookie: an opaque value; typically a proxy channel implementation instance (e.g.,
`BlockingChannel` instance)
"""
self._cookie = cookie
def _set_state(self, connection_state: int) -> None:
"""
Set the channel connection state to the specified state value.
:param connection_state: The connection_state value
"""
self._state = connection_state
def _on_unexpected_frame(self, frame_value: frame.Frame) -> None:
"""
Invoked when a frame is received that is not setup to be processed.
:param frame_value: The frame received
"""
LOGGER.error('Unexpected frame: %r', frame_value)
property
¶
consumer_tags: list[str]
Property method that returns a list of currently active consumers.
property
¶
is_closing: bool
Returns True if client-initiated closing of the channel is in progress.
__init__(
connection: Connection,
channel_number: int,
on_open_callback: _OnOpenCallback | None,
) -> None
Create a new instance of the Channel.
| PARAMETER | DESCRIPTION |
|---|---|
connection
|
The connection
TYPE:
|
channel_number
|
The channel number for this instance
TYPE:
|
on_open_callback
|
The callback to call on channel open. The callback will be invoked
with the
TYPE:
|
Source code in pika/channel.py
def __init__(self, connection: Connection, channel_number: int,
on_open_callback: _OnOpenCallback | None) -> None:
"""
Create a new instance of the Channel.
:param connection: The connection
:param channel_number: The channel number for this instance
:param on_open_callback: The callback to call on channel open. The callback will be invoked
with the `Channel` instance as its only argument.
"""
if not isinstance(channel_number, int):
raise exceptions.InvalidChannelNumber(channel_number)
validators.rpc_completion_callback(on_open_callback)
self.channel_number = channel_number
self.callbacks = connection.callbacks
self.connection = connection
# Initially, flow is assumed to be active
self.flow_active = True
self._content_assembler = ContentFrameAssembler()
self._blocked: deque = deque()
self._blocking: Any | None = None
self._has_on_flow_callback: bool = False
self._cancelled: set = set()
# Nowait-cancelled tags in cancellation order, bounding how many of
# them `_cancelled` retains; see `_retain_cancelled_tag`.
self._nowait_cancelled: deque = deque()
self._consumers: dict = {}
self._consumers_with_noack: set = set()
self._on_flowok_callback: Callable[..., Any] | None = None
self._on_getok_callback: Callable[..., Any] | None = None
self._on_ack_nack_callback: _OnAckNackCallback | None = None
self._on_openok_callback: Callable[..., Any] | None = on_open_callback
self._state: int = self.CLOSED
# We save the closing reason exception to be passed to on-channel-close
# callback at closing of the channel. Exception representing the closing
# reason; ChannelClosedByClient or ChannelClosedByBroker on controlled
# close; otherwise another exception describing the reason for failure
# (most likely connection failure).
self._closing_reason = None # type: None | Exception
# opaque cookie value set by wrapper layer (e.g., BlockingConnection)
# via _set_cookie
self._cookie: object = None
__int__() -> int
Return the channel object as its channel number.
Source code in pika/channel.py
def __int__(self) -> int:
"""Return the channel object as its channel number."""
return self.channel_number
add_callback(
callback: Callable[..., Any],
replies: Sequence[type[Method]],
one_shot: bool = True,
) -> None
Pass in a callback handler and a list replies from the RabbitMQ broker which you'd like the callback notified of. Callbacks should allow for the frame parameter to be passed in.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to call
TYPE:
|
replies
|
The replies to get a callback for
TYPE:
|
one_shot
|
Only handle the first type callback
TYPE:
|
Source code in pika/channel.py
def add_callback(self,
callback: Callable[..., Any],
replies: Sequence[type[amqp_object.Method]],
one_shot: bool = True) -> None:
"""
Pass in a callback handler and a list replies from the RabbitMQ broker which you'd like the
callback notified of. Callbacks should allow for the frame parameter to be passed in.
:param callback: The callback to call
:param replies: The replies to get a callback for
:param one_shot: Only handle the first type callback
"""
for reply in replies:
self.callbacks.add(self.channel_number, reply, callback, one_shot)
add_on_cancel_callback(callback: _OnCancelCallback) -> None
Pass a callback function that will be called when the basic_cancel is sent by the server. The callback function should receive a frame parameter.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to call on Basic.Cancel from broker
TYPE:
|
Source code in pika/channel.py
def add_on_cancel_callback(self, callback: _OnCancelCallback) -> None:
"""
Pass a callback function that will be called when the basic_cancel is sent by the server.
The callback function should receive a frame parameter.
:param callback: The callback to call on Basic.Cancel from broker
"""
self.callbacks.add(self.channel_number, spec.Basic.Cancel, callback,
False)
add_on_close_callback(callback: _OnCloseCallback) -> None
Pass a callback function that will be called when the channel is closed.
The callback function will receive the channel and an exception describing why the channel was closed.
If the channel is closed by broker via Channel.Close, the callback will receive
ChannelClosedByBroker as the reason.
If graceful user-initiated channel closing completes successfully ( either directly of
indirectly by closing a connection containing the channel) and closing concludes gracefully
without Channel.Close from the broker and without loss of connection, the callback will
receive ChannelClosedByClient exception as reason.
If channel was closed due to loss of connection, the callback will receive another exception type describing the failure.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback, having the signature: callback(Channel, Exception reason)
TYPE:
|
Source code in pika/channel.py
def add_on_close_callback(self, callback: _OnCloseCallback) -> None:
"""
Pass a callback function that will be called when the channel is closed.
The callback function will receive the channel and an exception describing why the channel
was closed.
If the channel is closed by broker via Channel.Close, the callback will receive
`ChannelClosedByBroker` as the reason.
If graceful user-initiated channel closing completes successfully ( either directly of
indirectly by closing a connection containing the channel) and closing concludes gracefully
without Channel.Close from the broker and without loss of connection, the callback will
receive `ChannelClosedByClient` exception as reason.
If channel was closed due to loss of connection, the callback will receive another exception
type describing the failure.
:param callback: The callback, having the signature: callback(Channel, Exception reason)
"""
self.callbacks.add(self.channel_number, '_on_channel_close', callback,
False, self)
add_on_flow_callback(callback: _OnFlowCallback) -> None
Pass a callback function that will be called when Channel.Flow is called by the remote server. Note that newer versions of RabbitMQ will not issue this but instead use TCP backpressure.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback function
TYPE:
|
Source code in pika/channel.py
def add_on_flow_callback(self, callback: _OnFlowCallback) -> None:
"""
Pass a callback function that will be called when Channel.Flow is called by the remote
server. Note that newer versions of RabbitMQ will not issue this but instead use TCP
backpressure.
:param callback: The callback function
"""
self._has_on_flow_callback = True
self.callbacks.add(self.channel_number, spec.Channel.Flow, callback,
False)
add_on_return_callback(callback: _OnReturnCallback) -> None
Pass a callback function that will be called when basic_publish is sent a message that has been rejected and returned by the server.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The function to call, having the signature callback(channel, method, properties, body) where - channel: pika.channel.Channel - method: pika.spec.Basic.Return - properties: pika.spec.BasicProperties - body: bytes
TYPE:
|
Source code in pika/channel.py
def add_on_return_callback(self, callback: _OnReturnCallback) -> None:
"""
Pass a callback function that will be called when basic_publish is sent a message that has
been rejected and returned by the server.
:param callback: The function to call, having the signature
callback(channel, method, properties, body)
where
- channel: pika.channel.Channel
- method: pika.spec.Basic.Return
- properties: pika.spec.BasicProperties
- body: bytes
"""
self.callbacks.add(self.channel_number, '_on_return', callback, False)
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
|
int/long 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/channel.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: int/long 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._raise_if_not_open()
return self._send_method(spec.Basic.Ack(delivery_tag, multiple))
basic_cancel(
consumer_tag: str = '',
callback: _OnBasicCancelCallback | None = None,
) -> None
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. It may also be sent from the server to the client in the event of the consumer being unexpectedly cancelled (i.e. cancelled for any reason other than the server receiving the corresponding basic.cancel from the client). This allows clients to be notified of the loss of consumers due to events such as queue deletion.
A cancelled consumer's tag is retained so that a delivery already in flight when the cancel
was sent is rejected rather than left unacknowledged. A cancel that expects a Basic.CancelOk
retires its own entry on arrival; a nowait cancel has no reply to retire it, so its tag is
kept only until _MAX_RETAINED_CANCELLED_TAGS later nowait cancels displace it (see
_retain_cancelled_tag). Past that point its retention lapses: a straggling delivery for it
is logged as unexpected and left unacknowledged rather than rejected, and the tag may be
reused by basic_consume, so reusing the same explicit consumer_tag risks a delivery for
the old consumer reaching the new one. The cap is a generous approximation of the broker's
in-flight window, so this only bites under extreme nowait-cancel churn.
| PARAMETER | DESCRIPTION |
|---|---|
consumer_tag
|
Identifier for the consumer
TYPE:
|
callback
|
callback(pika.frame.Method) for method Basic.CancelOk. If None, do not expect a Basic.CancelOk response, otherwise, callback must be callable
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def basic_cancel(self,
consumer_tag: str = '',
callback: _OnBasicCancelCallback | None = None) -> None:
"""
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. It may also be sent
from the server to the client in the event of the consumer being unexpectedly cancelled
(i.e. cancelled for any reason other than the server receiving the corresponding
basic.cancel from the client). This allows clients to be notified of the loss of consumers
due to events such as queue deletion.
A cancelled consumer's tag is retained so that a delivery already in flight when the cancel
was sent is rejected rather than left unacknowledged. A cancel that expects a Basic.CancelOk
retires its own entry on arrival; a nowait cancel has no reply to retire it, so its tag is
kept only until `_MAX_RETAINED_CANCELLED_TAGS` later nowait cancels displace it (see
`_retain_cancelled_tag`). Past that point its retention lapses: a straggling delivery for it
is logged as unexpected and left unacknowledged rather than rejected, and the tag may be
reused by `basic_consume`, so reusing the same explicit consumer_tag risks a delivery for
the old consumer reaching the new one. The cap is a generous approximation of the broker's
in-flight window, so this only bites under extreme nowait-cancel churn.
:param consumer_tag: Identifier for the consumer
:param callback: callback(pika.frame.Method) for method Basic.CancelOk. If None, do not
expect a Basic.CancelOk response, otherwise, callback must be callable
:raises ValueError:
"""
validators.require_string(consumer_tag, 'consumer_tag')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if consumer_tag in self._cancelled:
# We check for cancelled first, because basic_cancel removes
# consumers closed with nowait from self._consumers
LOGGER.warning('basic_cancel - consumer is already cancelling: %s',
consumer_tag)
return
if consumer_tag not in self._consumers:
# Could be cancelled by user or broker earlier
LOGGER.warning('basic_cancel - consumer not found: %s',
consumer_tag)
return
LOGGER.debug('Cancelling consumer: %s (nowait=%s)', consumer_tag,
nowait)
if nowait:
# This is our last opportunity while the channel is open to remove
# this consumer callback and help gc.
del self._consumers[consumer_tag]
if callback is not None:
self.callbacks.add(self.channel_number, spec.Basic.CancelOk,
callback)
self._cancelled.add(consumer_tag)
if nowait:
self._retain_cancelled_tag(consumer_tag)
self._rpc(spec.Basic.Cancel(consumer_tag=consumer_tag, nowait=nowait),
self._on_cancelok if not nowait else None,
[(spec.Basic.CancelOk, {
'consumer_tag': consumer_tag
})] if not nowait else [])
basic_consume(
queue: str,
on_message_callback: _OnMessageCallback,
auto_ack: bool = False,
exclusive: bool = False,
consumer_tag: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnBasicConsumeCallback | None = None,
) -> str
Sends the AMQP 0-9-1 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.
For more information on basic_consume, see: Tutorial 2 at https://www.rabbitmq.com/getstarted.html https://www.rabbitmq.com/confirms.html https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue to consume from. Use the empty string to specify the most recent server-named queue for this channel
TYPE:
|
on_message_callback
|
The function to call when consuming with the signature on_message_callback(channel, method, properties, body), where - channel: pika.channel.Channel - method: pika.spec.Basic.Deliver - properties: pika.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
|
Specify your own consumer tag
TYPE:
|
arguments
|
Custom key/value pair arguments for the consumer
TYPE:
|
callback
|
callback(pika.frame.Method) for method Basic.ConsumeOk.
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
str
|
Consumer tag which may be used to cancel the consumer. |
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def basic_consume(self,
queue: str,
on_message_callback: _OnMessageCallback,
auto_ack: bool = False,
exclusive: bool = False,
consumer_tag: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnBasicConsumeCallback | None = None) -> str:
"""
Sends the AMQP 0-9-1 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.
For more information on basic_consume, see:
Tutorial 2 at https://www.rabbitmq.com/getstarted.html
https://www.rabbitmq.com/confirms.html
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume
:param queue: The queue to consume from. Use the empty string to
specify the most recent server-named queue for this channel
:param on_message_callback: The function to call when
consuming with the signature
on_message_callback(channel, method, properties, body), where
- channel: pika.channel.Channel
- method: pika.spec.Basic.Deliver
- properties: pika.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: Specify your own consumer tag
:param arguments: Custom key/value pair arguments for the consumer
:param callback: callback(pika.frame.Method) for method
Basic.ConsumeOk.
:returns: Consumer tag which may be used to cancel the consumer.
:raises ValueError:
"""
validators.require_string(queue, 'queue')
validators.require_callback(on_message_callback)
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
# If a consumer tag was not passed, create one
if not consumer_tag:
consumer_tag = self._generate_consumer_tag()
if consumer_tag in self._consumers or consumer_tag in self._cancelled:
raise exceptions.DuplicateConsumerTag(consumer_tag)
if auto_ack:
self._consumers_with_noack.add(consumer_tag)
self._consumers[consumer_tag] = on_message_callback
rpc_callback: Callable[
...,
Any] | None = self._on_eventok if callback is None else callback
self._rpc(
spec.Basic.Consume(queue=queue,
consumer_tag=consumer_tag,
no_ack=auto_ack,
exclusive=exclusive,
arguments=arguments or {}), rpc_callback,
[(spec.Basic.ConsumeOk, {
'consumer_tag': consumer_tag
})])
return consumer_tag
basic_get(
queue: str,
callback: _OnBasicGetCallback,
auto_ack: bool = False,
) -> None
Get a single message from the AMQP broker.
If you want to be notified of Basic.GetEmpty, use the Channel.add_callback method adding your Basic.GetEmpty callback which should expect only one parameter, frame. Due to implementation details, this cannot be called a second time until the callback is executed. For more information on basic_get and its parameters, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.get
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue from which to get a message. Use the empty string to specify the most recent server-named queue for this channel
TYPE:
|
callback
|
The callback to call with a message that has the signature callback(channel, method, properties, body), where: - channel: pika.channel.Channel - method: pika.spec.Basic.GetOk - properties: pika.spec.BasicProperties - body: bytes
TYPE:
|
auto_ack
|
Tell the broker to not expect a reply
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def basic_get(self,
queue: str,
callback: _OnBasicGetCallback,
auto_ack: bool = False) -> None:
"""
Get a single message from the AMQP broker.
If you want to be notified of Basic.GetEmpty, use the Channel.add_callback method
adding your Basic.GetEmpty callback which should expect only one
parameter, frame. Due to implementation details, this cannot be called
a second time until the callback is executed. For more information on
basic_get and its parameters, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.get
:param queue: The queue from which to get a message. Use the empty
string to specify the most recent server-named queue for this
channel
:param callback: The callback to call with a message that has
the signature callback(channel, method, properties, body), where:
- channel: pika.channel.Channel
- method: pika.spec.Basic.GetOk
- properties: pika.spec.BasicProperties
- body: bytes
:param auto_ack: Tell the broker to not expect a reply
:raises ValueError:
"""
validators.require_string(queue, 'queue')
validators.require_callback(callback)
if self._on_getok_callback is not None:
raise exceptions.DuplicateGetOkCallback()
self._on_getok_callback = callback
# TODO Strangely, not using _rpc for the synchronous Basic.Get. Would
# need to extend _rpc to handle Basic.GetOk method, header, and body
# frames (or similar)
self._send_method(spec.Basic.Get(queue=queue, no_ack=auto_ack))
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
|
int/long 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/channel.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: int/long 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._raise_if_not_open()
return self._send_method(
spec.Basic.Nack(delivery_tag, multiple, requeue))
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
| PARAMETER | DESCRIPTION |
|---|---|
exchange
|
The exchange to publish to
TYPE:
|
routing_key
|
The routing key to bind on
TYPE:
|
body
|
The message body
TYPE:
|
properties
|
Basic.properties
TYPE:
|
mandatory
|
The mandatory flag
TYPE:
|
Source code in pika/channel.py
def basic_publish(self,
exchange: str,
routing_key: str,
body: bytes,
properties: 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
:param exchange: The exchange to publish to
:param routing_key: The routing key to bind on
:param body: The message body
:param properties: Basic.properties
:param mandatory: The mandatory flag
"""
self._raise_if_not_open()
body = as_bytes(body)
properties = properties or spec.BasicProperties()
self._send_method(
spec.Basic.Publish(exchange=exchange,
routing_key=routing_key,
mandatory=mandatory), (properties, body))
basic_qos(
prefetch_size: int = 0,
prefetch_count: int = 0,
global_qos: bool = False,
callback: _OnBasicQosCallback | None = None,
) -> None
Specify quality of service.
This method requests a specific quality of service. 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. The QoS can be applied separately to each new consumer on channel or shared across all consumers on 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 by consumers who have enabled the no-ack option.
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 by consumers who have enabled the no-ack option.
TYPE:
|
global_qos
|
Should the QoS be shared across all consumers on the channel.
TYPE:
|
callback
|
The callback to call for Basic.QosOk response
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def basic_qos(self,
prefetch_size: int = 0,
prefetch_count: int = 0,
global_qos: bool = False,
callback: _OnBasicQosCallback | None = None) -> None:
"""
Specify quality of service.
This method requests a specific quality of service. 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. The QoS can be
applied separately to each new consumer on channel or shared across all consumers on 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 by
consumers who have enabled the no-ack option.
: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 by consumers who have enabled the no-ack option.
:param global_qos: Should the QoS be shared across all consumers on the channel.
:param callback: The callback to call for Basic.QosOk response
:returns:``None``. Method frame from the Basic.Qos-ok response is delivered to ``callback``
when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
validators.zero_or_greater('prefetch_size', prefetch_size)
validators.zero_or_greater('prefetch_count', prefetch_count)
return self._rpc(
spec.Basic.Qos(prefetch_size, prefetch_count, global_qos), callback,
[spec.Basic.QosOk])
basic_recover(
requeue: bool = False,
callback: _OnBasicRecoverCallback | None = None,
) -> 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:
|
callback
|
callback(pika.frame.Method) for method Basic.RecoverOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def basic_recover(self,
requeue: bool = False,
callback: _OnBasicRecoverCallback | None = None) -> 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.
:param callback: callback(pika.frame.Method) for method Basic.RecoverOk
:returns:``None``. Method frame from the Basic.Recover-ok response is delivered to
``callback`` when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Basic.Recover(requeue), callback,
[spec.Basic.RecoverOk])
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
|
int/long 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:
|
| RAISES | DESCRIPTION |
|---|---|
TypeError
|
|
Source code in pika/channel.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: int/long 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.
:raises TypeError:
"""
self._raise_if_not_open()
if not isinstance(delivery_tag, int):
raise TypeError('delivery_tag must be an integer')
return self._send_method(spec.Basic.Reject(delivery_tag, requeue))
close(
reply_code: int = 0, reply_text: str = 'Normal shutdown'
) -> None
Invoke a graceful shutdown of the channel with the AMQP Broker.
If channel is OPENING, transition to CLOSING and suppress the incoming Channel.OpenOk, if any.
| PARAMETER | DESCRIPTION |
|---|---|
reply_code
|
The reason code to send to broker
TYPE:
|
reply_text
|
The reason text to send to broker
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
ChannelWrongStateError
|
if channel is closed or closing |
Source code in pika/channel.py
def close(self,
reply_code: int = 0,
reply_text: str = 'Normal shutdown') -> None:
"""
Invoke a graceful shutdown of the channel with the AMQP Broker.
If channel is OPENING, transition to CLOSING and suppress the incoming Channel.OpenOk, if
any.
:param reply_code: The reason code to send to broker
:param reply_text: The reason text to send to broker
:raises ChannelWrongStateError: if channel is closed or closing
"""
if self.is_closed or self.is_closing:
# Whoever is calling `close` might expect the on-channel-close-cb
# to be called, which won't happen when it's already closed.
self._raise_if_not_open()
# If channel is OPENING, we will transition it to CLOSING state,
# causing the _on_openok method to suppress the OPEN state transition
# and the on-channel-open-callback
LOGGER.info('Closing channel (%s): %r on %s', reply_code, reply_text,
self)
# Save the reason info so that we may use it in the '_on_channel_close'
# callback processing
self._closing_reason = exceptions.ChannelClosedByClient(
reply_code, reply_text)
for consumer_tag in list(self._consumers.keys()):
if consumer_tag not in self._cancelled:
self.basic_cancel(consumer_tag=consumer_tag)
# Change state after cancelling consumers to avoid
# ChannelWrongStateError exception from basic_cancel
self._set_state(self.CLOSING)
self._rpc(spec.Channel.Close(reply_code, reply_text, 0, 0),
self._on_closeok, [spec.Channel.CloseOk])
confirm_delivery(
ack_nack_callback: _OnAckNackCallback,
callback: _OnConfirmDeliveryCallback | None = None,
) -> None
Turn on Confirm mode in the channel.
Pass in a callback to be notified by the Broker when a message has been confirmed as received or rejected (Basic.Ack, Basic.Nack) from the broker to the publisher.
For more information see: https://www.rabbitmq.com/confirms.html
| PARAMETER | DESCRIPTION |
|---|---|
ack_nack_callback
|
Required callback for delivery
confirmations that has the following signature:
callback(pika.frame.Method), where method_frame contains
either method
TYPE:
|
callback
|
callback(pika.frame.Method) for method Confirm.SelectOk
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
TypeError
|
if .. note::
Calling this method more than once on the same channel replaces
the previously registered |
Source code in pika/channel.py
def confirm_delivery(
self,
ack_nack_callback: _OnAckNackCallback,
callback: _OnConfirmDeliveryCallback | None = None) -> None:
"""
Turn on Confirm mode in the channel.
Pass in a callback to be notified by the Broker when a message has been confirmed as received or
rejected (Basic.Ack, Basic.Nack) from the broker to the publisher.
For more information see:
https://www.rabbitmq.com/confirms.html
:param ack_nack_callback: Required callback for delivery
confirmations that has the following signature:
callback(pika.frame.Method), where method_frame contains
either method `spec.Basic.Ack` or `spec.Basic.Nack`.
:param callback: callback(pika.frame.Method) for method
Confirm.SelectOk
:raises TypeError: if `ack_nack_callback` is not callable
.. note::
Calling this method more than once on the same channel replaces
the previously registered ``ack_nack_callback`` rather than adding
an additional one. Only the most recently registered callback
receives ``Basic.Ack``/``Basic.Nack`` notifications.
"""
if not callable(ack_nack_callback):
# confirm_deliver requires a callback; it's meaningless
# without a user callback to receive Basic.Ack/Basic.Nack notifications
raise TypeError('confirm_delivery requires a callback '
'to receive Basic.Ack/Basic.Nack notifications')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if not (self.connection.publisher_confirms and
self.connection.basic_nack):
raise exceptions.MethodNotImplemented(
'Confirm.Select not Supported by Server')
# Replace any previously registered ack/nack callback so repeated
# calls don't stack listeners and fire stale callbacks (see #1602).
if self._on_ack_nack_callback is not None:
self.callbacks.remove(self.channel_number, spec.Basic.Ack,
self._on_ack_nack_callback)
self.callbacks.remove(self.channel_number, spec.Basic.Nack,
self._on_ack_nack_callback)
# Add the ack and nack callback
self.callbacks.add(self.channel_number, spec.Basic.Ack,
ack_nack_callback, False)
self.callbacks.add(self.channel_number, spec.Basic.Nack,
ack_nack_callback, False)
self._on_ack_nack_callback = ack_nack_callback
self._rpc(spec.Confirm.Select(nowait), callback,
[spec.Confirm.SelectOk] if not nowait else [])
exchange_bind(
destination: str,
source: str,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
callback: _OnExchangeBindCallback | None = None,
) -> None
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:
|
callback
|
callback(pika.frame.Method) for method Exchange.BindOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def exchange_bind(self,
destination: str,
source: str,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
callback: _OnExchangeBindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Exchange.BindOk
:returns:``None``. Method frame from the Exchange.Bind-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(destination, 'destination')
validators.require_string(source, 'source')
nowait = validators.rpc_completion_callback(callback)
return self._rpc(
spec.Exchange.Bind(0, destination, source, routing_key, nowait,
arguments or {}), callback,
[spec.Exchange.BindOk] if not nowait else [])
exchange_declare(
exchange: str,
exchange_type: str = direct,
passive: bool = False,
durable: bool = False,
auto_delete: bool = False,
internal: bool = False,
arguments: dict[str, Any] | None = None,
callback: _OnExchangeDeclareCallback | 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:
|
callback
|
callback(pika.frame.Method) for method Exchange.DeclareOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def exchange_declare(
self,
exchange: str,
exchange_type: str = ExchangeType.direct,
passive: bool = False,
durable: bool = False,
auto_delete: bool = False,
internal: bool = False,
arguments: dict[str, Any] | None = None,
callback: _OnExchangeDeclareCallback | 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
:param callback: callback(pika.frame.Method) for method Exchange.DeclareOk
:returns: ``None``. Method frame from the Exchange.Declare-ok response is
delivered to ``callback`` when synchronous (no ok frame in nowait
mode).
:raises ValueError:
"""
validators.require_string(exchange, 'exchange')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if isinstance(exchange_type, Enum):
exchange_type = exchange_type.value
return self._rpc(
spec.Exchange.Declare(0, exchange, exchange_type, passive, durable,
auto_delete, internal, nowait, arguments or
{}), callback,
[spec.Exchange.DeclareOk] if not nowait else [])
exchange_delete(
exchange: str | None = None,
if_unused: bool = False,
callback: _OnExchangeDeleteCallback | None = None,
) -> None
Delete the exchange.
| PARAMETER | DESCRIPTION |
|---|---|
exchange
|
The exchange name
TYPE:
|
if_unused
|
only delete if the exchange is unused
TYPE:
|
callback
|
callback(pika.frame.Method) for method Exchange.DeleteOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def exchange_delete(
self,
exchange: str | None = None,
if_unused: bool = False,
callback: _OnExchangeDeleteCallback | None = None) -> None:
"""
Delete the exchange.
:param exchange: The exchange name
:param if_unused: only delete if the exchange is unused
:param callback: callback(pika.frame.Method) for method Exchange.DeleteOk
:returns:``None``. Method frame from the Exchange.Delete-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
return self._rpc(spec.Exchange.Delete(0, exchange, if_unused,
nowait), callback,
[spec.Exchange.DeleteOk] if not nowait else [])
exchange_unbind(
destination: str | None = None,
source: str | None = None,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
callback: _OnExchangeUnbindCallback | None = None,
) -> None
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:
|
callback
|
callback(pika.frame.Method) for method Exchange.UnbindOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def exchange_unbind(
self,
destination: str | None = None,
source: str | None = None,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
callback: _OnExchangeUnbindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Exchange.UnbindOk
:returns:``None``. Method frame from the Exchange.Unbind-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
return self._rpc(
spec.Exchange.Unbind(0, destination, source, routing_key, nowait,
arguments), callback,
[spec.Exchange.UnbindOk] if not nowait else [])
flow(
active: bool, callback: _OnFlowCallback | None = None
) -> None
Turn Channel flow control off and on.
Pass a callback to be notified of the response from the server. active is a bool. Callback should expect a bool in response indicating channel flow state. For more information, please reference:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#channel.flow
| PARAMETER | DESCRIPTION |
|---|---|
active
|
Turn flow on or off
TYPE:
|
callback
|
callback(bool) upon completion
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def flow(self,
active: bool,
callback: _OnFlowCallback | None = None) -> None:
"""
Turn Channel flow control off and on.
Pass a callback to be notified of the response from the server. active is a bool. Callback
should expect a bool in response indicating channel flow state. For more information, please
reference:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#channel.flow
:param active: Turn flow on or off
:param callback: callback(bool) upon completion
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
self._on_flowok_callback = callback
self._rpc(spec.Channel.Flow(active), self._on_flowok,
[spec.Channel.FlowOk])
open() -> None
Open the channel.
Source code in pika/channel.py
def open(self) -> None:
"""Open the channel."""
self._set_state(self.OPENING)
self._add_callbacks()
self._rpc(spec.Channel.Open(), self._on_openok, [spec.Channel.OpenOk])
queue_bind(
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnQueueBindCallback | None = None,
) -> None
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:
|
callback
|
callback(pika.frame.Method) for method Queue.BindOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def queue_bind(self,
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnQueueBindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Queue.BindOk
:returns:``None``. Method frame from the Queue.Bind-ok response is delivered to ``callback``
when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
validators.require_string(queue, 'queue')
validators.require_string(exchange, 'exchange')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if routing_key is None:
routing_key = queue
return self._rpc(
spec.Queue.Bind(0, queue, exchange, routing_key, nowait,
arguments or {}), callback,
[spec.Queue.BindOk] if not nowait else [])
queue_declare(
queue: str,
passive: bool = False,
durable: bool = False,
exclusive: bool = False,
auto_delete: bool = False,
arguments: dict[str, Any] | None = None,
callback: _OnQueueDeclareCallback | None = None,
) -> None
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
| 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
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:
|
callback
|
callback(pika.frame.Method) for method Queue.DeclareOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.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,
callback: _OnQueueDeclareCallback | None = None) -> None:
"""
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
: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
: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
:param callback: callback(pika.frame.Method) for method Queue.DeclareOk
:returns: ``None``. Method frame from the Queue.Declare-ok response is
delivered to ``callback`` when synchronous (no ok frame in nowait
mode).
:raises ValueError:
"""
validators.require_string(queue, 'queue')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
condition: Any
if queue:
condition = (spec.Queue.DeclareOk, {'queue': queue})
else:
condition = spec.Queue.DeclareOk
replies = [condition] if not nowait else []
return self._rpc(
spec.Queue.Declare(0, queue, passive, durable, exclusive,
auto_delete, nowait, arguments or {}), callback,
replies)
queue_delete(
queue: str,
if_unused: bool = False,
if_empty: bool = False,
callback: _OnQueueDeleteCallback | None = None,
) -> None
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:
|
callback
|
callback(pika.frame.Method) for method Queue.DeleteOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def queue_delete(self,
queue: str,
if_unused: bool = False,
if_empty: bool = False,
callback: _OnQueueDeleteCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Queue.DeleteOk
:returns:``None``. Method frame from the Queue.Delete-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(queue, 'queue')
nowait = validators.rpc_completion_callback(callback)
replies = [spec.Queue.DeleteOk] if not nowait else []
return self._rpc(
spec.Queue.Delete(0, queue, if_unused, if_empty, nowait), callback,
replies)
queue_purge(
queue: str,
callback: _OnQueuePurgeCallback | None = None,
) -> None
Purge all of the messages from the specified queue.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue to purge
TYPE:
|
callback
|
callback(pika.frame.Method) for method Queue.PurgeOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def queue_purge(self,
queue: str,
callback: _OnQueuePurgeCallback | None = None) -> None:
"""
Purge all of the messages from the specified queue.
:param queue: The queue to purge
:param callback: callback(pika.frame.Method) for method Queue.PurgeOk
:returns:``None``. Method frame from the Queue.Purge-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(queue, 'queue')
nowait = validators.rpc_completion_callback(callback)
replies = [spec.Queue.PurgeOk] if not nowait else []
return self._rpc(spec.Queue.Purge(0, queue, nowait), callback, replies)
queue_unbind(
queue: str,
exchange: str | None = None,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnQueueUnbindCallback | None = None,
) -> None
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:
|
callback
|
callback(pika.frame.Method) for method Queue.UnbindOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def queue_unbind(self,
queue: str,
exchange: str | None = None,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnQueueUnbindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Queue.UnbindOk
:returns:``None``. Method frame from the Queue.Unbind-ok response is delivered to
``callback`` when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(queue, 'queue')
validators.rpc_completion_callback(callback)
if routing_key is None:
routing_key = queue
return self._rpc(
spec.Queue.Unbind(0, queue, exchange, routing_key, arguments or {}),
callback, [spec.Queue.UnbindOk])
remove_callback(
callback: Callable[..., Any],
replies: Sequence[type[Method]] | None = None,
) -> bool
Remove a callback previously registered via :meth:add_callback.
Mirrors :meth:add_callback: the callback is matched by identity and removed
from each reply key it is registered under. If replies is None, the
callback is removed from every reply key it is currently registered under.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to remove
TYPE:
|
replies
|
The replies to remove the callback from, or
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
bool
|
|
Source code in pika/channel.py
def remove_callback(
self,
callback: Callable[..., Any],
replies: Sequence[type[amqp_object.Method]] | None = None) -> bool:
"""
Remove a callback previously registered via :meth:`add_callback`.
Mirrors :meth:`add_callback`: the callback is matched by identity and removed
from each reply key it is registered under. If ``replies`` is ``None``, the
callback is removed from every reply key it is currently registered under.
:param callback: The callback to remove
:param replies: The replies to remove the callback from, or ``None`` to
remove it from every reply key it is registered under
:returns: ``True`` if at least one matching callback was removed
"""
reply_keys = (self.callbacks.keys(self.channel_number)
if replies is None else replies)
removed = False
for reply in reply_keys:
if self.callbacks.remove_matching(self.channel_number, reply,
lambda cb: cb == callback):
removed = True
return removed
remove_on_cancel_callback(
callback: _OnCancelCallback,
) -> bool
Remove a callback registered via :meth:add_on_cancel_callback.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to remove
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
bool
|
|
Source code in pika/channel.py
def remove_on_cancel_callback(self, callback: _OnCancelCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_cancel_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number,
spec.Basic.Cancel,
lambda cb: cb == callback)
remove_on_close_callback(
callback: _OnCloseCallback,
) -> bool
Remove a callback registered via :meth:add_on_close_callback.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to remove
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
bool
|
|
Source code in pika/channel.py
def remove_on_close_callback(self, callback: _OnCloseCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_close_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number,
'_on_channel_close',
lambda cb: cb == callback)
remove_on_flow_callback(callback: _OnFlowCallback) -> bool
Remove a callback registered via :meth:add_on_flow_callback.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to remove
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
bool
|
|
Source code in pika/channel.py
def remove_on_flow_callback(self, callback: _OnFlowCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_flow_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number,
spec.Channel.Flow,
lambda cb: cb == callback)
remove_on_return_callback(
callback: _OnReturnCallback,
) -> bool
Remove a callback registered via :meth:add_on_return_callback.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to remove
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
bool
|
|
Source code in pika/channel.py
def remove_on_return_callback(self, callback: _OnReturnCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_return_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number, '_on_return',
lambda cb: cb == callback)
tx_commit(
callback: _OnTxCommitCallback | None = None,
) -> None
Commit a transaction.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
callback(pika.frame.Method) for method Tx.CommitOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def tx_commit(self, callback: _OnTxCommitCallback | None = None) -> None:
"""
Commit a transaction.
:param callback: callback(pika.frame.Method) for method Tx.CommitOk
:returns:``None``. Method frame from the Tx.Commit-ok response is delivered to ``callback``
when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Tx.Commit(), callback, [spec.Tx.CommitOk])
tx_rollback(
callback: _OnTxRollbackCallback | None = None,
) -> None
Rollback a transaction.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
callback(pika.frame.Method) for method Tx.RollbackOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def tx_rollback(self,
callback: _OnTxRollbackCallback | None = None) -> None:
"""
Rollback a transaction.
:param callback: callback(pika.frame.Method) for method Tx.RollbackOk
:returns:``None``. Method frame from the Tx.Rollback-ok response is delivered to
``callback`` when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Tx.Rollback(), callback, [spec.Tx.RollbackOk])
tx_select(
callback: _OnTxSelectCallback | None = None,
) -> None
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.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
callback(pika.frame.Method) for method Tx.SelectOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def tx_select(self, callback: _OnTxSelectCallback | None = None) -> None:
"""
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.
:param callback: callback(pika.frame.Method) for method Tx.SelectOk
:returns:``None``. Method frame from the Tx.Select-ok response is delivered to ``callback``
when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Tx.Select(), callback, [spec.Tx.SelectOk])
Handle content related frames, building a message and return the message back in three parts upon receipt.
Source code in pika/channel.py
class ContentFrameAssembler:
"""Handle content related frames, building a message and return the message back in three parts
upon receipt.
"""
def __init__(self) -> None:
"""Create a new instance of the content frame assembler."""
self._method_frame: frame.Method | None = None
self._header_frame: frame.Header | None = None
self._seen_so_far = 0
self._body_fragments: list[bytes] = []
def process(
self, frame_value: frame.Frame
) -> tuple[frame.Method, frame.Header, bytes] | None:
"""
Invoked by the Channel object when passed frames that are not setup in the rpc process and
that don't have explicit reply types defined. This includes Basic.Publish, Basic.GetOk and
Basic.Return.
:param frame_value: The frame to process
"""
frame_type = frame_value.frame_type
if frame_type == spec.FRAME_METHOD:
assert isinstance(frame_value, frame.Method)
if spec.has_content(frame_value.method.INDEX):
self._method_frame = frame_value
return None
elif frame_type == spec.FRAME_HEADER:
assert isinstance(frame_value, frame.Header)
self._header_frame = frame_value
if frame_value.body_size == 0:
return self._finish()
return None
elif frame_type == spec.FRAME_BODY:
assert isinstance(frame_value, frame.Body)
return self._handle_body_frame(frame_value)
raise exceptions.UnexpectedFrameError(frame_value)
def _finish(self) -> tuple[frame.Method, frame.Header, bytes]:
"""Invoked when all of the message has been received."""
assert self._method_frame is not None
assert self._header_frame is not None
content = (self._method_frame, self._header_frame,
b''.join(self._body_fragments))
self._reset()
return content
def _handle_body_frame(
self, body_frame: frame.Body
) -> tuple[frame.Method, frame.Header, bytes] | None:
"""
Receive body frames and append them to the stack.
When the body size matches, call the finish method.
:param body_frame: The body frame
:raises: pika.exceptions.BodyTooLongError
"""
self._seen_so_far += len(body_frame.fragment)
self._body_fragments.append(body_frame.fragment)
assert self._header_frame is not None
if self._seen_so_far == self._header_frame.body_size:
return self._finish()
if self._seen_so_far > self._header_frame.body_size:
raise exceptions.BodyTooLongError(self._seen_so_far,
self._header_frame.body_size)
return None
def _reset(self) -> None:
"""Reset the values for processing frames."""
self._method_frame = None
self._header_frame = None
self._seen_so_far = 0
self._body_fragments = []
__init__() -> None
Create a new instance of the content frame assembler.
Source code in pika/channel.py
def __init__(self) -> None:
"""Create a new instance of the content frame assembler."""
self._method_frame: frame.Method | None = None
self._header_frame: frame.Header | None = None
self._seen_so_far = 0
self._body_fragments: list[bytes] = []
process(
frame_value: Frame,
) -> tuple[Method, Header, bytes] | None
Invoked by the Channel object when passed frames that are not setup in the rpc process and that don't have explicit reply types defined. This includes Basic.Publish, Basic.GetOk and Basic.Return.
| PARAMETER | DESCRIPTION |
|---|---|
frame_value
|
The frame to process
TYPE:
|
Source code in pika/channel.py
def process(
self, frame_value: frame.Frame
) -> tuple[frame.Method, frame.Header, bytes] | None:
"""
Invoked by the Channel object when passed frames that are not setup in the rpc process and
that don't have explicit reply types defined. This includes Basic.Publish, Basic.GetOk and
Basic.Return.
:param frame_value: The frame to process
"""
frame_type = frame_value.frame_type
if frame_type == spec.FRAME_METHOD:
assert isinstance(frame_value, frame.Method)
if spec.has_content(frame_value.method.INDEX):
self._method_frame = frame_value
return None
elif frame_type == spec.FRAME_HEADER:
assert isinstance(frame_value, frame.Header)
self._header_frame = frame_value
if frame_value.body_size == 0:
return self._finish()
return None
elif frame_type == spec.FRAME_BODY:
assert isinstance(frame_value, frame.Body)
return self._handle_body_frame(frame_value)
raise exceptions.UnexpectedFrameError(frame_value)
Channel¶
A Channel is the primary communication method for interacting with RabbitMQ.
It is recommended that you do not directly invoke the creation of a channel object in your application code but rather construct a channel by calling the active connection's channel() method.
Source code in pika/channel.py
class Channel:
"""
A Channel is the primary communication method for interacting with RabbitMQ.
It is recommended that you do not directly invoke the creation of a channel object in your
application code but rather construct a channel by calling the active connection's channel()
method.
"""
CLOSED = 0
OPENING = 1
OPEN = 2
CLOSING = 3 # client-initiated close in progress
_STATE_NAMES: ClassVar[dict[int, str]] = {
CLOSED: 'CLOSED',
OPENING: 'OPENING',
OPEN: 'OPEN',
CLOSING: 'CLOSING'
}
_ON_CHANNEL_CLEANUP_CB_KEY = '_on_channel_cleanup'
# Upper bound on the number of nowait-cancelled consumer tags retained in
# `_cancelled`; see `_retain_cancelled_tag`.
_MAX_RETAINED_CANCELLED_TAGS = 1024
def __init__(self, connection: Connection, channel_number: int,
on_open_callback: _OnOpenCallback | None) -> None:
"""
Create a new instance of the Channel.
:param connection: The connection
:param channel_number: The channel number for this instance
:param on_open_callback: The callback to call on channel open. The callback will be invoked
with the `Channel` instance as its only argument.
"""
if not isinstance(channel_number, int):
raise exceptions.InvalidChannelNumber(channel_number)
validators.rpc_completion_callback(on_open_callback)
self.channel_number = channel_number
self.callbacks = connection.callbacks
self.connection = connection
# Initially, flow is assumed to be active
self.flow_active = True
self._content_assembler = ContentFrameAssembler()
self._blocked: deque = deque()
self._blocking: Any | None = None
self._has_on_flow_callback: bool = False
self._cancelled: set = set()
# Nowait-cancelled tags in cancellation order, bounding how many of
# them `_cancelled` retains; see `_retain_cancelled_tag`.
self._nowait_cancelled: deque = deque()
self._consumers: dict = {}
self._consumers_with_noack: set = set()
self._on_flowok_callback: Callable[..., Any] | None = None
self._on_getok_callback: Callable[..., Any] | None = None
self._on_ack_nack_callback: _OnAckNackCallback | None = None
self._on_openok_callback: Callable[..., Any] | None = on_open_callback
self._state: int = self.CLOSED
# We save the closing reason exception to be passed to on-channel-close
# callback at closing of the channel. Exception representing the closing
# reason; ChannelClosedByClient or ChannelClosedByBroker on controlled
# close; otherwise another exception describing the reason for failure
# (most likely connection failure).
self._closing_reason = None # type: None | Exception
# opaque cookie value set by wrapper layer (e.g., BlockingConnection)
# via _set_cookie
self._cookie: object = None
def __int__(self) -> int:
"""Return the channel object as its channel number."""
return self.channel_number
@override
def __repr__(self) -> str:
return f'<{self.__class__.__name__} number={self.channel_number} {self._STATE_NAMES[self._state]} conn={self.connection!r}>'
def add_callback(self,
callback: Callable[..., Any],
replies: Sequence[type[amqp_object.Method]],
one_shot: bool = True) -> None:
"""
Pass in a callback handler and a list replies from the RabbitMQ broker which you'd like the
callback notified of. Callbacks should allow for the frame parameter to be passed in.
:param callback: The callback to call
:param replies: The replies to get a callback for
:param one_shot: Only handle the first type callback
"""
for reply in replies:
self.callbacks.add(self.channel_number, reply, callback, one_shot)
def add_on_cancel_callback(self, callback: _OnCancelCallback) -> None:
"""
Pass a callback function that will be called when the basic_cancel is sent by the server.
The callback function should receive a frame parameter.
:param callback: The callback to call on Basic.Cancel from broker
"""
self.callbacks.add(self.channel_number, spec.Basic.Cancel, callback,
False)
def add_on_close_callback(self, callback: _OnCloseCallback) -> None:
"""
Pass a callback function that will be called when the channel is closed.
The callback function will receive the channel and an exception describing why the channel
was closed.
If the channel is closed by broker via Channel.Close, the callback will receive
`ChannelClosedByBroker` as the reason.
If graceful user-initiated channel closing completes successfully ( either directly of
indirectly by closing a connection containing the channel) and closing concludes gracefully
without Channel.Close from the broker and without loss of connection, the callback will
receive `ChannelClosedByClient` exception as reason.
If channel was closed due to loss of connection, the callback will receive another exception
type describing the failure.
:param callback: The callback, having the signature: callback(Channel, Exception reason)
"""
self.callbacks.add(self.channel_number, '_on_channel_close', callback,
False, self)
def add_on_flow_callback(self, callback: _OnFlowCallback) -> None:
"""
Pass a callback function that will be called when Channel.Flow is called by the remote
server. Note that newer versions of RabbitMQ will not issue this but instead use TCP
backpressure.
:param callback: The callback function
"""
self._has_on_flow_callback = True
self.callbacks.add(self.channel_number, spec.Channel.Flow, callback,
False)
def add_on_return_callback(self, callback: _OnReturnCallback) -> None:
"""
Pass a callback function that will be called when basic_publish is sent a message that has
been rejected and returned by the server.
:param callback: The function to call, having the signature
callback(channel, method, properties, body)
where
- channel: pika.channel.Channel
- method: pika.spec.Basic.Return
- properties: pika.spec.BasicProperties
- body: bytes
"""
self.callbacks.add(self.channel_number, '_on_return', callback, False)
def remove_callback(
self,
callback: Callable[..., Any],
replies: Sequence[type[amqp_object.Method]] | None = None) -> bool:
"""
Remove a callback previously registered via :meth:`add_callback`.
Mirrors :meth:`add_callback`: the callback is matched by identity and removed
from each reply key it is registered under. If ``replies`` is ``None``, the
callback is removed from every reply key it is currently registered under.
:param callback: The callback to remove
:param replies: The replies to remove the callback from, or ``None`` to
remove it from every reply key it is registered under
:returns: ``True`` if at least one matching callback was removed
"""
reply_keys = (self.callbacks.keys(self.channel_number)
if replies is None else replies)
removed = False
for reply in reply_keys:
if self.callbacks.remove_matching(self.channel_number, reply,
lambda cb: cb == callback):
removed = True
return removed
def remove_on_cancel_callback(self, callback: _OnCancelCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_cancel_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number,
spec.Basic.Cancel,
lambda cb: cb == callback)
def remove_on_close_callback(self, callback: _OnCloseCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_close_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number,
'_on_channel_close',
lambda cb: cb == callback)
def remove_on_flow_callback(self, callback: _OnFlowCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_flow_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number,
spec.Channel.Flow,
lambda cb: cb == callback)
def remove_on_return_callback(self, callback: _OnReturnCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_return_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number, '_on_return',
lambda cb: cb == callback)
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: int/long 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._raise_if_not_open()
return self._send_method(spec.Basic.Ack(delivery_tag, multiple))
def basic_cancel(self,
consumer_tag: str = '',
callback: _OnBasicCancelCallback | None = None) -> None:
"""
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. It may also be sent
from the server to the client in the event of the consumer being unexpectedly cancelled
(i.e. cancelled for any reason other than the server receiving the corresponding
basic.cancel from the client). This allows clients to be notified of the loss of consumers
due to events such as queue deletion.
A cancelled consumer's tag is retained so that a delivery already in flight when the cancel
was sent is rejected rather than left unacknowledged. A cancel that expects a Basic.CancelOk
retires its own entry on arrival; a nowait cancel has no reply to retire it, so its tag is
kept only until `_MAX_RETAINED_CANCELLED_TAGS` later nowait cancels displace it (see
`_retain_cancelled_tag`). Past that point its retention lapses: a straggling delivery for it
is logged as unexpected and left unacknowledged rather than rejected, and the tag may be
reused by `basic_consume`, so reusing the same explicit consumer_tag risks a delivery for
the old consumer reaching the new one. The cap is a generous approximation of the broker's
in-flight window, so this only bites under extreme nowait-cancel churn.
:param consumer_tag: Identifier for the consumer
:param callback: callback(pika.frame.Method) for method Basic.CancelOk. If None, do not
expect a Basic.CancelOk response, otherwise, callback must be callable
:raises ValueError:
"""
validators.require_string(consumer_tag, 'consumer_tag')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if consumer_tag in self._cancelled:
# We check for cancelled first, because basic_cancel removes
# consumers closed with nowait from self._consumers
LOGGER.warning('basic_cancel - consumer is already cancelling: %s',
consumer_tag)
return
if consumer_tag not in self._consumers:
# Could be cancelled by user or broker earlier
LOGGER.warning('basic_cancel - consumer not found: %s',
consumer_tag)
return
LOGGER.debug('Cancelling consumer: %s (nowait=%s)', consumer_tag,
nowait)
if nowait:
# This is our last opportunity while the channel is open to remove
# this consumer callback and help gc.
del self._consumers[consumer_tag]
if callback is not None:
self.callbacks.add(self.channel_number, spec.Basic.CancelOk,
callback)
self._cancelled.add(consumer_tag)
if nowait:
self._retain_cancelled_tag(consumer_tag)
self._rpc(spec.Basic.Cancel(consumer_tag=consumer_tag, nowait=nowait),
self._on_cancelok if not nowait else None,
[(spec.Basic.CancelOk, {
'consumer_tag': consumer_tag
})] if not nowait else [])
def basic_consume(self,
queue: str,
on_message_callback: _OnMessageCallback,
auto_ack: bool = False,
exclusive: bool = False,
consumer_tag: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnBasicConsumeCallback | None = None) -> str:
"""
Sends the AMQP 0-9-1 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.
For more information on basic_consume, see:
Tutorial 2 at https://www.rabbitmq.com/getstarted.html
https://www.rabbitmq.com/confirms.html
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume
:param queue: The queue to consume from. Use the empty string to
specify the most recent server-named queue for this channel
:param on_message_callback: The function to call when
consuming with the signature
on_message_callback(channel, method, properties, body), where
- channel: pika.channel.Channel
- method: pika.spec.Basic.Deliver
- properties: pika.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: Specify your own consumer tag
:param arguments: Custom key/value pair arguments for the consumer
:param callback: callback(pika.frame.Method) for method
Basic.ConsumeOk.
:returns: Consumer tag which may be used to cancel the consumer.
:raises ValueError:
"""
validators.require_string(queue, 'queue')
validators.require_callback(on_message_callback)
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
# If a consumer tag was not passed, create one
if not consumer_tag:
consumer_tag = self._generate_consumer_tag()
if consumer_tag in self._consumers or consumer_tag in self._cancelled:
raise exceptions.DuplicateConsumerTag(consumer_tag)
if auto_ack:
self._consumers_with_noack.add(consumer_tag)
self._consumers[consumer_tag] = on_message_callback
rpc_callback: Callable[
...,
Any] | None = self._on_eventok if callback is None else callback
self._rpc(
spec.Basic.Consume(queue=queue,
consumer_tag=consumer_tag,
no_ack=auto_ack,
exclusive=exclusive,
arguments=arguments or {}), rpc_callback,
[(spec.Basic.ConsumeOk, {
'consumer_tag': consumer_tag
})])
return consumer_tag
def _generate_consumer_tag(self) -> str:
"""
Generate a consumer tag.
NOTE: this protected method may be called by derived classes
:returns: consumer tag
"""
return f'ctag{self.channel_number}.{uuid.uuid4().hex}'
def basic_get(self,
queue: str,
callback: _OnBasicGetCallback,
auto_ack: bool = False) -> None:
"""
Get a single message from the AMQP broker.
If you want to be notified of Basic.GetEmpty, use the Channel.add_callback method
adding your Basic.GetEmpty callback which should expect only one
parameter, frame. Due to implementation details, this cannot be called
a second time until the callback is executed. For more information on
basic_get and its parameters, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.get
:param queue: The queue from which to get a message. Use the empty
string to specify the most recent server-named queue for this
channel
:param callback: The callback to call with a message that has
the signature callback(channel, method, properties, body), where:
- channel: pika.channel.Channel
- method: pika.spec.Basic.GetOk
- properties: pika.spec.BasicProperties
- body: bytes
:param auto_ack: Tell the broker to not expect a reply
:raises ValueError:
"""
validators.require_string(queue, 'queue')
validators.require_callback(callback)
if self._on_getok_callback is not None:
raise exceptions.DuplicateGetOkCallback()
self._on_getok_callback = callback
# TODO Strangely, not using _rpc for the synchronous Basic.Get. Would
# need to extend _rpc to handle Basic.GetOk method, header, and body
# frames (or similar)
self._send_method(spec.Basic.Get(queue=queue, no_ack=auto_ack))
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: int/long 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._raise_if_not_open()
return self._send_method(
spec.Basic.Nack(delivery_tag, multiple, requeue))
def basic_publish(self,
exchange: str,
routing_key: str,
body: bytes,
properties: 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
:param exchange: The exchange to publish to
:param routing_key: The routing key to bind on
:param body: The message body
:param properties: Basic.properties
:param mandatory: The mandatory flag
"""
self._raise_if_not_open()
body = as_bytes(body)
properties = properties or spec.BasicProperties()
self._send_method(
spec.Basic.Publish(exchange=exchange,
routing_key=routing_key,
mandatory=mandatory), (properties, body))
def basic_qos(self,
prefetch_size: int = 0,
prefetch_count: int = 0,
global_qos: bool = False,
callback: _OnBasicQosCallback | None = None) -> None:
"""
Specify quality of service.
This method requests a specific quality of service. 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. The QoS can be
applied separately to each new consumer on channel or shared across all consumers on 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 by
consumers who have enabled the no-ack option.
: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 by consumers who have enabled the no-ack option.
:param global_qos: Should the QoS be shared across all consumers on the channel.
:param callback: The callback to call for Basic.QosOk response
:returns:``None``. Method frame from the Basic.Qos-ok response is delivered to ``callback``
when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
validators.zero_or_greater('prefetch_size', prefetch_size)
validators.zero_or_greater('prefetch_count', prefetch_count)
return self._rpc(
spec.Basic.Qos(prefetch_size, prefetch_count, global_qos), callback,
[spec.Basic.QosOk])
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: int/long 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.
:raises TypeError:
"""
self._raise_if_not_open()
if not isinstance(delivery_tag, int):
raise TypeError('delivery_tag must be an integer')
return self._send_method(spec.Basic.Reject(delivery_tag, requeue))
def basic_recover(self,
requeue: bool = False,
callback: _OnBasicRecoverCallback | None = None) -> 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.
:param callback: callback(pika.frame.Method) for method Basic.RecoverOk
:returns:``None``. Method frame from the Basic.Recover-ok response is delivered to
``callback`` when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Basic.Recover(requeue), callback,
[spec.Basic.RecoverOk])
def close(self,
reply_code: int = 0,
reply_text: str = 'Normal shutdown') -> None:
"""
Invoke a graceful shutdown of the channel with the AMQP Broker.
If channel is OPENING, transition to CLOSING and suppress the incoming Channel.OpenOk, if
any.
:param reply_code: The reason code to send to broker
:param reply_text: The reason text to send to broker
:raises ChannelWrongStateError: if channel is closed or closing
"""
if self.is_closed or self.is_closing:
# Whoever is calling `close` might expect the on-channel-close-cb
# to be called, which won't happen when it's already closed.
self._raise_if_not_open()
# If channel is OPENING, we will transition it to CLOSING state,
# causing the _on_openok method to suppress the OPEN state transition
# and the on-channel-open-callback
LOGGER.info('Closing channel (%s): %r on %s', reply_code, reply_text,
self)
# Save the reason info so that we may use it in the '_on_channel_close'
# callback processing
self._closing_reason = exceptions.ChannelClosedByClient(
reply_code, reply_text)
for consumer_tag in list(self._consumers.keys()):
if consumer_tag not in self._cancelled:
self.basic_cancel(consumer_tag=consumer_tag)
# Change state after cancelling consumers to avoid
# ChannelWrongStateError exception from basic_cancel
self._set_state(self.CLOSING)
self._rpc(spec.Channel.Close(reply_code, reply_text, 0, 0),
self._on_closeok, [spec.Channel.CloseOk])
def confirm_delivery(
self,
ack_nack_callback: _OnAckNackCallback,
callback: _OnConfirmDeliveryCallback | None = None) -> None:
"""
Turn on Confirm mode in the channel.
Pass in a callback to be notified by the Broker when a message has been confirmed as received or
rejected (Basic.Ack, Basic.Nack) from the broker to the publisher.
For more information see:
https://www.rabbitmq.com/confirms.html
:param ack_nack_callback: Required callback for delivery
confirmations that has the following signature:
callback(pika.frame.Method), where method_frame contains
either method `spec.Basic.Ack` or `spec.Basic.Nack`.
:param callback: callback(pika.frame.Method) for method
Confirm.SelectOk
:raises TypeError: if `ack_nack_callback` is not callable
.. note::
Calling this method more than once on the same channel replaces
the previously registered ``ack_nack_callback`` rather than adding
an additional one. Only the most recently registered callback
receives ``Basic.Ack``/``Basic.Nack`` notifications.
"""
if not callable(ack_nack_callback):
# confirm_deliver requires a callback; it's meaningless
# without a user callback to receive Basic.Ack/Basic.Nack notifications
raise TypeError('confirm_delivery requires a callback '
'to receive Basic.Ack/Basic.Nack notifications')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if not (self.connection.publisher_confirms and
self.connection.basic_nack):
raise exceptions.MethodNotImplemented(
'Confirm.Select not Supported by Server')
# Replace any previously registered ack/nack callback so repeated
# calls don't stack listeners and fire stale callbacks (see #1602).
if self._on_ack_nack_callback is not None:
self.callbacks.remove(self.channel_number, spec.Basic.Ack,
self._on_ack_nack_callback)
self.callbacks.remove(self.channel_number, spec.Basic.Nack,
self._on_ack_nack_callback)
# Add the ack and nack callback
self.callbacks.add(self.channel_number, spec.Basic.Ack,
ack_nack_callback, False)
self.callbacks.add(self.channel_number, spec.Basic.Nack,
ack_nack_callback, False)
self._on_ack_nack_callback = ack_nack_callback
self._rpc(spec.Confirm.Select(nowait), callback,
[spec.Confirm.SelectOk] if not nowait else [])
@property
def consumer_tags(self) -> list[str]:
"""Property method that returns a list of currently active consumers."""
return list(self._consumers.keys())
def exchange_bind(self,
destination: str,
source: str,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
callback: _OnExchangeBindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Exchange.BindOk
:returns:``None``. Method frame from the Exchange.Bind-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(destination, 'destination')
validators.require_string(source, 'source')
nowait = validators.rpc_completion_callback(callback)
return self._rpc(
spec.Exchange.Bind(0, destination, source, routing_key, nowait,
arguments or {}), callback,
[spec.Exchange.BindOk] if not nowait else [])
def exchange_declare(
self,
exchange: str,
exchange_type: str = ExchangeType.direct,
passive: bool = False,
durable: bool = False,
auto_delete: bool = False,
internal: bool = False,
arguments: dict[str, Any] | None = None,
callback: _OnExchangeDeclareCallback | 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
:param callback: callback(pika.frame.Method) for method Exchange.DeclareOk
:returns: ``None``. Method frame from the Exchange.Declare-ok response is
delivered to ``callback`` when synchronous (no ok frame in nowait
mode).
:raises ValueError:
"""
validators.require_string(exchange, 'exchange')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if isinstance(exchange_type, Enum):
exchange_type = exchange_type.value
return self._rpc(
spec.Exchange.Declare(0, exchange, exchange_type, passive, durable,
auto_delete, internal, nowait, arguments or
{}), callback,
[spec.Exchange.DeclareOk] if not nowait else [])
def exchange_delete(
self,
exchange: str | None = None,
if_unused: bool = False,
callback: _OnExchangeDeleteCallback | None = None) -> None:
"""
Delete the exchange.
:param exchange: The exchange name
:param if_unused: only delete if the exchange is unused
:param callback: callback(pika.frame.Method) for method Exchange.DeleteOk
:returns:``None``. Method frame from the Exchange.Delete-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
return self._rpc(spec.Exchange.Delete(0, exchange, if_unused,
nowait), callback,
[spec.Exchange.DeleteOk] if not nowait else [])
def exchange_unbind(
self,
destination: str | None = None,
source: str | None = None,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
callback: _OnExchangeUnbindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Exchange.UnbindOk
:returns:``None``. Method frame from the Exchange.Unbind-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
return self._rpc(
spec.Exchange.Unbind(0, destination, source, routing_key, nowait,
arguments), callback,
[spec.Exchange.UnbindOk] if not nowait else [])
def flow(self,
active: bool,
callback: _OnFlowCallback | None = None) -> None:
"""
Turn Channel flow control off and on.
Pass a callback to be notified of the response from the server. active is a bool. Callback
should expect a bool in response indicating channel flow state. For more information, please
reference:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#channel.flow
:param active: Turn flow on or off
:param callback: callback(bool) upon completion
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
self._on_flowok_callback = callback
self._rpc(spec.Channel.Flow(active), self._on_flowok,
[spec.Channel.FlowOk])
@property
def is_closed(self) -> bool:
"""Returns True if the channel is closed."""
return self._state == self.CLOSED
@property
def is_closing(self) -> bool:
"""Returns True if client-initiated closing of the channel is in progress."""
return self._state == self.CLOSING
@property
def is_open(self) -> bool:
"""Returns True if the channel is open."""
return self._state == self.OPEN
@property
def is_opening(self) -> bool:
"""Returns True if the channel is opening."""
return self._state == self.OPENING
def open(self) -> None:
"""Open the channel."""
self._set_state(self.OPENING)
self._add_callbacks()
self._rpc(spec.Channel.Open(), self._on_openok, [spec.Channel.OpenOk])
def queue_bind(self,
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnQueueBindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Queue.BindOk
:returns:``None``. Method frame from the Queue.Bind-ok response is delivered to ``callback``
when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
validators.require_string(queue, 'queue')
validators.require_string(exchange, 'exchange')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if routing_key is None:
routing_key = queue
return self._rpc(
spec.Queue.Bind(0, queue, exchange, routing_key, nowait,
arguments or {}), callback,
[spec.Queue.BindOk] if not nowait else [])
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,
callback: _OnQueueDeclareCallback | None = None) -> None:
"""
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
: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
: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
:param callback: callback(pika.frame.Method) for method Queue.DeclareOk
:returns: ``None``. Method frame from the Queue.Declare-ok response is
delivered to ``callback`` when synchronous (no ok frame in nowait
mode).
:raises ValueError:
"""
validators.require_string(queue, 'queue')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
condition: Any
if queue:
condition = (spec.Queue.DeclareOk, {'queue': queue})
else:
condition = spec.Queue.DeclareOk
replies = [condition] if not nowait else []
return self._rpc(
spec.Queue.Declare(0, queue, passive, durable, exclusive,
auto_delete, nowait, arguments or {}), callback,
replies)
def queue_delete(self,
queue: str,
if_unused: bool = False,
if_empty: bool = False,
callback: _OnQueueDeleteCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Queue.DeleteOk
:returns:``None``. Method frame from the Queue.Delete-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(queue, 'queue')
nowait = validators.rpc_completion_callback(callback)
replies = [spec.Queue.DeleteOk] if not nowait else []
return self._rpc(
spec.Queue.Delete(0, queue, if_unused, if_empty, nowait), callback,
replies)
def queue_purge(self,
queue: str,
callback: _OnQueuePurgeCallback | None = None) -> None:
"""
Purge all of the messages from the specified queue.
:param queue: The queue to purge
:param callback: callback(pika.frame.Method) for method Queue.PurgeOk
:returns:``None``. Method frame from the Queue.Purge-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(queue, 'queue')
nowait = validators.rpc_completion_callback(callback)
replies = [spec.Queue.PurgeOk] if not nowait else []
return self._rpc(spec.Queue.Purge(0, queue, nowait), callback, replies)
def queue_unbind(self,
queue: str,
exchange: str | None = None,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnQueueUnbindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Queue.UnbindOk
:returns:``None``. Method frame from the Queue.Unbind-ok response is delivered to
``callback`` when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(queue, 'queue')
validators.rpc_completion_callback(callback)
if routing_key is None:
routing_key = queue
return self._rpc(
spec.Queue.Unbind(0, queue, exchange, routing_key, arguments or {}),
callback, [spec.Queue.UnbindOk])
def tx_commit(self, callback: _OnTxCommitCallback | None = None) -> None:
"""
Commit a transaction.
:param callback: callback(pika.frame.Method) for method Tx.CommitOk
:returns:``None``. Method frame from the Tx.Commit-ok response is delivered to ``callback``
when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Tx.Commit(), callback, [spec.Tx.CommitOk])
def tx_rollback(self,
callback: _OnTxRollbackCallback | None = None) -> None:
"""
Rollback a transaction.
:param callback: callback(pika.frame.Method) for method Tx.RollbackOk
:returns:``None``. Method frame from the Tx.Rollback-ok response is delivered to
``callback`` when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Tx.Rollback(), callback, [spec.Tx.RollbackOk])
def tx_select(self, callback: _OnTxSelectCallback | None = None) -> None:
"""
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.
:param callback: callback(pika.frame.Method) for method Tx.SelectOk
:returns:``None``. Method frame from the Tx.Select-ok response is delivered to ``callback``
when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Tx.Select(), callback, [spec.Tx.SelectOk])
# Internal methods
def _add_callbacks(self) -> None:
"""Callbacks that add the required behavior for a channel when connecting and connected to a
server.
"""
# Add a callback for Basic.GetEmpty
self.callbacks.add(self.channel_number, spec.Basic.GetEmpty,
self._on_getempty, False)
# Add a callback for Basic.Cancel
self.callbacks.add(self.channel_number, spec.Basic.Cancel,
self._on_cancel, False)
# Deprecated in newer versions of RabbitMQ but still register for it
self.callbacks.add(self.channel_number, spec.Channel.Flow,
self._on_flow, False)
# Add a callback for when the server closes our channel
self.callbacks.add(self.channel_number, spec.Channel.Close,
self._on_close_from_broker, True)
def _add_on_cleanup_callback(self, callback: Callable[..., Any]) -> None:
"""
For internal use only (e.g., Connection needs to remove closed channels from its channel
container). Pass a callback function that will be called when the channel is being cleaned
up after all channel-close callbacks callbacks.
:param callback: The callback to call, having the
signature: callback(channel)
"""
self.callbacks.add(self.channel_number,
self._ON_CHANNEL_CLEANUP_CB_KEY,
callback,
one_shot=True,
only_caller=self)
def _cleanup(self) -> None:
"""Remove all consumers and any callbacks for the channel."""
self.callbacks.process(self.channel_number,
self._ON_CHANNEL_CLEANUP_CB_KEY, self, self)
self._consumers = {}
self._cancelled = set()
self._nowait_cancelled = deque()
self._consumers_with_noack = set()
self.callbacks.cleanup(str(self.channel_number))
self._cookie = None
def _cleanup_consumer_ref(self, consumer_tag: str) -> None:
"""
Remove any references to the consumer tag in internal structures for consumer state.
:param consumer_tag: The consumer tag to cleanup
"""
self._consumers_with_noack.discard(consumer_tag)
self._consumers.pop(consumer_tag, None)
self._cancelled.discard(consumer_tag)
def _retain_cancelled_tag(self, consumer_tag: str) -> None:
"""
Retain a nowait-cancelled consumer tag, evicting the oldest once the cap is reached.
A cancelled tag stays in `_cancelled` (and `_consumers_with_noack`) so that a delivery the
broker had already dispatched when `Basic.Cancel` was sent is rejected rather than left
unacknowledged; see `_on_deliver`. A cancel that expects a `Basic.CancelOk` retires its own
entry in `_on_cancelok`, but a nowait cancel asks the broker for no reply, so nothing
retires it and the entries would otherwise accumulate for the life of the channel.
Bound them here instead. The number of deliveries that can still be in flight for a
cancelled consumer is bounded by what the broker had already dispatched, so a cap on
retained nowait-cancelled tags approximates that window: evicting in cancellation order past
`_MAX_RETAINED_CANCELLED_TAGS` keeps retention constant in the number of cancels. The cap
is not the true window, though, since it is measured in cancels rather than deliveries, so
once a tag is evicted its reject-and-reserve behaviour lapses: a straggling delivery for it
is logged as unexpected and left unacknowledged (see `_on_deliver`), and `basic_consume`
will accept the tag again. The default is large enough that this only occurs under extreme
nowait-cancel churn.
A tag cannot be queued twice: `basic_consume` refuses a tag that is still in `_cancelled`,
and on the nowait path only eviction takes it back out again.
:param consumer_tag: The consumer tag just cancelled with nowait
"""
self._nowait_cancelled.append(consumer_tag)
while len(self._nowait_cancelled) > self._MAX_RETAINED_CANCELLED_TAGS:
self._cleanup_consumer_ref(self._nowait_cancelled.popleft())
def _get_cookie(self) -> Any:
"""
Used by the wrapper implementation (e.g., `BlockingChannel`) to retrieve the cookie that it
set via `_set_cookie`
:returns: opaque cookie value that was set via `_set_cookie`
"""
return self._cookie
def _handle_content_frame(self, frame_value: frame.Frame) -> None:
"""
This is invoked by the connection when frames that are not registered with the
CallbackManager have been found. This should only be the case when the frames are related to
content delivery.
The _content_assembler will be invoked which will return the fully formed message in three
parts when all of the body frames have been received.
:param frame_value: The frame to deliver
"""
try:
response = self._content_assembler.process(frame_value)
except exceptions.UnexpectedFrameError:
self._on_unexpected_frame(frame_value)
return
if response:
method_index = response[0].method.INDEX
if method_index == spec.Basic.Deliver.INDEX:
self._on_deliver(*response)
elif method_index == spec.Basic.GetOk.INDEX:
self._on_getok(*response)
elif method_index == spec.Basic.Return.INDEX:
self._on_return(*response)
def _on_cancel(self, method_frame: frame.Method) -> None:
"""
When the broker cancels a consumer, delete it from our internal dictionary.
Reply with `Basic.CancelOk` if the broker advertises the `accept_consumer_cancel_ok`
capability.
:param method_frame: The method frame received
"""
consumer_tag = method_frame.method.consumer_tag
# Sent before the `_cancelled` check below, so a user-initiated cancel
# racing a broker-sent one still gets a reply. That is safe in both
# orders, which is not obvious from here. A broker advertising the
# capability answers a `Basic.CancelOk` for a tag it is not waiting on
# with `{noreply, State}`, so a late or duplicate reply is ignored
# rather than treated as a protocol error. And if this reply reaches the
# broker first, it releases the consumer without replying, leaving the
# user's in-flight `Basic.Cancel` to arrive for a tag the broker no
# longer tracks - which `cancel_consumer` answers with a `Basic.CancelOk`
# anyway ("Spec requires we ignore this situation"), so the pending RPC
# still completes instead of hanging.
if self.is_open and self.connection.accept_consumer_cancel_ok:
self._send_method(spec.Basic.CancelOk(consumer_tag=consumer_tag))
if consumer_tag in self._cancelled:
# User-initiated cancel is waiting for Cancel-ok
return
self._cleanup_consumer_ref(consumer_tag)
def _on_cancelok(self, method_frame: frame.Method) -> None:
"""
Called in response to a frame from the Broker when the client sends Basic.Cancel.
:param method_frame: The method frame received
"""
self._cleanup_consumer_ref(method_frame.method.consumer_tag)
def _transition_to_closed(self) -> None:
"""Common logic for transitioning the channel to the CLOSED state:
Set state to CLOSED, dispatch callbacks registered via
`Channel.add_on_close_callback()`, and mop up.
Assumes that the channel is not in CLOSED state and that
`self._closing_reason` has been set up
"""
assert not self.is_closed
assert self._closing_reason is not None
self._set_state(self.CLOSED)
try:
self.callbacks.process(self.channel_number, '_on_channel_close',
self, self, self._closing_reason)
finally:
self._cleanup()
def _on_close_from_broker(self, method_frame: frame.Method) -> None:
"""
Handle `Channel.Close` from broker.
:param method_frame: Method frame with Channel.Close method
"""
LOGGER.warning('Received remote Channel.Close (%s): %r on %s',
method_frame.method.reply_code,
method_frame.method.reply_text, self)
# Note, we should not be called when channel is already closed
assert not self.is_closed
# AMQP 0.9.1 requires CloseOk response to Channel.Close;
self._send_method(spec.Channel.CloseOk())
# Save the details, possibly overriding user-provided values if
# user-initiated close is pending (in which case they will be provided
# to user callback when CloseOk arrives).
self._closing_reason = exceptions.ChannelClosedByBroker(
method_frame.method.reply_code, method_frame.method.reply_text)
if self.is_closing:
# Since we may have already put Channel.Close on the wire, we need
# to wait for CloseOk before cleaning up to avoid a race condition
# whereby our channel number might get reused before our CloseOk
# arrives
#
# NOTE: if our Channel.Close destined for the broker was blocked by
# an earlier synchronous method, this call will drop it and perform
# a meta-close (see `_on_close_meta()` which fakes receipt of
# `Channel.CloseOk` and dispatches the `'_on_channel_close'`
# callbacks.
self._drain_blocked_methods_on_remote_close()
else:
self._transition_to_closed()
def _on_close_meta(self, reason: Exception | None) -> None:
"""
Handle meta-close request from either a remote Channel.Close from the broker (when a pending
Channel.Close method is queued for execution) or a Connection's cleanup logic after sudden
connection loss. We use this opportunity to transition to CLOSED state, clean up the
channel, and dispatch the on-channel-closed callbacks.
:param reason: Exception describing the reason for closing.
"""
LOGGER.debug('Handling meta-close on %s: %r', self, reason)
if not self.is_closed:
self._closing_reason = reason
self._transition_to_closed()
def _on_closeok(self, method_frame: frame.Method) -> None:
"""
Invoked when RabbitMQ replies to a Channel.Close method.
:param method_frame: Method frame with Channel.CloseOk method
"""
LOGGER.info('Received %s on %s', method_frame.method, self)
self._transition_to_closed()
def _on_deliver(self, method_frame: frame.Method,
header_frame: frame.Header, body: bytes) -> None:
"""
Cope with reentrancy.
If a particular consumer is still active when another delivery appears for it, queue the
deliveries up until it finally exits.
:param method_frame: The method frame received
:param header_frame: The header frame received
:param body: The body received
"""
consumer_tag = method_frame.method.consumer_tag
if consumer_tag in self._cancelled:
if self.is_open and consumer_tag not in self._consumers_with_noack:
self.basic_reject(method_frame.method.delivery_tag)
return
if consumer_tag not in self._consumers:
LOGGER.error('Unexpected delivery: %r', method_frame)
return
self._consumers[consumer_tag](self, method_frame.method,
header_frame.properties, body)
def _on_eventok(self, method_frame: frame.Method) -> None:
"""
Generic events that returned ok that may have internal callbacks.
We keep a list of what we've yet to implement so that we don't silently drain events that we
don't support.
:param method_frame: The method frame received
"""
LOGGER.debug('Discarding frame %r', method_frame)
def _on_flow(self, _method_frame_unused: frame.Method) -> None:
"""
Called if the server sends a Channel.Flow frame.
:param _method_frame_unused: The Channel.Flow frame
"""
if self._has_on_flow_callback is False:
LOGGER.warning('Channel.Flow received from server')
def _on_flowok(self, method_frame: frame.Method) -> None:
"""
Called in response to us asking the server to toggle on Channel.Flow.
:param method_frame: The method frame received
"""
self.flow_active = method_frame.method.active
if self._on_flowok_callback:
self._on_flowok_callback(method_frame.method.active)
self._on_flowok_callback = None
else:
LOGGER.warning('Channel.FlowOk received with no active callbacks')
def _on_getempty(self, method_frame: frame.Method) -> None:
"""
When we receive an empty reply do nothing but log it.
:param method_frame: The method frame received
"""
LOGGER.debug('Received Basic.GetEmpty: %r', method_frame)
if self._on_getok_callback is not None:
self._on_getok_callback = None
def _on_getok(self, method_frame: frame.Method, header_frame: frame.Header,
body: bytes) -> None:
"""
Called in reply to a Basic.Get when there is a message.
:param method_frame: The method frame received
:param header_frame: The header frame received
:param body: The body received
"""
if self._on_getok_callback is not None:
callback = self._on_getok_callback
self._on_getok_callback = None
callback(self, method_frame.method, header_frame.properties, body)
else:
LOGGER.error('Basic.GetOk received with no active callback')
def _on_openok(self, method_frame: frame.Method) -> None:
"""
Called by our callback handler when we receive a Channel.OpenOk and subsequently calls our
_on_openok_callback which was passed into the Channel constructor. The reason we do this is
because we want to make sure that the on_open_callback parameter passed into the Channel
constructor is not the first callback we make.
Suppress the state transition and callback if channel is already in CLOSING state.
:param method_frame: Channel.OpenOk frame
"""
# Suppress OpenOk if the user or Connection.Close started closing it
# before open completed.
if self.is_closing:
LOGGER.debug('Suppressing while in closing state: %s', method_frame)
else:
self._set_state(self.OPEN)
if self._on_openok_callback is not None:
self._on_openok_callback(self)
def _on_return(self, method_frame: frame.Method, header_frame: frame.Header,
body: bytes) -> None:
"""
Called if the server sends a Basic.Return frame.
:param method_frame: The Basic.Return frame
:param header_frame: The content header frame
:param body: The message body
"""
if not self.callbacks.process(self.channel_number, '_on_return', self,
self, method_frame.method,
header_frame.properties, body):
LOGGER.debug('Basic.Return received from server (%r, %r)',
method_frame.method, header_frame.properties)
def _on_selectok(self, method_frame: frame.Method) -> None:
"""
Called when the broker sends a Confirm.SelectOk frame.
:param method_frame: The method frame received
"""
LOGGER.debug('Confirm.SelectOk Received: %r', method_frame)
def _on_synchronous_complete(self,
_method_frame_unused: frame.Method) -> None:
"""
This is called when a synchronous command is completed.
It will undo the blocking state and send all the frames that stacked up while we were in the
blocking state.
:param _method_frame_unused: The method frame received
"""
LOGGER.debug('%i blocked frames', len(self._blocked))
self._blocking = None
# self._blocking must be checked here as a callback could
# potentially change the state of that variable during an
# iteration of the while loop
while self._blocked and self._blocking is None:
self._rpc(*self._blocked.popleft())
def _drain_blocked_methods_on_remote_close(self) -> None:
"""
This is called when the broker sends a Channel.Close while the client is in CLOSING state.
This method checks the blocked method queue for a pending client-initiated Channel.Close
method and ensures its callbacks are processed, but does not send the method to the broker.
The broker may close the channel before responding to outstanding in-transit synchronous
methods, or even before these methods have been sent to the broker. AMQP 0.9.1 obliges the
server to drop all methods arriving on a closed channel other than Channel.CloseOk and
Channel.Close. Since the response to a synchronous method that blocked the channel never
arrives, the channel never becomes unblocked, and the Channel.Close, if any, in the blocked
queue has no opportunity to be sent, and thus its completion callback would never be called.
"""
LOGGER.debug(
'Draining %i blocked frames due to broker-requested Channel.Close',
len(self._blocked))
while self._blocked:
method = self._blocked.popleft()[0]
if isinstance(method, spec.Channel.Close):
# The desired reason is already in self._closing_reason
self._on_close_meta(self._closing_reason)
else:
LOGGER.debug('Ignoring drained blocked method: %s', method)
def _rpc(
self,
method: amqp_object.Method,
callback: Callable[..., Any] | None = None,
acceptable_replies: Sequence[type[amqp_object.Method] |
tuple[type[amqp_object.Method],
dict[str, Any]]] | None = None
) -> None:
"""
Make a synchronous channel RPC call for a synchronous method frame.
If the channel is already in the blocking state, then enqueue the request,
but don't send it at this time; it will be eventually sent by
`_on_synchronous_complete` after the prior blocking request receives a
response. If the channel is not in the blocking state and
`acceptable_replies` is not empty, transition the channel to the
blocking state and register for `_on_synchronous_complete` before
sending the request.
NOTE: A callback must be accompanied by non-empty acceptable_replies.
:param method: The AMQP method to invoke
:param callback: The callback for the RPC response
:param acceptable_replies: A (possibly empty) sequence of
replies this RPC call expects or None
"""
assert method.synchronous, (
f'Only synchronous-capable methods may be used with _rpc: {method!r}'
)
# Validate we got None or a list of acceptable_replies
if not isinstance(acceptable_replies, (type(None), list)):
raise TypeError('acceptable_replies should be list or None')
if callback is not None:
# Validate the callback is callable
if not callable(callback):
raise TypeError('callback should be None or a callable')
# Make sure that callback is accompanied by acceptable replies
if not acceptable_replies:
raise ValueError(
'Unexpected callback for asynchronous (nowait) operation.')
# Make sure the channel is not closed yet
if self.is_closed:
self._raise_if_not_open()
# If the channel is blocking, add subsequent commands to our stack
if self._blocking:
LOGGER.debug(
'Already in blocking state, so enqueueing method %s; '
'acceptable_replies=%r', method, acceptable_replies)
self._blocked.append([method, callback, acceptable_replies])
return
# Note: _send_method can throw exceptions if there are framing errors
# or invalid data passed in. Call it here to prevent self._blocking
# from being set if an exception is thrown. This also prevents
# acceptable_replies registering callbacks when exceptions are thrown
self._send_method(method)
# If acceptable replies are set, add callbacks
if acceptable_replies:
# Block until a response frame is received for synchronous frames
self._blocking = method.NAME
LOGGER.debug(
'Entering blocking state on frame %s; acceptable_replies=%r',
method, acceptable_replies)
for reply in acceptable_replies:
if isinstance(reply, tuple):
reply, arguments = reply
else:
arguments = None
LOGGER.debug('Adding on_synchronous_complete callback')
self.callbacks.add(self.channel_number,
reply,
self._on_synchronous_complete,
arguments=arguments)
if callback is not None:
LOGGER.debug('Adding passed-in RPC response callback')
self.callbacks.add(self.channel_number,
reply,
callback,
arguments=arguments)
def _raise_if_not_open(self) -> None:
"""
If channel is not in the OPEN state, raises ChannelWrongStateError with `reply_code` and
`reply_text` corresponding to current state.
:raises exceptions.ChannelWrongStateError: if channel is not in OPEN state.
"""
if self._state == self.OPEN:
return
if self._state == self.OPENING:
raise exceptions.ChannelWrongStateError(
'Channel is opening, but is not usable yet.')
if self._state == self.CLOSING:
raise exceptions.ChannelWrongStateError('Channel is closing.')
# Assumed self.CLOSED
assert self._state == self.CLOSED
raise exceptions.ChannelWrongStateError('Channel is closed.')
def _send_method(
self,
method: amqp_object.Method,
content: tuple[spec.BasicProperties, bytes] | None = None) -> None:
"""
Shortcut wrapper to send a method through our connection, passing in the channel number.
:param method: The method to send
:param content: If set, is a content frame, is tuple of properties and body.
"""
self.connection._send_method(self.channel_number, method, content)
def _set_cookie(self, cookie: object) -> None:
"""
Used by wrapper layer (e.g., `BlockingConnection`) to link the channel implementation back
to the proxy. See `_get_cookie`.
:param cookie: an opaque value; typically a proxy channel implementation instance (e.g.,
`BlockingChannel` instance)
"""
self._cookie = cookie
def _set_state(self, connection_state: int) -> None:
"""
Set the channel connection state to the specified state value.
:param connection_state: The connection_state value
"""
self._state = connection_state
def _on_unexpected_frame(self, frame_value: frame.Frame) -> None:
"""
Invoked when a frame is received that is not setup to be processed.
:param frame_value: The frame received
"""
LOGGER.error('Unexpected frame: %r', frame_value)
class-attribute
¶
_STATE_NAMES: dict[int, str] = {
CLOSED: 'CLOSED',
OPENING: 'OPENING',
OPEN: 'OPEN',
CLOSING: 'CLOSING',
}
class-attribute
instance-attribute
¶
_ON_CHANNEL_CLEANUP_CB_KEY = '_on_channel_cleanup'
class-attribute
instance-attribute
¶
_MAX_RETAINED_CANCELLED_TAGS = 1024
instance-attribute
¶
_on_openok_callback: Callable[..., Any] | None = (
on_open_callback
)
property
¶
consumer_tags: list[str]
Property method that returns a list of currently active consumers.
property
¶
is_closing: bool
Returns True if client-initiated closing of the channel is in progress.
__init__(
connection: Connection,
channel_number: int,
on_open_callback: _OnOpenCallback | None,
) -> None
Create a new instance of the Channel.
| PARAMETER | DESCRIPTION |
|---|---|
connection
|
The connection
TYPE:
|
channel_number
|
The channel number for this instance
TYPE:
|
on_open_callback
|
The callback to call on channel open. The callback will be invoked
with the
TYPE:
|
Source code in pika/channel.py
def __init__(self, connection: Connection, channel_number: int,
on_open_callback: _OnOpenCallback | None) -> None:
"""
Create a new instance of the Channel.
:param connection: The connection
:param channel_number: The channel number for this instance
:param on_open_callback: The callback to call on channel open. The callback will be invoked
with the `Channel` instance as its only argument.
"""
if not isinstance(channel_number, int):
raise exceptions.InvalidChannelNumber(channel_number)
validators.rpc_completion_callback(on_open_callback)
self.channel_number = channel_number
self.callbacks = connection.callbacks
self.connection = connection
# Initially, flow is assumed to be active
self.flow_active = True
self._content_assembler = ContentFrameAssembler()
self._blocked: deque = deque()
self._blocking: Any | None = None
self._has_on_flow_callback: bool = False
self._cancelled: set = set()
# Nowait-cancelled tags in cancellation order, bounding how many of
# them `_cancelled` retains; see `_retain_cancelled_tag`.
self._nowait_cancelled: deque = deque()
self._consumers: dict = {}
self._consumers_with_noack: set = set()
self._on_flowok_callback: Callable[..., Any] | None = None
self._on_getok_callback: Callable[..., Any] | None = None
self._on_ack_nack_callback: _OnAckNackCallback | None = None
self._on_openok_callback: Callable[..., Any] | None = on_open_callback
self._state: int = self.CLOSED
# We save the closing reason exception to be passed to on-channel-close
# callback at closing of the channel. Exception representing the closing
# reason; ChannelClosedByClient or ChannelClosedByBroker on controlled
# close; otherwise another exception describing the reason for failure
# (most likely connection failure).
self._closing_reason = None # type: None | Exception
# opaque cookie value set by wrapper layer (e.g., BlockingConnection)
# via _set_cookie
self._cookie: object = None
__int__() -> int
Return the channel object as its channel number.
Source code in pika/channel.py
def __int__(self) -> int:
"""Return the channel object as its channel number."""
return self.channel_number
__repr__() -> str
Source code in pika/channel.py
@override
def __repr__(self) -> str:
return f'<{self.__class__.__name__} number={self.channel_number} {self._STATE_NAMES[self._state]} conn={self.connection!r}>'
add_callback(
callback: Callable[..., Any],
replies: Sequence[type[Method]],
one_shot: bool = True,
) -> None
Pass in a callback handler and a list replies from the RabbitMQ broker which you'd like the callback notified of. Callbacks should allow for the frame parameter to be passed in.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to call
TYPE:
|
replies
|
The replies to get a callback for
TYPE:
|
one_shot
|
Only handle the first type callback
TYPE:
|
Source code in pika/channel.py
def add_callback(self,
callback: Callable[..., Any],
replies: Sequence[type[amqp_object.Method]],
one_shot: bool = True) -> None:
"""
Pass in a callback handler and a list replies from the RabbitMQ broker which you'd like the
callback notified of. Callbacks should allow for the frame parameter to be passed in.
:param callback: The callback to call
:param replies: The replies to get a callback for
:param one_shot: Only handle the first type callback
"""
for reply in replies:
self.callbacks.add(self.channel_number, reply, callback, one_shot)
add_on_cancel_callback(callback: _OnCancelCallback) -> None
Pass a callback function that will be called when the basic_cancel is sent by the server. The callback function should receive a frame parameter.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to call on Basic.Cancel from broker
TYPE:
|
Source code in pika/channel.py
def add_on_cancel_callback(self, callback: _OnCancelCallback) -> None:
"""
Pass a callback function that will be called when the basic_cancel is sent by the server.
The callback function should receive a frame parameter.
:param callback: The callback to call on Basic.Cancel from broker
"""
self.callbacks.add(self.channel_number, spec.Basic.Cancel, callback,
False)
add_on_close_callback(callback: _OnCloseCallback) -> None
Pass a callback function that will be called when the channel is closed.
The callback function will receive the channel and an exception describing why the channel was closed.
If the channel is closed by broker via Channel.Close, the callback will receive
ChannelClosedByBroker as the reason.
If graceful user-initiated channel closing completes successfully ( either directly of
indirectly by closing a connection containing the channel) and closing concludes gracefully
without Channel.Close from the broker and without loss of connection, the callback will
receive ChannelClosedByClient exception as reason.
If channel was closed due to loss of connection, the callback will receive another exception type describing the failure.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback, having the signature: callback(Channel, Exception reason)
TYPE:
|
Source code in pika/channel.py
def add_on_close_callback(self, callback: _OnCloseCallback) -> None:
"""
Pass a callback function that will be called when the channel is closed.
The callback function will receive the channel and an exception describing why the channel
was closed.
If the channel is closed by broker via Channel.Close, the callback will receive
`ChannelClosedByBroker` as the reason.
If graceful user-initiated channel closing completes successfully ( either directly of
indirectly by closing a connection containing the channel) and closing concludes gracefully
without Channel.Close from the broker and without loss of connection, the callback will
receive `ChannelClosedByClient` exception as reason.
If channel was closed due to loss of connection, the callback will receive another exception
type describing the failure.
:param callback: The callback, having the signature: callback(Channel, Exception reason)
"""
self.callbacks.add(self.channel_number, '_on_channel_close', callback,
False, self)
add_on_flow_callback(callback: _OnFlowCallback) -> None
Pass a callback function that will be called when Channel.Flow is called by the remote server. Note that newer versions of RabbitMQ will not issue this but instead use TCP backpressure.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback function
TYPE:
|
Source code in pika/channel.py
def add_on_flow_callback(self, callback: _OnFlowCallback) -> None:
"""
Pass a callback function that will be called when Channel.Flow is called by the remote
server. Note that newer versions of RabbitMQ will not issue this but instead use TCP
backpressure.
:param callback: The callback function
"""
self._has_on_flow_callback = True
self.callbacks.add(self.channel_number, spec.Channel.Flow, callback,
False)
add_on_return_callback(callback: _OnReturnCallback) -> None
Pass a callback function that will be called when basic_publish is sent a message that has been rejected and returned by the server.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The function to call, having the signature callback(channel, method, properties, body) where - channel: pika.channel.Channel - method: pika.spec.Basic.Return - properties: pika.spec.BasicProperties - body: bytes
TYPE:
|
Source code in pika/channel.py
def add_on_return_callback(self, callback: _OnReturnCallback) -> None:
"""
Pass a callback function that will be called when basic_publish is sent a message that has
been rejected and returned by the server.
:param callback: The function to call, having the signature
callback(channel, method, properties, body)
where
- channel: pika.channel.Channel
- method: pika.spec.Basic.Return
- properties: pika.spec.BasicProperties
- body: bytes
"""
self.callbacks.add(self.channel_number, '_on_return', callback, False)
remove_callback(
callback: Callable[..., Any],
replies: Sequence[type[Method]] | None = None,
) -> bool
Remove a callback previously registered via :meth:add_callback.
Mirrors :meth:add_callback: the callback is matched by identity and removed
from each reply key it is registered under. If replies is None, the
callback is removed from every reply key it is currently registered under.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to remove
TYPE:
|
replies
|
The replies to remove the callback from, or
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
bool
|
|
Source code in pika/channel.py
def remove_callback(
self,
callback: Callable[..., Any],
replies: Sequence[type[amqp_object.Method]] | None = None) -> bool:
"""
Remove a callback previously registered via :meth:`add_callback`.
Mirrors :meth:`add_callback`: the callback is matched by identity and removed
from each reply key it is registered under. If ``replies`` is ``None``, the
callback is removed from every reply key it is currently registered under.
:param callback: The callback to remove
:param replies: The replies to remove the callback from, or ``None`` to
remove it from every reply key it is registered under
:returns: ``True`` if at least one matching callback was removed
"""
reply_keys = (self.callbacks.keys(self.channel_number)
if replies is None else replies)
removed = False
for reply in reply_keys:
if self.callbacks.remove_matching(self.channel_number, reply,
lambda cb: cb == callback):
removed = True
return removed
remove_on_cancel_callback(
callback: _OnCancelCallback,
) -> bool
Remove a callback registered via :meth:add_on_cancel_callback.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to remove
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
bool
|
|
Source code in pika/channel.py
def remove_on_cancel_callback(self, callback: _OnCancelCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_cancel_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number,
spec.Basic.Cancel,
lambda cb: cb == callback)
remove_on_close_callback(
callback: _OnCloseCallback,
) -> bool
Remove a callback registered via :meth:add_on_close_callback.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to remove
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
bool
|
|
Source code in pika/channel.py
def remove_on_close_callback(self, callback: _OnCloseCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_close_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number,
'_on_channel_close',
lambda cb: cb == callback)
remove_on_flow_callback(callback: _OnFlowCallback) -> bool
Remove a callback registered via :meth:add_on_flow_callback.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to remove
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
bool
|
|
Source code in pika/channel.py
def remove_on_flow_callback(self, callback: _OnFlowCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_flow_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number,
spec.Channel.Flow,
lambda cb: cb == callback)
remove_on_return_callback(
callback: _OnReturnCallback,
) -> bool
Remove a callback registered via :meth:add_on_return_callback.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to remove
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
bool
|
|
Source code in pika/channel.py
def remove_on_return_callback(self, callback: _OnReturnCallback) -> bool:
"""
Remove a callback registered via :meth:`add_on_return_callback`.
:param callback: The callback to remove
:returns:``True`` if the callback was removed, ``False`` if it was absent
"""
return self.callbacks.remove_matching(self.channel_number, '_on_return',
lambda cb: cb == callback)
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
|
int/long 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/channel.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: int/long 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._raise_if_not_open()
return self._send_method(spec.Basic.Ack(delivery_tag, multiple))
basic_cancel(
consumer_tag: str = '',
callback: _OnBasicCancelCallback | None = None,
) -> None
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. It may also be sent from the server to the client in the event of the consumer being unexpectedly cancelled (i.e. cancelled for any reason other than the server receiving the corresponding basic.cancel from the client). This allows clients to be notified of the loss of consumers due to events such as queue deletion.
A cancelled consumer's tag is retained so that a delivery already in flight when the cancel
was sent is rejected rather than left unacknowledged. A cancel that expects a Basic.CancelOk
retires its own entry on arrival; a nowait cancel has no reply to retire it, so its tag is
kept only until _MAX_RETAINED_CANCELLED_TAGS later nowait cancels displace it (see
_retain_cancelled_tag). Past that point its retention lapses: a straggling delivery for it
is logged as unexpected and left unacknowledged rather than rejected, and the tag may be
reused by basic_consume, so reusing the same explicit consumer_tag risks a delivery for
the old consumer reaching the new one. The cap is a generous approximation of the broker's
in-flight window, so this only bites under extreme nowait-cancel churn.
| PARAMETER | DESCRIPTION |
|---|---|
consumer_tag
|
Identifier for the consumer
TYPE:
|
callback
|
callback(pika.frame.Method) for method Basic.CancelOk. If None, do not expect a Basic.CancelOk response, otherwise, callback must be callable
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def basic_cancel(self,
consumer_tag: str = '',
callback: _OnBasicCancelCallback | None = None) -> None:
"""
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. It may also be sent
from the server to the client in the event of the consumer being unexpectedly cancelled
(i.e. cancelled for any reason other than the server receiving the corresponding
basic.cancel from the client). This allows clients to be notified of the loss of consumers
due to events such as queue deletion.
A cancelled consumer's tag is retained so that a delivery already in flight when the cancel
was sent is rejected rather than left unacknowledged. A cancel that expects a Basic.CancelOk
retires its own entry on arrival; a nowait cancel has no reply to retire it, so its tag is
kept only until `_MAX_RETAINED_CANCELLED_TAGS` later nowait cancels displace it (see
`_retain_cancelled_tag`). Past that point its retention lapses: a straggling delivery for it
is logged as unexpected and left unacknowledged rather than rejected, and the tag may be
reused by `basic_consume`, so reusing the same explicit consumer_tag risks a delivery for
the old consumer reaching the new one. The cap is a generous approximation of the broker's
in-flight window, so this only bites under extreme nowait-cancel churn.
:param consumer_tag: Identifier for the consumer
:param callback: callback(pika.frame.Method) for method Basic.CancelOk. If None, do not
expect a Basic.CancelOk response, otherwise, callback must be callable
:raises ValueError:
"""
validators.require_string(consumer_tag, 'consumer_tag')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if consumer_tag in self._cancelled:
# We check for cancelled first, because basic_cancel removes
# consumers closed with nowait from self._consumers
LOGGER.warning('basic_cancel - consumer is already cancelling: %s',
consumer_tag)
return
if consumer_tag not in self._consumers:
# Could be cancelled by user or broker earlier
LOGGER.warning('basic_cancel - consumer not found: %s',
consumer_tag)
return
LOGGER.debug('Cancelling consumer: %s (nowait=%s)', consumer_tag,
nowait)
if nowait:
# This is our last opportunity while the channel is open to remove
# this consumer callback and help gc.
del self._consumers[consumer_tag]
if callback is not None:
self.callbacks.add(self.channel_number, spec.Basic.CancelOk,
callback)
self._cancelled.add(consumer_tag)
if nowait:
self._retain_cancelled_tag(consumer_tag)
self._rpc(spec.Basic.Cancel(consumer_tag=consumer_tag, nowait=nowait),
self._on_cancelok if not nowait else None,
[(spec.Basic.CancelOk, {
'consumer_tag': consumer_tag
})] if not nowait else [])
basic_consume(
queue: str,
on_message_callback: _OnMessageCallback,
auto_ack: bool = False,
exclusive: bool = False,
consumer_tag: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnBasicConsumeCallback | None = None,
) -> str
Sends the AMQP 0-9-1 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.
For more information on basic_consume, see: Tutorial 2 at https://www.rabbitmq.com/getstarted.html https://www.rabbitmq.com/confirms.html https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue to consume from. Use the empty string to specify the most recent server-named queue for this channel
TYPE:
|
on_message_callback
|
The function to call when consuming with the signature on_message_callback(channel, method, properties, body), where - channel: pika.channel.Channel - method: pika.spec.Basic.Deliver - properties: pika.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
|
Specify your own consumer tag
TYPE:
|
arguments
|
Custom key/value pair arguments for the consumer
TYPE:
|
callback
|
callback(pika.frame.Method) for method Basic.ConsumeOk.
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
str
|
Consumer tag which may be used to cancel the consumer. |
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def basic_consume(self,
queue: str,
on_message_callback: _OnMessageCallback,
auto_ack: bool = False,
exclusive: bool = False,
consumer_tag: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnBasicConsumeCallback | None = None) -> str:
"""
Sends the AMQP 0-9-1 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.
For more information on basic_consume, see:
Tutorial 2 at https://www.rabbitmq.com/getstarted.html
https://www.rabbitmq.com/confirms.html
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume
:param queue: The queue to consume from. Use the empty string to
specify the most recent server-named queue for this channel
:param on_message_callback: The function to call when
consuming with the signature
on_message_callback(channel, method, properties, body), where
- channel: pika.channel.Channel
- method: pika.spec.Basic.Deliver
- properties: pika.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: Specify your own consumer tag
:param arguments: Custom key/value pair arguments for the consumer
:param callback: callback(pika.frame.Method) for method
Basic.ConsumeOk.
:returns: Consumer tag which may be used to cancel the consumer.
:raises ValueError:
"""
validators.require_string(queue, 'queue')
validators.require_callback(on_message_callback)
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
# If a consumer tag was not passed, create one
if not consumer_tag:
consumer_tag = self._generate_consumer_tag()
if consumer_tag in self._consumers or consumer_tag in self._cancelled:
raise exceptions.DuplicateConsumerTag(consumer_tag)
if auto_ack:
self._consumers_with_noack.add(consumer_tag)
self._consumers[consumer_tag] = on_message_callback
rpc_callback: Callable[
...,
Any] | None = self._on_eventok if callback is None else callback
self._rpc(
spec.Basic.Consume(queue=queue,
consumer_tag=consumer_tag,
no_ack=auto_ack,
exclusive=exclusive,
arguments=arguments or {}), rpc_callback,
[(spec.Basic.ConsumeOk, {
'consumer_tag': consumer_tag
})])
return consumer_tag
_generate_consumer_tag() -> str
Generate a consumer tag.
NOTE: this protected method may be called by derived classes
| RETURNS | DESCRIPTION |
|---|---|
str
|
consumer tag |
Source code in pika/channel.py
def _generate_consumer_tag(self) -> str:
"""
Generate a consumer tag.
NOTE: this protected method may be called by derived classes
:returns: consumer tag
"""
return f'ctag{self.channel_number}.{uuid.uuid4().hex}'
basic_get(
queue: str,
callback: _OnBasicGetCallback,
auto_ack: bool = False,
) -> None
Get a single message from the AMQP broker.
If you want to be notified of Basic.GetEmpty, use the Channel.add_callback method adding your Basic.GetEmpty callback which should expect only one parameter, frame. Due to implementation details, this cannot be called a second time until the callback is executed. For more information on basic_get and its parameters, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.get
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue from which to get a message. Use the empty string to specify the most recent server-named queue for this channel
TYPE:
|
callback
|
The callback to call with a message that has the signature callback(channel, method, properties, body), where: - channel: pika.channel.Channel - method: pika.spec.Basic.GetOk - properties: pika.spec.BasicProperties - body: bytes
TYPE:
|
auto_ack
|
Tell the broker to not expect a reply
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def basic_get(self,
queue: str,
callback: _OnBasicGetCallback,
auto_ack: bool = False) -> None:
"""
Get a single message from the AMQP broker.
If you want to be notified of Basic.GetEmpty, use the Channel.add_callback method
adding your Basic.GetEmpty callback which should expect only one
parameter, frame. Due to implementation details, this cannot be called
a second time until the callback is executed. For more information on
basic_get and its parameters, see:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.get
:param queue: The queue from which to get a message. Use the empty
string to specify the most recent server-named queue for this
channel
:param callback: The callback to call with a message that has
the signature callback(channel, method, properties, body), where:
- channel: pika.channel.Channel
- method: pika.spec.Basic.GetOk
- properties: pika.spec.BasicProperties
- body: bytes
:param auto_ack: Tell the broker to not expect a reply
:raises ValueError:
"""
validators.require_string(queue, 'queue')
validators.require_callback(callback)
if self._on_getok_callback is not None:
raise exceptions.DuplicateGetOkCallback()
self._on_getok_callback = callback
# TODO Strangely, not using _rpc for the synchronous Basic.Get. Would
# need to extend _rpc to handle Basic.GetOk method, header, and body
# frames (or similar)
self._send_method(spec.Basic.Get(queue=queue, no_ack=auto_ack))
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
|
int/long 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/channel.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: int/long 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._raise_if_not_open()
return self._send_method(
spec.Basic.Nack(delivery_tag, multiple, requeue))
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
| PARAMETER | DESCRIPTION |
|---|---|
exchange
|
The exchange to publish to
TYPE:
|
routing_key
|
The routing key to bind on
TYPE:
|
body
|
The message body
TYPE:
|
properties
|
Basic.properties
TYPE:
|
mandatory
|
The mandatory flag
TYPE:
|
Source code in pika/channel.py
def basic_publish(self,
exchange: str,
routing_key: str,
body: bytes,
properties: 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
:param exchange: The exchange to publish to
:param routing_key: The routing key to bind on
:param body: The message body
:param properties: Basic.properties
:param mandatory: The mandatory flag
"""
self._raise_if_not_open()
body = as_bytes(body)
properties = properties or spec.BasicProperties()
self._send_method(
spec.Basic.Publish(exchange=exchange,
routing_key=routing_key,
mandatory=mandatory), (properties, body))
basic_qos(
prefetch_size: int = 0,
prefetch_count: int = 0,
global_qos: bool = False,
callback: _OnBasicQosCallback | None = None,
) -> None
Specify quality of service.
This method requests a specific quality of service. 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. The QoS can be applied separately to each new consumer on channel or shared across all consumers on 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 by consumers who have enabled the no-ack option.
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 by consumers who have enabled the no-ack option.
TYPE:
|
global_qos
|
Should the QoS be shared across all consumers on the channel.
TYPE:
|
callback
|
The callback to call for Basic.QosOk response
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def basic_qos(self,
prefetch_size: int = 0,
prefetch_count: int = 0,
global_qos: bool = False,
callback: _OnBasicQosCallback | None = None) -> None:
"""
Specify quality of service.
This method requests a specific quality of service. 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. The QoS can be
applied separately to each new consumer on channel or shared across all consumers on 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 by
consumers who have enabled the no-ack option.
: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 by consumers who have enabled the no-ack option.
:param global_qos: Should the QoS be shared across all consumers on the channel.
:param callback: The callback to call for Basic.QosOk response
:returns:``None``. Method frame from the Basic.Qos-ok response is delivered to ``callback``
when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
validators.zero_or_greater('prefetch_size', prefetch_size)
validators.zero_or_greater('prefetch_count', prefetch_count)
return self._rpc(
spec.Basic.Qos(prefetch_size, prefetch_count, global_qos), callback,
[spec.Basic.QosOk])
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
|
int/long 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:
|
| RAISES | DESCRIPTION |
|---|---|
TypeError
|
|
Source code in pika/channel.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: int/long 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.
:raises TypeError:
"""
self._raise_if_not_open()
if not isinstance(delivery_tag, int):
raise TypeError('delivery_tag must be an integer')
return self._send_method(spec.Basic.Reject(delivery_tag, requeue))
basic_recover(
requeue: bool = False,
callback: _OnBasicRecoverCallback | None = None,
) -> 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:
|
callback
|
callback(pika.frame.Method) for method Basic.RecoverOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def basic_recover(self,
requeue: bool = False,
callback: _OnBasicRecoverCallback | None = None) -> 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.
:param callback: callback(pika.frame.Method) for method Basic.RecoverOk
:returns:``None``. Method frame from the Basic.Recover-ok response is delivered to
``callback`` when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Basic.Recover(requeue), callback,
[spec.Basic.RecoverOk])
close(
reply_code: int = 0, reply_text: str = 'Normal shutdown'
) -> None
Invoke a graceful shutdown of the channel with the AMQP Broker.
If channel is OPENING, transition to CLOSING and suppress the incoming Channel.OpenOk, if any.
| PARAMETER | DESCRIPTION |
|---|---|
reply_code
|
The reason code to send to broker
TYPE:
|
reply_text
|
The reason text to send to broker
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
ChannelWrongStateError
|
if channel is closed or closing |
Source code in pika/channel.py
def close(self,
reply_code: int = 0,
reply_text: str = 'Normal shutdown') -> None:
"""
Invoke a graceful shutdown of the channel with the AMQP Broker.
If channel is OPENING, transition to CLOSING and suppress the incoming Channel.OpenOk, if
any.
:param reply_code: The reason code to send to broker
:param reply_text: The reason text to send to broker
:raises ChannelWrongStateError: if channel is closed or closing
"""
if self.is_closed or self.is_closing:
# Whoever is calling `close` might expect the on-channel-close-cb
# to be called, which won't happen when it's already closed.
self._raise_if_not_open()
# If channel is OPENING, we will transition it to CLOSING state,
# causing the _on_openok method to suppress the OPEN state transition
# and the on-channel-open-callback
LOGGER.info('Closing channel (%s): %r on %s', reply_code, reply_text,
self)
# Save the reason info so that we may use it in the '_on_channel_close'
# callback processing
self._closing_reason = exceptions.ChannelClosedByClient(
reply_code, reply_text)
for consumer_tag in list(self._consumers.keys()):
if consumer_tag not in self._cancelled:
self.basic_cancel(consumer_tag=consumer_tag)
# Change state after cancelling consumers to avoid
# ChannelWrongStateError exception from basic_cancel
self._set_state(self.CLOSING)
self._rpc(spec.Channel.Close(reply_code, reply_text, 0, 0),
self._on_closeok, [spec.Channel.CloseOk])
confirm_delivery(
ack_nack_callback: _OnAckNackCallback,
callback: _OnConfirmDeliveryCallback | None = None,
) -> None
Turn on Confirm mode in the channel.
Pass in a callback to be notified by the Broker when a message has been confirmed as received or rejected (Basic.Ack, Basic.Nack) from the broker to the publisher.
For more information see: https://www.rabbitmq.com/confirms.html
| PARAMETER | DESCRIPTION |
|---|---|
ack_nack_callback
|
Required callback for delivery
confirmations that has the following signature:
callback(pika.frame.Method), where method_frame contains
either method
TYPE:
|
callback
|
callback(pika.frame.Method) for method Confirm.SelectOk
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
TypeError
|
if .. note::
Calling this method more than once on the same channel replaces
the previously registered |
Source code in pika/channel.py
def confirm_delivery(
self,
ack_nack_callback: _OnAckNackCallback,
callback: _OnConfirmDeliveryCallback | None = None) -> None:
"""
Turn on Confirm mode in the channel.
Pass in a callback to be notified by the Broker when a message has been confirmed as received or
rejected (Basic.Ack, Basic.Nack) from the broker to the publisher.
For more information see:
https://www.rabbitmq.com/confirms.html
:param ack_nack_callback: Required callback for delivery
confirmations that has the following signature:
callback(pika.frame.Method), where method_frame contains
either method `spec.Basic.Ack` or `spec.Basic.Nack`.
:param callback: callback(pika.frame.Method) for method
Confirm.SelectOk
:raises TypeError: if `ack_nack_callback` is not callable
.. note::
Calling this method more than once on the same channel replaces
the previously registered ``ack_nack_callback`` rather than adding
an additional one. Only the most recently registered callback
receives ``Basic.Ack``/``Basic.Nack`` notifications.
"""
if not callable(ack_nack_callback):
# confirm_deliver requires a callback; it's meaningless
# without a user callback to receive Basic.Ack/Basic.Nack notifications
raise TypeError('confirm_delivery requires a callback '
'to receive Basic.Ack/Basic.Nack notifications')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if not (self.connection.publisher_confirms and
self.connection.basic_nack):
raise exceptions.MethodNotImplemented(
'Confirm.Select not Supported by Server')
# Replace any previously registered ack/nack callback so repeated
# calls don't stack listeners and fire stale callbacks (see #1602).
if self._on_ack_nack_callback is not None:
self.callbacks.remove(self.channel_number, spec.Basic.Ack,
self._on_ack_nack_callback)
self.callbacks.remove(self.channel_number, spec.Basic.Nack,
self._on_ack_nack_callback)
# Add the ack and nack callback
self.callbacks.add(self.channel_number, spec.Basic.Ack,
ack_nack_callback, False)
self.callbacks.add(self.channel_number, spec.Basic.Nack,
ack_nack_callback, False)
self._on_ack_nack_callback = ack_nack_callback
self._rpc(spec.Confirm.Select(nowait), callback,
[spec.Confirm.SelectOk] if not nowait else [])
exchange_bind(
destination: str,
source: str,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
callback: _OnExchangeBindCallback | None = None,
) -> None
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:
|
callback
|
callback(pika.frame.Method) for method Exchange.BindOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def exchange_bind(self,
destination: str,
source: str,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
callback: _OnExchangeBindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Exchange.BindOk
:returns:``None``. Method frame from the Exchange.Bind-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(destination, 'destination')
validators.require_string(source, 'source')
nowait = validators.rpc_completion_callback(callback)
return self._rpc(
spec.Exchange.Bind(0, destination, source, routing_key, nowait,
arguments or {}), callback,
[spec.Exchange.BindOk] if not nowait else [])
exchange_declare(
exchange: str,
exchange_type: str = direct,
passive: bool = False,
durable: bool = False,
auto_delete: bool = False,
internal: bool = False,
arguments: dict[str, Any] | None = None,
callback: _OnExchangeDeclareCallback | 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:
|
callback
|
callback(pika.frame.Method) for method Exchange.DeclareOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def exchange_declare(
self,
exchange: str,
exchange_type: str = ExchangeType.direct,
passive: bool = False,
durable: bool = False,
auto_delete: bool = False,
internal: bool = False,
arguments: dict[str, Any] | None = None,
callback: _OnExchangeDeclareCallback | 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
:param callback: callback(pika.frame.Method) for method Exchange.DeclareOk
:returns: ``None``. Method frame from the Exchange.Declare-ok response is
delivered to ``callback`` when synchronous (no ok frame in nowait
mode).
:raises ValueError:
"""
validators.require_string(exchange, 'exchange')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if isinstance(exchange_type, Enum):
exchange_type = exchange_type.value
return self._rpc(
spec.Exchange.Declare(0, exchange, exchange_type, passive, durable,
auto_delete, internal, nowait, arguments or
{}), callback,
[spec.Exchange.DeclareOk] if not nowait else [])
exchange_delete(
exchange: str | None = None,
if_unused: bool = False,
callback: _OnExchangeDeleteCallback | None = None,
) -> None
Delete the exchange.
| PARAMETER | DESCRIPTION |
|---|---|
exchange
|
The exchange name
TYPE:
|
if_unused
|
only delete if the exchange is unused
TYPE:
|
callback
|
callback(pika.frame.Method) for method Exchange.DeleteOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def exchange_delete(
self,
exchange: str | None = None,
if_unused: bool = False,
callback: _OnExchangeDeleteCallback | None = None) -> None:
"""
Delete the exchange.
:param exchange: The exchange name
:param if_unused: only delete if the exchange is unused
:param callback: callback(pika.frame.Method) for method Exchange.DeleteOk
:returns:``None``. Method frame from the Exchange.Delete-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
return self._rpc(spec.Exchange.Delete(0, exchange, if_unused,
nowait), callback,
[spec.Exchange.DeleteOk] if not nowait else [])
exchange_unbind(
destination: str | None = None,
source: str | None = None,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
callback: _OnExchangeUnbindCallback | None = None,
) -> None
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:
|
callback
|
callback(pika.frame.Method) for method Exchange.UnbindOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def exchange_unbind(
self,
destination: str | None = None,
source: str | None = None,
routing_key: str = '',
arguments: dict[str, Any] | None = None,
callback: _OnExchangeUnbindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Exchange.UnbindOk
:returns:``None``. Method frame from the Exchange.Unbind-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
return self._rpc(
spec.Exchange.Unbind(0, destination, source, routing_key, nowait,
arguments), callback,
[spec.Exchange.UnbindOk] if not nowait else [])
flow(
active: bool, callback: _OnFlowCallback | None = None
) -> None
Turn Channel flow control off and on.
Pass a callback to be notified of the response from the server. active is a bool. Callback should expect a bool in response indicating channel flow state. For more information, please reference:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#channel.flow
| PARAMETER | DESCRIPTION |
|---|---|
active
|
Turn flow on or off
TYPE:
|
callback
|
callback(bool) upon completion
TYPE:
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def flow(self,
active: bool,
callback: _OnFlowCallback | None = None) -> None:
"""
Turn Channel flow control off and on.
Pass a callback to be notified of the response from the server. active is a bool. Callback
should expect a bool in response indicating channel flow state. For more information, please
reference:
https://www.rabbitmq.com/amqp-0-9-1-reference.html#channel.flow
:param active: Turn flow on or off
:param callback: callback(bool) upon completion
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
self._on_flowok_callback = callback
self._rpc(spec.Channel.Flow(active), self._on_flowok,
[spec.Channel.FlowOk])
open() -> None
Open the channel.
Source code in pika/channel.py
def open(self) -> None:
"""Open the channel."""
self._set_state(self.OPENING)
self._add_callbacks()
self._rpc(spec.Channel.Open(), self._on_openok, [spec.Channel.OpenOk])
queue_bind(
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnQueueBindCallback | None = None,
) -> None
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:
|
callback
|
callback(pika.frame.Method) for method Queue.BindOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def queue_bind(self,
queue: str,
exchange: str,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnQueueBindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Queue.BindOk
:returns:``None``. Method frame from the Queue.Bind-ok response is delivered to ``callback``
when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
validators.require_string(queue, 'queue')
validators.require_string(exchange, 'exchange')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
if routing_key is None:
routing_key = queue
return self._rpc(
spec.Queue.Bind(0, queue, exchange, routing_key, nowait,
arguments or {}), callback,
[spec.Queue.BindOk] if not nowait else [])
queue_declare(
queue: str,
passive: bool = False,
durable: bool = False,
exclusive: bool = False,
auto_delete: bool = False,
arguments: dict[str, Any] | None = None,
callback: _OnQueueDeclareCallback | None = None,
) -> None
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
| 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
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:
|
callback
|
callback(pika.frame.Method) for method Queue.DeclareOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.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,
callback: _OnQueueDeclareCallback | None = None) -> None:
"""
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
: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
: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
:param callback: callback(pika.frame.Method) for method Queue.DeclareOk
:returns: ``None``. Method frame from the Queue.Declare-ok response is
delivered to ``callback`` when synchronous (no ok frame in nowait
mode).
:raises ValueError:
"""
validators.require_string(queue, 'queue')
self._raise_if_not_open()
nowait = validators.rpc_completion_callback(callback)
condition: Any
if queue:
condition = (spec.Queue.DeclareOk, {'queue': queue})
else:
condition = spec.Queue.DeclareOk
replies = [condition] if not nowait else []
return self._rpc(
spec.Queue.Declare(0, queue, passive, durable, exclusive,
auto_delete, nowait, arguments or {}), callback,
replies)
queue_delete(
queue: str,
if_unused: bool = False,
if_empty: bool = False,
callback: _OnQueueDeleteCallback | None = None,
) -> None
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:
|
callback
|
callback(pika.frame.Method) for method Queue.DeleteOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def queue_delete(self,
queue: str,
if_unused: bool = False,
if_empty: bool = False,
callback: _OnQueueDeleteCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Queue.DeleteOk
:returns:``None``. Method frame from the Queue.Delete-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(queue, 'queue')
nowait = validators.rpc_completion_callback(callback)
replies = [spec.Queue.DeleteOk] if not nowait else []
return self._rpc(
spec.Queue.Delete(0, queue, if_unused, if_empty, nowait), callback,
replies)
queue_purge(
queue: str,
callback: _OnQueuePurgeCallback | None = None,
) -> None
Purge all of the messages from the specified queue.
| PARAMETER | DESCRIPTION |
|---|---|
queue
|
The queue to purge
TYPE:
|
callback
|
callback(pika.frame.Method) for method Queue.PurgeOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def queue_purge(self,
queue: str,
callback: _OnQueuePurgeCallback | None = None) -> None:
"""
Purge all of the messages from the specified queue.
:param queue: The queue to purge
:param callback: callback(pika.frame.Method) for method Queue.PurgeOk
:returns:``None``. Method frame from the Queue.Purge-ok response is delivered to
``callback`` when synchronous (no ok frame in nowait mode).
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(queue, 'queue')
nowait = validators.rpc_completion_callback(callback)
replies = [spec.Queue.PurgeOk] if not nowait else []
return self._rpc(spec.Queue.Purge(0, queue, nowait), callback, replies)
queue_unbind(
queue: str,
exchange: str | None = None,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnQueueUnbindCallback | None = None,
) -> None
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:
|
callback
|
callback(pika.frame.Method) for method Queue.UnbindOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def queue_unbind(self,
queue: str,
exchange: str | None = None,
routing_key: str | None = None,
arguments: dict[str, Any] | None = None,
callback: _OnQueueUnbindCallback | None = None) -> None:
"""
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
:param callback: callback(pika.frame.Method) for method Queue.UnbindOk
:returns:``None``. Method frame from the Queue.Unbind-ok response is delivered to
``callback`` when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.require_string(queue, 'queue')
validators.rpc_completion_callback(callback)
if routing_key is None:
routing_key = queue
return self._rpc(
spec.Queue.Unbind(0, queue, exchange, routing_key, arguments or {}),
callback, [spec.Queue.UnbindOk])
tx_commit(
callback: _OnTxCommitCallback | None = None,
) -> None
Commit a transaction.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
callback(pika.frame.Method) for method Tx.CommitOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def tx_commit(self, callback: _OnTxCommitCallback | None = None) -> None:
"""
Commit a transaction.
:param callback: callback(pika.frame.Method) for method Tx.CommitOk
:returns:``None``. Method frame from the Tx.Commit-ok response is delivered to ``callback``
when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Tx.Commit(), callback, [spec.Tx.CommitOk])
tx_rollback(
callback: _OnTxRollbackCallback | None = None,
) -> None
Rollback a transaction.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
callback(pika.frame.Method) for method Tx.RollbackOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def tx_rollback(self,
callback: _OnTxRollbackCallback | None = None) -> None:
"""
Rollback a transaction.
:param callback: callback(pika.frame.Method) for method Tx.RollbackOk
:returns:``None``. Method frame from the Tx.Rollback-ok response is delivered to
``callback`` when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Tx.Rollback(), callback, [spec.Tx.RollbackOk])
tx_select(
callback: _OnTxSelectCallback | None = None,
) -> None
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.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
callback(pika.frame.Method) for method Tx.SelectOk
TYPE:
|
| RETURNS | DESCRIPTION |
|---|---|
None
|
|
| RAISES | DESCRIPTION |
|---|---|
ValueError
|
|
Source code in pika/channel.py
def tx_select(self, callback: _OnTxSelectCallback | None = None) -> None:
"""
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.
:param callback: callback(pika.frame.Method) for method Tx.SelectOk
:returns:``None``. Method frame from the Tx.Select-ok response is delivered to ``callback``
when provided.
:raises ValueError:
"""
self._raise_if_not_open()
validators.rpc_completion_callback(callback)
return self._rpc(spec.Tx.Select(), callback, [spec.Tx.SelectOk])
_add_callbacks() -> None
Callbacks that add the required behavior for a channel when connecting and connected to a server.
Source code in pika/channel.py
def _add_callbacks(self) -> None:
"""Callbacks that add the required behavior for a channel when connecting and connected to a
server.
"""
# Add a callback for Basic.GetEmpty
self.callbacks.add(self.channel_number, spec.Basic.GetEmpty,
self._on_getempty, False)
# Add a callback for Basic.Cancel
self.callbacks.add(self.channel_number, spec.Basic.Cancel,
self._on_cancel, False)
# Deprecated in newer versions of RabbitMQ but still register for it
self.callbacks.add(self.channel_number, spec.Channel.Flow,
self._on_flow, False)
# Add a callback for when the server closes our channel
self.callbacks.add(self.channel_number, spec.Channel.Close,
self._on_close_from_broker, True)
_add_on_cleanup_callback(
callback: Callable[..., Any],
) -> None
For internal use only (e.g., Connection needs to remove closed channels from its channel container). Pass a callback function that will be called when the channel is being cleaned up after all channel-close callbacks callbacks.
| PARAMETER | DESCRIPTION |
|---|---|
callback
|
The callback to call, having the signature: callback(channel)
TYPE:
|
Source code in pika/channel.py
def _add_on_cleanup_callback(self, callback: Callable[..., Any]) -> None:
"""
For internal use only (e.g., Connection needs to remove closed channels from its channel
container). Pass a callback function that will be called when the channel is being cleaned
up after all channel-close callbacks callbacks.
:param callback: The callback to call, having the
signature: callback(channel)
"""
self.callbacks.add(self.channel_number,
self._ON_CHANNEL_CLEANUP_CB_KEY,
callback,
one_shot=True,
only_caller=self)
_cleanup() -> None
Remove all consumers and any callbacks for the channel.
Source code in pika/channel.py
def _cleanup(self) -> None:
"""Remove all consumers and any callbacks for the channel."""
self.callbacks.process(self.channel_number,
self._ON_CHANNEL_CLEANUP_CB_KEY, self, self)
self._consumers = {}
self._cancelled = set()
self._nowait_cancelled = deque()
self._consumers_with_noack = set()
self.callbacks.cleanup(str(self.channel_number))
self._cookie = None
_cleanup_consumer_ref(consumer_tag: str) -> None
Remove any references to the consumer tag in internal structures for consumer state.
| PARAMETER | DESCRIPTION |
|---|---|
consumer_tag
|
The consumer tag to cleanup
TYPE:
|
Source code in pika/channel.py
def _cleanup_consumer_ref(self, consumer_tag: str) -> None:
"""
Remove any references to the consumer tag in internal structures for consumer state.
:param consumer_tag: The consumer tag to cleanup
"""
self._consumers_with_noack.discard(consumer_tag)
self._consumers.pop(consumer_tag, None)
self._cancelled.discard(consumer_tag)
_retain_cancelled_tag(consumer_tag: str) -> None
Retain a nowait-cancelled consumer tag, evicting the oldest once the cap is reached.
A cancelled tag stays in _cancelled (and _consumers_with_noack) so that a delivery the
broker had already dispatched when Basic.Cancel was sent is rejected rather than left
unacknowledged; see _on_deliver. A cancel that expects a Basic.CancelOk retires its own
entry in _on_cancelok, but a nowait cancel asks the broker for no reply, so nothing
retires it and the entries would otherwise accumulate for the life of the channel.
Bound them here instead. The number of deliveries that can still be in flight for a
cancelled consumer is bounded by what the broker had already dispatched, so a cap on
retained nowait-cancelled tags approximates that window: evicting in cancellation order past
_MAX_RETAINED_CANCELLED_TAGS keeps retention constant in the number of cancels. The cap
is not the true window, though, since it is measured in cancels rather than deliveries, so
once a tag is evicted its reject-and-reserve behaviour lapses: a straggling delivery for it
is logged as unexpected and left unacknowledged (see _on_deliver), and basic_consume
will accept the tag again. The default is large enough that this only occurs under extreme
nowait-cancel churn.
A tag cannot be queued twice: basic_consume refuses a tag that is still in _cancelled,
and on the nowait path only eviction takes it back out again.
| PARAMETER | DESCRIPTION |
|---|---|
consumer_tag
|
The consumer tag just cancelled with nowait
TYPE:
|
Source code in pika/channel.py
def _retain_cancelled_tag(self, consumer_tag: str) -> None:
"""
Retain a nowait-cancelled consumer tag, evicting the oldest once the cap is reached.
A cancelled tag stays in `_cancelled` (and `_consumers_with_noack`) so that a delivery the
broker had already dispatched when `Basic.Cancel` was sent is rejected rather than left
unacknowledged; see `_on_deliver`. A cancel that expects a `Basic.CancelOk` retires its own
entry in `_on_cancelok`, but a nowait cancel asks the broker for no reply, so nothing
retires it and the entries would otherwise accumulate for the life of the channel.
Bound them here instead. The number of deliveries that can still be in flight for a
cancelled consumer is bounded by what the broker had already dispatched, so a cap on
retained nowait-cancelled tags approximates that window: evicting in cancellation order past
`_MAX_RETAINED_CANCELLED_TAGS` keeps retention constant in the number of cancels. The cap
is not the true window, though, since it is measured in cancels rather than deliveries, so
once a tag is evicted its reject-and-reserve behaviour lapses: a straggling delivery for it
is logged as unexpected and left unacknowledged (see `_on_deliver`), and `basic_consume`
will accept the tag again. The default is large enough that this only occurs under extreme
nowait-cancel churn.
A tag cannot be queued twice: `basic_consume` refuses a tag that is still in `_cancelled`,
and on the nowait path only eviction takes it back out again.
:param consumer_tag: The consumer tag just cancelled with nowait
"""
self._nowait_cancelled.append(consumer_tag)
while len(self._nowait_cancelled) > self._MAX_RETAINED_CANCELLED_TAGS:
self._cleanup_consumer_ref(self._nowait_cancelled.popleft())
_get_cookie() -> Any
Used by the wrapper implementation (e.g., BlockingChannel) to retrieve the cookie that it
set via _set_cookie
| RETURNS | DESCRIPTION |
|---|---|
Any
|
opaque cookie value that was set via |
Source code in pika/channel.py
def _get_cookie(self) -> Any:
"""
Used by the wrapper implementation (e.g., `BlockingChannel`) to retrieve the cookie that it
set via `_set_cookie`
:returns: opaque cookie value that was set via `_set_cookie`
"""
return self._cookie
_handle_content_frame(frame_value: Frame) -> None
This is invoked by the connection when frames that are not registered with the CallbackManager have been found. This should only be the case when the frames are related to content delivery.
The _content_assembler will be invoked which will return the fully formed message in three parts when all of the body frames have been received.
| PARAMETER | DESCRIPTION |
|---|---|
frame_value
|
The frame to deliver
TYPE:
|
Source code in pika/channel.py
def _handle_content_frame(self, frame_value: frame.Frame) -> None:
"""
This is invoked by the connection when frames that are not registered with the
CallbackManager have been found. This should only be the case when the frames are related to
content delivery.
The _content_assembler will be invoked which will return the fully formed message in three
parts when all of the body frames have been received.
:param frame_value: The frame to deliver
"""
try:
response = self._content_assembler.process(frame_value)
except exceptions.UnexpectedFrameError:
self._on_unexpected_frame(frame_value)
return
if response:
method_index = response[0].method.INDEX
if method_index == spec.Basic.Deliver.INDEX:
self._on_deliver(*response)
elif method_index == spec.Basic.GetOk.INDEX:
self._on_getok(*response)
elif method_index == spec.Basic.Return.INDEX:
self._on_return(*response)
_on_cancel(method_frame: Method) -> None
When the broker cancels a consumer, delete it from our internal dictionary.
Reply with Basic.CancelOk if the broker advertises the accept_consumer_cancel_ok
capability.
| PARAMETER | DESCRIPTION |
|---|---|
method_frame
|
The method frame received
TYPE:
|
Source code in pika/channel.py
def _on_cancel(self, method_frame: frame.Method) -> None:
"""
When the broker cancels a consumer, delete it from our internal dictionary.
Reply with `Basic.CancelOk` if the broker advertises the `accept_consumer_cancel_ok`
capability.
:param method_frame: The method frame received
"""
consumer_tag = method_frame.method.consumer_tag
# Sent before the `_cancelled` check below, so a user-initiated cancel
# racing a broker-sent one still gets a reply. That is safe in both
# orders, which is not obvious from here. A broker advertising the
# capability answers a `Basic.CancelOk` for a tag it is not waiting on
# with `{noreply, State}`, so a late or duplicate reply is ignored
# rather than treated as a protocol error. And if this reply reaches the
# broker first, it releases the consumer without replying, leaving the
# user's in-flight `Basic.Cancel` to arrive for a tag the broker no
# longer tracks - which `cancel_consumer` answers with a `Basic.CancelOk`
# anyway ("Spec requires we ignore this situation"), so the pending RPC
# still completes instead of hanging.
if self.is_open and self.connection.accept_consumer_cancel_ok:
self._send_method(spec.Basic.CancelOk(consumer_tag=consumer_tag))
if consumer_tag in self._cancelled:
# User-initiated cancel is waiting for Cancel-ok
return
self._cleanup_consumer_ref(consumer_tag)
_on_cancelok(method_frame: Method) -> None
Called in response to a frame from the Broker when the client sends Basic.Cancel.
| PARAMETER | DESCRIPTION |
|---|---|
method_frame
|
The method frame received
TYPE:
|
Source code in pika/channel.py
def _on_cancelok(self, method_frame: frame.Method) -> None:
"""
Called in response to a frame from the Broker when the client sends Basic.Cancel.
:param method_frame: The method frame received
"""
self._cleanup_consumer_ref(method_frame.method.consumer_tag)
_transition_to_closed() -> None
Common logic for transitioning the channel to the CLOSED state:
Set state to CLOSED, dispatch callbacks registered via
Channel.add_on_close_callback(), and mop up.
Assumes that the channel is not in CLOSED state and that
self._closing_reason has been set up
Source code in pika/channel.py
def _transition_to_closed(self) -> None:
"""Common logic for transitioning the channel to the CLOSED state:
Set state to CLOSED, dispatch callbacks registered via
`Channel.add_on_close_callback()`, and mop up.
Assumes that the channel is not in CLOSED state and that
`self._closing_reason` has been set up
"""
assert not self.is_closed
assert self._closing_reason is not None
self._set_state(self.CLOSED)
try:
self.callbacks.process(self.channel_number, '_on_channel_close',
self, self, self._closing_reason)
finally:
self._cleanup()
_on_close_from_broker(method_frame: Method) -> None
Handle Channel.Close from broker.
| PARAMETER | DESCRIPTION |
|---|---|
method_frame
|
Method frame with Channel.Close method
TYPE:
|
Source code in pika/channel.py
def _on_close_from_broker(self, method_frame: frame.Method) -> None:
"""
Handle `Channel.Close` from broker.
:param method_frame: Method frame with Channel.Close method
"""
LOGGER.warning('Received remote Channel.Close (%s): %r on %s',
method_frame.method.reply_code,
method_frame.method.reply_text, self)
# Note, we should not be called when channel is already closed
assert not self.is_closed
# AMQP 0.9.1 requires CloseOk response to Channel.Close;
self._send_method(spec.Channel.CloseOk())
# Save the details, possibly overriding user-provided values if
# user-initiated close is pending (in which case they will be provided
# to user callback when CloseOk arrives).
self._closing_reason = exceptions.ChannelClosedByBroker(
method_frame.method.reply_code, method_frame.method.reply_text)
if self.is_closing:
# Since we may have already put Channel.Close on the wire, we need
# to wait for CloseOk before cleaning up to avoid a race condition
# whereby our channel number might get reused before our CloseOk
# arrives
#
# NOTE: if our Channel.Close destined for the broker was blocked by
# an earlier synchronous method, this call will drop it and perform
# a meta-close (see `_on_close_meta()` which fakes receipt of
# `Channel.CloseOk` and dispatches the `'_on_channel_close'`
# callbacks.
self._drain_blocked_methods_on_remote_close()
else:
self._transition_to_closed()
_on_close_meta(reason: Exception | None) -> None
Handle meta-close request from either a remote Channel.Close from the broker (when a pending Channel.Close method is queued for execution) or a Connection's cleanup logic after sudden connection loss. We use this opportunity to transition to CLOSED state, clean up the channel, and dispatch the on-channel-closed callbacks.
| PARAMETER | DESCRIPTION |
|---|---|
reason
|
Exception describing the reason for closing.
TYPE:
|
Source code in pika/channel.py
def _on_close_meta(self, reason: Exception | None) -> None:
"""
Handle meta-close request from either a remote Channel.Close from the broker (when a pending
Channel.Close method is queued for execution) or a Connection's cleanup logic after sudden
connection loss. We use this opportunity to transition to CLOSED state, clean up the
channel, and dispatch the on-channel-closed callbacks.
:param reason: Exception describing the reason for closing.
"""
LOGGER.debug('Handling meta-close on %s: %r', self, reason)
if not self.is_closed:
self._closing_reason = reason
self._transition_to_closed()
_on_closeok(method_frame: Method) -> None
Invoked when RabbitMQ replies to a Channel.Close method.
| PARAMETER | DESCRIPTION |
|---|---|
method_frame
|
Method frame with Channel.CloseOk method
TYPE:
|
Source code in pika/channel.py
def _on_closeok(self, method_frame: frame.Method) -> None:
"""
Invoked when RabbitMQ replies to a Channel.Close method.
:param method_frame: Method frame with Channel.CloseOk method
"""
LOGGER.info('Received %s on %s', method_frame.method, self)
self._transition_to_closed()
_on_deliver(
method_frame: Method, header_frame: Header, body: bytes
) -> None
Cope with reentrancy.
If a particular consumer is still active when another delivery appears for it, queue the deliveries up until it finally exits.
| PARAMETER | DESCRIPTION |
|---|---|
method_frame
|
The method frame received
TYPE:
|
header_frame
|
The header frame received
TYPE:
|
body
|
The body received
TYPE:
|
Source code in pika/channel.py
def _on_deliver(self, method_frame: frame.Method,
header_frame: frame.Header, body: bytes) -> None:
"""
Cope with reentrancy.
If a particular consumer is still active when another delivery appears for it, queue the
deliveries up until it finally exits.
:param method_frame: The method frame received
:param header_frame: The header frame received
:param body: The body received
"""
consumer_tag = method_frame.method.consumer_tag
if consumer_tag in self._cancelled:
if self.is_open and consumer_tag not in self._consumers_with_noack:
self.basic_reject(method_frame.method.delivery_tag)
return
if consumer_tag not in self._consumers:
LOGGER.error('Unexpected delivery: %r', method_frame)
return
self._consumers[consumer_tag](self, method_frame.method,
header_frame.properties, body)
_on_eventok(method_frame: Method) -> None
Generic events that returned ok that may have internal callbacks.
We keep a list of what we've yet to implement so that we don't silently drain events that we don't support.
| PARAMETER | DESCRIPTION |
|---|---|
method_frame
|
The method frame received
TYPE:
|
Source code in pika/channel.py
def _on_eventok(self, method_frame: frame.Method) -> None:
"""
Generic events that returned ok that may have internal callbacks.
We keep a list of what we've yet to implement so that we don't silently drain events that we
don't support.
:param method_frame: The method frame received
"""
LOGGER.debug('Discarding frame %r', method_frame)
_on_flow(_method_frame_unused: Method) -> None
Called if the server sends a Channel.Flow frame.
| PARAMETER | DESCRIPTION |
|---|---|
_method_frame_unused
|
The Channel.Flow frame
TYPE:
|
Source code in pika/channel.py
def _on_flow(self, _method_frame_unused: frame.Method) -> None:
"""
Called if the server sends a Channel.Flow frame.
:param _method_frame_unused: The Channel.Flow frame
"""
if self._has_on_flow_callback is False:
LOGGER.warning('Channel.Flow received from server')
_on_flowok(method_frame: Method) -> None
Called in response to us asking the server to toggle on Channel.Flow.
| PARAMETER | DESCRIPTION |
|---|---|
method_frame
|
The method frame received
TYPE:
|
Source code in pika/channel.py
def _on_flowok(self, method_frame: frame.Method) -> None:
"""
Called in response to us asking the server to toggle on Channel.Flow.
:param method_frame: The method frame received
"""
self.flow_active = method_frame.method.active
if self._on_flowok_callback:
self._on_flowok_callback(method_frame.method.active)
self._on_flowok_callback = None
else:
LOGGER.warning('Channel.FlowOk received with no active callbacks')
_on_getempty(method_frame: Method) -> None
When we receive an empty reply do nothing but log it.
| PARAMETER | DESCRIPTION |
|---|---|
method_frame
|
The method frame received
TYPE:
|
Source code in pika/channel.py
def _on_getempty(self, method_frame: frame.Method) -> None:
"""
When we receive an empty reply do nothing but log it.
:param method_frame: The method frame received
"""
LOGGER.debug('Received Basic.GetEmpty: %r', method_frame)
if self._on_getok_callback is not None:
self._on_getok_callback = None
_on_getok(
method_frame: Method, header_frame: Header, body: bytes
) -> None
Called in reply to a Basic.Get when there is a message.
| PARAMETER | DESCRIPTION |
|---|---|
method_frame
|
The method frame received
TYPE:
|
header_frame
|
The header frame received
TYPE:
|
body
|
The body received
TYPE:
|
Source code in pika/channel.py
def _on_getok(self, method_frame: frame.Method, header_frame: frame.Header,
body: bytes) -> None:
"""
Called in reply to a Basic.Get when there is a message.
:param method_frame: The method frame received
:param header_frame: The header frame received
:param body: The body received
"""
if self._on_getok_callback is not None:
callback = self._on_getok_callback
self._on_getok_callback = None
callback(self, method_frame.method, header_frame.properties, body)
else:
LOGGER.error('Basic.GetOk received with no active callback')
_on_openok(method_frame: Method) -> None
Called by our callback handler when we receive a Channel.OpenOk and subsequently calls our _on_openok_callback which was passed into the Channel constructor. The reason we do this is because we want to make sure that the on_open_callback parameter passed into the Channel constructor is not the first callback we make.
Suppress the state transition and callback if channel is already in CLOSING state.
| PARAMETER | DESCRIPTION |
|---|---|
method_frame
|
Channel.OpenOk frame
TYPE:
|
Source code in pika/channel.py
def _on_openok(self, method_frame: frame.Method) -> None:
"""
Called by our callback handler when we receive a Channel.OpenOk and subsequently calls our
_on_openok_callback which was passed into the Channel constructor. The reason we do this is
because we want to make sure that the on_open_callback parameter passed into the Channel
constructor is not the first callback we make.
Suppress the state transition and callback if channel is already in CLOSING state.
:param method_frame: Channel.OpenOk frame
"""
# Suppress OpenOk if the user or Connection.Close started closing it
# before open completed.
if self.is_closing:
LOGGER.debug('Suppressing while in closing state: %s', method_frame)
else:
self._set_state(self.OPEN)
if self._on_openok_callback is not None:
self._on_openok_callback(self)
_on_return(
method_frame: Method, header_frame: Header, body: bytes
) -> None
Called if the server sends a Basic.Return frame.
| PARAMETER | DESCRIPTION |
|---|---|
method_frame
|
The Basic.Return frame
TYPE:
|
header_frame
|
The content header frame
TYPE:
|
body
|
The message body
TYPE:
|
Source code in pika/channel.py
def _on_return(self, method_frame: frame.Method, header_frame: frame.Header,
body: bytes) -> None:
"""
Called if the server sends a Basic.Return frame.
:param method_frame: The Basic.Return frame
:param header_frame: The content header frame
:param body: The message body
"""
if not self.callbacks.process(self.channel_number, '_on_return', self,
self, method_frame.method,
header_frame.properties, body):
LOGGER.debug('Basic.Return received from server (%r, %r)',
method_frame.method, header_frame.properties)
_on_selectok(method_frame: Method) -> None
Called when the broker sends a Confirm.SelectOk frame.
| PARAMETER | DESCRIPTION |
|---|---|
method_frame
|
The method frame received
TYPE:
|
Source code in pika/channel.py
def _on_selectok(self, method_frame: frame.Method) -> None:
"""
Called when the broker sends a Confirm.SelectOk frame.
:param method_frame: The method frame received
"""
LOGGER.debug('Confirm.SelectOk Received: %r', method_frame)
_on_synchronous_complete(
_method_frame_unused: Method,
) -> None
This is called when a synchronous command is completed.
It will undo the blocking state and send all the frames that stacked up while we were in the blocking state.
| PARAMETER | DESCRIPTION |
|---|---|
_method_frame_unused
|
The method frame received
TYPE:
|
Source code in pika/channel.py
def _on_synchronous_complete(self,
_method_frame_unused: frame.Method) -> None:
"""
This is called when a synchronous command is completed.
It will undo the blocking state and send all the frames that stacked up while we were in the
blocking state.
:param _method_frame_unused: The method frame received
"""
LOGGER.debug('%i blocked frames', len(self._blocked))
self._blocking = None
# self._blocking must be checked here as a callback could
# potentially change the state of that variable during an
# iteration of the while loop
while self._blocked and self._blocking is None:
self._rpc(*self._blocked.popleft())
_drain_blocked_methods_on_remote_close() -> None
This is called when the broker sends a Channel.Close while the client is in CLOSING state. This method checks the blocked method queue for a pending client-initiated Channel.Close method and ensures its callbacks are processed, but does not send the method to the broker.
The broker may close the channel before responding to outstanding in-transit synchronous methods, or even before these methods have been sent to the broker. AMQP 0.9.1 obliges the server to drop all methods arriving on a closed channel other than Channel.CloseOk and Channel.Close. Since the response to a synchronous method that blocked the channel never arrives, the channel never becomes unblocked, and the Channel.Close, if any, in the blocked queue has no opportunity to be sent, and thus its completion callback would never be called.
Source code in pika/channel.py
def _drain_blocked_methods_on_remote_close(self) -> None:
"""
This is called when the broker sends a Channel.Close while the client is in CLOSING state.
This method checks the blocked method queue for a pending client-initiated Channel.Close
method and ensures its callbacks are processed, but does not send the method to the broker.
The broker may close the channel before responding to outstanding in-transit synchronous
methods, or even before these methods have been sent to the broker. AMQP 0.9.1 obliges the
server to drop all methods arriving on a closed channel other than Channel.CloseOk and
Channel.Close. Since the response to a synchronous method that blocked the channel never
arrives, the channel never becomes unblocked, and the Channel.Close, if any, in the blocked
queue has no opportunity to be sent, and thus its completion callback would never be called.
"""
LOGGER.debug(
'Draining %i blocked frames due to broker-requested Channel.Close',
len(self._blocked))
while self._blocked:
method = self._blocked.popleft()[0]
if isinstance(method, spec.Channel.Close):
# The desired reason is already in self._closing_reason
self._on_close_meta(self._closing_reason)
else:
LOGGER.debug('Ignoring drained blocked method: %s', method)
_rpc(
method: Method,
callback: Callable[..., Any] | None = None,
acceptable_replies: Sequence[
type[Method] | tuple[type[Method], dict[str, Any]]
]
| None = None,
) -> None
Make a synchronous channel RPC call for a synchronous method frame.
If the channel is already in the blocking state, then enqueue the request,
but don't send it at this time; it will be eventually sent by
_on_synchronous_complete after the prior blocking request receives a
response. If the channel is not in the blocking state and
acceptable_replies is not empty, transition the channel to the
blocking state and register for _on_synchronous_complete before
sending the request.
NOTE: A callback must be accompanied by non-empty acceptable_replies.
| PARAMETER | DESCRIPTION |
|---|---|
method
|
The AMQP method to invoke
TYPE:
|
callback
|
The callback for the RPC response
TYPE:
|
acceptable_replies
|
A (possibly empty) sequence of replies this RPC call expects or None
TYPE:
|
Source code in pika/channel.py
def _rpc(
self,
method: amqp_object.Method,
callback: Callable[..., Any] | None = None,
acceptable_replies: Sequence[type[amqp_object.Method] |
tuple[type[amqp_object.Method],
dict[str, Any]]] | None = None
) -> None:
"""
Make a synchronous channel RPC call for a synchronous method frame.
If the channel is already in the blocking state, then enqueue the request,
but don't send it at this time; it will be eventually sent by
`_on_synchronous_complete` after the prior blocking request receives a
response. If the channel is not in the blocking state and
`acceptable_replies` is not empty, transition the channel to the
blocking state and register for `_on_synchronous_complete` before
sending the request.
NOTE: A callback must be accompanied by non-empty acceptable_replies.
:param method: The AMQP method to invoke
:param callback: The callback for the RPC response
:param acceptable_replies: A (possibly empty) sequence of
replies this RPC call expects or None
"""
assert method.synchronous, (
f'Only synchronous-capable methods may be used with _rpc: {method!r}'
)
# Validate we got None or a list of acceptable_replies
if not isinstance(acceptable_replies, (type(None), list)):
raise TypeError('acceptable_replies should be list or None')
if callback is not None:
# Validate the callback is callable
if not callable(callback):
raise TypeError('callback should be None or a callable')
# Make sure that callback is accompanied by acceptable replies
if not acceptable_replies:
raise ValueError(
'Unexpected callback for asynchronous (nowait) operation.')
# Make sure the channel is not closed yet
if self.is_closed:
self._raise_if_not_open()
# If the channel is blocking, add subsequent commands to our stack
if self._blocking:
LOGGER.debug(
'Already in blocking state, so enqueueing method %s; '
'acceptable_replies=%r', method, acceptable_replies)
self._blocked.append([method, callback, acceptable_replies])
return
# Note: _send_method can throw exceptions if there are framing errors
# or invalid data passed in. Call it here to prevent self._blocking
# from being set if an exception is thrown. This also prevents
# acceptable_replies registering callbacks when exceptions are thrown
self._send_method(method)
# If acceptable replies are set, add callbacks
if acceptable_replies:
# Block until a response frame is received for synchronous frames
self._blocking = method.NAME
LOGGER.debug(
'Entering blocking state on frame %s; acceptable_replies=%r',
method, acceptable_replies)
for reply in acceptable_replies:
if isinstance(reply, tuple):
reply, arguments = reply
else:
arguments = None
LOGGER.debug('Adding on_synchronous_complete callback')
self.callbacks.add(self.channel_number,
reply,
self._on_synchronous_complete,
arguments=arguments)
if callback is not None:
LOGGER.debug('Adding passed-in RPC response callback')
self.callbacks.add(self.channel_number,
reply,
callback,
arguments=arguments)
_raise_if_not_open() -> None
If channel is not in the OPEN state, raises ChannelWrongStateError with reply_code and
reply_text corresponding to current state.
| RAISES | DESCRIPTION |
|---|---|
exceptions.ChannelWrongStateError
|
if channel is not in OPEN state. |
Source code in pika/channel.py
def _raise_if_not_open(self) -> None:
"""
If channel is not in the OPEN state, raises ChannelWrongStateError with `reply_code` and
`reply_text` corresponding to current state.
:raises exceptions.ChannelWrongStateError: if channel is not in OPEN state.
"""
if self._state == self.OPEN:
return
if self._state == self.OPENING:
raise exceptions.ChannelWrongStateError(
'Channel is opening, but is not usable yet.')
if self._state == self.CLOSING:
raise exceptions.ChannelWrongStateError('Channel is closing.')
# Assumed self.CLOSED
assert self._state == self.CLOSED
raise exceptions.ChannelWrongStateError('Channel is closed.')
_send_method(
method: Method,
content: tuple[BasicProperties, bytes] | None = None,
) -> None
Shortcut wrapper to send a method through our connection, passing in the channel number.
| PARAMETER | DESCRIPTION |
|---|---|
method
|
The method to send
TYPE:
|
content
|
If set, is a content frame, is tuple of properties and body.
TYPE:
|
Source code in pika/channel.py
def _send_method(
self,
method: amqp_object.Method,
content: tuple[spec.BasicProperties, bytes] | None = None) -> None:
"""
Shortcut wrapper to send a method through our connection, passing in the channel number.
:param method: The method to send
:param content: If set, is a content frame, is tuple of properties and body.
"""
self.connection._send_method(self.channel_number, method, content)
_set_cookie(cookie: object) -> None
Used by wrapper layer (e.g., BlockingConnection) to link the channel implementation back
to the proxy. See _get_cookie.
| PARAMETER | DESCRIPTION |
|---|---|
cookie
|
an opaque value; typically a proxy channel implementation instance (e.g.,
TYPE:
|
Source code in pika/channel.py
def _set_cookie(self, cookie: object) -> None:
"""
Used by wrapper layer (e.g., `BlockingConnection`) to link the channel implementation back
to the proxy. See `_get_cookie`.
:param cookie: an opaque value; typically a proxy channel implementation instance (e.g.,
`BlockingChannel` instance)
"""
self._cookie = cookie
_set_state(connection_state: int) -> None
Set the channel connection state to the specified state value.
| PARAMETER | DESCRIPTION |
|---|---|
connection_state
|
The connection_state value
TYPE:
|
Source code in pika/channel.py
def _set_state(self, connection_state: int) -> None:
"""
Set the channel connection state to the specified state value.
:param connection_state: The connection_state value
"""
self._state = connection_state
_on_unexpected_frame(frame_value: Frame) -> None
Invoked when a frame is received that is not setup to be processed.
| PARAMETER | DESCRIPTION |
|---|---|
frame_value
|
The frame received
TYPE:
|
Source code in pika/channel.py
def _on_unexpected_frame(self, frame_value: frame.Frame) -> None:
"""
Invoked when a frame is received that is not setup to be processed.
:param frame_value: The frame received
"""
LOGGER.error('Unexpected frame: %r', frame_value)