我使用 basic_consume() 接收消息和 basic_cancel 取消消费，但有一个问题。
这是 pika.channel 的代码
def basic_consume(self, consumer_callback, queue='', no_ack=False,
exclusive=False, consumer_tag=None):
"""Sends the AMQP command Basic.Consume to the broker and binds messages
for the consumer_tag to the consumer callback. If you do not pass in
a consumer_tag, one will be automatically generated for you. Returns
the consumer tag.
For more information on basic_consume, see:
http://www.rabbitmq.com/amqp-0-9-1-reference.html#basic.consume
:param method consumer_callback: The method to callback when consuming
:param queue: The queue to consume from
:type queue: str or unicode
:param bool no_ack: Tell the broker to not expect a response
:param bool exclusive: Don't allow other consumers on the queue
:param consumer_tag: Specify your own consumer tag
:type consumer_tag: str or unicode
:rtype: str
"""
self._validate_channel_and_callback(consumer_callback)
# If a consumer tag was not passed, create one
consumer_tag = consumer_tag or 'ctag%i.%s' % (self.channel_number,
uuid.uuid4().get_hex())
if consumer_tag in self._consumers or consumer_tag in self._cancelled:
raise exceptions.DuplicateConsumerTag(consumer_tag)
self._consumers[consumer_tag] = consumer_callback
self._pending[consumer_tag] = list()
self._rpc(spec.Basic.Consume(queue=queue,
consumer_tag=consumer_tag,
no_ack=no_ack,
exclusive=exclusive),
self._on_eventok,
[(spec.Basic.ConsumeOk,
{'consumer_tag': consumer_tag})])
return consumer_tag
def basic_cancel(self, callback=None, consumer_tag='', nowait=False):
"""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.
:param method callback: Method to call for a Basic.CancelOk response
:param str consumer_tag: Identifier for the consumer
:param bool nowait: Do not expect a Basic.CancelOk response
:raises: ValueError
"""
self._validate_channel_and_callback(callback)
if consumer_tag not in self.consumer_tags:
return
if callback:
if nowait is True:
raise ValueError('Can not pass a callback if nowait is True')
self.callbacks.add(self.channel_number,
spec.Basic.CancelOk,
callback)
self._cancelled.append(consumer_tag)
self._rpc(spec.Basic.Cancel(consumer_tag=consumer_tag,
nowait=nowait),
self._on_cancelok,
[(spec.Basic.CancelOk,
{'consumer_tag': consumer_tag})] if nowait is False else [])
正如您所看到的，每次我取消消费时都会将 consumer_tag 添加到 _canceled 列表中。如果我再次在 basic_consume 中使用这个标签，就会引发 duplicateConsumer 异常。好吧，我每次都可以使用一个新的 consumer_tag，但实际上我不是。因为迟早生成的标签将与之前的一些标签完全匹配。
我应该如何在 pika 中优雅地暂停和恢复消费？