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queue.py
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queue.py
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import asyncio
from collections import namedtuple
from functools import partial
from logging import getLogger
from typing import Optional, Callable, Any
import aiormq
from aiormq.types import DeliveredMessage
from .exceptions import QueueEmpty
from .exchange import Exchange
from .types import ExchangeType as ExchangeType_
from .message import IncomingMessage
from .tools import create_task, shield
log = getLogger(__name__)
ConsumerTag = str
DeclarationResult = namedtuple(
'DeclarationResult', ('message_count', 'consumer_count')
)
async def consumer(callback, msg: DeliveredMessage, *, no_ack, loop):
message = IncomingMessage(msg, no_ack=no_ack)
return await create_task(callback, message, loop=loop)
class Queue:
""" AMQP queue abstraction """
def __init__(self, connection, channel: aiormq.Channel, name,
durable, exclusive, auto_delete, arguments,
passive: bool = False):
self.loop = connection.loop
self._channel = channel
self.name = name or ''
self.durable = durable
self.exclusive = exclusive
self.auto_delete = auto_delete
self.arguments = arguments
self.passive = passive
self.declaration_result = None # type: aiormq.spec.Queue.DeclareOk
self._get_lock = asyncio.Lock()
@property
def channel(self) -> aiormq.Channel:
if self._channel is None:
raise RuntimeError("Channel not opened")
return self._channel
def __str__(self):
return "%s" % self.name
def __repr__(self):
return (
"<Queue(%s): "
"auto_delete=%s, "
"durable=%s, "
"exclusive=%s, "
"arguments=%r>"
) % (
self,
self.auto_delete,
self.durable,
self.exclusive,
self.arguments,
)
async def declare(self, timeout: int=None) -> aiormq.spec.Queue.DeclareOk:
""" Declare queue.
:param timeout: execution timeout
:param passive: Only check to see if the queue exists.
:return: :class:`None`
"""
log.debug("Declaring queue: %r", self)
self.declaration_result = await asyncio.wait_for(
self._channel.queue_declare(
queue=self.name, durable=self.durable,
exclusive=self.exclusive, auto_delete=self.auto_delete,
arguments=self.arguments, passive=self.passive,
), timeout=timeout
) # type: aiormq.spec.Queue.DeclareOk
self.name = self.declaration_result.queue
return self.declaration_result
async def bind(
self, exchange: ExchangeType_, routing_key: str=None, *,
arguments=None, timeout: int=None
) -> aiormq.spec.Queue.BindOk:
""" A binding is a relationship between an exchange and a queue.
This can be simply read as: the queue is interested in messages
from this exchange.
Bindings can take an extra routing_key parameter. To avoid
the confusion with a basic_publish parameter we're going to
call it a binding key.
:param exchange: :class:`aio_pika.exchange.Exchange` instance
:param routing_key: routing key
:param arguments: additional arguments
:param timeout: execution timeout
:raises asyncio.TimeoutError:
when the binding timeout period has elapsed.
:return: :class:`None`
"""
if routing_key is None:
routing_key = self.name
log.debug(
"Binding queue %r: exchange=%r, routing_key=%r, arguments=%r",
self, exchange, routing_key, arguments
)
return await asyncio.wait_for(
self.channel.queue_bind(
self.name,
exchange=Exchange._get_exchange_name(exchange),
routing_key=routing_key,
arguments=arguments
), timeout=timeout
)
async def unbind(
self, exchange: ExchangeType_, routing_key: str=None,
arguments: dict=None, timeout: int=None
) -> aiormq.spec.Queue.UnbindOk:
""" Remove binding from exchange for this :class:`Queue` instance
:param exchange: :class:`aio_pika.exchange.Exchange` instance
:param routing_key: routing key
:param arguments: additional arguments
:param timeout: execution timeout
:raises asyncio.TimeoutError:
when the unbinding timeout period has elapsed.
:return: :class:`None`
"""
if routing_key is None:
routing_key = self.name
log.debug(
"Unbinding queue %r: exchange=%r, routing_key=%r, arguments=%r",
self, exchange, routing_key, arguments
)
return await asyncio.wait_for(
self.channel.queue_unbind(
queue=self.name,
exchange=Exchange._get_exchange_name(exchange),
routing_key=routing_key,
arguments=arguments
), timeout=timeout
)
async def consume(
self, callback: Callable[[IncomingMessage], Any], no_ack: bool = False,
exclusive: bool = False, arguments: dict = None,
consumer_tag=None, timeout=None
) -> ConsumerTag:
""" Start to consuming the :class:`Queue`.
:param timeout: :class:`asyncio.TimeoutError` will be raises when the
Future was not finished after this time.
:param callback: Consuming callback. Could be a coroutine.
:param no_ack:
if :class:`True` you don't need to call
:func:`aio_pika.message.IncomingMessage.ack`
:param exclusive:
Makes this queue exclusive. Exclusive queues may only
be accessed by the current connection, and are deleted
when that connection closes. Passive declaration of an
exclusive queue by other connections are not allowed.
:param arguments: additional arguments
:param consumer_tag: optional consumer tag
:raises asyncio.TimeoutError:
when the consuming timeout period has elapsed.
:return str: consumer tag :class:`str`
"""
log.debug("Start to consuming queue: %r", self)
return (await asyncio.wait_for(
self.channel.basic_consume(
queue=self.name,
consumer_callback=partial(
consumer, callback, no_ack=no_ack, loop=self.loop
),
exclusive=exclusive,
no_ack=no_ack,
arguments=arguments,
consumer_tag=consumer_tag,
),
timeout=timeout
)).consumer_tag
async def cancel(self, consumer_tag: ConsumerTag, timeout=None,
nowait: bool=False) -> aiormq.spec.Basic.CancelOk:
""" 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 consumer_tag:
consumer tag returned by :func:`~aio_pika.Queue.consume`
:param timeout: execution timeout
:param bool nowait: Do not expect a Basic.CancelOk response
:return: Basic.CancelOk when operation completed successfully
"""
return await asyncio.wait_for(
self.channel.basic_cancel(
consumer_tag=consumer_tag,
nowait=nowait
),
timeout=timeout
)
async def get(
self, *, no_ack=False, fail=True, timeout=5
) -> Optional[IncomingMessage]:
""" Get message from the queue.
:param no_ack: if :class:`True` you don't need to call
:func:`aio_pika.message.IncomingMessage.ack`
:param timeout: execution timeout
:param fail: Should return :class:`None` instead of raise an
exception :class:`aio_pika.exceptions.QueueEmpty`.
:return: :class:`aio_pika.message.IncomingMessage`
"""
msg = await asyncio.wait_for(self.channel.basic_get(
self.name, no_ack=no_ack
), timeout=timeout
) # type: Optional[DeliveredMessage]
if msg is None:
if fail:
raise QueueEmpty
return
return IncomingMessage(msg, no_ack=no_ack)
async def purge(
self, no_wait=False, timeout=None
) -> aiormq.spec.Queue.PurgeOk:
""" Purge all messages from the queue.
:param no_wait: no wait response
:param timeout: execution timeout
:return: :class:`None`
"""
log.info("Purging queue: %r", self)
return await asyncio.wait_for(
self.channel.queue_purge(
self.name,
nowait=no_wait,
), timeout=timeout
)
async def delete(self, *, if_unused=True, if_empty=True,
timeout=None) -> aiormq.spec.Queue.DeclareOk:
""" Delete the queue.
:param if_unused: Perform delete only when unused
:param if_empty: Perform delete only when empty
:param timeout: execution timeout
:return: :class:`None`
"""
log.info("Deleting %r", self)
return await asyncio.wait_for(
self.channel.queue_delete(
self.name, if_unused=if_unused, if_empty=if_empty
), timeout=timeout
)
def __aiter__(self) -> 'QueueIterator':
return self.iterator()
def iterator(self, **kwargs) -> 'QueueIterator':
""" Returns an iterator for async for expression.
Full example:
.. code-block:: python
import aio_pika
async def main():
connection = await aio_pika.connect()
async with connection:
channel = await connection.channel()
queue = await channel.declare_queue('test')
async with queue.iterator() as q:
async for message in q:
print(message.body)
When your program runs with run_forever the iterator will be closed
in background. In this case the context processor for iterator might
be skipped and the queue might be used in the "async for"
expression directly.
.. code-block:: python
import aio_pika
async def main():
connection = await aio_pika.connect()
async with connection:
channel = await connection.channel()
queue = await channel.declare_queue('test')
async for message in queue:
print(message.body)
:return: QueueIterator
"""
return QueueIterator(self, **kwargs)
class QueueIterator:
@shield
async def close(self):
if not self._consumer_tag:
return
await self._amqp_queue.cancel(self._consumer_tag)
self._consumer_tag = None
def get_msg():
try:
return self._queue.get_nowait()
except asyncio.QueueEmpty:
return
# Reject all messages
msg = get_msg() # type: IncomingMessage
while msg and not self._amqp_queue.channel.closing.done():
await msg.reject(requeue=True)
msg = get_msg() # type: IncomingMessage
def __str__(self):
return 'queue[%s](...)' % self._amqp_queue.name
def __init__(self, queue: Queue, **kwargs):
self.loop = queue.loop
self._amqp_queue = queue
self._queue = asyncio.Queue()
self._consumer_tag = None
self._consume_kwargs = kwargs
async def on_message(self, message: IncomingMessage):
await self._queue.put(message)
async def consume(self):
self._consumer_tag = await self._amqp_queue.consume(
self.on_message,
**self._consume_kwargs
)
def __aiter__(self):
return self
@shield
async def __aenter__(self):
if self._consumer_tag is None:
await self.consume()
return self
async def __aexit__(self, exc_type, exc_val, exc_tb):
await self.close()
async def __anext__(self) -> IncomingMessage:
if not self._consumer_tag:
await self.consume()
try:
return await self._queue.get()
except asyncio.CancelledError:
await self.close()
raise
__all__ = 'Queue', 'QueueIterator', 'DeclarationResult', 'ConsumerTag'