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"""Use pika with the Asyncio EventLoop"""
import asyncio
import logging
import sys
from pika.adapters import base_connection
from pika.adapters.utils import nbio_interface, io_services_utils
LOGGER = logging.getLogger(__name__)
if sys.platform == 'win32':
asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
class AsyncioConnection(base_connection.BaseConnection):
""" The AsyncioConnection runs on the Asyncio EventLoop.
"""
def __init__(self,
parameters=None,
on_open_callback=None,
on_open_error_callback=None,
on_close_callback=None,
custom_ioloop=None,
internal_connection_workflow=True):
""" Create a new instance of the AsyncioConnection class, connecting
to RabbitMQ automatically
:param pika.connection.Parameters parameters: Connection parameters
:param callable on_open_callback: The method to call when the connection
is open
:param None | method on_open_error_callback: Called if the connection
can't be established or connection establishment is interrupted by
`Connection.close()`: on_open_error_callback(Connection, exception).
:param None | method on_close_callback: Called when a previously fully
open connection is closed:
`on_close_callback(Connection, exception)`, where `exception` is
either an instance of `exceptions.ConnectionClosed` if closed by
user or broker or exception of another type that describes the cause
of connection failure.
:param None | asyncio.AbstractEventLoop |
nbio_interface.AbstractIOServices custom_ioloop:
Defaults to asyncio.get_event_loop().
:param bool internal_connection_workflow: True for autonomous connection
establishment which is default; False for externally-managed
connection workflow via the `create_connection()` factory.
"""
if isinstance(custom_ioloop, nbio_interface.AbstractIOServices):
nbio = custom_ioloop
else:
nbio = _AsyncioIOServicesAdapter(custom_ioloop)
super().__init__(
parameters,
on_open_callback,
on_open_error_callback,
on_close_callback,
nbio,
internal_connection_workflow=internal_connection_workflow)
@classmethod
def create_connection(cls,
connection_configs,
on_done,
custom_ioloop=None,
workflow=None):
"""Implement
:py:classmethod::`pika.adapters.BaseConnection.create_connection()`.
"""
nbio = _AsyncioIOServicesAdapter(custom_ioloop)
def connection_factory(params):
"""Connection factory."""
if params is None:
raise ValueError('Expected pika.connection.Parameters '
'instance, but got None in params arg.')
return cls(
parameters=params,
custom_ioloop=nbio,
internal_connection_workflow=False)
return cls._start_connection_workflow(
connection_configs=connection_configs,
connection_factory=connection_factory,
nbio=nbio,
workflow=workflow,
on_done=on_done)
class _AsyncioIOServicesAdapter(io_services_utils.SocketConnectionMixin,
io_services_utils.StreamingConnectionMixin,
nbio_interface.AbstractIOServices,
nbio_interface.AbstractFileDescriptorServices):
"""Implements
:py:class:`.utils.nbio_interface.AbstractIOServices` interface
on top of `asyncio`.
NOTE:
:py:class:`.utils.nbio_interface.AbstractFileDescriptorServices`
interface is only required by the mixins.
"""
def __init__(self, loop=None):
"""
:param asyncio.AbstractEventLoop | None loop: If None, gets default
event loop from asyncio.
"""
self._loop = loop or asyncio.get_event_loop()
def get_native_ioloop(self):
"""Implement
:py:meth:`.utils.nbio_interface.AbstractIOServices.get_native_ioloop()`.
"""
return self._loop
def close(self):
"""Implement
:py:meth:`.utils.nbio_interface.AbstractIOServices.close()`.
"""
self._loop.close()
def run(self):
"""Implement :py:meth:`.utils.nbio_interface.AbstractIOServices.run()`.
"""
self._loop.run_forever()
def stop(self):
"""Implement :py:meth:`.utils.nbio_interface.AbstractIOServices.stop()`.
"""
self._loop.stop()
def add_callback_threadsafe(self, callback):
"""Implement
:py:meth:`.utils.nbio_interface.AbstractIOServices.add_callback_threadsafe()`.
"""
self._loop.call_soon_threadsafe(callback)
def call_later(self, delay, callback):
"""Implement
:py:meth:`.utils.nbio_interface.AbstractIOServices.call_later()`.
"""
return _TimerHandle(self._loop.call_later(delay, callback))
def getaddrinfo(self,
host,
port,
on_done,
family=0,
socktype=0,
proto=0,
flags=0):
"""Implement
:py:meth:`.utils.nbio_interface.AbstractIOServices.getaddrinfo()`.
"""
return self._schedule_and_wrap_in_io_ref(
self._loop.getaddrinfo(
host,
port,
family=family,
type=socktype,
proto=proto,
flags=flags), on_done)
def set_reader(self, fd, on_readable):
"""Implement
:py:meth:`.utils.nbio_interface.AbstractFileDescriptorServices.set_reader()`.
"""
self._loop.add_reader(fd, on_readable)
LOGGER.debug('set_reader(%s, _)', fd)
def remove_reader(self, fd):
"""Implement
:py:meth:`.utils.nbio_interface.AbstractFileDescriptorServices.remove_reader()`.
"""
LOGGER.debug('remove_reader(%s)', fd)
return self._loop.remove_reader(fd)
def set_writer(self, fd, on_writable):
"""Implement
:py:meth:`.utils.nbio_interface.AbstractFileDescriptorServices.set_writer()`.
"""
self._loop.add_writer(fd, on_writable)
LOGGER.debug('set_writer(%s, _)', fd)
def remove_writer(self, fd):
"""Implement
:py:meth:`.utils.nbio_interface.AbstractFileDescriptorServices.remove_writer()`.
"""
LOGGER.debug('remove_writer(%s)', fd)
return self._loop.remove_writer(fd)
def _schedule_and_wrap_in_io_ref(self, coro, on_done):
"""Schedule the coroutine to run and return _AsyncioIOReference
:param coroutine-obj coro:
:param callable on_done: user callback that takes the completion result
or exception as its only arg. It will not be called if the operation
was cancelled.
:rtype: _AsyncioIOReference which is derived from
nbio_interface.AbstractIOReference
"""
if not callable(on_done):
raise TypeError(
'on_done arg must be callable, but got {!r}'.format(on_done))
return _AsyncioIOReference(
asyncio.ensure_future(coro, loop=self._loop), on_done)
class _TimerHandle(nbio_interface.AbstractTimerReference):
"""This module's adaptation of `nbio_interface.AbstractTimerReference`.
"""
def __init__(self, handle):
"""
:param asyncio.Handle handle:
"""
self._handle = handle
def cancel(self):
if self._handle is not None:
self._handle.cancel()
self._handle = None
class _AsyncioIOReference(nbio_interface.AbstractIOReference):
"""This module's adaptation of `nbio_interface.AbstractIOReference`.
"""
def __init__(self, future, on_done):
"""
:param asyncio.Future future:
:param callable on_done: user callback that takes the completion result
or exception as its only arg. It will not be called if the operation
was cancelled.
"""
if not callable(on_done):
raise TypeError(
'on_done arg must be callable, but got {!r}'.format(on_done))
self._future = future
def on_done_adapter(future):
"""Handle completion callback from the future instance"""
# NOTE: Asyncio schedules callback for cancelled futures, but pika
# doesn't want that
if not future.cancelled():
on_done(future.exception() or future.result())
future.add_done_callback(on_done_adapter)
def cancel(self):
"""Cancel pending operation
:returns: False if was already done or cancelled; True otherwise
:rtype: bool
"""
return self._future.cancel()
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