import asyncio
from functools import wraps
from logging import getLogger
from typing import Callable, Generator, Any
import pika.channel
from pika.exceptions import ChannelClosed
from .adapter import AsyncioConnection
from .exceptions import ProbableAuthenticationError
from .connection import Connection, connect
from .robust_channel import RobustChannel
log = getLogger(__name__)
def _ensure_connection(func):
@wraps(func)
def wrap(self, *args, **kwargs):
if self.is_closed:
raise RuntimeError("Connection closed")
return func(self, *args, **kwargs)
return wrap
class RobustConnection(Connection):
""" Robust connection """
DEFAULT_RECONNECT_INTERVAL = 1
CHANNEL_CLASS = RobustChannel
def __init__(self, host: str = 'localhost', port: int=5672, login: str = 'guest',
password: str = 'guest', virtual_host: str = '/',
ssl: bool=False, *, loop=None, **kwargs):
self.reconnect_interval = kwargs.pop('reconnect_interval',
self.DEFAULT_RECONNECT_INTERVAL)
super().__init__(host=host, port=port, login=login, password=password,
virtual_host=virtual_host, ssl=ssl, loop=loop, **kwargs)
self._closed = False
self._on_connection_lost_callbacks = []
self._on_reconnect_callbacks = []
self._on_close_callbacks = []
def add_connection_lost_callback(self, callback: Callable[[], None]):
""" Add callback which will be called after connection was lost.
:return: None
"""
self._on_connection_lost_callbacks.append(lambda c: callback(c))
def add_reconnect_callback(self, callback: Callable[[], None]):
""" Add callback which will be called after reconnect.
:return: None
"""
self._on_reconnect_callbacks.append(lambda c: callback(c))
def add_close_callback(self, callback: Callable[[], None]):
""" Add callback which will be called after connection will be closed.
:return: None
"""
self._on_close_callbacks.append(lambda c: callback(c))
def _on_connection_lost(self, future: asyncio.Future, connection: AsyncioConnection, code, reason):
for callback in self._on_connection_lost_callbacks:
callback(self)
if self._closed:
return super()._on_connection_lost(future, connection, code, reason)
if isinstance(reason, ProbableAuthenticationError):
log.error("Authentication error: %d - %s", code, reason)
if isinstance(reason, ConnectionRefusedError):
log.error("Connection refused: %d - %s", code, reason)
if not future.done():
future.set_result(None)
self.loop.call_later(
self.reconnect_interval,
lambda: self.loop.create_task(self.connect())
)
def _channel_cleanup(self, channel: pika.channel.Channel):
ch = self._channels[channel.channel_number] # type: RobustChannel
ch._futures.reject_all(ChannelClosed)
if ch._closed:
self._channels.pop(channel.channel_number) # type: RobustChannel
def _on_channel_error(self, channel: pika.channel.Channel):
log.error("Channel closed: %s. Will attempt to reconnect", channel)
channel.connection.close(reply_code=500, reply_text="Channel canceled")
def _on_channel_cancel(self, channel: pika.channel.Channel):
log.debug("Channel canceled: %s", channel)
self._on_channel_error(channel)
@asyncio.coroutine
def connect(self):
result = yield from super().connect()
while self._connection is None:
yield from asyncio.sleep(self.reconnect_interval, loop=self.loop)
result = yield from super().connect()
for number, channel in tuple(self._channels.items()):
try:
yield from channel.on_reconnect(self, number)
except ChannelClosed:
self._on_channel_error(channel._channel)
return
for callback in self._on_reconnect_callbacks:
callback(self)
return result
@property
def is_closed(self):
""" Is this connection is closed """
return self._closed or super().is_closed
def close(self) -> asyncio.Task:
""" Close AMQP connection """
self._closed = True
try:
for callback in self._on_close_callbacks:
callback(self)
finally:
return super().close()
[docs]@asyncio.coroutine
def connect_robust(url: str=None, *, host: str='localhost',
port: int=5672, login: str='guest',
password: str='guest', virtualhost: str='/',
ssl: bool=False, loop=None,
connection_class=RobustConnection, **kwargs) -> Generator[Any, None, Connection]:
""" Make robust connection to the broker.
That means that connection state will be restored after reconnect.
After connection has been established the channels, the queues and the
exchanges with their bindings will be restored.
Example:
.. code-block:: python
import aio_pika
async def main():
connection = await aio_pika.connect_robust("amqp://guest:guest@127.0.0.1/")
Connect to localhost with default credentials:
.. code-block:: python
import aio_pika
async def main():
connection = await aio_pika.connect_robust()
:param url: `RFC3986`_ formatted broker address. When :class:`None` will be used keyword arguments.
:param host: hostname of the broker
:param port: broker port 5672 by default
:param login:
username string. `'guest'` by default. Provide empty string for pika.credentials.ExternalCredentials usage.
:param password: password string. `'guest'` by default.
:param virtualhost: virtualhost parameter. `'/'` by default
:param ssl: use SSL for connection. Should be used with addition kwargs. See `pika documentation`_ for more info.
:param loop: Event loop (:func:`asyncio.get_event_loop()` when :class:`None`)
:param connection_class: Factory of a new connection
:param kwargs: addition parameters which will be passed to the pika connection.
:return: :class:`aio_pika.connection.Connection`
.. _RFC3986: https://tools.ietf.org/html/rfc3986
.. _pika documentation: https://goo.gl/TdVuZ9
"""
return (
yield from connect(
url=url, host=host, port=port, login=login,
password=password, virtualhost=virtualhost, ssl=ssl,
loop=loop, connection_class=connection_class, **kwargs
)
)
__all__ = 'RobustConnection', 'connect_robust',
