Skip to content

Commit

Permalink
Merge d7ed3e7 into cc5ffa1
Browse files Browse the repository at this point in the history
  • Loading branch information
@lukebakken
lukebakken committed Feb 2, 2019
2 parents cc5ffa1 + d7ed3e7 commit 494f747
Showing 1 changed file with 91 additions and 72 deletions.
163 changes: 91 additions & 72 deletions examples/asynchronous_consumer_example.py
View file
@@ -1,11 +1,13 @@
# -*- coding: utf-8 -*-
# pylint: disable=C0111,C0103,R0205

import functools
import logging
import time
import pika

LOG_FORMAT = ('%(levelname) -10s %(asctime)s %(name) -30s %(funcName) '
'-35s %(lineno) -5d: %(message)s')
'-35s %(lineno) -5d: %(message)s')
LOGGER = logging.getLogger(__name__)


Expand Down Expand Up @@ -34,12 +36,15 @@ def __init__(self, amqp_url):
:param str amqp_url: The AMQP url to connect with
"""
self.should_reconnect = False
self.was_consuming = False

self._connection = None
self._channel = None
self._closing = False
self._consumer_tag = None
self._url = amqp_url
self._reconnect_delay = 0
self._consuming = False

def connect(self):
"""This method connects to RabbitMQ, returning the connection handle.
Expand All @@ -50,12 +55,13 @@ def connect(self):
"""
LOGGER.info('Connecting to %s', self._url)
return pika.SelectConnection(parameters=pika.URLParameters(self._url),
on_open_callback=self.on_connection_open,
on_open_error_callback=self.on_connection_open_error,
on_close_callback=self.on_connection_closed)
return pika.SelectConnection(
parameters=pika.URLParameters(self._url),
on_open_callback=self.on_connection_open,
on_open_error_callback=self.on_connection_open_error,
on_close_callback=self.on_connection_closed)

def on_connection_open(self, unused_connection):
def on_connection_open(self, _unused_connection):
"""This method is called by pika once the connection to RabbitMQ has
been established. It passes the handle to the connection object in
case we need it, but in this case, we'll just mark it unused.
Expand All @@ -66,7 +72,7 @@ def on_connection_open(self, unused_connection):
LOGGER.info('Connection opened')
self.open_channel()

def on_connection_open_error(self, unused_connection, err):
def on_connection_open_error(self, _unused_connection, err):
"""This method is called by pika if the connection to RabbitMQ
can't be established.
Expand All @@ -75,9 +81,9 @@ def on_connection_open_error(self, unused_connection, err):
"""
LOGGER.error('Connection open failed: %s', err)
self._connection.ioloop.call_later(self._get_reconnect_delay(), self.reconnect)
self.reconnect()

def on_connection_closed(self, connection, reason):
def on_connection_closed(self, _unused_connection, reason):
"""This method is invoked by pika when the connection to RabbitMQ is
closed unexpectedly. Since it is unexpected, we will reconnect to
RabbitMQ if it disconnects.
Expand All @@ -92,24 +98,16 @@ def on_connection_closed(self, connection, reason):
self._connection.ioloop.stop()
else:
LOGGER.warning('Connection closed, reopening in 5 seconds: %s',
reason)
self._connection.ioloop.call_later(self._get_reconnect_delay(), self.reconnect)
reason)
self.reconnect()

def reconnect(self):
"""Will be invoked by the IOLoop timer if the connection is
closed. See the on_connection_closed method.
"""
# This is the old connection IOLoop instance, stop its ioloop
self._connection.ioloop.stop()

if not self._closing:

# Create a new connection
self._connection = self.connect()

# There is now a new connection, needs a new ioloop to run
self._connection.ioloop.start()
self.should_reconnect = True
self.stop()

def open_channel(self):
"""Open a new channel with RabbitMQ by issuing the Channel.Open RPC
Expand Down Expand Up @@ -154,7 +152,7 @@ def on_channel_closed(self, channel, reason):
"""
LOGGER.warning('Channel %i was closed: %s', channel, reason)
self._connection.close()
self.close_connection()

def setup_exchange(self, exchange_name):
"""Setup the exchange on RabbitMQ by invoking the Exchange.Declare RPC
Expand All @@ -167,12 +165,14 @@ def setup_exchange(self, exchange_name):
LOGGER.info('Declaring exchange: %s', exchange_name)
# Note: using functools.partial is not required, it is demonstrating
# how arbitrary data can be passed to the callback when it is called
cb = functools.partial(self.on_exchange_declareok, userdata=exchange_name)
self._channel.exchange_declare(exchange=exchange_name,
exchange_type=self.EXCHANGE_TYPE,
callback=cb)

def on_exchange_declareok(self, unused_frame, userdata):
cb = functools.partial(
self.on_exchange_declareok, userdata=exchange_name)
self._channel.exchange_declare(
exchange=exchange_name,
exchange_type=self.EXCHANGE_TYPE,
callback=cb)

def on_exchange_declareok(self, _unused_frame, userdata):
"""Invoked by pika when RabbitMQ has finished the Exchange.Declare RPC
command.
Expand All @@ -192,37 +192,36 @@ def setup_queue(self, queue_name):
"""
LOGGER.info('Declaring queue %s', queue_name)
cb = functools.partial(self.on_queue_declareok,
userdata=queue_name)
cb = functools.partial(self.on_queue_declareok, userdata=queue_name)
self._channel.queue_declare(queue=queue_name, callback=cb)

def on_queue_declareok(self, method_frame, userdata):
def on_queue_declareok(self, _unused_frame, userdata):
"""Method invoked by pika when the Queue.Declare RPC call made in
setup_queue has completed. In this method we will bind the queue
and exchange together with the routing key by issuing the Queue.Bind
RPC command. When this command is complete, the on_bindok method will
be invoked by pika.
:param pika.frame.Method method_frame: The Queue.DeclareOk frame
:param pika.frame.Method _unused_frame: The Queue.DeclareOk frame
:param str|unicode userdata: Extra user data (queue name)
"""
queue_name = userdata
LOGGER.info('Binding %s to %s with %s',
self.EXCHANGE, queue_name, self.ROUTING_KEY)
cb = functools.partial(self.on_bindok,
userdata=queue_name)
self._channel.queue_bind(queue_name,
self.EXCHANGE,
routing_key=self.ROUTING_KEY,
callback=cb)

def on_bindok(self, unused_frame, userdata):
LOGGER.info('Binding %s to %s with %s', self.EXCHANGE, queue_name,
self.ROUTING_KEY)
cb = functools.partial(self.on_bindok, userdata=queue_name)
self._channel.queue_bind(
queue_name,
self.EXCHANGE,
routing_key=self.ROUTING_KEY,
callback=cb)

def on_bindok(self, _unused_frame, userdata):
"""Invoked by pika when the Queue.Bind method has completed. At this
point we will start consuming messages by calling start_consuming
which will invoke the needed RPC commands to start the process.
:param pika.frame.Method unused_frame: The Queue.BindOk response frame
:param pika.frame.Method _unused_frame: The Queue.BindOk response frame
:param str|unicode userdata: Extra user data (queue name)
"""
Expand All @@ -241,8 +240,10 @@ def start_consuming(self):
"""
LOGGER.info('Issuing consumer related RPC commands')
self.add_on_cancel_callback()
self._consumer_tag = self._channel.basic_consume(self.QUEUE,
self.on_message)
self._consumer_tag = self._channel.basic_consume(
self.QUEUE, self.on_message)
self.was_consuming = True
self._consuming = True

def add_on_cancel_callback(self):
"""Add a callback that will be invoked if RabbitMQ cancels the consumer
Expand All @@ -265,15 +266,15 @@ def on_consumer_cancelled(self, method_frame):
if self._channel:
self._channel.close()

def on_message(self, unused_channel, basic_deliver, properties, body):
def on_message(self, _unused_channel, basic_deliver, properties, body):
"""Invoked by pika when a message is delivered from RabbitMQ. The
channel is passed for your convenience. The basic_deliver object that
is passed in carries the exchange, routing key, delivery tag and
a redelivered flag for the message. The properties passed in is an
instance of BasicProperties with the message properties and the body
is the message that was sent.
:param pika.channel.Channel unused_channel: The channel object
:param pika.channel.Channel _unused_channel: The channel object
:param pika.Spec.Basic.Deliver: basic_deliver method
:param pika.Spec.BasicProperties: properties
:param str|unicode body: The message body
Expand All @@ -300,21 +301,24 @@ def stop_consuming(self):
"""
if self._channel:
LOGGER.info('Sending a Basic.Cancel RPC command to RabbitMQ')
cb = functools.partial(self.on_cancelok,
userdata=self._consumer_tag)
cb = functools.partial(
self.on_cancelok, userdata=self._consumer_tag)
self._channel.basic_cancel(self._consumer_tag, cb)

def on_cancelok(self, unused_frame, userdata):
def on_cancelok(self, _unused_frame, userdata):
"""This method is invoked by pika when RabbitMQ acknowledges the
cancellation of a consumer. At this point we will close the channel.
This will invoke the on_channel_closed method once the channel has been
closed, which will in-turn close the connection.
:param pika.frame.Method unused_frame: The Basic.CancelOk frame
:param pika.frame.Method _unused_frame: The Basic.CancelOk frame
:param str|unicode userdata: Extra user data (consumer tag)
"""
LOGGER.info('RabbitMQ acknowledged the cancellation of the consumer: %s', userdata)
self._consuming = False
LOGGER.info(
'RabbitMQ acknowledged the cancellation of the consumer: %s',
userdata)
self.close_channel()

def close_channel(self):
Expand Down Expand Up @@ -344,30 +348,45 @@ def stop(self):
the IOLoop will be buffered but not processed.
"""
LOGGER.info('Stopping')
self._closing = True
self.stop_consuming()
self._connection.ioloop.start()
LOGGER.info('Stopped')
if not self._closing:
self._closing = True
LOGGER.info('Stopping')
if self._consuming:
self.stop_consuming()
self._connection.ioloop.start()
else:
self._connection.ioloop.stop()
LOGGER.info('Stopped')

def close_connection(self):
"""This method closes the connection to RabbitMQ."""
LOGGER.info('Closing connection')
self._connection.close()

def _get_reconnect_delay(self):
self._reconnect_delay = self._reconnect_delay + 1
LOGGER.info('Reconnect delay: %d', self._reconnect_delay)
return self._reconnect_delay
self._consuming = False
if self._connection.is_closing or self._connection.is_closed:
LOGGER.info('Connection is closing or already closed')
else:
LOGGER.info('Closing connection')
self._connection.close()


def main():
logging.basicConfig(level=logging.INFO, format=LOG_FORMAT)
example = ExampleConsumer('amqp://guest:guest@localhost:5672/%2F')
try:
example.run()
except KeyboardInterrupt:
example.stop()
reconnect_delay = 0
logging.basicConfig(level=logging.DEBUG, format=LOG_FORMAT)
while True:
try:
example = ExampleConsumer('amqp://guest:guest@localhost:5672/%2F')
example.run()
except KeyboardInterrupt:
example.stop()
break
if example.should_reconnect:
example.stop()
if example.was_consuming:
reconnect_delay = 0
else:
reconnect_delay += 1
if reconnect_delay > 30:
reconnect_delay = 30
LOGGER.info('Reconnecting after %d seconds', reconnect_delay)
time.sleep(reconnect_delay)


if __name__ == '__main__':
Expand Down

0 comments on commit 494f747

Please sign in to comment.