Thann/tornado_rabbit.py

## tornado_rabbit.py
## Mostly taken from https://github.com/pika/pika/blob/03542ef616a2a849e8bfb0845427f50e741ea0c6/docs/examples/tornado_consumer.rst
# -*- coding: utf-8 -*-

import json
import pika
import uuid
from tornado import gen
from tornado.log import app_log
from tornado.ioloop import IOLoop
from tornado.concurrent import Future

LOGGER = app_log
RABBIT_URL = 'amqp://username:password@hostname'
## Usage:
# rabbit_realtime = RealtimePublisher(RABBIT_URL)

# Consumes tasks and Publishes those results
class RabbitWorker(object):
    """This is an example consumer that will handle unexpected interactions
    with RabbitMQ such as channel and connection closures.

    If RabbitMQ closes the connection, it will reopen it. You should
    look at the output, as there are limited reasons why the connection may
    be closed, which usually are tied to permission related issues or
    socket timeouts.

    If the channel is closed, it will indicate a problem with one of the
    commands that were issued and that should surface in the output as well.

    """
    EXCHANGE = 'message'
    EXCHANGE_TYPE = 'topic'

    CONSUME_QUEUE = (
        'tasks', {
            'durable': True,
            'exclusive': False,
            'auto_delete': False,
            'arguments': {'x-max-priority': 10}
        }
    )
    PUBLISH_QUEUE = (
        'results', {
            'durable': True,
            'exclusive': False,
            'auto_delete': False,
        }
    )

    def __init__(self, amqp_url):
        """Create a new instance of the consumer class, passing in the AMQP
        URL used to connect to RabbitMQ.

        :param str amqp_url: The AMQP url to connect with

        """
        self._connection = None
        self._channel = None
        self._closing = False
        self._consumer_tag = None
        self._url = amqp_url

        self._deliveries = []
        self._acked = 0
        self._nacked = 0
        self._message_number = 0

        # connect automatically!
        IOLoop.instance().spawn_callback(self.connect)

    ## Overload this or add handlers
    def on_consume_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.Spec.Basic.Deliver: basic_deliver method
        :param pika.Spec.BasicProperties: properties
        :param str|unicode body: The message body

        """

        body = json.loads(body)
        LOGGER.info('Received message # %s from %s [%s]: %s',
                    basic_deliver.delivery_tag, properties.app_id, body.get('_id') or body)
        # TODO: add handlers!
        # TODO: connect to arbitrary queue
        self._channel.basic_publish(self.EXCHANGE, self.PUBLISH_QUEUE[0],
                                    json.dumps(body),
                                    properties)

    def connect(self):
        """This method connects to RabbitMQ, returning the connection handle.
        When the connection is established, the on_connection_open method
        will be invoked by pika.

        :rtype: pika.SelectConnection

        """
        LOGGER.info('Connecting to %s', self._url)
        self._connection = pika.adapters.TornadoConnection(pika.URLParameters(self._url),
                                                           self.on_connection_open,
                                                           self.on_connection_closed)
        return self._connection

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

    def on_connection_closed(self, connection, reason, other=None):
        """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.

        :param pika.connection.Connection connection: The closed connection obj
        :param Exception reason: exception representing reason for loss of
            connection.

        """
        self._channel = None
        if self._closing:
            self._connection.ioloop.stop()
        else:
            LOGGER.warning('Connection closed, reopening in 5 seconds: %s',
                           reason)
            self._connection.ioloop.call_later(5, self.reconnect)

    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.

        :type unused_connection: pika.SelectConnection

        """
        LOGGER.info('Connection opened')
        self._connection.add_on_close_callback(self.on_connection_closed)
        self.open_channel()

    def reconnect(self):
        """Will be invoked by the IOLoop timer if the connection is
        closed. See the on_connection_closed method.

        """
        if not self._closing:
            # Create a new connection
            self._connection = self.connect()

    def add_on_channel_close_callback(self):
        """This method tells pika to call the on_channel_closed method if
        RabbitMQ unexpectedly closes the channel.

        """
        LOGGER.info('Adding channel close callback')
        self._channel.add_on_close_callback(self.on_channel_closed)

    def on_channel_closed(self, channel, reason, other):
        """Invoked by pika when RabbitMQ unexpectedly closes the channel.
        Channels are usually closed if you attempt to do something that
        violates the protocol, such as re-declare an exchange or queue with
        different parameters. In this case, we'll close the connection
        to shutdown the object.

        :param pika.channel.Channel: The closed channel
        :param Exception reason: why the channel was closed

        """
        LOGGER.warning('Channel %i was closed: %s <%s>', channel, reason, other)
        self._connection.close()

    def on_channel_open(self, channel):
        """This method is invoked by pika when the channel has been opened.
        The channel object is passed in so we can make use of it.

        Since the channel is now open, we'll declare the exchange to use.

        :param pika.channel.Channel channel: The channel object

        """
        LOGGER.info('Channel opened')
        self._channel = channel
        self.add_on_channel_close_callback()
        self.setup_exchange(self.EXCHANGE)

    def setup_exchange(self, exchange_name):
        """Setup the exchange on RabbitMQ by invoking the Exchange.Declare RPC
        command. When it is complete, the on_exchange_declareok method will
        be invoked by pika.

        :param str|unicode exchange_name: The name of the exchange to declare

        """
        LOGGER.info('Declaring exchange %s', exchange_name)
        self._channel.exchange_declare(self.on_exchange_declareok,
                                       exchange_name,
                                       self.EXCHANGE_TYPE)

    def on_exchange_declareok(self, unused_frame):
        """Invoked by pika when RabbitMQ has finished the Exchange.Declare RPC
        command.

        :param pika.Frame.Method unused_frame: Exchange.DeclareOk response frame

        """
        LOGGER.info('Exchange declared')
        LOGGER.info('Declaring publish queue %s', self.PUBLISH_QUEUE[0])
        self._channel.queue_declare(self.on_publisher_queue_declareok,
                                    self.PUBLISH_QUEUE[0],
                                    **self.PUBLISH_QUEUE[1])
        LOGGER.info('Declaring consume queue %s', self.CONSUME_QUEUE[0])
        self._channel.queue_declare(self.on_consumer_queue_declareok,
                                    self.CONSUME_QUEUE[0],
                                    **self.CONSUME_QUEUE[1])

    def on_queue_declareok(self, method_frame, callback, routing_key):
        """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

        """
        LOGGER.info('Binding %s to %s with %s',
                    # self.EXCHANGE, self.QUEUE, self.ROUTING_KEY)
                    self.EXCHANGE, method_frame.method.queue, routing_key)
        # self._channel.queue_bind(self.on_bindok, self.QUEUE,
        #                          self.EXCHANGE, self.ROUTING_KEY)
        self._channel.queue_bind(callback, method_frame.method.queue,
                                 self.EXCHANGE,  routing_key)
                                 # self.EXCHANGE,  method_frame.method.queue)

    def on_publisher_queue_declareok(self, method_frame):
        self.on_queue_declareok(method_frame, self.on_publisher_bindok,
                                self.PUBLISH_QUEUE[0])

    def on_consumer_queue_declareok(self, method_frame):
        self.on_queue_declareok(method_frame, self.on_consumer_bindok,
                                self.CONSUME_QUEUE[0])

    def on_consumer_cancelled(self, method_frame):
        """Invoked by pika when RabbitMQ sends a Basic.Cancel for a consumer
        receiving messages.

        :param pika.frame.Method method_frame: The Basic.Cancel frame

        """
        LOGGER.info('Consumer was cancelled remotely, shutting down: %r',
                    method_frame)
        if self._channel:
            self._channel.close()

    def acknowledge_message(self, delivery_tag):
        """Acknowledge the message delivery from RabbitMQ by sending a
        Basic.Ack RPC method for the delivery tag.

        :param int delivery_tag: The delivery tag from the Basic.Deliver frame

        """
        LOGGER.info('Acknowledging message %s', delivery_tag)
        self._channel.basic_ack(delivery_tag)

    def on_cancelok(self, unused_frame):
        """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

        """
        LOGGER.info('RabbitMQ acknowledged the cancellation of the consumer')
        self.close_channel()

    def stop_consuming(self):
        """Tell RabbitMQ that you would like to stop consuming by sending the
        Basic.Cancel RPC command.

        """
        if self._channel:
            LOGGER.info('Sending a Basic.Cancel RPC command to RabbitMQ')
            self._channel.basic_cancel(self.on_cancelok, self._consumer_tag)

    def on_consumer_bindok(self, unused_frame):
        """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

        """
        LOGGER.info('Queue bound')
        LOGGER.info('Issuing consumer related RPC commands')
        self._channel.add_on_cancel_callback(self.on_consumer_cancelled)
        LOGGER.info('Consuming on %s', self.CONSUME_QUEUE[0])
        self._consumer_tag = self._channel.basic_consume(self.on_consume_message,
                                                         self.CONSUME_QUEUE[0])

    def on_publisher_bindok(self, unused_frame):
        """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

        """
        LOGGER.info('Queue bound')
        # self.start_consuming()
        LOGGER.info('Issuing publisher related RPC commands')
        # self.add_on_cancel_callback()
        self._channel.add_on_cancel_callback(self.on_consumer_cancelled)

        """Send the Confirm.Select RPC method to RabbitMQ to enable delivery
        confirmations on the channel. The only way to turn this off is to close
        the channel and create a new one.

        When the message is confirmed from RabbitMQ, the
        on_delivery_confirmation method will be invoked passing in a Basic.Ack
        or Basic.Nack method from RabbitMQ that will indicate which messages it
        is confirming or rejecting.

        """
        self._channel.confirm_delivery(self.on_delivery_confirmation)

    def on_delivery_confirmation(self, method_frame):
        """Invoked by pika when RabbitMQ responds to a Basic.Publish RPC
        command, passing in either a Basic.Ack or Basic.Nack frame with
        the delivery tag of the message that was published. The delivery tag
        is an integer counter indicating the message number that was sent
        on the channel via Basic.Publish. Here we're just doing house keeping
        to keep track of stats and remove message numbers that we expect
        a delivery confirmation of from the list used to keep track of messages
        that are pending confirmation.

        :param pika.frame.Method method_frame: Basic.Ack or Basic.Nack frame

        """
        confirmation_type = method_frame.method.NAME.split('.')[1].lower()
        LOGGER.info('Received %s for delivery tag: %i',
                    confirmation_type,
                    method_frame.method.delivery_tag)
        if confirmation_type == 'ack':
            self._acked += 1
        elif confirmation_type == 'nack':
            self._nacked += 1
        self._deliveries.remove(method_frame.method.delivery_tag)
        LOGGER.info('Published %i messages, %i have yet to be confirmed, '
                    '%i were acked and %i were nacked',
                    self._message_number, len(self._deliveries),
                    self._acked, self._nacked)

    def close_channel(self):
        """Call to close the channel with RabbitMQ cleanly by issuing the
        Channel.Close RPC command.

        """
        LOGGER.info('Closing the channel')
        self._channel.close()

    def open_channel(self):
        """Open a new channel with RabbitMQ by issuing the Channel.Open RPC
        command. When RabbitMQ responds that the channel is open, the
        on_channel_open callback will be invoked by pika.

        """
        LOGGER.info('Creating a new channel')
        self._connection.channel(on_open_callback=self.on_channel_open)

    def run(self):
        """Run the example consumer by connecting to RabbitMQ and then
        starting the IOLoop to block and allow the SelectConnection to operate.

        """
        self._connection = self.connect()
        self._connection.ioloop.start()

    def stop(self):
        """Cleanly shutdown the connection to RabbitMQ by stopping the consumer
        with RabbitMQ. When RabbitMQ confirms the cancellation, on_cancelok
        will be invoked by pika, which will then closing the channel and
        connection. The IOLoop is started again because this method is invoked
        when CTRL-C is pressed raising a KeyboardInterrupt exception. This
        exception stops the IOLoop which needs to be running for pika to
        communicate with RabbitMQ. All of the commands issued prior to starting
        the IOLoop will be buffered but not processed.

        """
        LOGGER.info('Stopping')
        self._closing = True
        self.stop_consuming()
        self._connection.ioloop.start()
        LOGGER.info('Stopped')


# Publishes tasks and Consumes those results
class RealtimePublisher(RabbitWorker):
    PUBLISH_QUEUE = (
        'tasks', {
            'durable': True,
            'exclusive': False,
            'auto_delete': False,
            'arguments': {'x-max-priority': 10}
        }
    )
    CONSUME_QUEUE = (
        'realtime_results', {
            'durable': False,
            'exclusive': False,
            'auto_delete': True,
        }
    )

    def __init__(self, *args, **kwargs):
        self._promises = {}
        # Create unique results queue
        self.CONSUME_QUEUE = (self.CONSUME_QUEUE[0] + '_'+ str(uuid.uuid4()),
                              self.CONSUME_QUEUE[1])
        super(RealtimePublisher, self).__init__(*args, **kwargs)

    def on_consume_message(self, unused_channel, basic_deliver, properties, body):
        body = json.loads(body)
        LOGGER.info('Received message # %s from %s [%s]: %s',
                    basic_deliver.delivery_tag, properties.app_id, body.get('_id'), body)
        body = json.loads(body)
        p = self._promises.get(body.get('_id'))
        if p:  p.set_result(body)
        else: LOGGER.error('Failed to find task [%s] in %s',
                            body.get('_id'), self._promises.keys())
        self.acknowledge_message(basic_deliver.delivery_tag)

    def publish_task(self, task_data):
        properties = pika.BasicProperties(app_id='tornado-realtime-publisher',
                                          content_type='application/json')

        task_data['_id'] = str(uuid.uuid4())
        task_data['result_queue'] = self.CONSUME_QUEUE[0]
        self._channel.basic_publish(self.EXCHANGE, self.PUBLISH_QUEUE[0],
                                    json.dumps(task_data),
                                    properties)
        self._message_number += 1
        self._deliveries.append(self._message_number)
        LOGGER.info('Published message # %i [%s]',
                    self._message_number, task_data['_id'])
        return

    @gen.coroutine
    def publish_task_result(self, task_data):
        """ This is where the magic happens, publish a task and await the result """
        future = Future()
        task_id = self.publish_task(task_data)
        self._promises[task_id] = future
        yield future
        raise gen.Return(future.result())
	## Mostly taken from https://github.com/pika/pika/blob/03542ef616a2a849e8bfb0845427f50e741ea0c6/docs/examples/tornado_consumer.rst
	# -- coding: utf-8 --

	import json
	import pika
	import uuid
	from tornado import gen
	from tornado.log import app_log
	from tornado.ioloop import IOLoop
	from tornado.concurrent import Future

	LOGGER = app_log
	RABBIT_URL = 'amqp://username:password@hostname'
	## Usage:
	# rabbit_realtime = RealtimePublisher(RABBIT_URL)

	# Consumes tasks and Publishes those results
	class RabbitWorker(object):
	"""This is an example consumer that will handle unexpected interactions
	with RabbitMQ such as channel and connection closures.

	If RabbitMQ closes the connection, it will reopen it. You should
	look at the output, as there are limited reasons why the connection may
	be closed, which usually are tied to permission related issues or
	socket timeouts.

	If the channel is closed, it will indicate a problem with one of the
	commands that were issued and that should surface in the output as well.

	"""
	EXCHANGE = 'message'
	EXCHANGE_TYPE = 'topic'

	CONSUME_QUEUE = (
	'tasks', {
	'durable': True,
	'exclusive': False,
	'auto_delete': False,
	'arguments': {'x-max-priority': 10}
	}
	)
	PUBLISH_QUEUE = (
	'results', {
	'durable': True,
	'exclusive': False,
	'auto_delete': False,
	}
	)

	def __init__(self, amqp_url):
	"""Create a new instance of the consumer class, passing in the AMQP
	URL used to connect to RabbitMQ.

	:param str amqp_url: The AMQP url to connect with

	"""
	self._connection = None
	self._channel = None
	self._closing = False
	self._consumer_tag = None
	self._url = amqp_url

	self._deliveries = []
	self._acked = 0
	self._nacked = 0
	self._message_number = 0

	# connect automatically!
	IOLoop.instance().spawn_callback(self.connect)

	## Overload this or add handlers
	def on_consume_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.Spec.Basic.Deliver: basic_deliver method
	:param pika.Spec.BasicProperties: properties
	:param str\|unicode body: The message body

	"""

	body = json.loads(body)
	LOGGER.info('Received message # %s from %s [%s]: %s',
	basic_deliver.delivery_tag, properties.app_id, body.get('_id') or body)
	# TODO: add handlers!
	# TODO: connect to arbitrary queue
	self._channel.basic_publish(self.EXCHANGE, self.PUBLISH_QUEUE[0],
	json.dumps(body),
	properties)

	def connect(self):
	"""This method connects to RabbitMQ, returning the connection handle.
	When the connection is established, the on_connection_open method
	will be invoked by pika.

	:rtype: pika.SelectConnection

	"""
	LOGGER.info('Connecting to %s', self._url)
	self._connection = pika.adapters.TornadoConnection(pika.URLParameters(self._url),
	self.on_connection_open,
	self.on_connection_closed)
	return self._connection

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

	def on_connection_closed(self, connection, reason, other=None):
	"""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.

	:param pika.connection.Connection connection: The closed connection obj
	:param Exception reason: exception representing reason for loss of
	connection.

	"""
	self._channel = None
	if self._closing:
	self._connection.ioloop.stop()
	else:
	LOGGER.warning('Connection closed, reopening in 5 seconds: %s',
	reason)
	self._connection.ioloop.call_later(5, self.reconnect)

	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.

	:type unused_connection: pika.SelectConnection

	"""
	LOGGER.info('Connection opened')
	self._connection.add_on_close_callback(self.on_connection_closed)
	self.open_channel()

	def reconnect(self):
	"""Will be invoked by the IOLoop timer if the connection is
	closed. See the on_connection_closed method.

	"""
	if not self._closing:
	# Create a new connection
	self._connection = self.connect()

	def add_on_channel_close_callback(self):
	"""This method tells pika to call the on_channel_closed method if
	RabbitMQ unexpectedly closes the channel.

	"""
	LOGGER.info('Adding channel close callback')
	self._channel.add_on_close_callback(self.on_channel_closed)

	def on_channel_closed(self, channel, reason, other):
	"""Invoked by pika when RabbitMQ unexpectedly closes the channel.
	Channels are usually closed if you attempt to do something that
	violates the protocol, such as re-declare an exchange or queue with
	different parameters. In this case, we'll close the connection
	to shutdown the object.

	:param pika.channel.Channel: The closed channel
	:param Exception reason: why the channel was closed

	"""
	LOGGER.warning('Channel %i was closed: %s <%s>', channel, reason, other)
	self._connection.close()

	def on_channel_open(self, channel):
	"""This method is invoked by pika when the channel has been opened.
	The channel object is passed in so we can make use of it.

	Since the channel is now open, we'll declare the exchange to use.

	:param pika.channel.Channel channel: The channel object

	"""
	LOGGER.info('Channel opened')
	self._channel = channel
	self.add_on_channel_close_callback()
	self.setup_exchange(self.EXCHANGE)

	def setup_exchange(self, exchange_name):
	"""Setup the exchange on RabbitMQ by invoking the Exchange.Declare RPC
	command. When it is complete, the on_exchange_declareok method will
	be invoked by pika.

	:param str\|unicode exchange_name: The name of the exchange to declare

	"""
	LOGGER.info('Declaring exchange %s', exchange_name)
	self._channel.exchange_declare(self.on_exchange_declareok,
	exchange_name,
	self.EXCHANGE_TYPE)

	def on_exchange_declareok(self, unused_frame):
	"""Invoked by pika when RabbitMQ has finished the Exchange.Declare RPC
	command.

	:param pika.Frame.Method unused_frame: Exchange.DeclareOk response frame

	"""
	LOGGER.info('Exchange declared')
	LOGGER.info('Declaring publish queue %s', self.PUBLISH_QUEUE[0])
	self._channel.queue_declare(self.on_publisher_queue_declareok,
	self.PUBLISH_QUEUE[0],
	**self.PUBLISH_QUEUE[1])
	LOGGER.info('Declaring consume queue %s', self.CONSUME_QUEUE[0])
	self._channel.queue_declare(self.on_consumer_queue_declareok,
	self.CONSUME_QUEUE[0],
	**self.CONSUME_QUEUE[1])

	def on_queue_declareok(self, method_frame, callback, routing_key):
	"""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

	"""
	LOGGER.info('Binding %s to %s with %s',
	# self.EXCHANGE, self.QUEUE, self.ROUTING_KEY)
	self.EXCHANGE, method_frame.method.queue, routing_key)
	# self._channel.queue_bind(self.on_bindok, self.QUEUE,
	# self.EXCHANGE, self.ROUTING_KEY)
	self._channel.queue_bind(callback, method_frame.method.queue,
	self.EXCHANGE, routing_key)
	# self.EXCHANGE, method_frame.method.queue)

	def on_publisher_queue_declareok(self, method_frame):
	self.on_queue_declareok(method_frame, self.on_publisher_bindok,
	self.PUBLISH_QUEUE[0])

	def on_consumer_queue_declareok(self, method_frame):
	self.on_queue_declareok(method_frame, self.on_consumer_bindok,
	self.CONSUME_QUEUE[0])

	def on_consumer_cancelled(self, method_frame):
	"""Invoked by pika when RabbitMQ sends a Basic.Cancel for a consumer
	receiving messages.

	:param pika.frame.Method method_frame: The Basic.Cancel frame

	"""
	LOGGER.info('Consumer was cancelled remotely, shutting down: %r',
	method_frame)
	if self._channel:
	self._channel.close()

	def acknowledge_message(self, delivery_tag):
	"""Acknowledge the message delivery from RabbitMQ by sending a
	Basic.Ack RPC method for the delivery tag.

	:param int delivery_tag: The delivery tag from the Basic.Deliver frame

	"""
	LOGGER.info('Acknowledging message %s', delivery_tag)
	self._channel.basic_ack(delivery_tag)

	def on_cancelok(self, unused_frame):
	"""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

	"""
	LOGGER.info('RabbitMQ acknowledged the cancellation of the consumer')
	self.close_channel()

	def stop_consuming(self):
	"""Tell RabbitMQ that you would like to stop consuming by sending the
	Basic.Cancel RPC command.

	"""
	if self._channel:
	LOGGER.info('Sending a Basic.Cancel RPC command to RabbitMQ')
	self._channel.basic_cancel(self.on_cancelok, self._consumer_tag)

	def on_consumer_bindok(self, unused_frame):
	"""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

	"""
	LOGGER.info('Queue bound')
	LOGGER.info('Issuing consumer related RPC commands')
	self._channel.add_on_cancel_callback(self.on_consumer_cancelled)
	LOGGER.info('Consuming on %s', self.CONSUME_QUEUE[0])
	self._consumer_tag = self._channel.basic_consume(self.on_consume_message,
	self.CONSUME_QUEUE[0])

	def on_publisher_bindok(self, unused_frame):
	"""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

	"""
	LOGGER.info('Queue bound')
	# self.start_consuming()
	LOGGER.info('Issuing publisher related RPC commands')
	# self.add_on_cancel_callback()
	self._channel.add_on_cancel_callback(self.on_consumer_cancelled)

	"""Send the Confirm.Select RPC method to RabbitMQ to enable delivery
	confirmations on the channel. The only way to turn this off is to close
	the channel and create a new one.

	When the message is confirmed from RabbitMQ, the
	on_delivery_confirmation method will be invoked passing in a Basic.Ack
	or Basic.Nack method from RabbitMQ that will indicate which messages it
	is confirming or rejecting.

	"""
	self._channel.confirm_delivery(self.on_delivery_confirmation)

	def on_delivery_confirmation(self, method_frame):
	"""Invoked by pika when RabbitMQ responds to a Basic.Publish RPC
	command, passing in either a Basic.Ack or Basic.Nack frame with
	the delivery tag of the message that was published. The delivery tag
	is an integer counter indicating the message number that was sent
	on the channel via Basic.Publish. Here we're just doing house keeping
	to keep track of stats and remove message numbers that we expect
	a delivery confirmation of from the list used to keep track of messages
	that are pending confirmation.

	:param pika.frame.Method method_frame: Basic.Ack or Basic.Nack frame

	"""
	confirmation_type = method_frame.method.NAME.split('.')[1].lower()
	LOGGER.info('Received %s for delivery tag: %i',
	confirmation_type,
	method_frame.method.delivery_tag)
	if confirmation_type == 'ack':
	self._acked += 1
	elif confirmation_type == 'nack':
	self._nacked += 1
	self._deliveries.remove(method_frame.method.delivery_tag)
	LOGGER.info('Published %i messages, %i have yet to be confirmed, '
	'%i were acked and %i were nacked',
	self._message_number, len(self._deliveries),
	self._acked, self._nacked)

	def close_channel(self):
	"""Call to close the channel with RabbitMQ cleanly by issuing the
	Channel.Close RPC command.

	"""
	LOGGER.info('Closing the channel')
	self._channel.close()

	def open_channel(self):
	"""Open a new channel with RabbitMQ by issuing the Channel.Open RPC
	command. When RabbitMQ responds that the channel is open, the
	on_channel_open callback will be invoked by pika.

	"""
	LOGGER.info('Creating a new channel')
	self._connection.channel(on_open_callback=self.on_channel_open)

	def run(self):
	"""Run the example consumer by connecting to RabbitMQ and then
	starting the IOLoop to block and allow the SelectConnection to operate.

	"""
	self._connection = self.connect()
	self._connection.ioloop.start()

	def stop(self):
	"""Cleanly shutdown the connection to RabbitMQ by stopping the consumer
	with RabbitMQ. When RabbitMQ confirms the cancellation, on_cancelok
	will be invoked by pika, which will then closing the channel and
	connection. The IOLoop is started again because this method is invoked
	when CTRL-C is pressed raising a KeyboardInterrupt exception. This
	exception stops the IOLoop which needs to be running for pika to
	communicate with RabbitMQ. All of the commands issued prior to starting
	the IOLoop will be buffered but not processed.

	"""
	LOGGER.info('Stopping')
	self._closing = True
	self.stop_consuming()
	self._connection.ioloop.start()
	LOGGER.info('Stopped')


	# Publishes tasks and Consumes those results
	class RealtimePublisher(RabbitWorker):
	PUBLISH_QUEUE = (
	'tasks', {
	'durable': True,
	'exclusive': False,
	'auto_delete': False,
	'arguments': {'x-max-priority': 10}
	}
	)
	CONSUME_QUEUE = (
	'realtime_results', {
	'durable': False,
	'exclusive': False,
	'auto_delete': True,
	}
	)

	def __init__(self, args, *kwargs):
	self._promises = {}
	# Create unique results queue
	self.CONSUME_QUEUE = (self.CONSUME_QUEUE[0] + '_'+ str(uuid.uuid4()),
	self.CONSUME_QUEUE[1])
	super(RealtimePublisher, self).__init__(args, *kwargs)

	def on_consume_message(self, unused_channel, basic_deliver, properties, body):
	body = json.loads(body)
	LOGGER.info('Received message # %s from %s [%s]: %s',
	basic_deliver.delivery_tag, properties.app_id, body.get('_id'), body)
	body = json.loads(body)
	p = self._promises.get(body.get('_id'))
	if p: p.set_result(body)
	else: LOGGER.error('Failed to find task [%s] in %s',
	body.get('_id'), self._promises.keys())
	self.acknowledge_message(basic_deliver.delivery_tag)

	def publish_task(self, task_data):
	properties = pika.BasicProperties(app_id='tornado-realtime-publisher',
	content_type='application/json')

	task_data['_id'] = str(uuid.uuid4())
	task_data['result_queue'] = self.CONSUME_QUEUE[0]
	self._channel.basic_publish(self.EXCHANGE, self.PUBLISH_QUEUE[0],
	json.dumps(task_data),
	properties)
	self._message_number += 1
	self._deliveries.append(self._message_number)
	LOGGER.info('Published message # %i [%s]',
	self._message_number, task_data['_id'])
	return

	@gen.coroutine
	def publish_task_result(self, task_data):
	""" This is where the magic happens, publish a task and await the result """
	future = Future()
	task_id = self.publish_task(task_data)
	self._promises[task_id] = future
	yield future
	raise gen.Return(future.result())