Synnefo

# Copyright 2011 GRNET S.A. All rights reserved.

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import time

import socket

from logging import getLogger

from amqplib import client_0_8 as amqp

from django.conf import settings

log = getLogger('synnefo.logic')

_conn = None

_chan = None

def _connect():

    global _conn, _chan

    # Force the _conn object to re-initialize

    _conn = None

    retry = 0

    while _conn == None:

        try:

            _conn = amqp.Connection(host=settings.RABBIT_HOST,

                                   userid=settings.RABBIT_USERNAME,

                                   password=settings.RABBIT_PASSWORD,

                                   virtual_host=settings.RABBIT_VHOST)

        except socket.error:

            retry += 1

            if retry < 5 :

                log.exception("Cannot establish connection to AMQP. Retrying...")

                time.sleep(1)

            else:

                raise AMQPError("Queue error")

    _chan = _conn.channel()

def send(payload, exchange, key):

    """

        Send payload to the specified exchange using the provided routing key.

        This method will try reconnecting to the message server if a connection

        error occurs when sending the message. All other errors are forwarded

        to the client.

    """

    global _conn, _chan

    if payload is None:

        raise AMQPError("Message is empty")

    if exchange is None:

        raise AMQPError("Unknown exchange")

    if key is None:

        raise AMQPError("Unknown routing key")

    msg = amqp.Message(payload)

    msg.properties["delivery_mode"] = 2  # Persistent

    while True:

        try:

           _chan.basic_publish(msg,

                               exchange=exchange,

                               routing_key=key)

           return

        except socket.error as se:

           log.exception("Server went away, reconnecting...")

           _connect()

        except Exception as e:

            if _conn is None:

               _connect()

            else:

                log.exception('Caught unexpected exception (msg: %s)', msg)

                raise AMQPError("Error sending message to exchange %s with \

                                key %s.Payload: %s. Error was: %s",

                                (exchange, key, payload, e.message))

def __init__():

    _connect()

class AMQPError(Exception):

    pass