AIL-framework/bin/Helper.py

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#!/usr/bin/env python2
# -*-coding:UTF-8 -*
"""
Queue helper module
============================
This module subscribe to a Publisher stream and put the received messages
into a Redis-list waiting to be popped later by others scripts.
..note:: Module ZMQ_Something_Q and ZMQ_Something are closely bound, always put
the same Subscriber name in both of them.
"""
import redis
import ConfigParser
import os
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import zmq
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class Redis_Queues(object):
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def __init__(self, conf_section, conf_channel, subscriber_name):
configfile = os.path.join(os.environ['AIL_BIN'], 'packages/config.cfg')
print configfile
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if not os.path.exists(configfile):
raise Exception('Unable to find the configuration file. \
Did you set environment variables? \
Or activate the virtualenv.')
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self.config = ConfigParser.ConfigParser()
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self.config.read(configfile)
self.subscriber_name = subscriber_name
self.sub_channel = self.config.get(conf_section, conf_channel)
self.redis_channel = self.sub_channel + self.subscriber_name
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# Redis Queue
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config_section = "Redis_Queues"
self.r_queues = redis.StrictRedis(
host=self.config.get(config_section, "host"),
port=self.config.getint(config_section, "port"),
db=self.config.getint(config_section, "db"))
def zmq_sub(self, conf_section):
sub_address = self.config.get(conf_section, 'adress')
context = zmq.Context()
self.sub_socket = context.socket(zmq.SUB)
self.sub_socket.connect(sub_address)
self.sub_socket.setsockopt(zmq.SUBSCRIBE, self.sub_channel)
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def zmq_pub(self, config_section, config_channel):
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context = zmq.Context()
self.pub_socket = context.socket(zmq.PUB)
self.pub_socket.bind(self.config.get(config_section, 'adress'))
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if config_channel is not None:
self.pub_channel = self.config.get(config_section, config_channel)
else:
# The publishing channel is defined dynamically
self.pub_channel = None
def zmq_pub_send(self, msg):
if self.pub_channel is None:
raise Exception('A channel is reqired to send a message.')
self.pub_socket.send('{} {}'.format(self.pub_channel, msg))
def redis_rpop(self):
return self.r_queues.rpop(self.redis_channel)
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def redis_queue_shutdown(self, is_queue=False):
if is_queue:
flag = self.subscriber_name + '_Q'
else:
flag = self.subscriber_name
# srem returns False if the element does not exists
return self.r_queues.srem('SHUTDOWN_FLAGS', flag)
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def redis_queue_subscribe(self, publisher):
publisher.info("Suscribed to channel {}".format(self.sub_channel))
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while True:
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msg = self.sub_socket.recv()
p = self.r_queues.pipeline()
p.sadd("queues", self.redis_channel)
p.lpush(self.redis_channel, msg)
p.execute()
if self.redis_queue_shutdown(True):
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print "Shutdown Flag Up: Terminating"
publisher.warning("Shutdown Flag Up: Terminating.")
break