Files
deb-python-taskflow/taskflow/engines/worker_based/proxy.py
Christian Berendt 6132647fb7 Enabled hacking checks H305 and H307
* H305  imports not grouped correctly
* H307  like imports should be grouped together

Change-Id: If1dd9c89f65ede6959865a885777cb08c263eca0
2014-07-17 09:05:48 +02:00

115 lines
4.3 KiB
Python

# -*- coding: utf-8 -*-
# Copyright (C) 2014 Yahoo! Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import logging
import socket
import threading
import kombu
import six
LOG = logging.getLogger(__name__)
# NOTE(skudriashev): A timeout of 1 is often used in environments where
# the socket can get "stuck", and is a best practice for Kombu consumers.
DRAIN_EVENTS_PERIOD = 1
class Proxy(object):
"""A proxy processes messages from/to the named exchange."""
def __init__(self, topic, exchange_name, on_message, on_wait=None,
**kwargs):
self._topic = topic
self._exchange_name = exchange_name
self._on_message = on_message
self._on_wait = on_wait
self._running = threading.Event()
self._url = kwargs.get('url')
self._transport = kwargs.get('transport')
self._transport_opts = kwargs.get('transport_options')
self._drain_events_timeout = DRAIN_EVENTS_PERIOD
if self._transport == 'memory' and self._transport_opts:
polling_interval = self._transport_opts.get('polling_interval')
if polling_interval:
self._drain_events_timeout = polling_interval
# create connection
self._conn = kombu.Connection(self._url, transport=self._transport,
transport_options=self._transport_opts)
# create exchange
self._exchange = kombu.Exchange(name=self._exchange_name,
durable=False,
auto_delete=True)
@property
def is_running(self):
"""Return whether the proxy is running."""
return self._running.is_set()
def _make_queue(self, name, exchange, **kwargs):
"""Make named queue for the given exchange."""
return kombu.Queue(name="%s_%s" % (self._exchange_name, name),
exchange=exchange,
routing_key=name,
durable=False,
auto_delete=True,
**kwargs)
def publish(self, msg, routing_key, **kwargs):
"""Publish message to the named exchange with given routing key."""
LOG.debug("Sending %s", msg)
if isinstance(routing_key, six.string_types):
routing_keys = [routing_key]
else:
routing_keys = routing_key
with kombu.producers[self._conn].acquire(block=True) as producer:
for routing_key in routing_keys:
queue = self._make_queue(routing_key, self._exchange)
producer.publish(body=msg.to_dict(),
routing_key=routing_key,
exchange=self._exchange,
declare=[queue],
type=msg.TYPE,
**kwargs)
def start(self):
"""Start proxy."""
LOG.info("Starting to consume from the '%s' exchange.",
self._exchange_name)
with kombu.connections[self._conn].acquire(block=True) as conn:
queue = self._make_queue(self._topic, self._exchange, channel=conn)
with conn.Consumer(queues=queue,
callbacks=[self._on_message]):
self._running.set()
while self.is_running:
try:
conn.drain_events(timeout=self._drain_events_timeout)
except socket.timeout:
pass
if self._on_wait is not None:
self._on_wait()
def wait(self):
"""Wait until proxy is started."""
self._running.wait()
def stop(self):
"""Stop proxy."""
self._running.clear()