280 lines
10 KiB
Python
280 lines
10 KiB
Python
# Copyright 2014, Red Hat, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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Driver for the 'amqp' transport.
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This module provides a transport driver that speaks version 1.0 of the AMQP
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messaging protocol. The driver sends messages and creates subscriptions via
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'tasks' that are performed on its behalf via the controller module.
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"""
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import logging
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import threading
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import time
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import proton
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from six import moves
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from oslo import messaging
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from oslo.messaging._drivers import base
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from oslo.messaging._drivers import common
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from oslo.messaging._drivers.protocols.amqp import controller
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from oslo.messaging import target as messaging_target
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from oslo.serialization import jsonutils
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LOG = logging.getLogger(__name__)
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class SendTask(controller.Task):
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"""A task that sends a message to a target, and optionally allows for the
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calling thread to wait for a reply.
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"""
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def __init__(self, target, request, reply_expected, deadline):
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super(SendTask, self).__init__()
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self._target = target
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self._request = request
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self._deadline = deadline
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if reply_expected:
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self._reply_queue = moves.queue.Queue()
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else:
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self._reply_queue = None
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def execute(self, controller):
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"""Runs on eventloop thread - sends request."""
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if not self._deadline or self._deadline > time.time():
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controller.request(self._target, self._request, self._reply_queue)
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else:
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LOG.warn("Send request to %s aborted: TTL expired.", self._target)
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def get_reply(self, timeout):
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"""Retrieve the reply."""
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if not self._reply_queue:
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return None
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try:
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return self._reply_queue.get(timeout=timeout)
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except moves.queue.Empty:
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raise messaging.MessagingTimeout('Timed out waiting for a reply')
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class ListenTask(controller.Task):
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"""A task that creates a subscription to the given target. Messages
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arriving from the target are given to the listener.
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"""
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def __init__(self, target, listener, notifications=False):
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"""Create a subscription to the target."""
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super(ListenTask, self).__init__()
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self._target = target
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self._listener = listener
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self._notifications = notifications
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def execute(self, controller):
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"""Run on the eventloop thread - subscribes to target. Inbound messages
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are queued to the listener's incoming queue.
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"""
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if self._notifications:
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controller.subscribe_notifications(self._target,
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self._listener.incoming)
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else:
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controller.subscribe(self._target, self._listener.incoming)
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class ReplyTask(controller.Task):
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"""A task that sends 'response' message to address."""
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def __init__(self, address, response, log_failure):
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super(ReplyTask, self).__init__()
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self._address = address
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self._response = response
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self._log_failure = log_failure
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def execute(self, controller):
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"""Run on the eventloop thread - send the response message."""
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controller.response(self._address, self._response)
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def marshal_response(reply=None, failure=None):
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# TODO(grs): do replies have a context?
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msg = proton.Message()
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if failure:
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failure = common.serialize_remote_exception(failure)
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data = {"failure": failure}
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else:
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data = {"response": reply}
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msg.body = jsonutils.dumps(data)
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return msg
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def unmarshal_response(message, allowed):
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# TODO(kgiusti) This may fail to unpack and raise an exception. Need to
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# communicate this to the caller!
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data = jsonutils.loads(message.body)
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failure = data.get('failure')
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if failure is not None:
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raise common.deserialize_remote_exception(failure, allowed)
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return data.get("response")
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def marshal_request(request, context, envelope):
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msg = proton.Message()
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if envelope:
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request = common.serialize_msg(request)
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data = {
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"request": request,
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"context": context
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}
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msg.body = jsonutils.dumps(data)
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return msg
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def unmarshal_request(message):
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data = jsonutils.loads(message.body)
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return (data.get("request"), data.get("context"))
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class ProtonIncomingMessage(base.IncomingMessage):
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def __init__(self, listener, ctxt, request, message):
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super(ProtonIncomingMessage, self).__init__(listener, ctxt, request)
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self._reply_to = message.reply_to
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self._correlation_id = message.id
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def reply(self, reply=None, failure=None, log_failure=True):
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"""Schedule a ReplyTask to send the reply."""
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if self._reply_to:
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response = marshal_response(reply=reply, failure=failure)
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response.correlation_id = self._correlation_id
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LOG.debug("Replying to %s", self._correlation_id)
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task = ReplyTask(self._reply_to, response, log_failure)
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self.listener.driver._ctrl.add_task(task)
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else:
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LOG.debug("Ignoring reply as no reply address available")
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def acknowledge(self):
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pass
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def requeue(self):
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pass
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class ProtonListener(base.Listener):
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def __init__(self, driver):
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super(ProtonListener, self).__init__(driver)
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self.incoming = moves.queue.Queue()
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def poll(self):
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message = self.incoming.get()
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request, ctxt = unmarshal_request(message)
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LOG.debug("Returning incoming message")
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return ProtonIncomingMessage(self, ctxt, request, message)
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class ProtonDriver(base.BaseDriver):
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def __init__(self, conf, url,
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default_exchange=None, allowed_remote_exmods=[]):
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# TODO(kgiusti) Remove once driver fully stabilizes:
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LOG.warning("Support for the 'amqp' transport is EXPERIMENTAL.")
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if proton is None or hasattr(controller, "fake_controller"):
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raise NotImplementedError("Proton AMQP C libraries not installed")
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super(ProtonDriver, self).__init__(conf, url, default_exchange,
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allowed_remote_exmods)
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# Create a Controller that connects to the messaging service:
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self._ctrl = controller.Controller(url.hosts, default_exchange, conf)
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# lazy connection setup - don't cause the controller to connect until
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# after the first messaging request:
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self._connect_called = False
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self._lock = threading.Lock()
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def _ensure_connect_called(func):
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"""Causes the controller to connect to the messaging service when it is
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first used. It is safe to push tasks to it whether connected or not,
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but those tasks won't be processed until connection completes.
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"""
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def wrap(self, *args, **kws):
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with self._lock:
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connect_called = self._connect_called
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self._connect_called = True
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if not connect_called:
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self._ctrl.connect()
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return func(self, *args, **kws)
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return wrap
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@_ensure_connect_called
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def send(self, target, ctxt, message,
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wait_for_reply=None, timeout=None, envelope=False,
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retry=None):
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"""Send a message to the given target."""
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# TODO(kgiusti) need to add support for retry
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if retry is not None:
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raise NotImplementedError('"retry" not implemented by'
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'this transport driver')
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request = marshal_request(message, ctxt, envelope)
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expire = 0
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if timeout:
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expire = time.time() + timeout # when the caller times out
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# amqp uses millisecond time values, timeout is seconds
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request.ttl = int(timeout * 1000)
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request.expiry_time = int(expire * 1000)
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LOG.debug("Send to %s", target)
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task = SendTask(target, request, wait_for_reply, expire)
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self._ctrl.add_task(task)
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result = None
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if wait_for_reply:
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# the following can raise MessagingTimeout if no reply received:
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reply = task.get_reply(timeout)
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# TODO(kgiusti) how to handle failure to un-marshal? Must log, and
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# determine best way to communicate this failure back up to the
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# caller
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result = unmarshal_response(reply, self._allowed_remote_exmods)
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LOG.debug("Send to %s returning", target)
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return result
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@_ensure_connect_called
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def send_notification(self, target, ctxt, message, version,
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retry=None):
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"""Send a notification message to the given target."""
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# TODO(kgiusti) need to add support for retry
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if retry is not None:
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raise NotImplementedError('"retry" not implemented by'
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'this transport driver')
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return self.send(target, ctxt, message, envelope=(version == 2.0))
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@_ensure_connect_called
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def listen(self, target):
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"""Construct a Listener for the given target."""
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LOG.debug("Listen to %s", target)
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listener = ProtonListener(self)
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self._ctrl.add_task(ListenTask(target, listener))
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return listener
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@_ensure_connect_called
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def listen_for_notifications(self, targets_and_priorities):
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LOG.debug("Listen for notifications %s", targets_and_priorities)
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listener = ProtonListener(self)
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for target, priority in targets_and_priorities:
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topic = '%s.%s' % (target.topic, priority)
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t = messaging_target.Target(topic=topic)
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self._ctrl.add_task(ListenTask(t, listener, True))
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return listener
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def cleanup(self):
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"""Release all resources."""
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LOG.debug("Cleaning up ProtonDriver")
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self._ctrl.destroy()
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self._ctrl = None
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