115 lines
3.5 KiB
Python
115 lines
3.5 KiB
Python
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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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import abc
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import logging
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import six
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from oslo_messaging._i18n import _
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__all__ = [
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"DispatcherBase",
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"DispatcherExecutorContext"
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]
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LOG = logging.getLogger(__name__)
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class DispatcherExecutorContext(object):
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"""Dispatcher executor context helper
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A dispatcher can have work to do before and after the dispatch of the
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request in the main server thread while the dispatcher itself can be
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done in its own thread.
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The executor can use the helper like this:
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callback = dispatcher(incoming)
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callback.prepare()
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thread = MyWhateverThread()
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thread.on_done(callback.done)
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thread.run(callback.run)
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"""
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def __init__(self, incoming, dispatch, executor_callback=None,
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post=None):
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self._result = None
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self._incoming = incoming
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self._dispatch = dispatch
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self._post = post
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self._executor_callback = executor_callback
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def run(self):
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"""The incoming message dispath itself
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Can be run in an other thread/greenlet/corotine if the executor is
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able to do it.
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"""
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try:
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self._result = self._dispatch(self._incoming,
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self._executor_callback)
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except Exception:
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msg = _('The dispatcher method must catches all exceptions')
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LOG.exception(msg)
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raise RuntimeError(msg)
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def done(self):
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"""Callback after the incoming message have been dispathed
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Should be ran in the main executor thread/greenlet/corotine
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"""
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# FIXME(sileht): this is not currently true, this works only because
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# the driver connection used for polling write on the wire only to
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# ack/requeue message, but what if one day, the driver do something
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# else
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if self._post is not None:
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self._post(self._incoming, self._result)
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@six.add_metaclass(abc.ABCMeta)
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class DispatcherBase(object):
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"Base class for dispatcher"
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batch_size = 1
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"Number of messages to wait before calling endpoints callacks"
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batch_timeout = None
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"Number of seconds to wait before calling endpoints callacks"
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@abc.abstractmethod
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def _listen(self, transport):
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"""Initiate the driver Listener
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Usualy the driver Listener is start with the transport helper methods:
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* transport._listen()
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* transport._listen_for_notifications()
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:param transport: the transport object
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:type transport: oslo_messaging.transport.Transport
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:returns: a driver Listener object
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:rtype: oslo_messaging._drivers.base.Listener
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"""
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@abc.abstractmethod
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def __call__(self, incoming, executor_callback=None):
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"""Called by the executor to get the DispatcherExecutorContext
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:param incoming: list of messages
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:type incoming: oslo_messging._drivers.base.IncomingMessage
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:returns: DispatcherExecutorContext
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:rtype: DispatcherExecutorContext
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"""
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