d700c38279
This change formalises locking in MessageHandlingServer. It allows the user to make calls in any order and it will ensure, with locking, that these will be reordered appropriately. It also adds locking for internal state when using the blocking executor, which closes a number of races. It fixes a regression introduced in change gI3cfbe1bf02d451e379b1dcc23dacb0139c03be76. If multiple threads called wait() simultaneously, only 1 of them would wait and the others would return immediately, despite message handling not having completed. With this change only 1 will call the underlying wait, but all will wait on its completion. We add a common logging mechanism when waiting too long. Specifically, we now log a single message when waiting on any lock for longer than 30 seconds. We remove DummyCondition as it no longer has any users. Change-Id: I9d516b208446963dcd80b75e2d5a2cecb1187efa
131 lines
4.1 KiB
Python
131 lines
4.1 KiB
Python
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# Copyright 2013 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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import logging
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import threading
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LOG = logging.getLogger(__name__)
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def version_is_compatible(imp_version, version):
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"""Determine whether versions are compatible.
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:param imp_version: The version implemented
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:param version: The version requested by an incoming message.
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"""
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version_parts = version.split('.')
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imp_version_parts = imp_version.split('.')
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try:
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rev = version_parts[2]
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except IndexError:
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rev = 0
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try:
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imp_rev = imp_version_parts[2]
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except IndexError:
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imp_rev = 0
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if int(version_parts[0]) != int(imp_version_parts[0]): # Major
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return False
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if int(version_parts[1]) > int(imp_version_parts[1]): # Minor
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return False
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if (int(version_parts[1]) == int(imp_version_parts[1]) and
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int(rev) > int(imp_rev)): # Revision
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return False
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return True
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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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def fetch_current_thread_functor():
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# Until https://github.com/eventlet/eventlet/issues/172 is resolved
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# or addressed we have to use complicated workaround to get a object
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# that will not be recycled; the usage of threading.current_thread()
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# doesn't appear to currently be monkey patched and therefore isn't
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# reliable to use (and breaks badly when used as all threads share
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# the same current_thread() object)...
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try:
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import eventlet
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from eventlet import patcher
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green_threaded = patcher.is_monkey_patched('thread')
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except ImportError:
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green_threaded = False
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if green_threaded:
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return lambda: eventlet.getcurrent()
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else:
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return lambda: threading.current_thread()
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class DummyLock(object):
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def acquire(self):
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pass
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def release(self):
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pass
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def __enter__(self):
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self.acquire()
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def __exit__(self, type, value, traceback):
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self.release()
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