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# -*- 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 collections
import threading
from concurrent import futures
from oslo.config import cfg
from oslo.utils import excutils
from oslo_messaging._executors import base
_pool_opts = [
cfg.IntOpt('rpc_thread_pool_size',
default=64,
help='Size of RPC thread pool.'),
]
class PooledExecutor(base.ExecutorBase):
"""A message executor which integrates with threads.
A message process that polls for messages from a dispatching thread and
on reception of an incoming message places the message to be processed in
a thread pool to be executed at a later time.
"""
# NOTE(harlowja): if eventlet is being used and the thread module is monkey
# patched this should/is supposed to work the same as the eventlet based
# executor.
# NOTE(harlowja): Make it somewhat easy to change this via
# inheritance (since there does exist other executor types that could be
# used/tried here).
_executor_cls = futures.ThreadPoolExecutor
_event_cls = threading.Event
_lock_cls = threading.Lock
_thread_cls = threading.Thread
def __init__(self, conf, listener, dispatcher):
super(PooledExecutor, self).__init__(conf, listener, dispatcher)
self.conf.register_opts(_pool_opts)
self._poller = None
self._executor = None
self._tombstone = self._event_cls()
self._incomplete = collections.deque()
self._mutator = self._lock_cls()
@excutils.forever_retry_uncaught_exceptions
def _runner(self):
while not self._tombstone.is_set():
incoming = self.listener.poll()
if incoming is None:
continue
callback = self.dispatcher(incoming, self._executor_callback)
try:
fut = self._executor.submit(callback.run)
except RuntimeError:
# This is triggered when the executor has been shutdown...
#
# TODO(harlowja): should we put whatever we pulled off back
# since when this is thrown it means the executor has been
# shutdown already??
callback.done()
return
else:
with self._mutator:
self._incomplete.append(fut)
# Run the other post processing of the callback when done...
fut.add_done_callback(lambda f: callback.done())
def start(self):
if self._executor is None:
self._executor = self._executor_cls(self.conf.rpc_thread_pool_size)
self._tombstone.clear()
if self._poller is None or not self._poller.is_alive():
self._poller = self._thread_cls(target=self._runner)
self._poller.daemon = True
self._poller.start()
def stop(self):
if self._executor is not None:
self._executor.shutdown(wait=False)
self._tombstone.set()
self.listener.stop()
def wait(self):
# TODO(harlowja): this method really needs a timeout.
if self._poller is not None:
self._tombstone.wait()
self._poller.join()
self._poller = None
if self._executor is not None:
with self._mutator:
incomplete_fs = list(self._incomplete)
self._incomplete.clear()
if incomplete_fs:
futures.wait(incomplete_fs, return_when=futures.ALL_COMPLETED)
self._executor = None