68 lines
2.6 KiB
Python
68 lines
2.6 KiB
Python
# 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 threading
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import eventlet
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class BatchNotifier(object):
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def __init__(self, batch_interval, callback):
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self._pending_events = eventlet.Queue()
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self.callback = callback
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self.batch_interval = batch_interval
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self._mutex = threading.Lock()
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def queue_event(self, event):
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"""Called to queue sending an event with the next batch of events.
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Sending events individually, as they occur, has been problematic as it
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can result in a flood of sends. Previously, there was a loopingcall
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thread that would send batched events on a periodic interval. However,
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maintaining a persistent thread in the loopingcall was also
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problematic.
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This replaces the loopingcall with a mechanism that creates a
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short-lived thread on demand whenever an event is queued. That thread
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will check if the lock is released, send all queued events and then
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sleep for 'batch_interval' seconds. If at the end of this sleep time,
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other threads have added new events to the event queue, the same thread
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will process them.
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At the same time, other threads will be able to add new events to the
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queue and will spawn new "synced_send" threads to process them. But if
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the mutex is locked, the spawned thread will end immediately.
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:param event: the event that occurred.
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"""
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if not event:
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return
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self._pending_events.put(event)
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def synced_send():
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if not self._mutex.locked():
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with self._mutex:
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while not self._pending_events.empty():
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self._notify()
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# sleeping after send while holding the lock allows
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# subsequent events to batch up
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eventlet.sleep(self.batch_interval)
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eventlet.spawn_n(synced_send)
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def _notify(self):
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batched_events = []
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while not self._pending_events.empty():
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batched_events.append(self._pending_events.get())
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self.callback(batched_events)
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