7dbd17a5aa
Former-commit-id:133dc97f67[formerlya02aeb236c] [formerly9f19e3f712] [formerly133dc97f67[formerlya02aeb236c] [formerly9f19e3f712] [formerly06a8b51d6d[formerly9f19e3f712[formerly 64fa9254b946eae7e61bbc3f513b7c3696c4f54f]]]] Former-commit-id:06a8b51d6dFormer-commit-id:9bb8decbcf[formerly8e80217e59] [formerly377dcd10b9[formerly3360eb6c5f]] Former-commit-id:377dcd10b9Former-commit-id:e2ecdcfe33
88 lines
2.7 KiB
Python
88 lines
2.7 KiB
Python
#
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# Licensed to the Apache Software Foundation (ASF) under one
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# or more contributor license agreements. See the NOTICE file
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# distributed with this work for additional information
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# regarding copyright ownership. The ASF licenses this file
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# to you under the Apache License, Version 2.0 (the
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# "License"); you may not use this file except in compliance
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# with the License. You may obtain 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,
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# software distributed under the License is distributed on an
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# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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# KIND, either express or implied. See the License for the
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# specific language governing permissions and limitations
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# under the License.
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#
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"""
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This module augments the standard python multithreaded Queue
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implementation to add a close() method so that threads blocking on the
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content of a queue can be notified if the queue is no longer in use.
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"""
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from Queue import Queue as BaseQueue, Empty, Full
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from threading import Thread
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from exceptions import Closed
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class Queue(BaseQueue):
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END = object()
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STOP = object()
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def __init__(self, *args, **kwargs):
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BaseQueue.__init__(self, *args, **kwargs)
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self.error = None
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self.listener = None
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self.exc_listener = None
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self.thread = None
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def close(self, error = None):
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self.error = error
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self.put(Queue.END)
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if self.thread is not None:
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self.thread.join()
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self.thread = None
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def get(self, block = True, timeout = None):
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result = BaseQueue.get(self, block, timeout)
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if result == Queue.END:
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# this guarantees that any other waiting threads or any future
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# calls to get will also result in a Closed exception
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self.put(Queue.END)
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raise Closed(self.error)
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else:
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return result
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def listen(self, listener, exc_listener = None):
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if listener is None and exc_listener is not None:
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raise ValueError("cannot set exception listener without setting listener")
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if listener is None:
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if self.thread is not None:
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self.put(Queue.STOP)
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# loop and timed join permit keyboard interrupts to work
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while self.thread.isAlive():
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self.thread.join(3)
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self.thread = None
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self.listener = listener
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self.exc_listener = exc_listener
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if listener is not None and self.thread is None:
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self.thread = Thread(target = self.run)
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self.thread.setDaemon(True)
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self.thread.start()
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def run(self):
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while True:
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try:
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o = self.get()
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if o == Queue.STOP: break
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self.listener(o)
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except Closed, e:
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if self.exc_listener is not None:
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self.exc_listener(e)
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break
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