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Threaded generator wrapper for Python
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# A simple generator wrapper, not sure if it's good for anything at all. | |
# With basic python threading | |
from threading import Thread | |
try: | |
from queue import Queue | |
except ImportError: | |
from Queue import Queue | |
# ... or use multiprocessing versions | |
# WARNING: use sentinel based on value, not identity | |
from multiprocessing import Process, Queue as MpQueue | |
class ThreadedGenerator(object): | |
""" | |
Generator that runs on a separate thread, returning values to calling | |
thread. Care must be taken that the iterator does not mutate any shared | |
variables referenced in the calling thread. | |
""" | |
def __init__(self, iterator, | |
sentinel=object(), | |
queue_maxsize=0, | |
daemon=False, | |
Thread=Thread, | |
Queue=Queue): | |
self._iterator = iterator | |
self._sentinel = sentinel | |
self._queue = Queue(maxsize=queue_maxsize) | |
self._thread = Thread( | |
name=repr(iterator), | |
target=self._run | |
) | |
self._thread.daemon = daemon | |
def __repr__(self): | |
return 'ThreadedGenerator({!r})'.format(self._iterator) | |
def _run(self): | |
try: | |
for value in self._iterator: | |
self._queue.put(value) | |
finally: | |
self._queue.put(self._sentinel) | |
def __iter__(self): | |
self._thread.start() | |
for value in iter(self._queue.get, self._sentinel): | |
yield value | |
self._thread.join() |
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