buffering.py 文件源码

def buffered_gen_threaded(source_gen, buffer_size=5):
    """
    Generator that runs a slow source generator in a separate thread. Beware of the GIL!
    buffer_size: the maximal number of items to pre-generate (length of the buffer)
    """
    if buffer_size < 2:
        raise RuntimeError("Minimal buffer size is 2!")

    buffer = Queue.Queue(maxsize=buffer_size - 1)

    # the effective buffer size is one less, because the generation process
    # will generate one extra element and block until there is room in the buffer.

    def _buffered_generation_thread(source_gen, buffer):
        for data in source_gen:
            buffer.put(data, block=True)
        buffer.put(None)  # sentinel: signal the end of the iterator

    thread = threading.Thread(target=_buffered_generation_thread, args=(source_gen, buffer))
    thread.daemon = True
    thread.start()

    for data in iter(buffer.get, None):
        yield data