零q zmq.Poller & stdin

Question

是否可以使用zmq.Poller来轮询stdin上的数据可用性？如果不是，在某个时候(理想情况下)，在zeromq套接字和stdin上轮询数据的最有效等待是什么？

Answer 1

是的，zmq计票器确实支持本地do，包括stdin，等等，所以您只需要检查sys.stdin.fileno()。

poller = zmq.Poller()
poller.register(sys.stdin, zmq.POLLIN)
poller.register(mysocket, zmq.POLLIN)
evts = dict(poller.poll(1000))
stdin_ready = evts.get(sys.stdin.fileno(), False)
socket_ready = evts.get(mysocket, False)

Answer 2

如果您确信您永远不会在Windows上运行，您可以简单地将sys.stdin注册到zmq.Poller (作为described by minrk, above)。

但是，select() implementation in Winsock只支持套接字，不能用于轮询“常规”文件描述符(如标准输入)。因此，在Windows上运行时，需要将标准输入与inproc传输上的0MQ套接字连接起来。

建议使用独占对套接字实现：

def forward_lines(stream, socket):
    """Read lines from `stream` and send them over `socket`."""
    try:
        line = stream.readline()
        while line:
            socket.send(line[:-1])
            line = stream.readline()
        socket.send('')  # send "eof message".
    finally:
        # NOTE: `zmq.Context.term()` in the main thread will block until this
        #       socket is closed, so we can't run this function in daemon
        #       thread hoping that it will just close itself.
        socket.close()


def forward_standard_input(context):
    """Start a thread that will bridge the standard input to a 0MQ socket and
    return an exclusive pair socket from which you can read lines retrieved
    from the standard input.  You will receive a final empty line when the EOF
    character is input to the keyboard."""
    reader = context.socket(zmq.PAIR)
    reader.connect('inproc://standard-input')
    writer = context.socket(zmq.PAIR)
    writer.bind('inproc://standard-input')
    thread = threading.Thread(target=forward_lines,
                              args=(sys.stdin, writer))
    thread.start()
    return reader


if __name__ == '__main__':
    context = zmq.Context()
    reader = forward_standard_input(context)
    poller = zmq.Poller()
    poller.register(reader, zmq.POLLIN)
    poller.register(...)

    events = dict(poller.poll())
    if events.get(reader, 0) & zmq.POLLIN:
        line = reader.recv()
        # process line.
    if events.get(..., 0) & zmq.POLLIN:
        # ...