websocket.py 文件源码

def read_message(self, callback=None):
        """Reads a message from the WebSocket server.

        If on_message_callback was specified at WebSocket
        initialization, this function will never return messages

        Returns a future whose result is the message, or None
        if the connection is closed.  If a callback argument
        is given it will be called with the future when it is
        ready.
        """
        assert self.read_future is None
        future = TracebackFuture()
        if self.read_queue:
            future.set_result(self.read_queue.popleft())
        else:
            self.read_future = future
        if callback is not None:
            self.io_loop.add_future(future, callback)
        return future