_io_kqueue.py 文件源码

def handle_io(self, timeout):
        # max_events must be > 0 or kqueue gets cranky
        # and we generally want this to be strictly larger than the actual
        # number of events we get, so that we can tell that we've gotten
        # all the events in just 1 call.
        max_events = len(self._registered) + 1
        events = []
        while True:
            batch = self._kqueue.control([], max_events, timeout)
            events += batch
            if len(batch) < max_events:
                break
            else:
                timeout = 0
                # and loop back to the start
        for event in events:
            key = (event.ident, event.filter)
            receiver = self._registered[key]
            if event.flags & select.KQ_EV_ONESHOT:
                del self._registered[key]
            if type(receiver) is _core.Task:
                _core.reschedule(receiver, _core.Value(event))
            else:
                receiver.put_nowait(event)

    # kevent registration is complicated -- e.g. aio submission can
    # implicitly perform a EV_ADD, and EVFILT_PROC with NOTE_TRACK will
    # automatically register filters for child processes. So our lowlevel
    # API is *very* low-level: we expose the kqueue itself for adding
    # events or sticking into AIO submission structs, and split waiting
    # off into separate methods. It's your responsibility to make sure
    # that handle_io never receives an event without a corresponding
    # registration! This may be challenging if you want to be careful
    # about e.g. KeyboardInterrupt. Possibly this API could be improved to
    # be more ergonomic...