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546 lines
18 KiB
546 lines
18 KiB
"""Future-returning APIs for coroutines."""
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# Copyright (c) PyZMQ Developers.
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# Distributed under the terms of the Modified BSD License.
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from collections import namedtuple, deque
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from itertools import chain
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from zmq import EVENTS, POLLOUT, POLLIN
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import zmq as _zmq
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_FutureEvent = namedtuple('_FutureEvent', ('future', 'kind', 'kwargs', 'msg'))
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# These are incomplete classes and need a Mixin for compatibility with an eventloop
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# defining the followig attributes:
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#
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# _Future
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# _READ
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# _WRITE
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# _default_loop()
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class _AsyncPoller(_zmq.Poller):
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"""Poller that returns a Future on poll, instead of blocking."""
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def poll(self, timeout=-1):
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"""Return a Future for a poll event"""
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future = self._Future()
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if timeout == 0:
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try:
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result = super(_AsyncPoller, self).poll(0)
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except Exception as e:
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future.set_exception(e)
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else:
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future.set_result(result)
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return future
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loop = self._default_loop()
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# register Future to be called as soon as any event is available on any socket
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watcher = self._Future()
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# watch raw sockets:
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raw_sockets = []
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def wake_raw(*args):
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if not watcher.done():
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watcher.set_result(None)
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watcher.add_done_callback(lambda f: self._unwatch_raw_sockets(loop, *raw_sockets))
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for socket, mask in self.sockets:
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if isinstance(socket, _zmq.Socket):
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if not isinstance(socket, self._socket_class):
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# it's a blocking zmq.Socket, wrap it in async
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socket = self._socket_class.from_socket(socket)
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if mask & _zmq.POLLIN:
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socket._add_recv_event('poll', future=watcher)
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if mask & _zmq.POLLOUT:
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socket._add_send_event('poll', future=watcher)
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else:
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raw_sockets.append(socket)
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evt = 0
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if mask & _zmq.POLLIN:
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evt |= self._READ
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if mask & _zmq.POLLOUT:
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evt |= self._WRITE
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self._watch_raw_socket(loop, socket, evt, wake_raw)
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def on_poll_ready(f):
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if future.done():
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return
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if watcher.cancelled():
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try:
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future.cancel()
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except RuntimeError:
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# RuntimeError may be called during teardown
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pass
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return
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if watcher.exception():
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future.set_exception(watcher.exception())
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else:
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try:
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result = super(_AsyncPoller, self).poll(0)
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except Exception as e:
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future.set_exception(e)
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else:
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future.set_result(result)
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watcher.add_done_callback(on_poll_ready)
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if timeout is not None and timeout > 0:
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# schedule cancel to fire on poll timeout, if any
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def trigger_timeout():
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if not watcher.done():
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watcher.set_result(None)
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timeout_handle = loop.call_later(
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1e-3 * timeout,
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trigger_timeout
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)
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def cancel_timeout(f):
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if hasattr(timeout_handle, 'cancel'):
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timeout_handle.cancel()
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else:
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loop.remove_timeout(timeout_handle)
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future.add_done_callback(cancel_timeout)
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def cancel_watcher(f):
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if not watcher.done():
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watcher.cancel()
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future.add_done_callback(cancel_watcher)
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return future
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class _AsyncSocket(_zmq.Socket):
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# Warning : these class variables are only here to allow to call super().__setattr__.
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# They be overridden at instance initialization and not shared in the whole class
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_recv_futures = None
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_send_futures = None
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_state = 0
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_shadow_sock = None
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_poller_class = _AsyncPoller
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io_loop = None
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_fd = None
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def __init__(self, context=None, socket_type=-1, io_loop=None, **kwargs):
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if isinstance(context, _zmq.Socket):
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context, from_socket = (None, context)
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else:
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from_socket = kwargs.pop('_from_socket', None)
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if from_socket is not None:
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super(_AsyncSocket, self).__init__(shadow=from_socket.underlying)
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self._shadow_sock = from_socket
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else:
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super(_AsyncSocket, self).__init__(context, socket_type, **kwargs)
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self._shadow_sock = _zmq.Socket.shadow(self.underlying)
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self.io_loop = io_loop or self._default_loop()
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self._recv_futures = deque()
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self._send_futures = deque()
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self._state = 0
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self._fd = self._shadow_sock.FD
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self._init_io_state()
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@classmethod
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def from_socket(cls, socket, io_loop=None):
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"""Create an async socket from an existing Socket"""
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return cls(_from_socket=socket, io_loop=io_loop)
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def close(self, linger=None):
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if not self.closed:
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for event in list(chain(self._recv_futures, self._send_futures)):
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if not event.future.done():
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try:
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event.future.cancel()
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except RuntimeError:
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# RuntimeError may be called during teardown
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pass
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self._clear_io_state()
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super(_AsyncSocket, self).close(linger=linger)
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close.__doc__ = _zmq.Socket.close.__doc__
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def get(self, key):
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result = super(_AsyncSocket, self).get(key)
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if key == EVENTS:
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self._schedule_remaining_events(result)
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return result
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get.__doc__ = _zmq.Socket.get.__doc__
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def recv_multipart(self, flags=0, copy=True, track=False):
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"""Receive a complete multipart zmq message.
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Returns a Future whose result will be a multipart message.
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"""
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return self._add_recv_event('recv_multipart',
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dict(flags=flags, copy=copy, track=track)
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)
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def recv(self, flags=0, copy=True, track=False):
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"""Receive a single zmq frame.
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Returns a Future, whose result will be the received frame.
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Recommend using recv_multipart instead.
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"""
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return self._add_recv_event('recv',
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dict(flags=flags, copy=copy, track=track)
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)
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def send_multipart(self, msg, flags=0, copy=True, track=False, **kwargs):
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"""Send a complete multipart zmq message.
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Returns a Future that resolves when sending is complete.
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"""
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kwargs['flags'] = flags
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kwargs['copy'] = copy
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kwargs['track'] = track
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return self._add_send_event('send_multipart', msg=msg, kwargs=kwargs)
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def send(self, msg, flags=0, copy=True, track=False, **kwargs):
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"""Send a single zmq frame.
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Returns a Future that resolves when sending is complete.
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Recommend using send_multipart instead.
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"""
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kwargs['flags'] = flags
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kwargs['copy'] = copy
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kwargs['track'] = track
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kwargs.update(dict(flags=flags, copy=copy, track=track))
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return self._add_send_event('send', msg=msg, kwargs=kwargs)
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def _deserialize(self, recvd, load):
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"""Deserialize with Futures"""
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f = self._Future()
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def _chain(_):
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"""Chain result through serialization to recvd"""
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if f.done():
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return
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if recvd.exception():
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f.set_exception(recvd.exception())
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else:
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buf = recvd.result()
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try:
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loaded = load(buf)
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except Exception as e:
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f.set_exception(e)
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else:
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f.set_result(loaded)
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recvd.add_done_callback(_chain)
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def _chain_cancel(_):
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"""Chain cancellation from f to recvd"""
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if recvd.done():
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return
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if f.cancelled():
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recvd.cancel()
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f.add_done_callback(_chain_cancel)
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return f
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def poll(self, timeout=None, flags=_zmq.POLLIN):
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"""poll the socket for events
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returns a Future for the poll results.
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"""
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if self.closed:
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raise _zmq.ZMQError(_zmq.ENOTSUP)
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p = self._poller_class()
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p.register(self, flags)
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f = p.poll(timeout)
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future = self._Future()
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def unwrap_result(f):
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if future.done():
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return
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if f.cancelled():
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try:
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future.cancel()
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except RuntimeError:
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# RuntimeError may be called during teardown
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pass
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return
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if f.exception():
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future.set_exception(f.exception())
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else:
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evts = dict(f.result())
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future.set_result(evts.get(self, 0))
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if f.done():
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# hook up result if
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unwrap_result(f)
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else:
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f.add_done_callback(unwrap_result)
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return future
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def _add_timeout(self, future, timeout):
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"""Add a timeout for a send or recv Future"""
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def future_timeout():
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if future.done():
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# future already resolved, do nothing
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return
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# raise EAGAIN
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future.set_exception(_zmq.Again())
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self._call_later(timeout, future_timeout)
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def _call_later(self, delay, callback):
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"""Schedule a function to be called later
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Override for different IOLoop implementations
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Tornado and asyncio happen to both have ioloop.call_later
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with the same signature.
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"""
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self.io_loop.call_later(delay, callback)
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@staticmethod
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def _remove_finished_future(future, event_list):
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"""Make sure that futures are removed from the event list when they resolve
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Avoids delaying cleanup until the next send/recv event,
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which may never come.
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"""
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for f_idx, (f, kind, kwargs, _) in enumerate(event_list):
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if f is future:
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break
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else:
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return
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# "future" instance is shared between sockets, but each socket has its own event list.
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event_list.remove(event_list[f_idx])
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def _add_recv_event(self, kind, kwargs=None, future=None):
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"""Add a recv event, returning the corresponding Future"""
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f = future or self._Future()
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if kind.startswith('recv') and kwargs.get('flags', 0) & _zmq.DONTWAIT:
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# short-circuit non-blocking calls
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recv = getattr(self._shadow_sock, kind)
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try:
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r = recv(**kwargs)
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except Exception as e:
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f.set_exception(e)
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else:
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f.set_result(r)
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return f
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# we add it to the list of futures before we add the timeout as the
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# timeout will remove the future from recv_futures to avoid leaks
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self._recv_futures.append(
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_FutureEvent(f, kind, kwargs, msg=None)
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)
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# Don't let the Future sit in _recv_events after it's done
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f.add_done_callback(lambda f: self._remove_finished_future(f, self._recv_futures))
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if hasattr(_zmq, 'RCVTIMEO'):
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timeout_ms = self._shadow_sock.rcvtimeo
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if timeout_ms >= 0:
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self._add_timeout(f, timeout_ms * 1e-3)
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if self._shadow_sock.get(EVENTS) & POLLIN:
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# recv immediately, if we can
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self._handle_recv()
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if self._recv_futures:
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self._add_io_state(POLLIN)
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return f
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def _add_send_event(self, kind, msg=None, kwargs=None, future=None):
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"""Add a send event, returning the corresponding Future"""
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f = future or self._Future()
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# attempt send with DONTWAIT if no futures are waiting
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# short-circuit for sends that will resolve immediately
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# only call if no send Futures are waiting
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if (
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kind in ('send', 'send_multipart')
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and not self._send_futures
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):
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flags = kwargs.get('flags', 0)
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nowait_kwargs = kwargs.copy()
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nowait_kwargs['flags'] = flags | _zmq.DONTWAIT
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# short-circuit non-blocking calls
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send = getattr(self._shadow_sock, kind)
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# track if the send resolved or not
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# (EAGAIN if DONTWAIT is not set should proceed with)
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finish_early = True
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try:
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r = send(msg, **nowait_kwargs)
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except _zmq.Again as e:
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if flags & _zmq.DONTWAIT:
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f.set_exception(e)
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else:
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# EAGAIN raised and DONTWAIT not requested,
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# proceed with async send
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finish_early = False
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except Exception as e:
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f.set_exception(e)
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else:
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f.set_result(r)
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if finish_early:
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# short-circuit resolved, return finished Future
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# schedule wake for recv if there are any receivers waiting
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if self._recv_futures:
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self._schedule_remaining_events()
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return f
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# we add it to the list of futures before we add the timeout as the
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# timeout will remove the future from recv_futures to avoid leaks
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self._send_futures.append(
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_FutureEvent(f, kind, kwargs=kwargs, msg=msg)
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)
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# Don't let the Future sit in _send_futures after it's done
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f.add_done_callback(lambda f: self._remove_finished_future(f, self._send_futures))
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if hasattr(_zmq, 'SNDTIMEO'):
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timeout_ms = self._shadow_sock.get(_zmq.SNDTIMEO)
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if timeout_ms >= 0:
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self._add_timeout(f, timeout_ms * 1e-3)
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self._add_io_state(POLLOUT)
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return f
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def _handle_recv(self):
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"""Handle recv events"""
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if not self._shadow_sock.get(EVENTS) & POLLIN:
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# event triggered, but state may have been changed between trigger and callback
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return
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f = None
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while self._recv_futures:
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f, kind, kwargs, _ = self._recv_futures.popleft()
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# skip any cancelled futures
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if f.done():
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f = None
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else:
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break
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if not self._recv_futures:
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self._drop_io_state(POLLIN)
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if f is None:
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return
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if kind == 'poll':
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# on poll event, just signal ready, nothing else.
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f.set_result(None)
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return
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elif kind == 'recv_multipart':
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recv = self._shadow_sock.recv_multipart
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elif kind == 'recv':
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recv = self._shadow_sock.recv
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else:
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raise ValueError("Unhandled recv event type: %r" % kind)
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kwargs['flags'] |= _zmq.DONTWAIT
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try:
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result = recv(**kwargs)
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except Exception as e:
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f.set_exception(e)
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else:
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f.set_result(result)
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def _handle_send(self):
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if not self._shadow_sock.get(EVENTS) & POLLOUT:
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# event triggered, but state may have been changed between trigger and callback
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return
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f = None
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while self._send_futures:
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f, kind, kwargs, msg = self._send_futures.popleft()
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# skip any cancelled futures
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if f.done():
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f = None
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else:
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break
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if not self._send_futures:
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self._drop_io_state(POLLOUT)
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if f is None:
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return
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if kind == 'poll':
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# on poll event, just signal ready, nothing else.
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f.set_result(None)
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return
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elif kind == 'send_multipart':
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send = self._shadow_sock.send_multipart
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elif kind == 'send':
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send = self._shadow_sock.send
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else:
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raise ValueError("Unhandled send event type: %r" % kind)
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kwargs['flags'] |= _zmq.DONTWAIT
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try:
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result = send(msg, **kwargs)
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except Exception as e:
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f.set_exception(e)
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else:
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f.set_result(result)
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# event masking from ZMQStream
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def _handle_events(self, fd=0, events=0):
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"""Dispatch IO events to _handle_recv, etc."""
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zmq_events = self._shadow_sock.get(EVENTS)
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if zmq_events & _zmq.POLLIN:
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self._handle_recv()
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if zmq_events & _zmq.POLLOUT:
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self._handle_send()
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self._schedule_remaining_events()
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def _schedule_remaining_events(self, events=None):
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"""Schedule a call to handle_events next loop iteration
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If there are still events to handle.
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"""
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# edge-triggered handling
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# allow passing events in, in case this is triggered by retrieving events,
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# so we don't have to retrieve it twice.
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if self._state == 0:
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# not watching for anything, nothing to schedule
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return
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if events is None:
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events = self._shadow_sock.get(EVENTS)
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if events & self._state:
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self._call_later(0, self._handle_events)
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def _add_io_state(self, state):
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"""Add io_state to poller."""
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if self._state != state:
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state = self._state = self._state | state
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self._update_handler(self._state)
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def _drop_io_state(self, state):
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"""Stop poller from watching an io_state."""
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if self._state & state:
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self._state = self._state & (~state)
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self._update_handler(self._state)
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def _update_handler(self, state):
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"""Update IOLoop handler with state.
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zmq FD is always read-only.
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"""
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self._schedule_remaining_events()
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def _init_io_state(self):
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"""initialize the ioloop event handler"""
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self.io_loop.add_handler(self._shadow_sock, self._handle_events, self._READ)
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self._call_later(0, self._handle_events)
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def _clear_io_state(self):
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"""unregister the ioloop event handler
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called once during close
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"""
|
|
fd = self._shadow_sock
|
|
if self._shadow_sock.closed:
|
|
fd = self._fd
|
|
self.io_loop.remove_handler(fd)
|
|
|
|
|