Source code for taskflow.utils.async_utils

# -*- coding: utf-8 -*-

#    Copyright (C) 2013 Yahoo! Inc. All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
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from concurrent import futures as _futures
from concurrent.futures import _base
import futurist
from oslo_utils import importutils

greenthreading = importutils.try_import('eventlet.green.threading')

from taskflow.utils import eventlet_utils as eu


_DONE_STATES = frozenset([
    _base.CANCELLED_AND_NOTIFIED,
    _base.FINISHED,
])


[docs]def make_completed_future(result): """Make and return a future completed with a given result.""" future = futurist.Future() future.set_result(result) return future
[docs]def wait_for_any(fs, timeout=None): """Wait for one of the futures to complete. Works correctly with both green and non-green futures (but not both together, since this can't be guaranteed to avoid dead-lock due to how the waiting implementations are different when green threads are being used). Returns pair (done futures, not done futures). """ # TODO(harlowja): remove this when # https://review.openstack.org/#/c/196269/ is merged and is made # available. green_fs = sum(1 for f in fs if isinstance(f, futurist.GreenFuture)) if not green_fs: return _futures.wait(fs, timeout=timeout, return_when=_futures.FIRST_COMPLETED) else: non_green_fs = len(fs) - green_fs if non_green_fs: raise RuntimeError("Can not wait on %s green futures and %s" " non-green futures in the same `wait_for_any`" " call" % (green_fs, non_green_fs)) else: return _wait_for_any_green(fs, timeout=timeout)
class _GreenWaiter(object): """Provides the event that wait_for_any() blocks on.""" def __init__(self): self.event = greenthreading.Event() def add_result(self, future): self.event.set() def add_exception(self, future): self.event.set() def add_cancelled(self, future): self.event.set() def _partition_futures(fs): done = set() not_done = set() for f in fs: if f._state in _DONE_STATES: done.add(f) else: not_done.add(f) return done, not_done def _wait_for_any_green(fs, timeout=None): eu.check_for_eventlet(RuntimeError('Eventlet is needed to wait on' ' green futures')) with _base._AcquireFutures(fs): done, not_done = _partition_futures(fs) if done: return _base.DoneAndNotDoneFutures(done, not_done) waiter = _GreenWaiter() for f in fs: f._waiters.append(waiter) waiter.event.wait(timeout) for f in fs: f._waiters.remove(waiter) with _base._AcquireFutures(fs): done, not_done = _partition_futures(fs) return _base.DoneAndNotDoneFutures(done, not_done)