b014fc7d48
Move the currently existing green future executor and associated code to a new futures types module so that it can be accessed from this new location (TODO: deprecate the old location and link the old to the new for one release so that we can remove the old link in N + 1 release). This unifies the API that the existing pool (thread or process) future executors and the green thread pool future executor, and the newly added synchronous executor (replacing the previous `make_completed_future` function) provide so there usage is as seamless as possible. Part of blueprint top-level-types Change-Id: Ie5500eaa7f4425edb604b2dd13a15f82909a673b
111 lines
3.3 KiB
Python
111 lines
3.3 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2013 Yahoo! Inc. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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from concurrent import futures as _futures
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from concurrent.futures import _base
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try:
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from eventlet.green import threading as greenthreading
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EVENTLET_AVAILABLE = True
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except ImportError:
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EVENTLET_AVAILABLE = False
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from taskflow.types import futures
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_DONE_STATES = frozenset([
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_base.CANCELLED_AND_NOTIFIED,
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_base.FINISHED,
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])
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def make_completed_future(result, exception=False):
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"""Make a future completed with a given result."""
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future = futures.Future()
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if exception:
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future.set_exception(result)
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else:
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future.set_result(result)
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return future
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def wait_for_any(fs, timeout=None):
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"""Wait for one of the futures to complete.
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Works correctly with both green and non-green futures (but not both
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together, since this can't be guaranteed to avoid dead-lock due to how
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the waiting implementations are different when green threads are being
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used).
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Returns pair (done futures, not done futures).
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"""
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green_fs = sum(1 for f in fs if isinstance(f, futures.GreenFuture))
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if not green_fs:
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return tuple(_futures.wait(fs, timeout=timeout,
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return_when=_futures.FIRST_COMPLETED))
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else:
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non_green_fs = len(fs) - green_fs
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if non_green_fs:
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raise RuntimeError("Can not wait on %s green futures and %s"
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" non-green futures in the same `wait_for_any`"
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" call" % (green_fs, non_green_fs))
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else:
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return _wait_for_any_green(fs, timeout=timeout)
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class _GreenWaiter(object):
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"""Provides the event that wait_for_any() blocks on."""
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def __init__(self):
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self.event = greenthreading.Event()
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def add_result(self, future):
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self.event.set()
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def add_exception(self, future):
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self.event.set()
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def add_cancelled(self, future):
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self.event.set()
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def _wait_for_any_green(fs, timeout=None):
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assert EVENTLET_AVAILABLE, 'eventlet is needed to wait on green futures'
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def _partition_futures(fs):
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done = set()
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not_done = set()
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for f in fs:
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if f._state in _DONE_STATES:
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done.add(f)
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else:
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not_done.add(f)
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return (done, not_done)
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with _base._AcquireFutures(fs):
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(done, not_done) = _partition_futures(fs)
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if done:
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return (done, not_done)
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waiter = _GreenWaiter()
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for f in fs:
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f._waiters.append(waiter)
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waiter.event.wait(timeout)
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for f in fs:
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f._waiters.remove(waiter)
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with _base._AcquireFutures(fs):
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return _partition_futures(fs)
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