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- /*
- * Copyright 2004-present Facebook, Inc.
- *
- * 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 under the License.
- */
- #pragma once
- #include <atomic>
- #include <condition_variable>
- namespace folly {
- /**
- * The behavior of the atomic_wait() family of functions is semantically
- * identical to futex(). Correspondingly, calling atomic_notify_one(),
- * atomic_notify_all() is identical to futexWake() with 1 and
- * std::numeric_limits<int>::max() respectively
- *
- * The difference here compared to the futex API above is that it works with
- * all types of atomic widths. When a 32 bit atomic integer is used, the
- * implementation falls back to using futex() if possible, and the
- * compatibility implementation for non-linux systems otherwise. For all
- * other integer widths, the compatibility implementation is used
- *
- * The templating of this API is changed from the standard in the following
- * ways
- *
- * - At the time of writing, libstdc++'s implementation of std::atomic<> does
- * not include the value_type alias. So we rely on the atomic type being a
- * template class such that the first type is the underlying value type
- * - The Atom parameter allows this API to be compatible with
- * DeterministicSchedule testing.
- * - atomic_wait_until() does not exist in the linked paper, the version here
- * is identical to futexWaitUntil() and returns std::cv_status
- */
- // mimic: std::atomic_wait, p1135r0
- template <typename Integer>
- void atomic_wait(const std::atomic<Integer>* atomic, Integer expected);
- template <typename Integer, typename Clock, typename Duration>
- std::cv_status atomic_wait_until(
- const std::atomic<Integer>* atomic,
- Integer expected,
- const std::chrono::time_point<Clock, Duration>& deadline);
- // mimic: std::atomic_notify_one, p1135r0
- template <typename Integer>
- void atomic_notify_one(const std::atomic<Integer>* atomic);
- // mimic: std::atomic_notify_all, p1135r0
- template <typename Integer>
- void atomic_notify_all(const std::atomic<Integer>* atomic);
- // mimic: std::atomic_uint_fast_wait_t, p1135r0
- using atomic_uint_fast_wait_t = std::atomic<std::uint32_t>;
- } // namespace folly
- #include <folly/synchronization/AtomicNotification-inl.h>
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