91 lines
3.3 KiB
C++
91 lines
3.3 KiB
C++
/**************************************************************************/
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/* semaphore.h */
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/**************************************************************************/
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/* This file is part of: */
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/* GODOT ENGINE */
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/* https://godotengine.org */
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/**************************************************************************/
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
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/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
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/* */
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/* Permission is hereby granted, free of charge, to any person obtaining */
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/* a copy of this software and associated documentation files (the */
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/* "Software"), to deal in the Software without restriction, including */
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/* without limitation the rights to use, copy, modify, merge, publish, */
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/* distribute, sublicense, and/or sell copies of the Software, and to */
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/* permit persons to whom the Software is furnished to do so, subject to */
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/* the following conditions: */
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/* */
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/* The above copyright notice and this permission notice shall be */
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/* included in all copies or substantial portions of the Software. */
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/* */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
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/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
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/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
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/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
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/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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/**************************************************************************/
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#ifndef SEMAPHORE_H
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#define SEMAPHORE_H
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#include "core/error_list.h"
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#include "core/typedefs.h"
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#if !defined(NO_THREADS)
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#include <condition_variable>
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#include <mutex>
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class Semaphore {
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private:
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mutable std::mutex mutex;
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mutable std::condition_variable condition;
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mutable uint32_t count = 0; // Initialized as locked.
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public:
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_ALWAYS_INLINE_ void post() const {
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std::lock_guard<std::mutex> lock(mutex);
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count++;
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condition.notify_one();
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}
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_ALWAYS_INLINE_ void wait() const {
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std::unique_lock<std::mutex> lock(mutex);
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while (!count) { // Handle spurious wake-ups.
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condition.wait(lock);
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}
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count--;
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}
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_ALWAYS_INLINE_ bool try_wait() const {
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std::lock_guard<std::mutex> lock(mutex);
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if (count) {
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count--;
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return true;
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} else {
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return false;
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}
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}
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_ALWAYS_INLINE_ int get() const {
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std::lock_guard<std::mutex> lock(mutex);
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return count;
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}
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};
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#else
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class Semaphore {
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public:
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_ALWAYS_INLINE_ void post() const {}
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_ALWAYS_INLINE_ void wait() const {}
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_ALWAYS_INLINE_ bool try_wait() const { return true; }
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_ALWAYS_INLINE_ int get() const { return 1; }
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};
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#endif
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#endif // SEMAPHORE_H
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