84 lines
3.3 KiB
C++
84 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) 2007-2020 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md). */
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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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#include <condition_variable>
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#include <mutex>
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class Semaphore {
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private:
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std::mutex mutex_;
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std::condition_variable condition_;
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unsigned long count_ = 0; // Initialized as locked.
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public:
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_ALWAYS_INLINE_ void post() {
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std::lock_guard<decltype(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() {
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std::unique_lock<decltype(mutex_)> lock(mutex_);
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while (!count_) // Handle spurious wake-ups.
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condition_.wait(lock);
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--count_;
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}
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_ALWAYS_INLINE_ bool try_wait() {
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std::lock_guard<decltype(mutex_)> lock(mutex_);
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if (count_) {
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--count_;
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return true;
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}
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return false;
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}
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};
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class SemaphoreOld {
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protected:
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static SemaphoreOld *(*create_func)();
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public:
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virtual Error wait() = 0; ///< wait until semaphore has positive value, then decrement and pass
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virtual Error post() = 0; ///< unlock the semaphore, incrementing the value
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virtual int get() const = 0; ///< get semaphore value
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static SemaphoreOld *create(); ///< Create a mutex
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virtual ~SemaphoreOld();
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};
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#endif
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