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/*************************************************************************/
/* semaphore.h */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md). */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/*************************************************************************/
#ifndef SEMAPHORE_H
#define SEMAPHORE_H
#include "core/error/error_list.h"
#include "core/typedefs.h"
#if !defined(NO_THREADS)
#include <condition_variable>
#include <mutex>
class Semaphore {
private:
mutable std::mutex mutex_;
mutable std::condition_variable condition_;
mutable unsigned long count_ = 0; // Initialized as locked.
public:
_ALWAYS_INLINE_ void post() const {
std::lock_guard<decltype(mutex_)> lock(mutex_);
++count_;
condition_.notify_one();
}
_ALWAYS_INLINE_ void wait() const {
std::unique_lock<decltype(mutex_)> lock(mutex_);
while (!count_) { // Handle spurious wake-ups.
condition_.wait(lock);
}
--count_;
}
_ALWAYS_INLINE_ bool try_wait() const {
std::lock_guard<decltype(mutex_)> lock(mutex_);
if (count_) {
--count_;
return true;
}
return false;
}
};
#else
class Semaphore {
public:
_ALWAYS_INLINE_ void post() const {}
_ALWAYS_INLINE_ void wait() const {}
_ALWAYS_INLINE_ bool try_wait() const { return true; }
};
#endif
#endif // SEMAPHORE_H
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