/*************************************************************************/ /* 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