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Merge pull request #87893 from vittorioromeo/extract_safe_binary_mutex
Extract `SafeBinaryMutex` to separate header
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/**************************************************************************/ | ||
/* safe_binary_mutex.h */ | ||
/**************************************************************************/ | ||
/* This file is part of: */ | ||
/* GODOT ENGINE */ | ||
/* https://godotengine.org */ | ||
/**************************************************************************/ | ||
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */ | ||
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */ | ||
/* */ | ||
/* 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. */ | ||
/**************************************************************************/ | ||
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#ifndef SAFE_BINARY_MUTEX_H | ||
#define SAFE_BINARY_MUTEX_H | ||
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#include "core/error/error_macros.h" | ||
#include "core/os/mutex.h" | ||
#include "core/typedefs.h" | ||
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#ifdef THREADS_ENABLED | ||
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// A very special kind of mutex, used in scenarios where these | ||
// requirements hold at the same time: | ||
// - Must be used with a condition variable (only binary mutexes are suitable). | ||
// - Must have recursive semnantics (or simulate, as this one does). | ||
// The implementation keeps the lock count in TS. Therefore, only | ||
// one object of each version of the template can exists; hence the Tag argument. | ||
// Tags must be unique across the Godot codebase. | ||
// Also, don't forget to declare the thread_local variable on each use. | ||
template <int Tag> | ||
class SafeBinaryMutex { | ||
friend class MutexLock<SafeBinaryMutex>; | ||
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using StdMutexType = THREADING_NAMESPACE::mutex; | ||
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mutable THREADING_NAMESPACE::mutex mutex; | ||
static thread_local uint32_t count; | ||
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public: | ||
_ALWAYS_INLINE_ void lock() const { | ||
if (++count == 1) { | ||
mutex.lock(); | ||
} | ||
} | ||
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_ALWAYS_INLINE_ void unlock() const { | ||
DEV_ASSERT(count); | ||
if (--count == 0) { | ||
mutex.unlock(); | ||
} | ||
} | ||
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_ALWAYS_INLINE_ bool try_lock() const { | ||
if (count) { | ||
count++; | ||
return true; | ||
} else { | ||
if (mutex.try_lock()) { | ||
count++; | ||
return true; | ||
} else { | ||
return false; | ||
} | ||
} | ||
} | ||
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~SafeBinaryMutex() { | ||
DEV_ASSERT(!count); | ||
} | ||
}; | ||
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// This specialization is needed so manual locking and MutexLock can be used | ||
// at the same time on a SafeBinaryMutex. | ||
template <int Tag> | ||
class MutexLock<SafeBinaryMutex<Tag>> { | ||
friend class ConditionVariable; | ||
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THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> lock; | ||
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public: | ||
_ALWAYS_INLINE_ explicit MutexLock(const SafeBinaryMutex<Tag> &p_mutex) : | ||
lock(p_mutex.mutex) { | ||
SafeBinaryMutex<Tag>::count++; | ||
}; | ||
_ALWAYS_INLINE_ ~MutexLock() { | ||
SafeBinaryMutex<Tag>::count--; | ||
}; | ||
}; | ||
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#else // No threads. | ||
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template <int Tag> | ||
class SafeBinaryMutex : public MutexImpl { | ||
static thread_local uint32_t count; | ||
}; | ||
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template <int Tag> | ||
class MutexLock<SafeBinaryMutex<Tag>> { | ||
public: | ||
MutexLock(const SafeBinaryMutex<Tag> &p_mutex) {} | ||
~MutexLock() {} | ||
}; | ||
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#endif // THREADS_ENABLED | ||
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#endif // SAFE_BINARY_MUTEX_H |