125 lines
4.4 KiB
C++
125 lines
4.4 KiB
C++
/**************************************************************************/
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/* safe_binary_mutex.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 SAFE_BINARY_MUTEX_H
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#define SAFE_BINARY_MUTEX_H
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#include "core/error/error_macros.h"
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#include "core/os/mutex.h"
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#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
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// requirements hold at the same time:
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// - Must be used with a condition variable (only binary mutexes are suitable).
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// - Must have recursive semnantics (or simulate, as this one does).
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// The implementation keeps the lock count in TS. Therefore, only
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// one object of each version of the template can exists; hence the Tag argument.
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// Tags must be unique across the Godot codebase.
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// Also, don't forget to declare the thread_local variable on each use.
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template <int Tag>
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class SafeBinaryMutex {
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friend class MutexLock<SafeBinaryMutex<Tag>>;
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using StdMutexType = THREADING_NAMESPACE::mutex;
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mutable THREADING_NAMESPACE::mutex mutex;
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struct TLSData {
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mutable THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> lock;
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uint32_t count = 0;
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TLSData(SafeBinaryMutex<Tag> &p_mutex) :
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lock(p_mutex.mutex, THREADING_NAMESPACE::defer_lock) {}
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};
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static thread_local TLSData tls_data;
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public:
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_ALWAYS_INLINE_ void lock() const {
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if (++tls_data.count == 1) {
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tls_data.lock.lock();
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}
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}
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_ALWAYS_INLINE_ void unlock() const {
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DEV_ASSERT(tls_data.count);
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if (--tls_data.count == 0) {
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tls_data.lock.unlock();
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}
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}
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_ALWAYS_INLINE_ THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> &_get_lock() const {
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return const_cast<THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> &>(tls_data.lock);
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}
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_ALWAYS_INLINE_ SafeBinaryMutex() {
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}
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_ALWAYS_INLINE_ ~SafeBinaryMutex() {
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DEV_ASSERT(!tls_data.count);
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}
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};
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template <int Tag>
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class MutexLock<SafeBinaryMutex<Tag>> {
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friend class ConditionVariable;
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const SafeBinaryMutex<Tag> &mutex;
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public:
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explicit MutexLock(const SafeBinaryMutex<Tag> &p_mutex) :
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mutex(p_mutex) {
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mutex.lock();
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}
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~MutexLock() {
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mutex.unlock();
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}
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};
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#else // No threads.
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template <int Tag>
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class SafeBinaryMutex {
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struct TLSData {
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TLSData(SafeBinaryMutex<Tag> &p_mutex) {}
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};
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static thread_local TLSData tls_data;
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public:
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void lock() const {}
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void unlock() const {}
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};
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#endif // THREADS_ENABLED
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#endif // SAFE_BINARY_MUTEX_H
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