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9444d297ed
This commits rewrites the sync logic in a way that the `use_system_threads_for_low_priority_tasks` setting, which was added due to the lack of a cross-platform wait-for-multiple-objects functionality, can be removed (it's as if it was effectively hardcoded to `false`). With the new implementation, we have the best of both worlds: threads don't have to poll, plus no bespoke threads are used. In addition, regarding deadlock prevention, since not every possible case of wait-deadlock could be avoided, this commits removes the current best-effort avoidance mechanisms and keeps only a simple, pessimistic way of detection. It turns out that the only current user of deadlock prevention, ResourceLoader, works fine with it and so every possible situation in resource loading is now properly handled, with no possibilities of deadlocking. There's a comment in the code with further details. Lastly, a potential for load tasks never being awaited/disposed is cleared.
70 lines
3.4 KiB
C++
70 lines
3.4 KiB
C++
/**************************************************************************/
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/* condition_variable.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 CONDITION_VARIABLE_H
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#define CONDITION_VARIABLE_H
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#include "core/os/mutex.h"
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#ifdef MINGW_ENABLED
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#define MINGW_STDTHREAD_REDUNDANCY_WARNING
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#include "thirdparty/mingw-std-threads/mingw.condition_variable.h"
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#define THREADING_NAMESPACE mingw_stdthread
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#else
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#include <condition_variable>
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#define THREADING_NAMESPACE std
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#endif
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// An object one or multiple threads can wait on a be notified by some other.
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// Normally, you want to use a semaphore for such scenarios, but when the
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// condition is something different than a count being greater than zero
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// (which is the built-in logic in a semaphore) or you want to provide your
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// own mutex to tie the wait-notify to some other behavior, you need to use this.
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class ConditionVariable {
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mutable THREADING_NAMESPACE::condition_variable condition;
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public:
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template <class BinaryMutexT>
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_ALWAYS_INLINE_ void wait(const MutexLock<BinaryMutexT> &p_lock) const {
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condition.wait(const_cast<THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> &>(p_lock.lock));
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}
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_ALWAYS_INLINE_ void notify_one() const {
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condition.notify_one();
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}
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_ALWAYS_INLINE_ void notify_all() const {
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condition.notify_all();
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}
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};
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#endif // CONDITION_VARIABLE_H
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