godot/core/os/condition_variable.h
Pedro J. Estébanez f4d76853b9 WorkerThreadPool (plus friends): Overhaul unlock allowance zones
This fixes a rare but possible deadlock, maybe due to undefined behavior. The new implementation is safer, at the cost of some added boilerplate.
2024-08-21 12:22:52 +02:00

90 lines
3.9 KiB
C++

/**************************************************************************/
/* condition_variable.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. */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/**************************************************************************/
#ifndef CONDITION_VARIABLE_H
#define CONDITION_VARIABLE_H
#include "core/os/mutex.h"
#include "core/os/safe_binary_mutex.h"
#ifdef THREADS_ENABLED
#ifdef MINGW_ENABLED
#define MINGW_STDTHREAD_REDUNDANCY_WARNING
#include "thirdparty/mingw-std-threads/mingw.condition_variable.h"
#define THREADING_NAMESPACE mingw_stdthread
#else
#include <condition_variable>
#define THREADING_NAMESPACE std
#endif
// An object one or multiple threads can wait on a be notified by some other.
// Normally, you want to use a semaphore for such scenarios, but when the
// condition is something different than a count being greater than zero
// (which is the built-in logic in a semaphore) or you want to provide your
// own mutex to tie the wait-notify to some other behavior, you need to use this.
class ConditionVariable {
mutable THREADING_NAMESPACE::condition_variable condition;
public:
template <typename BinaryMutexT>
_ALWAYS_INLINE_ void wait(const MutexLock<BinaryMutexT> &p_lock) const {
condition.wait(const_cast<THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> &>(p_lock._get_lock()));
}
template <int Tag>
_ALWAYS_INLINE_ void wait(const MutexLock<SafeBinaryMutex<Tag>> &p_lock) const {
condition.wait(const_cast<THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> &>(p_lock.mutex._get_lock()));
}
_ALWAYS_INLINE_ void notify_one() const {
condition.notify_one();
}
_ALWAYS_INLINE_ void notify_all() const {
condition.notify_all();
}
};
#else // No threads.
class ConditionVariable {
public:
template <typename BinaryMutexT>
void wait(const MutexLock<BinaryMutexT> &p_lock) const {}
void notify_one() const {}
void notify_all() const {}
};
#endif // THREADS_ENABLED
#endif // CONDITION_VARIABLE_H