/*************************************************************************/ /* safe_refcount.h */ /*************************************************************************/ /* This file is part of: */ /* GODOT ENGINE */ /* https://godotengine.org */ /*************************************************************************/ /* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur. */ /* Copyright (c) 2014-2019 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 SAFE_REFCOUNT_H #define SAFE_REFCOUNT_H #include "core/os/mutex.h" #include "core/typedefs.h" #include "platform_config.h" // Atomic functions, these are used for multithread safe reference counters! #ifdef NO_THREADS /* Bogus implementation unaware of multiprocessing */ template <class T> static _ALWAYS_INLINE_ T atomic_conditional_increment(volatile T *pw) { if (*pw == 0) return 0; (*pw)++; return *pw; } template <class T> static _ALWAYS_INLINE_ T atomic_decrement(volatile T *pw) { (*pw)--; return *pw; } template <class T> static _ALWAYS_INLINE_ T atomic_increment(volatile T *pw) { (*pw)++; return *pw; } template <class T, class V> static _ALWAYS_INLINE_ T atomic_sub(volatile T *pw, volatile V val) { (*pw) -= val; return *pw; } template <class T, class V> static _ALWAYS_INLINE_ T atomic_add(volatile T *pw, volatile V val) { (*pw) += val; return *pw; } template <class T, class V> static _ALWAYS_INLINE_ T atomic_exchange_if_greater(volatile T *pw, volatile V val) { if (val > *pw) *pw = val; return *pw; } #elif defined(__GNUC__) /* Implementation for GCC & Clang */ // GCC guarantees atomic intrinsics for sizes of 1, 2, 4 and 8 bytes. // Clang states it supports GCC atomic builtins. template <class T> static _ALWAYS_INLINE_ T atomic_conditional_increment(volatile T *pw) { while (true) { T tmp = static_cast<T const volatile &>(*pw); if (tmp == 0) return 0; // if zero, can't add to it anymore if (__sync_val_compare_and_swap(pw, tmp, tmp + 1) == tmp) return tmp + 1; } } template <class T> static _ALWAYS_INLINE_ T atomic_decrement(volatile T *pw) { return __sync_sub_and_fetch(pw, 1); } template <class T> static _ALWAYS_INLINE_ T atomic_increment(volatile T *pw) { return __sync_add_and_fetch(pw, 1); } template <class T, class V> static _ALWAYS_INLINE_ T atomic_sub(volatile T *pw, volatile V val) { return __sync_sub_and_fetch(pw, val); } template <class T, class V> static _ALWAYS_INLINE_ T atomic_add(volatile T *pw, volatile V val) { return __sync_add_and_fetch(pw, val); } template <class T, class V> static _ALWAYS_INLINE_ T atomic_exchange_if_greater(volatile T *pw, volatile V val) { while (true) { T tmp = static_cast<T const volatile &>(*pw); if (tmp >= val) return tmp; // already greater, or equal if (__sync_val_compare_and_swap(pw, tmp, val) == tmp) return val; } } #elif defined(_MSC_VER) // For MSVC use a separate compilation unit to prevent windows.h from polluting // the global namespace. uint32_t atomic_conditional_increment(volatile uint32_t *pw); uint32_t atomic_decrement(volatile uint32_t *pw); uint32_t atomic_increment(volatile uint32_t *pw); uint32_t atomic_sub(volatile uint32_t *pw, volatile uint32_t val); uint32_t atomic_add(volatile uint32_t *pw, volatile uint32_t val); uint32_t atomic_exchange_if_greater(volatile uint32_t *pw, volatile uint32_t val); uint64_t atomic_conditional_increment(volatile uint64_t *pw); uint64_t atomic_decrement(volatile uint64_t *pw); uint64_t atomic_increment(volatile uint64_t *pw); uint64_t atomic_sub(volatile uint64_t *pw, volatile uint64_t val); uint64_t atomic_add(volatile uint64_t *pw, volatile uint64_t val); uint64_t atomic_exchange_if_greater(volatile uint64_t *pw, volatile uint64_t val); #else //no threads supported? #error Must provide atomic functions for this platform or compiler! #endif struct SafeRefCount { uint32_t count; public: // destroy() is called when weak_count_ drops to zero. _ALWAYS_INLINE_ bool ref() { // true on success return atomic_conditional_increment(&count) != 0; } _ALWAYS_INLINE_ uint32_t refval() { // none-zero on success return atomic_conditional_increment(&count); } _ALWAYS_INLINE_ bool unref() { // true if must be disposed of return atomic_decrement(&count) == 0; } _ALWAYS_INLINE_ uint32_t unrefval() { // 0 if must be disposed of return atomic_decrement(&count); } _ALWAYS_INLINE_ uint32_t get() const { // nothrow return count; } _ALWAYS_INLINE_ void init(uint32_t p_value = 1) { count = p_value; } }; #endif