158c3fbf3c
Differences with this aren't huge but the effort is minimal, in some workloads gain a couple of percent of performance.
283 lines
8.6 KiB
C++
283 lines
8.6 KiB
C++
/*************************************************************************/
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/* safe_refcount.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) 2007-2017 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2017 Godot Engine contributors (cf. AUTHORS.md) */
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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_REFCOUNT_H
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#define SAFE_REFCOUNT_H
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#include "os/mutex.h"
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/* x86/x86_64 GCC */
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#include "platform_config.h"
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#include "typedefs.h"
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// Atomic functions, these are used for multithread safe reference counters!
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#ifdef NO_THREADS
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/* Bogus implementation unaware of multiprocessing */
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template <class T>
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static _ALWAYS_INLINE_ T atomic_conditional_increment(register T *pw) {
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if (*pw == 0)
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return 0;
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(*pw)++;
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return *pw;
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}
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template <class T>
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static _ALWAYS_INLINE_ T atomic_decrement(register T *pw) {
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(*pw)--;
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return *pw;
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}
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template <class T>
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static _ALWAYS_INLINE_ T atomic_increment(register T *pw) {
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(*pw)++;
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return *pw;
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}
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template <class T, class V>
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static _ALWAYS_INLINE_ T atomic_sub(register T *pw, register V val) {
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(*pw) -= val;
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return *pw;
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}
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template <class T, class V>
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static _ALWAYS_INLINE_ T atomic_add(register T *pw, register V val) {
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(*pw) += val;
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return *pw;
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}
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template <class T, class V>
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static _ALWAYS_INLINE_ T atomic_exchange_if_greater(register T *pw, register V val) {
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if (val > *pw)
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*pw = val;
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return *pw;
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}
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#elif defined(__GNUC__)
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/* Implementation for GCC & Clang */
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// GCC guarantees atomic intrinsics for sizes of 1, 2, 4 and 8 bytes.
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// Clang states it supports GCC atomic builtins.
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template <class T>
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static _ALWAYS_INLINE_ T atomic_conditional_increment(register T *pw) {
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while (true) {
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T tmp = static_cast<T const volatile &>(*pw);
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if (tmp == 0)
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return 0; // if zero, can't add to it anymore
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if (__sync_val_compare_and_swap(pw, tmp, tmp + 1) == tmp)
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return tmp + 1;
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}
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}
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template <class T>
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static _ALWAYS_INLINE_ T atomic_decrement(register T *pw) {
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return __sync_sub_and_fetch(pw, 1);
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}
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template <class T>
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static _ALWAYS_INLINE_ T atomic_increment(register T *pw) {
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return __sync_add_and_fetch(pw, 1);
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}
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template <class T, class V>
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static _ALWAYS_INLINE_ T atomic_sub(register T *pw, register V val) {
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return __sync_sub_and_fetch(pw, val);
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}
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template <class T, class V>
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static _ALWAYS_INLINE_ T atomic_add(register T *pw, register V val) {
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return __sync_add_and_fetch(pw, val);
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}
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template <class T, class V>
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static _ALWAYS_INLINE_ T atomic_exchange_if_greater(register T *pw, register V val) {
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while (true) {
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T tmp = static_cast<T const volatile &>(*pw);
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if (tmp >= val)
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return tmp; // already greater, or equal
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if (__sync_val_compare_and_swap(pw, tmp, val) == tmp)
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return val;
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}
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}
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#elif defined(_MSC_VER)
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/* Implementation for MSVC-Windows */
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// don't pollute my namespace!
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#include <windows.h>
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#define ATOMIC_CONDITIONAL_INCREMENT_BODY(m_pw, m_win_type, m_win_cmpxchg, m_cpp_type) \
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/* try to increment until it actually works */ \
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/* taken from boost */ \
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while (true) { \
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m_cpp_type tmp = static_cast<m_cpp_type const volatile &>(*(m_pw)); \
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if (tmp == 0) \
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return 0; /* if zero, can't add to it anymore */ \
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if (m_win_cmpxchg((m_win_type volatile *)(m_pw), tmp + 1, tmp) == tmp) \
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return tmp + 1; \
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}
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#define ATOMIC_EXCHANGE_IF_GREATER_BODY(m_pw, m_val, m_win_type, m_win_cmpxchg, m_cpp_type) \
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while (true) { \
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m_cpp_type tmp = static_cast<m_cpp_type const volatile &>(*(m_pw)); \
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if (tmp >= m_val) \
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return tmp; /* already greater, or equal */ \
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if (m_win_cmpxchg((m_win_type volatile *)(m_pw), m_val, tmp) == tmp) \
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return m_val; \
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}
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static _ALWAYS_INLINE_ uint32_t atomic_conditional_increment(register uint32_t *pw) {
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ATOMIC_CONDITIONAL_INCREMENT_BODY(pw, LONG, InterlockedCompareExchange, uint32_t)
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}
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static _ALWAYS_INLINE_ uint32_t atomic_decrement(register uint32_t *pw) {
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return InterlockedDecrement((LONG volatile *)pw);
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}
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static _ALWAYS_INLINE_ uint32_t atomic_increment(register uint32_t *pw) {
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return InterlockedIncrement((LONG volatile *)pw);
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}
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static _ALWAYS_INLINE_ uint32_t atomic_sub(register uint32_t *pw, register uint32_t val) {
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return InterlockedExchangeAdd((LONG volatile *)pw, -(int32_t)val) - val;
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}
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static _ALWAYS_INLINE_ uint32_t atomic_add(register uint32_t *pw, register uint32_t val) {
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return InterlockedAdd((LONG volatile *)pw, val);
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}
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static _ALWAYS_INLINE_ uint32_t atomic_exchange_if_greater(register uint32_t *pw, register uint32_t val) {
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ATOMIC_EXCHANGE_IF_GREATER_BODY(pw, val, LONG, InterlockedCompareExchange, uint32_t)
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}
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static _ALWAYS_INLINE_ uint64_t atomic_conditional_increment(register uint64_t *pw) {
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ATOMIC_CONDITIONAL_INCREMENT_BODY(pw, LONGLONG, InterlockedCompareExchange64, uint64_t)
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}
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static _ALWAYS_INLINE_ uint64_t atomic_decrement(register uint64_t *pw) {
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return InterlockedDecrement64((LONGLONG volatile *)pw);
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}
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static _ALWAYS_INLINE_ uint64_t atomic_increment(register uint64_t *pw) {
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return InterlockedIncrement64((LONGLONG volatile *)pw);
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}
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static _ALWAYS_INLINE_ uint64_t atomic_sub(register uint64_t *pw, register uint64_t val) {
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return InterlockedExchangeAdd64((LONGLONG volatile *)pw, -(int64_t)val) - val;
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}
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static _ALWAYS_INLINE_ uint64_t atomic_add(register uint64_t *pw, register uint64_t val) {
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return InterlockedAdd64((LONGLONG volatile *)pw, val);
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}
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static _ALWAYS_INLINE_ uint64_t atomic_exchange_if_greater(register uint64_t *pw, register uint64_t val) {
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ATOMIC_EXCHANGE_IF_GREATER_BODY(pw, val, LONGLONG, InterlockedCompareExchange64, uint64_t)
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}
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#else
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//no threads supported?
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#error Must provide atomic functions for this platform or compiler!
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#endif
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struct SafeRefCount {
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uint32_t count;
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public:
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// destroy() is called when weak_count_ drops to zero.
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_ALWAYS_INLINE_ bool ref() { //true on success
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return atomic_conditional_increment(&count) != 0;
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}
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_ALWAYS_INLINE_ uint32_t refval() { //true on success
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return atomic_conditional_increment(&count);
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}
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_ALWAYS_INLINE_ bool unref() { // true if must be disposed of
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if (atomic_decrement(&count) == 0) {
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return true;
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}
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return false;
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}
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_ALWAYS_INLINE_ uint32_t get() const { // nothrow
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return count;
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}
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_ALWAYS_INLINE_ void init(uint32_t p_value = 1) {
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count = p_value;
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}
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};
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#endif
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