| /* |
| * Copyright 2015 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef SkAtomics_DEFINED |
| #define SkAtomics_DEFINED |
| |
| // This file is not part of the public Skia API. |
| #include "SkTypes.h" |
| |
| enum sk_memory_order { |
| sk_memory_order_relaxed, |
| sk_memory_order_consume, |
| sk_memory_order_acquire, |
| sk_memory_order_release, |
| sk_memory_order_acq_rel, |
| sk_memory_order_seq_cst, |
| }; |
| |
| template <typename T> |
| T sk_atomic_load(const T*, sk_memory_order = sk_memory_order_seq_cst); |
| |
| template <typename T> |
| void sk_atomic_store(T*, T, sk_memory_order = sk_memory_order_seq_cst); |
| |
| template <typename T> |
| T sk_atomic_fetch_add(T*, T, sk_memory_order = sk_memory_order_seq_cst); |
| |
| template <typename T> |
| T sk_atomic_fetch_sub(T*, T, sk_memory_order = sk_memory_order_seq_cst); |
| |
| template <typename T> |
| bool sk_atomic_compare_exchange(T*, T* expected, T desired, |
| sk_memory_order success = sk_memory_order_seq_cst, |
| sk_memory_order failure = sk_memory_order_seq_cst); |
| |
| template <typename T> |
| T sk_atomic_exchange(T*, T, sk_memory_order = sk_memory_order_seq_cst); |
| |
| // A little wrapper class for small T (think, builtins: int, float, void*) to |
| // ensure they're always used atomically. This is our stand-in for std::atomic<T>. |
| // !!! Please _really_ know what you're doing if you change default_memory_order. !!! |
| template <typename T, sk_memory_order default_memory_order = sk_memory_order_seq_cst> |
| class SkAtomic : SkNoncopyable { |
| public: |
| SkAtomic() {} |
| explicit SkAtomic(const T& val) : fVal(val) {} |
| |
| // It is essential we return by value rather than by const&. fVal may change at any time. |
| T load(sk_memory_order mo = default_memory_order) const { |
| return sk_atomic_load(&fVal, mo); |
| } |
| |
| void store(const T& val, sk_memory_order mo = default_memory_order) { |
| sk_atomic_store(&fVal, val, mo); |
| } |
| |
| // Alias for .load(default_memory_order). |
| operator T() const { |
| return this->load(); |
| } |
| |
| // Alias for .store(v, default_memory_order). |
| T operator=(const T& v) { |
| this->store(v); |
| return v; |
| } |
| |
| T fetch_add(const T& val, sk_memory_order mo = default_memory_order) { |
| return sk_atomic_fetch_add(&fVal, val, mo); |
| } |
| |
| T fetch_sub(const T& val, sk_memory_order mo = default_memory_order) { |
| return sk_atomic_fetch_sub(&fVal, val, mo); |
| } |
| |
| bool compare_exchange(T* expected, const T& desired, |
| sk_memory_order success = default_memory_order, |
| sk_memory_order failure = default_memory_order) { |
| return sk_atomic_compare_exchange(&fVal, expected, desired, success, failure); |
| } |
| private: |
| T fVal; |
| }; |
| |
| // IWYU pragma: begin_exports |
| #if defined(_MSC_VER) |
| #include "../ports/SkAtomics_std.h" |
| #elif !defined(SK_BUILD_FOR_IOS) && defined(__ATOMIC_RELAXED) |
| #include "../ports/SkAtomics_atomic.h" |
| #else |
| #include "../ports/SkAtomics_sync.h" |
| #endif |
| // IWYU pragma: end_exports |
| |
| // From here down we have shims for our old atomics API, to be weaned off of. |
| // We use the default sequentially-consistent memory order to make things simple |
| // and to match the practical reality of our old _sync and _win implementations. |
| |
| inline int32_t sk_atomic_inc(int32_t* ptr) { return sk_atomic_fetch_add(ptr, +1); } |
| inline int32_t sk_atomic_dec(int32_t* ptr) { return sk_atomic_fetch_add(ptr, -1); } |
| inline int32_t sk_atomic_add(int32_t* ptr, int32_t v) { return sk_atomic_fetch_add(ptr, v); } |
| |
| inline int64_t sk_atomic_inc(int64_t* ptr) { return sk_atomic_fetch_add<int64_t>(ptr, +1); } |
| |
| inline bool sk_atomic_cas(int32_t* ptr, int32_t expected, int32_t desired) { |
| return sk_atomic_compare_exchange(ptr, &expected, desired); |
| } |
| |
| inline void* sk_atomic_cas(void** ptr, void* expected, void* desired) { |
| (void)sk_atomic_compare_exchange(ptr, &expected, desired); |
| return expected; |
| } |
| |
| inline int32_t sk_atomic_conditional_inc(int32_t* ptr) { |
| int32_t prev = sk_atomic_load(ptr); |
| do { |
| if (0 == prev) { |
| break; |
| } |
| } while(!sk_atomic_compare_exchange(ptr, &prev, prev+1)); |
| return prev; |
| } |
| |
| template <typename T> |
| T sk_acquire_load(T* ptr) { return sk_atomic_load(ptr, sk_memory_order_acquire); } |
| |
| template <typename T> |
| void sk_release_store(T* ptr, T val) { sk_atomic_store(ptr, val, sk_memory_order_release); } |
| |
| inline void sk_membar_acquire__after_atomic_dec() {} |
| inline void sk_membar_acquire__after_atomic_conditional_inc() {} |
| |
| #endif//SkAtomics_DEFINED |