81da061f72
Now that we have sk_atomic_cas, we can replace all the platform-specific CAS loops with one. BUG=skia: R=bungeman@google.com, mtklein@google.com, reed@google.com Author: mtklein@chromium.org Review URL: https://codereview.chromium.org/300553003 git-svn-id: http://skia.googlecode.com/svn/trunk@14892 2bbb7eff-a529-9590-31e7-b0007b416f81
118 lines
3.3 KiB
C++
118 lines
3.3 KiB
C++
/*
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* Copyright 2006 The Android Open Source Project
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkThread_DEFINED
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#define SkThread_DEFINED
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#include "SkTypes.h"
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// SK_ATOMICS_PLATFORM_H must provide inline implementations for the following declarations.
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/** Atomically adds one to the int referenced by addr and returns the previous value.
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* No additional memory barrier is required; this must act as a compiler barrier.
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*/
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static int32_t sk_atomic_inc(int32_t* addr);
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/** Atomically adds inc to the int referenced by addr and returns the previous value.
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* No additional memory barrier is required; this must act as a compiler barrier.
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*/
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static int32_t sk_atomic_add(int32_t* addr, int32_t inc);
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/** Atomically subtracts one from the int referenced by addr and returns the previous value.
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* This must act as a release (SL/S) memory barrier and as a compiler barrier.
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*/
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static int32_t sk_atomic_dec(int32_t* addr);
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/** Atomic compare and set.
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* If *addr == before, set *addr to after and return true, otherwise return false.
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* This must act as a release (SL/S) memory barrier and as a compiler barrier.
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*/
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static bool sk_atomic_cas(int32_t* addr, int32_t before, int32_t after);
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/** If sk_atomic_dec does not act as an acquire (L/SL) barrier,
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* this must act as an acquire (L/SL) memory barrier and as a compiler barrier.
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*/
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static void sk_membar_acquire__after_atomic_dec();
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/** If sk_atomic_conditional_inc does not act as an acquire (L/SL) barrier,
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* this must act as an acquire (L/SL) memory barrier and as a compiler barrier.
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*/
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static void sk_membar_acquire__after_atomic_conditional_inc();
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#include SK_ATOMICS_PLATFORM_H
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/** Atomically adds one to the int referenced by addr iff the referenced int was not 0
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* and returns the previous value.
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* No additional memory barrier is required; this must act as a compiler barrier.
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*/
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static inline int32_t sk_atomic_conditional_inc(int32_t* addr) {
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int32_t prev;
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do {
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prev = *addr;
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if (0 == prev) {
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break;
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}
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} while (!sk_atomic_cas(addr, prev, prev+1));
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return prev;
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}
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/** SK_MUTEX_PLATFORM_H must provide the following (or equivalent) declarations.
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class SkBaseMutex {
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public:
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void acquire();
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void release();
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};
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class SkMutex : SkBaseMutex {
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public:
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SkMutex();
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~SkMutex();
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};
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#define SK_DECLARE_STATIC_MUTEX(name) static SkBaseMutex name = ...
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#define SK_DECLARE_GLOBAL_MUTEX(name) SkBaseMutex name = ...
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*/
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#include SK_MUTEX_PLATFORM_H
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class SkAutoMutexAcquire : SkNoncopyable {
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public:
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explicit SkAutoMutexAcquire(SkBaseMutex& mutex) : fMutex(&mutex) {
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SkASSERT(fMutex != NULL);
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mutex.acquire();
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}
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explicit SkAutoMutexAcquire(SkBaseMutex* mutex) : fMutex(mutex) {
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if (mutex) {
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mutex->acquire();
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}
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}
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/** If the mutex has not been released, release it now. */
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~SkAutoMutexAcquire() {
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if (fMutex) {
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fMutex->release();
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}
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}
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/** If the mutex has not been released, release it now. */
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void release() {
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if (fMutex) {
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fMutex->release();
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fMutex = NULL;
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}
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}
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private:
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SkBaseMutex* fMutex;
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};
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#define SkAutoMutexAcquire(...) SK_REQUIRE_LOCAL_VAR(SkAutoMutexAcquire)
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#endif
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