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/*
* Copyright 2006 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkThread_DEFINED
#define SkThread_DEFINED
#include "SkTypes.h"
// SK_ATOMICS_PLATFORM_H must provide inline implementations for the following declarations.
/** Atomically adds one to the int referenced by addr and returns the previous value.
* No additional memory barrier is required; this must act as a compiler barrier.
*/
static int32_t sk_atomic_inc(int32_t* addr);
/** Atomically adds inc to the int referenced by addr and returns the previous value.
* No additional memory barrier is required; this must act as a compiler barrier.
*/
static int32_t sk_atomic_add(int32_t* addr, int32_t inc);
/** Atomically subtracts one from the int referenced by addr and returns the previous value.
* This must act as a release (SL/S) memory barrier and as a compiler barrier.
*/
static int32_t sk_atomic_dec(int32_t* addr);
/** Atomically adds one to the int referenced by addr iff the referenced int was not 0
* and returns the previous value.
* No additional memory barrier is required; this must act as a compiler barrier.
*/
static int32_t sk_atomic_conditional_inc(int32_t* addr);
/** Atomic compare and set.
* If *addr == before, set *addr to after and return true, otherwise return false.
* This must act as a release (SL/S) memory barrier and as a compiler barrier.
*/
static bool sk_atomic_cas(int32_t* addr, int32_t before, int32_t after);
/** If sk_atomic_dec does not act as an acquire (L/SL) barrier,
* this must act as an acquire (L/SL) memory barrier and as a compiler barrier.
*/
static void sk_membar_acquire__after_atomic_dec();
/** If sk_atomic_conditional_inc does not act as an acquire (L/SL) barrier,
* this must act as an acquire (L/SL) memory barrier and as a compiler barrier.
*/
static void sk_membar_acquire__after_atomic_conditional_inc();
#include SK_ATOMICS_PLATFORM_H
// This is POD and must be zero-initialized.
struct SkSpinlock {
void acquire() {
SkASSERT(shouldBeZero == 0);
// No memory barrier needed, but sk_atomic_cas gives us at least release anyway.
while (!sk_atomic_cas(&thisIsPrivate, 0, 1)) {
// spin
}
}
void release() {
SkASSERT(shouldBeZero == 0);
// This requires a release memory barrier before storing, which sk_atomic_cas guarantees.
SkAssertResult(sk_atomic_cas(&thisIsPrivate, 1, 0));
}
int32_t thisIsPrivate;
SkDEBUGCODE(int32_t shouldBeZero;)
};
class SkAutoSpinlock : SkNoncopyable {
public:
explicit SkAutoSpinlock(SkSpinlock* lock) : fLock(lock) { fLock->acquire(); }
~SkAutoSpinlock() { fLock->release(); }
private:
SkSpinlock* fLock;
};
#define SkAutoSpinlock(...) SK_REQUIRE_LOCAL_VAR(SkAutoSpinlock)
/** SK_MUTEX_PLATFORM_H must provide the following (or equivalent) declarations.
class SkBaseMutex {
public:
void acquire();
void release();
};
class SkMutex : SkBaseMutex {
public:
SkMutex();
~SkMutex();
};
#define SK_DECLARE_STATIC_MUTEX(name) static SkBaseMutex name = ...
#define SK_DECLARE_GLOBAL_MUTEX(name) SkBaseMutex name = ...
*/
#include SK_MUTEX_PLATFORM_H
class SkAutoMutexAcquire : SkNoncopyable {
public:
explicit SkAutoMutexAcquire(SkBaseMutex& mutex) : fMutex(&mutex) {
SkASSERT(fMutex != NULL);
mutex.acquire();
}
explicit SkAutoMutexAcquire(SkBaseMutex* mutex) : fMutex(mutex) {
if (mutex) {
mutex->acquire();
}
}
/** If the mutex has not been released, release it now. */
~SkAutoMutexAcquire() {
if (fMutex) {
fMutex->release();
}
}
/** If the mutex has not been released, release it now. */
void release() {
if (fMutex) {
fMutex->release();
fMutex = NULL;
}
}
private:
SkBaseMutex* fMutex;
};
#define SkAutoMutexAcquire(...) SK_REQUIRE_LOCAL_VAR(SkAutoMutexAcquire)
#endif
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