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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_platform_DEFINED
#define SkThread_platform_DEFINED
#if defined(SK_BUILD_FOR_ANDROID)
#if defined(SK_BUILD_FOR_ANDROID_NDK)
#include <stdint.h>
/* Just use the GCC atomic intrinsics. They're supported by the NDK toolchain,
* have reasonable performance, and provide full memory barriers
*/
static inline __attribute__((always_inline)) int32_t sk_atomic_inc(int32_t *addr) {
return __sync_fetch_and_add(addr, 1);
}
static inline __attribute__((always_inline)) int32_t sk_atomic_dec(int32_t *addr) {
return __sync_fetch_and_add(addr, -1);
}
static inline __attribute__((always_inline)) void sk_membar_aquire__after_atomic_dec() { }
static inline __attribute__((always_inline)) int32_t sk_atomic_conditional_inc(int32_t* addr) {
int32_t value = *addr;
while (true) {
if (value == 0) {
return 0;
}
int32_t before = __sync_val_compare_and_swap(addr, value, value + 1);
if (before == value) {
return value;
} else {
value = before;
}
}
}
static inline __attribute__((always_inline)) void sk_membar_aquire__after_atomic_conditional_inc() { }
#else // !SK_BUILD_FOR_ANDROID_NDK
/* The platform atomics operations are slightly more efficient than the
* GCC built-ins, so use them.
*/
#include <utils/Atomic.h>
#define sk_atomic_inc(addr) android_atomic_inc(addr)
#define sk_atomic_dec(addr) android_atomic_dec(addr)
void sk_membar_aquire__after_atomic_dec() {
//HACK: Android is actually using full memory barriers.
// Should this change, uncomment below.
//int dummy;
//android_atomic_aquire_store(0, &dummy);
}
int32_t sk_atomic_conditional_inc(int32_t* addr) {
while (true) {
int32_t value = *addr;
if (value == 0) {
return 0;
}
if (0 == android_atomic_release_cas(value, value + 1, addr)) {
return value;
}
}
}
void sk_membar_aquire__after_atomic_conditional_inc() {
//HACK: Android is actually using full memory barriers.
// Should this change, uncomment below.
//int dummy;
//android_atomic_aquire_store(0, &dummy);
}
#endif // !SK_BUILD_FOR_ANDROID_NDK
#else // !SK_BUILD_FOR_ANDROID
/** Implemented by the porting layer, this function adds one to the int
specified by the address (in a thread-safe manner), and returns the
previous value.
No additional memory barrier is required.
This must act as a compiler barrier.
*/
SK_API int32_t sk_atomic_inc(int32_t* addr);
/** Implemented by the porting layer, this function subtracts one from the int
specified by the address (in a thread-safe manner), and returns the
previous value.
Expected to act as a release (SL/S) memory barrier and a compiler barrier.
*/
SK_API int32_t sk_atomic_dec(int32_t* addr);
/** If sk_atomic_dec does not act as an aquire (L/SL) barrier, this is expected
to act as an aquire (L/SL) memory barrier and as a compiler barrier.
*/
SK_API void sk_membar_aquire__after_atomic_dec();
/** Implemented by the porting layer, this function adds one to the int
specified by the address iff the int specified by the address is not zero
(in a thread-safe manner), and returns the previous value.
No additional memory barrier is required.
This must act as a compiler barrier.
*/
SK_API int32_t sk_atomic_conditional_inc(int32_t*);
/** If sk_atomic_conditional_inc does not act as an aquire (L/SL) barrier, this
is expected to act as an aquire (L/SL) memory barrier and as a compiler
barrier.
*/
SK_API void sk_membar_aquire__after_atomic_conditional_inc();
#endif // !SK_BUILD_FOR_ANDROID
#ifdef SK_USE_POSIX_THREADS
#include <pthread.h>
// A SkBaseMutex is a POD structure that can be directly initialized
// at declaration time with SK_DECLARE_STATIC/GLOBAL_MUTEX. This avoids the
// generation of a static initializer in the final machine code (and
// a corresponding static finalizer).
//
struct SkBaseMutex {
void acquire() { pthread_mutex_lock(&fMutex); }
void release() { pthread_mutex_unlock(&fMutex); }
pthread_mutex_t fMutex;
};
// Using POD-style initialization prevents the generation of a static initializer
// and keeps the acquire() implementation small and fast.
#define SK_DECLARE_STATIC_MUTEX(name) static SkBaseMutex name = { PTHREAD_MUTEX_INITIALIZER }
// Special case used when the static mutex must be available globally.
#define SK_DECLARE_GLOBAL_MUTEX(name) SkBaseMutex name = { PTHREAD_MUTEX_INITIALIZER }
#define SK_DECLARE_MUTEX_ARRAY(name, count) SkBaseMutex name[count] = { { PTHREAD_MUTEX_INITIALIZER } }
// A normal mutex that requires to be initialized through normal C++ construction,
// i.e. when it's a member of another class, or allocated on the heap.
class SkMutex : public SkBaseMutex, SkNoncopyable {
public:
SkMutex();
~SkMutex();
};
#else // !SK_USE_POSIX_THREADS
// In the generic case, SkBaseMutex and SkMutex are the same thing, and we
// can't easily get rid of static initializers.
//
class SkMutex : SkNoncopyable {
public:
SkMutex();
~SkMutex();
void acquire();
void release();
private:
bool fIsGlobal;
enum {
kStorageIntCount = 64
};
uint32_t fStorage[kStorageIntCount];
};
typedef SkMutex SkBaseMutex;
#define SK_DECLARE_STATIC_MUTEX(name) static SkBaseMutex name
#define SK_DECLARE_GLOBAL_MUTEX(name) SkBaseMutex name
#define SK_DECLARE_MUTEX_ARRAY(name, count) SkBaseMutex name[count]
#endif // !SK_USE_POSIX_THREADS
#endif
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