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Improve on virAtomic implementation

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This patch improves the previously added virAtomicInt implementation
by using gcc-builtins if possible. The needed builtins are available
since GCC >= 4.1. At least the 4.0 docs don't mention them.
This commit is contained in:
Stefan Berger 2012-04-24 11:13:53 -04:00 committed by Stefan Berger
parent 3ac303616f
commit a4a5c00be9
1 changed files with 79 additions and 16 deletions
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95
src/util/viratomic.h
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@ -30,6 +30,29 @@
typedef struct _virAtomicInt virAtomicInt;
typedef virAtomicInt *virAtomicIntPtr;
# define __VIR_ATOMIC_USES_LOCK
# if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 1)) || (__GNUC__ > 4)
# undef __VIR_ATOMIC_USES_LOCK
# endif
static inline int virAtomicIntInit(virAtomicIntPtr vaip)
ATTRIBUTE_NONNULL(1) ATTRIBUTE_RETURN_CHECK;
static inline int virAtomicIntRead(virAtomicIntPtr vaip)
ATTRIBUTE_NONNULL(1);
static inline void virAtomicIntSet(virAtomicIntPtr vaip, int val)
ATTRIBUTE_NONNULL(1);
static inline int virAtomicIntAdd(virAtomicIntPtr vaip, int add)
ATTRIBUTE_NONNULL(1);
static inline int virAtomicIntSub(virAtomicIntPtr vaip, int add)
ATTRIBUTE_NONNULL(1);
static inline int virAtomicIntInc(virAtomicIntPtr vaip)
ATTRIBUTE_NONNULL(1);
static inline int virAtomicIntDec(virAtomicIntPtr vaip)
ATTRIBUTE_NONNULL(1);
# ifdef __VIR_ATOMIC_USES_LOCK
struct _virAtomicInt {
virMutex lock;
int value;
@ -42,22 +65,6 @@ virAtomicIntInit(virAtomicIntPtr vaip)
return virMutexInit(&vaip->lock);
}
static inline void
virAtomicIntSet(virAtomicIntPtr vaip, int value)
{
virMutexLock(&vaip->lock);
vaip->value = value;
virMutexUnlock(&vaip->lock);
}
static inline int
virAtomicIntRead(virAtomicIntPtr vaip)
{
return vaip->value;
}
static inline int
virAtomicIntAdd(virAtomicIntPtr vaip, int add)
{
@ -88,4 +95,60 @@ virAtomicIntSub(virAtomicIntPtr vaip, int sub)
return ret;
}
# else /* __VIR_ATOMIC_USES_LOCK */
struct _virAtomicInt {
int value;
};
static inline int
virAtomicIntInit(virAtomicIntPtr vaip)
{
vaip->value = 0;
return 0;
}
static inline int
virAtomicIntAdd(virAtomicIntPtr vaip, int add)
{
return __sync_add_and_fetch(&vaip->value, add);
}
static inline int
virAtomicIntSub(virAtomicIntPtr vaip, int sub)
{
return __sync_sub_and_fetch(&vaip->value, sub);
}
# endif /* __VIR_ATOMIC_USES_LOCK */
/* common operations that need no locking or build on others */
static inline void
virAtomicIntSet(virAtomicIntPtr vaip, int value)
{
vaip->value = value;
}
static inline int
virAtomicIntRead(virAtomicIntPtr vaip)
{
return *(volatile int *)&vaip->value;
}
static inline int
virAtomicIntInc(virAtomicIntPtr vaip)
{
return virAtomicIntAdd(vaip, 1);
}
static inline int
virAtomicIntDec(virAtomicIntPtr vaip)
{
return virAtomicIntSub(vaip, 1);
}
#endif /* __VIR_ATOMIC_H */