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#ifndef GC_DARWIN_SEMAPHORE_H
#define GC_DARWIN_SEMAPHORE_H
#if !defined(GC_DARWIN_THREADS)
#error darwin_semaphore.h included with GC_DARWIN_THREADS not defined
#endif
/*
This is a very simple semaphore implementation for darwin. It
is implemented in terms of pthreads calls so it isn't async signal
safe. This isn't a problem because signals aren't used to
suspend threads on darwin.
*/
typedef struct {
pthread_mutex_t mutex;
pthread_cond_t cond;
int value;
} sem_t;
static int sem_init(sem_t *sem, int pshared, int value) {
int ret;
if(pshared)
GC_abort("sem_init with pshared set");
sem->value = value;
ret = pthread_mutex_init(&sem->mutex,NULL);
if(ret < 0) return -1;
ret = pthread_cond_init(&sem->cond,NULL);
if(ret < 0) return -1;
return 0;
}
static int sem_post(sem_t *sem) {
if(pthread_mutex_lock(&sem->mutex) < 0)
return -1;
sem->value++;
if(pthread_cond_signal(&sem->cond) < 0) {
pthread_mutex_unlock(&sem->mutex);
return -1;
}
if(pthread_mutex_unlock(&sem->mutex) < 0)
return -1;
return 0;
}
static int sem_wait(sem_t *sem) {
if(pthread_mutex_lock(&sem->mutex) < 0)
return -1;
while(sem->value == 0) {
pthread_cond_wait(&sem->cond,&sem->mutex);
}
sem->value--;
if(pthread_mutex_unlock(&sem->mutex) < 0)
return -1;
return 0;
}
static int sem_destroy(sem_t *sem) {
int ret;
ret = pthread_cond_destroy(&sem->cond);
if(ret < 0) return -1;
ret = pthread_mutex_destroy(&sem->mutex);
if(ret < 0) return -1;
return 0;
}
#endif
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