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