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/*
* Copyright (c) 1994 by Xerox Corporation. All rights reserved.
* Copyright (c) 1996 by Silicon Graphics. All rights reserved.
* Copyright (c) 1998 by Fergus Henderson. All rights reserved.
* Copyright (c) 2000-2009 by Hewlett-Packard Development Company.
* All rights reserved.
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose, provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/
#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 pthread calls so it is not async signal */
/* safe. But this is not a problem because signals are not used to */
/* suspend threads on Darwin. */
typedef struct {
pthread_mutex_t mutex;
pthread_cond_t cond;
int value;
} sem_t;
GC_INLINE int sem_init(sem_t *sem, int pshared, int value) {
if (pshared != 0) {
errno = EPERM; /* unsupported */
return -1;
}
sem->value = value;
if (pthread_mutex_init(&sem->mutex, NULL) != 0)
return -1;
if (pthread_cond_init(&sem->cond, NULL) != 0) {
(void)pthread_mutex_destroy(&sem->mutex);
return -1;
}
return 0;
}
GC_INLINE int sem_post(sem_t *sem) {
if (pthread_mutex_lock(&sem->mutex) != 0)
return -1;
sem->value++;
if (pthread_cond_signal(&sem->cond) != 0) {
(void)pthread_mutex_unlock(&sem->mutex);
return -1;
}
return pthread_mutex_unlock(&sem->mutex) != 0 ? -1 : 0;
}
GC_INLINE int sem_wait(sem_t *sem) {
if (pthread_mutex_lock(&sem->mutex) != 0)
return -1;
while (sem->value == 0) {
if (pthread_cond_wait(&sem->cond, &sem->mutex) != 0) {
(void)pthread_mutex_unlock(&sem->mutex);
return -1;
}
}
sem->value--;
return pthread_mutex_unlock(&sem->mutex) != 0 ? -1 : 0;
}
GC_INLINE int sem_destroy(sem_t *sem) {
return pthread_cond_destroy(&sem->cond) != 0
|| pthread_mutex_destroy(&sem->mutex) != 0 ? -1 : 0;
}
#endif
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