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