280 lines
7.0 KiB
C
280 lines
7.0 KiB
C
#include <pthread.h>
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int pthread_rwlockattr_init (pthread_rwlockattr_t * attr)
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{
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if (!attr) return EINVAL;
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*attr = PTHREAD_PROCESS_PRIVATE;
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return 0;
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}
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RTM_EXPORT(pthread_rwlockattr_init);
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int pthread_rwlockattr_destroy (pthread_rwlockattr_t * attr)
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{
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if (!attr) return EINVAL;
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return 0;
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}
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RTM_EXPORT(pthread_rwlockattr_destroy);
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int pthread_rwlockattr_getpshared (const pthread_rwlockattr_t * attr, int *pshared)
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{
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if (!attr || !pshared) return EINVAL;
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*pshared = PTHREAD_PROCESS_PRIVATE;
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return 0;
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}
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RTM_EXPORT(pthread_rwlockattr_getpshared);
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int pthread_rwlockattr_setpshared (pthread_rwlockattr_t * attr, int pshared)
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{
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if (!attr || pshared != PTHREAD_PROCESS_PRIVATE) return EINVAL;
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return 0;
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}
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RTM_EXPORT(pthread_rwlockattr_setpshared);
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int pthread_rwlock_init (pthread_rwlock_t *rwlock, const pthread_rwlockattr_t * attr)
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{
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if (!rwlock) return EINVAL;
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rwlock->attr = PTHREAD_PROCESS_PRIVATE;
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pthread_mutex_init(&(rwlock->rw_mutex), NULL);
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pthread_cond_init(&(rwlock->rw_condreaders), NULL);
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pthread_cond_init(&(rwlock->rw_condwriters), NULL);
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rwlock->rw_nwaitwriters = 0;
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rwlock->rw_nwaitreaders = 0;
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rwlock->rw_refcount = 0;
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return 0;
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}
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RTM_EXPORT(pthread_rwlock_init);
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int pthread_rwlock_destroy (pthread_rwlock_t *rwlock)
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{
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int result;
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if (!rwlock) return EINVAL;
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if (rwlock->attr == -1) return 0; /* rwlock is not initialized */
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if ( (result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
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return(result);
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if (rwlock->rw_refcount != 0 ||
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rwlock->rw_nwaitreaders != 0 || rwlock->rw_nwaitwriters != 0)
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{
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result = EBUSY;
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return(EBUSY);
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}
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else
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{
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/* check whether busy */
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result = rt_sem_trytake(&(rwlock->rw_condreaders.sem));
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if (result == RT_EOK)
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{
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result = rt_sem_trytake(&(rwlock->rw_condwriters.sem));
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if (result == RT_EOK)
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{
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rt_sem_release(&(rwlock->rw_condreaders.sem));
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rt_sem_release(&(rwlock->rw_condwriters.sem));
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pthread_cond_destroy(&rwlock->rw_condreaders);
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pthread_cond_destroy(&rwlock->rw_condwriters);
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}
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else
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{
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rt_sem_release(&(rwlock->rw_condreaders.sem));
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result = EBUSY;
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}
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}
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else result = EBUSY;
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}
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pthread_mutex_unlock(&rwlock->rw_mutex);
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if (result == 0) pthread_mutex_destroy(&rwlock->rw_mutex);
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return result;
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}
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RTM_EXPORT(pthread_rwlock_destroy);
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int pthread_rwlock_rdlock (pthread_rwlock_t *rwlock)
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{
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int result;
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if (!rwlock) return EINVAL;
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if (rwlock->attr == -1) pthread_rwlock_init(rwlock, NULL);
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if ( (result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
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return(result);
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/* give preference to waiting writers */
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while (rwlock->rw_refcount < 0 || rwlock->rw_nwaitwriters > 0)
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{
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rwlock->rw_nwaitreaders++;
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result = pthread_cond_wait(&rwlock->rw_condreaders, &rwlock->rw_mutex);
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rwlock->rw_nwaitreaders--;
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if (result != 0)
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break;
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}
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/* another reader has a read lock */
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if (result == 0) rwlock->rw_refcount++;
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pthread_mutex_unlock(&rwlock->rw_mutex);
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return (result);
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}
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RTM_EXPORT(pthread_rwlock_rdlock);
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int pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock)
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{
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int result;
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if (!rwlock) return EINVAL;
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if (rwlock->attr == -1) pthread_rwlock_init(rwlock, NULL);
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if ((result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
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return(result);
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if (rwlock->rw_refcount < 0 || rwlock->rw_nwaitwriters > 0)
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result = EBUSY; /* held by a writer or waiting writers */
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else
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rwlock->rw_refcount++; /* increment count of reader locks */
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pthread_mutex_unlock(&rwlock->rw_mutex);
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return(result);
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}
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RTM_EXPORT(pthread_rwlock_tryrdlock);
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int pthread_rwlock_timedrdlock (pthread_rwlock_t * rwlock, const struct timespec *abstime)
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{
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int result;
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if (!rwlock) return EINVAL;
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if (rwlock->attr == -1) pthread_rwlock_init(rwlock, NULL);
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if ( (result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
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return(result);
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/* give preference to waiting writers */
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while (rwlock->rw_refcount < 0 || rwlock->rw_nwaitwriters > 0)
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{
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rwlock->rw_nwaitreaders++;
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result = pthread_cond_timedwait(&rwlock->rw_condreaders, &rwlock->rw_mutex, abstime);
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rwlock->rw_nwaitreaders--;
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if (result != 0)
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break;
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}
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/* another reader has a read lock */
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if (result == 0) rwlock->rw_refcount++;
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pthread_mutex_unlock(&rwlock->rw_mutex);
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return (result);
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}
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RTM_EXPORT(pthread_rwlock_timedrdlock);
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int pthread_rwlock_timedwrlock (pthread_rwlock_t *rwlock, const struct timespec *abstime)
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{
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int result;
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if (!rwlock) return EINVAL;
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if (rwlock->attr == -1) pthread_rwlock_init(rwlock, NULL);
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if ( (result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
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return(result);
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while (rwlock->rw_refcount != 0)
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{
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rwlock->rw_nwaitwriters++;
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result = pthread_cond_timedwait(&rwlock->rw_condwriters, &rwlock->rw_mutex, abstime);
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rwlock->rw_nwaitwriters--;
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if (result != 0) break;
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}
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if (result == 0) rwlock->rw_refcount = -1;
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pthread_mutex_unlock(&rwlock->rw_mutex);
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return(result);
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}
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RTM_EXPORT(pthread_rwlock_timedwrlock);
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int pthread_rwlock_trywrlock (pthread_rwlock_t *rwlock)
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{
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int result;
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if (!rwlock) return EINVAL;
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if (rwlock->attr == -1) pthread_rwlock_init(rwlock, NULL);
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if ( (result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
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return(result);
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if (rwlock->rw_refcount != 0)
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result = EBUSY; /* held by either writer or reader(s) */
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else
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rwlock->rw_refcount = -1; /* available, indicate a writer has it */
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pthread_mutex_unlock(&rwlock->rw_mutex);
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return(result);
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}
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RTM_EXPORT(pthread_rwlock_trywrlock);
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int pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
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{
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int result;
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if (!rwlock) return EINVAL;
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if (rwlock->attr == -1) pthread_rwlock_init(rwlock, NULL);
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if ( (result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
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return(result);
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if (rwlock->rw_refcount > 0)
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rwlock->rw_refcount--; /* releasing a reader */
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else if (rwlock->rw_refcount == -1)
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rwlock->rw_refcount = 0; /* releasing a reader */
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/* give preference to waiting writers over waiting readers */
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if (rwlock->rw_nwaitwriters > 0)
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{
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if (rwlock->rw_refcount == 0)
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result = pthread_cond_signal(&rwlock->rw_condwriters);
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}
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else if (rwlock->rw_nwaitreaders > 0)
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{
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result = pthread_cond_broadcast(&rwlock->rw_condreaders);
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}
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pthread_mutex_unlock(&rwlock->rw_mutex);
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return(result);
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}
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RTM_EXPORT(pthread_rwlock_unlock);
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int pthread_rwlock_wrlock (pthread_rwlock_t *rwlock)
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{
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int result;
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if (!rwlock) return EINVAL;
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if (rwlock->attr == -1) pthread_rwlock_init(rwlock, NULL);
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if ( (result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
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return(result);
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while (rwlock->rw_refcount != 0)
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{
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rwlock->rw_nwaitwriters++;
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result = pthread_cond_wait(&rwlock->rw_condwriters, &rwlock->rw_mutex);
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rwlock->rw_nwaitwriters--;
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if (result != 0) break;
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}
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if (result == 0) rwlock->rw_refcount = -1;
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pthread_mutex_unlock(&rwlock->rw_mutex);
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return(result);
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}
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RTM_EXPORT(pthread_rwlock_wrlock);
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