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-rw-r--r--components/libc/pthreads/pthread_rwlock.c354
1 files changed, 354 insertions, 0 deletions
diff --git a/components/libc/pthreads/pthread_rwlock.c b/components/libc/pthreads/pthread_rwlock.c
new file mode 100644
index 0000000000..3e009034cc
--- /dev/null
+++ b/components/libc/pthreads/pthread_rwlock.c
@@ -0,0 +1,354 @@
+/*
+ * File : pthread_rwlock.c
+ * This file is part of RT-Thread RTOS
+ * COPYRIGHT (C) 2006 - 2010, RT-Thread Development Team
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Change Logs:
+ * Date Author Notes
+ * 2010-10-26 Bernard the first version
+ */
+
+#include <pthread.h>
+
+int pthread_rwlockattr_init(pthread_rwlockattr_t *attr)
+{
+ if (!attr)
+ return EINVAL;
+ *attr = PTHREAD_PROCESS_PRIVATE;
+
+ return 0;
+}
+RTM_EXPORT(pthread_rwlockattr_init);
+
+int pthread_rwlockattr_destroy(pthread_rwlockattr_t *attr)
+{
+ if (!attr)
+ return EINVAL;
+
+ return 0;
+}
+RTM_EXPORT(pthread_rwlockattr_destroy);
+
+int pthread_rwlockattr_getpshared(const pthread_rwlockattr_t *attr,
+ int *pshared)
+{
+ if (!attr || !pshared)
+ return EINVAL;
+
+ *pshared = PTHREAD_PROCESS_PRIVATE;
+
+ return 0;
+}
+RTM_EXPORT(pthread_rwlockattr_getpshared);
+
+int pthread_rwlockattr_setpshared(pthread_rwlockattr_t *attr, int pshared)
+{
+ if (!attr || pshared != PTHREAD_PROCESS_PRIVATE)
+ return EINVAL;
+
+ return 0;
+}
+RTM_EXPORT(pthread_rwlockattr_setpshared);
+
+int pthread_rwlock_init(pthread_rwlock_t *rwlock,
+ const pthread_rwlockattr_t *attr)
+{
+ if (!rwlock)
+ return EINVAL;
+
+ rwlock->attr = PTHREAD_PROCESS_PRIVATE;
+ pthread_mutex_init(&(rwlock->rw_mutex), NULL);
+ pthread_cond_init(&(rwlock->rw_condreaders), NULL);
+ pthread_cond_init(&(rwlock->rw_condwriters), NULL);
+
+ rwlock->rw_nwaitwriters = 0;
+ rwlock->rw_nwaitreaders = 0;
+ rwlock->rw_refcount = 0;
+
+ return 0;
+}
+RTM_EXPORT(pthread_rwlock_init);
+
+int pthread_rwlock_destroy (pthread_rwlock_t *rwlock)
+{
+ int result;
+
+ if (!rwlock)
+ return EINVAL;
+ if (rwlock->attr == -1)
+ return 0; /* rwlock is not initialized */
+
+ if ( (result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
+ return(result);
+
+ if (rwlock->rw_refcount != 0 ||
+ rwlock->rw_nwaitreaders != 0 ||
+ rwlock->rw_nwaitwriters != 0)
+ {
+ result = EBUSY;
+
+ return result;
+ }
+ else
+ {
+ /* check whether busy */
+ result = rt_sem_trytake(&(rwlock->rw_condreaders.sem));
+ if (result == RT_EOK)
+ {
+ result = rt_sem_trytake(&(rwlock->rw_condwriters.sem));
+ if (result == RT_EOK)
+ {
+ rt_sem_release(&(rwlock->rw_condreaders.sem));
+ rt_sem_release(&(rwlock->rw_condwriters.sem));
+
+ pthread_cond_destroy(&rwlock->rw_condreaders);
+ pthread_cond_destroy(&rwlock->rw_condwriters);
+ }
+ else
+ {
+ rt_sem_release(&(rwlock->rw_condreaders.sem));
+ result = EBUSY;
+ }
+ }
+ else
+ result = EBUSY;
+ }
+
+ pthread_mutex_unlock(&rwlock->rw_mutex);
+ if (result == 0)
+ pthread_mutex_destroy(&rwlock->rw_mutex);
+
+ return result;
+}
+RTM_EXPORT(pthread_rwlock_destroy);
+
+int pthread_rwlock_rdlock(pthread_rwlock_t *rwlock)
+{
+ int result;
+
+ if (!rwlock)
+ return EINVAL;
+ if (rwlock->attr == -1)
+ pthread_rwlock_init(rwlock, NULL);
+
+ if ((result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
+ return(result);
+
+ /* give preference to waiting writers */
+ while (rwlock->rw_refcount < 0 || rwlock->rw_nwaitwriters > 0)
+ {
+ rwlock->rw_nwaitreaders++;
+ /* rw_mutex will be released when waiting for rw_condreaders */
+ result = pthread_cond_wait(&rwlock->rw_condreaders, &rwlock->rw_mutex);
+ /* rw_mutex should have been taken again when returned from waiting */
+ rwlock->rw_nwaitreaders--;
+ if (result != 0) /* wait error */
+ break;
+ }
+
+ /* another reader has a read lock */
+ if (result == 0)
+ rwlock->rw_refcount++;
+
+ pthread_mutex_unlock(&rwlock->rw_mutex);
+
+ return (result);
+}
+RTM_EXPORT(pthread_rwlock_rdlock);
+
+int pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock)
+{
+ int result;
+
+ if (!rwlock)
+ return EINVAL;
+ if (rwlock->attr == -1)
+ pthread_rwlock_init(rwlock, NULL);
+
+ if ((result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
+ return(result);
+
+ if (rwlock->rw_refcount < 0 || rwlock->rw_nwaitwriters > 0)
+ result = EBUSY; /* held by a writer or waiting writers */
+ else
+ rwlock->rw_refcount++; /* increment count of reader locks */
+
+ pthread_mutex_unlock(&rwlock->rw_mutex);
+
+ return(result);
+}
+RTM_EXPORT(pthread_rwlock_tryrdlock);
+
+int pthread_rwlock_timedrdlock(pthread_rwlock_t *rwlock,
+ const struct timespec *abstime)
+{
+ int result;
+
+ if (!rwlock)
+ return EINVAL;
+ if (rwlock->attr == -1)
+ pthread_rwlock_init(rwlock, NULL);
+
+ if ( (result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
+ return(result);
+
+ /* give preference to waiting writers */
+ while (rwlock->rw_refcount < 0 || rwlock->rw_nwaitwriters > 0)
+ {
+ rwlock->rw_nwaitreaders++;
+ /* rw_mutex will be released when waiting for rw_condreaders */
+ result = pthread_cond_timedwait(&rwlock->rw_condreaders, &rwlock->rw_mutex, abstime);
+ /* rw_mutex should have been taken again when returned from waiting */
+ rwlock->rw_nwaitreaders--;
+ if (result != 0)
+ break;
+ }
+
+ /* another reader has a read lock */
+ if (result == 0)
+ rwlock->rw_refcount++;
+
+ pthread_mutex_unlock(&rwlock->rw_mutex);
+
+ return (result);
+}
+RTM_EXPORT(pthread_rwlock_timedrdlock);
+
+int pthread_rwlock_timedwrlock(pthread_rwlock_t *rwlock,
+ const struct timespec *abstime)
+{
+ int result;
+
+ if (!rwlock)
+ return EINVAL;
+ if (rwlock->attr == -1)
+ pthread_rwlock_init(rwlock, NULL);
+
+ if ((result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
+ return(result);
+
+ while (rwlock->rw_refcount != 0)
+ {
+ rwlock->rw_nwaitwriters++;
+ /* rw_mutex will be released when waiting for rw_condwriters */
+ result = pthread_cond_timedwait(&rwlock->rw_condwriters, &rwlock->rw_mutex, abstime);
+ /* rw_mutex should have been taken again when returned from waiting */
+ rwlock->rw_nwaitwriters--;
+
+ if (result != 0)
+ break;
+ }
+
+ if (result == 0)
+ rwlock->rw_refcount = -1;
+
+ pthread_mutex_unlock(&rwlock->rw_mutex);
+
+ return(result);
+}
+RTM_EXPORT(pthread_rwlock_timedwrlock);
+
+int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock)
+{
+ int result;
+
+ if (!rwlock)
+ return EINVAL;
+ if (rwlock->attr == -1)
+ pthread_rwlock_init(rwlock, NULL);
+
+ if ((result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
+ return(result);
+
+ if (rwlock->rw_refcount != 0)
+ result = EBUSY; /* held by either writer or reader(s) */
+ else
+ rwlock->rw_refcount = -1; /* available, indicate a writer has it */
+
+ pthread_mutex_unlock(&rwlock->rw_mutex);
+
+ return(result);
+}
+RTM_EXPORT(pthread_rwlock_trywrlock);
+
+int pthread_rwlock_unlock(pthread_rwlock_t *rwlock)
+{
+ int result;
+
+ if (!rwlock)
+ return EINVAL;
+ if (rwlock->attr == -1)
+ pthread_rwlock_init(rwlock, NULL);
+
+ if ( (result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
+ return(result);
+
+ if (rwlock->rw_refcount > 0)
+ rwlock->rw_refcount--; /* releasing a reader */
+ else if (rwlock->rw_refcount == -1)
+ rwlock->rw_refcount = 0; /* releasing a writer */
+
+ /* give preference to waiting writers over waiting readers */
+ if (rwlock->rw_nwaitwriters > 0)
+ {
+ if (rwlock->rw_refcount == 0)
+ result = pthread_cond_signal(&rwlock->rw_condwriters);
+ }
+ else if (rwlock->rw_nwaitreaders > 0)
+ {
+ result = pthread_cond_broadcast(&rwlock->rw_condreaders);
+ }
+
+ pthread_mutex_unlock(&rwlock->rw_mutex);
+
+ return(result);
+}
+RTM_EXPORT(pthread_rwlock_unlock);
+
+int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock)
+{
+ int result;
+
+ if (!rwlock)
+ return EINVAL;
+ if (rwlock->attr == -1)
+ pthread_rwlock_init(rwlock, NULL);
+
+ if ((result = pthread_mutex_lock(&rwlock->rw_mutex)) != 0)
+ return(result);
+
+ while (rwlock->rw_refcount != 0)
+ {
+ rwlock->rw_nwaitwriters++;
+ /* rw_mutex will be released when waiting for rw_condwriters */
+ result = pthread_cond_wait(&rwlock->rw_condwriters, &rwlock->rw_mutex);
+ /* rw_mutex should have been taken again when returned from waiting */
+ rwlock->rw_nwaitwriters--;
+
+ if (result != 0)
+ break;
+ }
+
+ if (result == 0)
+ rwlock->rw_refcount = -1;
+
+ pthread_mutex_unlock(&rwlock->rw_mutex);
+
+ return(result);
+}
+RTM_EXPORT(pthread_rwlock_wrlock);
+
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