nuttx/libs/libc/pthread/pthread_rwlock.c
Alin Jerpelea e8f3c9441e libs: Mark Schulte: update licenses to Apache
Mark Schulte has submitted the ICLA and we can migrate the licenses
 to Apache.

Gregory Nutt has submitted the SGA and we can migrate the licenses
 to Apache.

Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
2021-04-01 12:13:12 -05:00

112 lines
2.7 KiB
C

/****************************************************************************
* libs/libc/pthread/pthread_rwlock.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <pthread.h>
#include <errno.h>
#include <debug.h>
/****************************************************************************
* Public Functions
****************************************************************************/
int pthread_rwlock_init(FAR pthread_rwlock_t *lock,
FAR const pthread_rwlockattr_t *attr)
{
int err;
if (attr != NULL)
{
return ENOSYS;
}
lock->num_readers = 0;
lock->num_writers = 0;
lock->write_in_progress = false;
err = pthread_cond_init(&lock->cv, NULL);
if (err != 0)
{
return err;
}
err = pthread_mutex_init(&lock->lock, NULL);
if (err != 0)
{
pthread_cond_destroy(&lock->cv);
return err;
}
return err;
}
int pthread_rwlock_destroy(FAR pthread_rwlock_t *lock)
{
int cond_err = pthread_cond_destroy(&lock->cv);
int mutex_err = pthread_mutex_destroy(&lock->lock);
if (mutex_err)
{
return mutex_err;
}
return cond_err;
}
int pthread_rwlock_unlock(FAR pthread_rwlock_t *rw_lock)
{
int err;
err = pthread_mutex_lock(&rw_lock->lock);
if (err != 0)
{
return err;
}
if (rw_lock->num_readers > 0)
{
rw_lock->num_readers--;
if (rw_lock->num_readers == 0)
{
err = pthread_cond_broadcast(&rw_lock->cv);
}
}
else if (rw_lock->write_in_progress)
{
rw_lock->write_in_progress = false;
err = pthread_cond_broadcast(&rw_lock->cv);
}
else
{
err = EINVAL;
}
pthread_mutex_unlock(&rw_lock->lock);
return err;
}