127 lines
3.5 KiB
C
127 lines
3.5 KiB
C
/****************************************************************************
|
|
* libs/libc/pthread/pthread_rwlock.c
|
|
*
|
|
* Copyright (C) 2017 Mark Schulte. All rights reserved.
|
|
* Author: Mark Schulte <mark@mjs.pw>
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in
|
|
* the documentation and/or other materials provided with the
|
|
* distribution.
|
|
* 3. Neither the name NuttX nor the names of its contributors may be
|
|
* used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
|
|
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
|
|
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
|
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
|
|
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
|
|
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
|
|
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* 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;
|
|
}
|