149 lines
4.0 KiB
C
149 lines
4.0 KiB
C
/****************************************************************************
|
|
* libc/pthread/pthread_rwlockwrite.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>
|
|
|
|
#include <nuttx/semaphore.h>
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: pthread_rwlock_rdlock
|
|
*
|
|
* Description:
|
|
* Locks a read/write lock for reading
|
|
*
|
|
* Parameters:
|
|
* None
|
|
*
|
|
* Return Value:
|
|
* None
|
|
*
|
|
* Assumptions:
|
|
*
|
|
****************************************************************************/
|
|
|
|
int pthread_rwlock_trywrlock(FAR pthread_rwlock_t *rw_lock)
|
|
{
|
|
int err = pthread_mutex_trylock(&rw_lock->lock);
|
|
|
|
if (err != 0)
|
|
{
|
|
return err;
|
|
}
|
|
|
|
if (rw_lock->num_readers > 0 || rw_lock->write_in_progress)
|
|
{
|
|
err = EBUSY;
|
|
}
|
|
else
|
|
{
|
|
rw_lock->write_in_progress = true;
|
|
}
|
|
|
|
pthread_mutex_unlock(&rw_lock->lock);
|
|
return err;
|
|
}
|
|
|
|
int pthread_rwlock_timedwrlock(FAR pthread_rwlock_t *rw_lock,
|
|
FAR const struct timespec *ts)
|
|
{
|
|
int err = pthread_mutex_lock(&rw_lock->lock);
|
|
|
|
if (err != 0)
|
|
{
|
|
return err;
|
|
}
|
|
|
|
if (rw_lock->num_writers == UINT_MAX)
|
|
{
|
|
err = EAGAIN;
|
|
goto exit_with_mutex;
|
|
}
|
|
|
|
rw_lock->num_writers++;
|
|
|
|
while (rw_lock->write_in_progress || rw_lock->num_readers > 0)
|
|
{
|
|
if (ts != NULL)
|
|
{
|
|
err = pthread_cond_timedwait(&rw_lock->cv, &rw_lock->lock, ts);
|
|
}
|
|
else
|
|
{
|
|
err = pthread_cond_wait(&rw_lock->cv, &rw_lock->lock);
|
|
}
|
|
|
|
if (err != 0)
|
|
{
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (err == 0)
|
|
{
|
|
rw_lock->write_in_progress = true;
|
|
}
|
|
|
|
else
|
|
{
|
|
/* In case of error, notify any blocked readers. */
|
|
|
|
(void) pthread_cond_broadcast(&rw_lock->cv);
|
|
}
|
|
|
|
rw_lock->num_writers--;
|
|
|
|
exit_with_mutex:
|
|
pthread_mutex_unlock(&rw_lock->lock);
|
|
return err;
|
|
}
|
|
|
|
int pthread_rwlock_wrlock(FAR pthread_rwlock_t *rw_lock)
|
|
{
|
|
return pthread_rwlock_timedwrlock(rw_lock, NULL);
|
|
}
|