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pthread_rwlock_destroy.c    144 lines (128 with data), 4.0 kB

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/*
* pthread_rwlock_destroy.c
*
* Description:
* This translation unit implements read/write lock primitives.
*
* --------------------------------------------------------------------------
*
* Pthreads-win32 - POSIX Threads Library for Win32
* Copyright(C) 1998 John E. Bossom
* Copyright(C) 1999,2005 Pthreads-win32 contributors
*
* Contact Email: rpj@callisto.canberra.edu.au
*
* The current list of contributors is contained
* in the file CONTRIBUTORS included with the source
* code distribution. The list can also be seen at the
* following World Wide Web location:
* http://sources.redhat.com/pthreads-win32/contributors.html
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library in the file COPYING.LIB;
* if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <limits.h>
#include "pthread.h"
#include "implement.h"
int
pthread_rwlock_destroy (pthread_rwlock_t * rwlock)
{
pthread_rwlock_t rwl;
int result = 0, result1 = 0, result2 = 0;
if (rwlock == NULL || *rwlock == NULL)
{
return EINVAL;
}
if (*rwlock != PTHREAD_RWLOCK_INITIALIZER)
{
rwl = *rwlock;
if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
{
return EINVAL;
}
if ((result = pthread_mutex_lock (&(rwl->mtxExclusiveAccess))) != 0)
{
return result;
}
if ((result =
pthread_mutex_lock (&(rwl->mtxSharedAccessCompleted))) != 0)
{
(void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
return result;
}
/*
* Check whether any threads own/wait for the lock (wait for ex.access);
* report "BUSY" if so.
*/
if (rwl->nExclusiveAccessCount > 0
|| rwl->nSharedAccessCount > rwl->nCompletedSharedAccessCount)
{
result = pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted));
result1 = pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
result2 = EBUSY;
}
else
{
rwl->nMagic = 0;
if ((result =
pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted))) != 0)
{
pthread_mutex_unlock (&rwl->mtxExclusiveAccess);
return result;
}
if ((result =
pthread_mutex_unlock (&(rwl->mtxExclusiveAccess))) != 0)
{
return result;
}
*rwlock = NULL; /* Invalidate rwlock before anything else */
result = pthread_cond_destroy (&(rwl->cndSharedAccessCompleted));
result1 = pthread_mutex_destroy (&(rwl->mtxSharedAccessCompleted));
result2 = pthread_mutex_destroy (&(rwl->mtxExclusiveAccess));
(void) free (rwl);
}
}
else
{
ptw32_mcs_local_node_t node;
/*
* See notes in ptw32_rwlock_check_need_init() above also.
*/
ptw32_mcs_lock_acquire(&ptw32_rwlock_test_init_lock, &node);
/*
* Check again.
*/
if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
{
/*
* This is all we need to do to destroy a statically
* initialised rwlock that has not yet been used (initialised).
* If we get to here, another thread
* waiting to initialise this rwlock will get an EINVAL.
*/
*rwlock = NULL;
}
else
{
/*
* The rwlock has been initialised while we were waiting
* so assume it's in use.
*/
result = EBUSY;
}
ptw32_mcs_lock_release(&node);
}
return ((result != 0) ? result : ((result1 != 0) ? result1 : result2));
}