144 lines
4 KiB
C
144 lines
4 KiB
C
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/*
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* pthread_rwlock_destroy.c
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*
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* Description:
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* This translation unit implements read/write lock primitives.
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*
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* --------------------------------------------------------------------------
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*
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* Pthreads-win32 - POSIX Threads Library for Win32
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* Copyright(C) 1998 John E. Bossom
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* Copyright(C) 1999,2005 Pthreads-win32 contributors
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*
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* Contact Email: rpj@callisto.canberra.edu.au
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*
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* The current list of contributors is contained
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* in the file CONTRIBUTORS included with the source
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* code distribution. The list can also be seen at the
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* following World Wide Web location:
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* http://sources.redhat.com/pthreads-win32/contributors.html
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library in the file COPYING.LIB;
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* if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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#include <limits.h>
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#include "pthread.h"
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#include "implement.h"
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int
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pthread_rwlock_destroy (pthread_rwlock_t * rwlock)
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{
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pthread_rwlock_t rwl;
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int result = 0, result1 = 0, result2 = 0;
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if (rwlock == NULL || *rwlock == NULL)
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{
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return EINVAL;
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}
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if (*rwlock != PTHREAD_RWLOCK_INITIALIZER)
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{
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rwl = *rwlock;
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if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
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{
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return EINVAL;
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}
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if ((result = pthread_mutex_lock (&(rwl->mtxExclusiveAccess))) != 0)
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{
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return result;
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}
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if ((result =
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pthread_mutex_lock (&(rwl->mtxSharedAccessCompleted))) != 0)
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{
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(void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
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return result;
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}
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/*
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* Check whether any threads own/wait for the lock (wait for ex.access);
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* report "BUSY" if so.
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*/
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if (rwl->nExclusiveAccessCount > 0
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|| rwl->nSharedAccessCount > rwl->nCompletedSharedAccessCount)
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{
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result = pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted));
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result1 = pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
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result2 = EBUSY;
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}
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else
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{
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rwl->nMagic = 0;
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if ((result =
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pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted))) != 0)
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{
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pthread_mutex_unlock (&rwl->mtxExclusiveAccess);
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return result;
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}
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if ((result =
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pthread_mutex_unlock (&(rwl->mtxExclusiveAccess))) != 0)
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{
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return result;
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}
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*rwlock = NULL; /* Invalidate rwlock before anything else */
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result = pthread_cond_destroy (&(rwl->cndSharedAccessCompleted));
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result1 = pthread_mutex_destroy (&(rwl->mtxSharedAccessCompleted));
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result2 = pthread_mutex_destroy (&(rwl->mtxExclusiveAccess));
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(void) free (rwl);
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}
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}
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else
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{
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ptw32_mcs_local_node_t node;
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/*
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* See notes in ptw32_rwlock_check_need_init() above also.
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*/
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ptw32_mcs_lock_acquire(&ptw32_rwlock_test_init_lock, &node);
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/*
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* Check again.
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*/
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if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
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{
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/*
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* This is all we need to do to destroy a statically
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* initialised rwlock that has not yet been used (initialised).
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* If we get to here, another thread
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* waiting to initialise this rwlock will get an EINVAL.
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*/
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*rwlock = NULL;
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}
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else
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{
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/*
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* The rwlock has been initialised while we were waiting
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* so assume it's in use.
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*/
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result = EBUSY;
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}
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ptw32_mcs_lock_release(&node);
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}
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return ((result != 0) ? result : ((result1 != 0) ? result1 : result2));
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}
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