diff options
Diffstat (limited to 'pthread_rwlock_wrlock.c')
| -rw-r--r-- | pthread_rwlock_wrlock.c | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/pthread_rwlock_wrlock.c b/pthread_rwlock_wrlock.c new file mode 100644 index 0000000..6e85bf1 --- /dev/null +++ b/pthread_rwlock_wrlock.c @@ -0,0 +1,146 @@ +/* + * pthread_rwlock_wrlock.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) 1999,2002 Pthreads-win32 contributors + * + * Contact Email: rpj@ise.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 <errno.h> +#include <limits.h> + +#include "pthread.h" +#include "implement.h" + +static void +ptw32_rwlock_cancelwrwait(void * arg) +{ + pthread_rwlock_t rwl = (pthread_rwlock_t) arg; + + rwl->nSharedAccessCount = -rwl->nCompletedSharedAccessCount; + rwl->nCompletedSharedAccessCount = 0; + + (void) pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted)); + (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess)); +} + +int +pthread_rwlock_wrlock(pthread_rwlock_t * rwlock) +{ + int result; + pthread_rwlock_t rwl; + + if (rwlock == NULL || *rwlock == NULL) + { + return EINVAL; + } + + /* + * We do a quick check to see if we need to do more work + * to initialise a static rwlock. We check + * again inside the guarded section of ptw32_rwlock_check_need_init() + * to avoid race conditions. + */ + if (*rwlock == PTHREAD_RWLOCK_INITIALIZER) + { + result = ptw32_rwlock_check_need_init(rwlock); + + if (result != 0 && result != EBUSY) + { + return result; + } + } + + 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; + } + + if (rwl->nExclusiveAccessCount == 0) + { + if (rwl->nCompletedSharedAccessCount > 0) + { + rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount; + rwl->nCompletedSharedAccessCount = 0; + } + + if (rwl->nSharedAccessCount > 0) + { + rwl->nCompletedSharedAccessCount = -rwl->nSharedAccessCount; + + /* + * This routine may be a cancelation point + * according to POSIX 1003.1j section 18.1.2. + */ +#ifdef _MSC_VER +#pragma inline_depth(0) +#endif + pthread_cleanup_push(ptw32_rwlock_cancelwrwait, (void*)rwl); + + do + { + result = pthread_cond_wait(&(rwl->cndSharedAccessCompleted), + &(rwl->mtxSharedAccessCompleted)); + } + while (result == 0 && rwl->nCompletedSharedAccessCount < 0); + + pthread_cleanup_pop ((result != 0) ? 1 : 0); +#ifdef _MSC_VER +#pragma inline_depth() +#endif + + if (result == 0) + { + rwl->nSharedAccessCount = 0; + } + } + } + + if (result == 0) + { + rwl->nExclusiveAccessCount++; + } + + return result; +} |