2 * pthread_rwlock_trywrlock.c
5 * This translation unit implements read/write lock primitives.
7 * --------------------------------------------------------------------------
9 * Pthreads-win32 - POSIX Threads Library for Win32
10 * Copyright(C) 1998 John E. Bossom
11 * Copyright(C) 1999,2005 Pthreads-win32 contributors
13 * Contact Email: rpj@callisto.canberra.edu.au
15 * The current list of contributors is contained
16 * in the file CONTRIBUTORS included with the source
17 * code distribution. The list can also be seen at the
18 * following World Wide Web location:
19 * http://sources.redhat.com/pthreads-win32/contributors.html
21 * This library is free software; you can redistribute it and/or
22 * modify it under the terms of the GNU Lesser General Public
23 * License as published by the Free Software Foundation; either
24 * version 2 of the License, or (at your option) any later version.
26 * This library is distributed in the hope that it will be useful,
27 * but WITHOUT ANY WARRANTY; without even the implied warranty of
28 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
29 * Lesser General Public License for more details.
31 * You should have received a copy of the GNU Lesser General Public
32 * License along with this library in the file COPYING.LIB;
33 * if not, write to the Free Software Foundation, Inc.,
34 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
40 #include "implement.h"
43 pthread_rwlock_trywrlock (pthread_rwlock_t * rwlock)
48 if (rwlock == NULL || *rwlock == NULL)
54 * We do a quick check to see if we need to do more work
55 * to initialise a static rwlock. We check
56 * again inside the guarded section of ptw32_rwlock_check_need_init()
57 * to avoid race conditions.
59 if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
61 result = ptw32_rwlock_check_need_init (rwlock);
63 if (result != 0 && result != EBUSY)
71 if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
76 if ((result = pthread_mutex_trylock (&(rwl->mtxExclusiveAccess))) != 0)
82 pthread_mutex_trylock (&(rwl->mtxSharedAccessCompleted))) != 0)
84 result1 = pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
85 return ((result1 != 0) ? result1 : result);
88 if (rwl->nExclusiveAccessCount == 0)
90 if (rwl->nCompletedSharedAccessCount > 0)
92 rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount;
93 rwl->nCompletedSharedAccessCount = 0;
96 if (rwl->nSharedAccessCount > 0)
99 pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted))) != 0)
101 (void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
106 pthread_mutex_unlock (&(rwl->mtxExclusiveAccess))) == 0)
113 rwl->nExclusiveAccessCount = 1;