diff options
Diffstat (limited to 'pthreads/src/pthread_mutex_trylock.c')
| -rw-r--r-- | pthreads/src/pthread_mutex_trylock.c | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/pthreads/src/pthread_mutex_trylock.c b/pthreads/src/pthread_mutex_trylock.c new file mode 100644 index 0000000..d6b6872 --- /dev/null +++ b/pthreads/src/pthread_mutex_trylock.c @@ -0,0 +1,154 @@ +/* + * pthread_mutex_trylock.c + * + * Description: + * This translation unit implements mutual exclusion (mutex) 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 "pthread.h" +#include "implement.h" + + +int +pthread_mutex_trylock (pthread_mutex_t * mutex) +{ + pthread_mutex_t mx; + int kind; + int result = 0; + + /* + * Let the system deal with invalid pointers. + */ + + /* + * We do a quick check to see if we need to do more work + * to initialise a static mutex. We check + * again inside the guarded section of ptw32_mutex_check_need_init() + * to avoid race conditions. + */ + if (*mutex >= PTHREAD_ERRORCHECK_MUTEX_INITIALIZER) + { + if ((result = ptw32_mutex_check_need_init (mutex)) != 0) + { + return (result); + } + } + + mx = *mutex; + kind = mx->kind; + + if (kind >= 0) + { + /* Non-robust */ + if (0 == (PTW32_INTERLOCKED_LONG) PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG ( + (PTW32_INTERLOCKED_LONGPTR) &mx->lock_idx, + (PTW32_INTERLOCKED_LONG) 1, + (PTW32_INTERLOCKED_LONG) 0)) + { + if (kind != PTHREAD_MUTEX_NORMAL) + { + mx->recursive_count = 1; + mx->ownerThread = pthread_self (); + } + } + else + { + if (kind == PTHREAD_MUTEX_RECURSIVE && + pthread_equal (mx->ownerThread, pthread_self ())) + { + mx->recursive_count++; + } + else + { + result = EBUSY; + } + } + } + else + { + /* + * Robust types + * All types record the current owner thread. + * The mutex is added to a per thread list when ownership is acquired. + */ + pthread_t self; + ptw32_robust_state_t* statePtr = &mx->robustNode->stateInconsistent; + + if ((PTW32_INTERLOCKED_LONG)PTW32_ROBUST_NOTRECOVERABLE == + PTW32_INTERLOCKED_EXCHANGE_ADD_LONG( + (PTW32_INTERLOCKED_LONGPTR)statePtr, + (PTW32_INTERLOCKED_LONG)0)) + { + return ENOTRECOVERABLE; + } + + self = pthread_self(); + kind = -kind - 1; /* Convert to non-robust range */ + + if (0 == (PTW32_INTERLOCKED_LONG) PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG ( + (PTW32_INTERLOCKED_LONGPTR) &mx->lock_idx, + (PTW32_INTERLOCKED_LONG) 1, + (PTW32_INTERLOCKED_LONG) 0)) + { + if (kind != PTHREAD_MUTEX_NORMAL) + { + mx->recursive_count = 1; + } + ptw32_robust_mutex_add(mutex, self); + } + else + { + if (PTHREAD_MUTEX_RECURSIVE == kind && + pthread_equal (mx->ownerThread, pthread_self ())) + { + mx->recursive_count++; + } + else + { + if (EOWNERDEAD == (result = ptw32_robust_mutex_inherit(mutex))) + { + mx->recursive_count = 1; + ptw32_robust_mutex_add(mutex, self); + } + else + { + if (0 == result) + { + result = EBUSY; + } + } + } + } + } + + return (result); +} |