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Diffstat (limited to 'pthread_mutex_consistent.c')
| -rwxr-xr-x | pthread_mutex_consistent.c | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/pthread_mutex_consistent.c b/pthread_mutex_consistent.c new file mode 100755 index 0000000..b5dcc15 --- /dev/null +++ b/pthread_mutex_consistent.c @@ -0,0 +1,190 @@ +/* + * pthread_mutex_consistent.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 + */ + +/* + * From the Sun Multi-threaded Programming Guide + * + * robustness defines the behavior when the owner of the mutex terminates without unlocking the + * mutex, usually because its process terminated abnormally. The value of robustness that is + * defined in pthread.h is PTHREAD_MUTEX_ROBUST or PTHREAD_MUTEX_STALLED. The + * default value is PTHREAD_MUTEX_STALLED . + * ■ PTHREAD_MUTEX_STALLED + * When the owner of the mutex terminates without unlocking the mutex, all subsequent calls + * to pthread_mutex_lock() are blocked from progress in an unspecified manner. + * ■ PTHREAD_MUTEX_ROBUST + * When the owner of the mutex terminates without unlocking the mutex, the mutex is + * unlocked. The next owner of this mutex acquires the mutex with an error return of + * EOWNERDEAD. + * Note – Your application must always check the return code from pthread_mutex_lock() for + * a mutex initialized with the PTHREAD_MUTEX_ROBUST attribute. + * ■ The new owner of this mutex should make the state protected by the mutex consistent. + * This state might have been left inconsistent when the previous owner terminated. + * ■ If the new owner is able to make the state consistent, call + * pthread_mutex_consistent() for the mutex before unlocking the mutex. This + * marks the mutex as consistent and subsequent calls to pthread_mutex_lock() and + * pthread_mutex_unlock() will behave in the normal manner. + * ■ If the new owner is not able to make the state consistent, do not call + * pthread_mutex_consistent() for the mutex, but unlock the mutex. + * All waiters are woken up and all subsequent calls to pthread_mutex_lock() fail to + * acquire the mutex. The return code is ENOTRECOVERABLE. The mutex can be made + * consistent by calling pthread_mutex_destroy() to uninitialize the mutex, and calling + * pthread_mutex_int() to reinitialize the mutex.However, the state that was protected + * by the mutex remains inconsistent and some form of application recovery is required. + * ■ If the thread that acquires the lock with EOWNERDEAD terminates without unlocking the + * mutex, the next owner acquires the lock with an EOWNERDEAD return code. + */ +#ifndef _UWIN +/*# include <process.h> */ +#endif +#include "pthread.h" +#include "implement.h" + +INLINE +int +ptw32_robust_mutex_inherit(pthread_mutex_t * mutex) +{ + int result; + pthread_mutex_t mx = *mutex; + ptw32_robust_node_t* robust = mx->robustNode; + + switch (PTW32_INTERLOCKED_COMPARE_EXCHANGE( + (LPLONG)&robust->stateInconsistent, + (LONG)PTW32_ROBUST_INCONSISTENT, + -1L /* The terminating thread sets this */)) + { + case -1L: + result = EOWNERDEAD; + break; + case (LONG)PTW32_ROBUST_NOTRECOVERABLE: + result = ENOTRECOVERABLE; + break; + default: + result = 0; + break; + } + + return result; +} + +/* + * The next two internal support functions depend on only being + * called by the thread that owns the robust mutex. This enables + * us to avoid additional locks. + * Any mutex currently in the thread's robust mutex list is held + * by the thread, again eliminating the need for locks. + * The forward/backward links allow the thread to unlock mutexes + * in any order, not necessarily the reverse locking order. + * This is all possible because it is an error if a thread that + * does not own the [robust] mutex attempts to unlock it. + */ + +INLINE +void +ptw32_robust_mutex_add(pthread_mutex_t* mutex, pthread_t self) +{ + ptw32_robust_node_t** list; + pthread_mutex_t mx = *mutex; + ptw32_thread_t* tp = (ptw32_thread_t*)self.p; + ptw32_robust_node_t* robust = mx->robustNode; + + list = &tp->robustMxList; + mx->ownerThread = self; + if (NULL == *list) + { + robust->prev = NULL; + robust->next = NULL; + *list = robust; + } + else + { + robust->prev = NULL; + robust->next = *list; + (*list)->prev = robust; + *list = robust; + } +} + +INLINE +void +ptw32_robust_mutex_remove(pthread_mutex_t* mutex, ptw32_thread_t* otp) +{ + ptw32_robust_node_t** list; + pthread_mutex_t mx = *mutex; + ptw32_robust_node_t* robust = mx->robustNode; + + list = &(((ptw32_thread_t*)mx->ownerThread.p)->robustMxList); + mx->ownerThread.p = otp; + if (robust->next != NULL) + { + robust->next->prev = robust->prev; + } + if (robust->prev != NULL) + { + robust->prev->next = robust->next; + } + if (*list == robust) + { + *list = robust->next; + } +} + + +int +pthread_mutex_consistent (pthread_mutex_t* mutex) +{ + pthread_mutex_t mx = *mutex; + int result = 0; + + /* + * Let the system deal with invalid pointers. + */ + if (mx == NULL) + { + return EINVAL; + } + + if (mx->kind >= 0 + || (LONG)PTW32_ROBUST_INCONSISTENT != PTW32_INTERLOCKED_COMPARE_EXCHANGE( + (LPLONG)&mx->robustNode->stateInconsistent, + (LONG)PTW32_ROBUST_CONSISTENT, + (LONG)PTW32_ROBUST_INCONSISTENT)) + { + result = EINVAL; + } + + return (result); +} + |