191 lines
6.8 KiB
C
191 lines
6.8 KiB
C
/*
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* pthread_mutex_consistent.c
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*
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* Description:
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* This translation unit implements mutual exclusion (mutex) 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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* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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/*
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* From the Sun Multi-threaded Programming Guide
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*
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* robustness defines the behavior when the owner of the mutex terminates without unlocking the
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* mutex, usually because its process terminated abnormally. The value of robustness that is
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* defined in pthread.h is PTHREAD_MUTEX_ROBUST or PTHREAD_MUTEX_STALLED. The
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* default value is PTHREAD_MUTEX_STALLED .
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* ■ PTHREAD_MUTEX_STALLED
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* When the owner of the mutex terminates without unlocking the mutex, all subsequent calls
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* to pthread_mutex_lock() are blocked from progress in an unspecified manner.
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* ■ PTHREAD_MUTEX_ROBUST
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* When the owner of the mutex terminates without unlocking the mutex, the mutex is
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* unlocked. The next owner of this mutex acquires the mutex with an error return of
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* EOWNERDEAD.
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* Note – Your application must always check the return code from pthread_mutex_lock() for
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* a mutex initialized with the PTHREAD_MUTEX_ROBUST attribute.
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* ■ The new owner of this mutex should make the state protected by the mutex consistent.
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* This state might have been left inconsistent when the previous owner terminated.
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* ■ If the new owner is able to make the state consistent, call
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* pthread_mutex_consistent() for the mutex before unlocking the mutex. This
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* marks the mutex as consistent and subsequent calls to pthread_mutex_lock() and
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* pthread_mutex_unlock() will behave in the normal manner.
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* ■ If the new owner is not able to make the state consistent, do not call
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* pthread_mutex_consistent() for the mutex, but unlock the mutex.
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* All waiters are woken up and all subsequent calls to pthread_mutex_lock() fail to
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* acquire the mutex. The return code is ENOTRECOVERABLE. The mutex can be made
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* consistent by calling pthread_mutex_destroy() to uninitialize the mutex, and calling
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* pthread_mutex_int() to reinitialize the mutex.However, the state that was protected
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* by the mutex remains inconsistent and some form of application recovery is required.
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* ■ If the thread that acquires the lock with EOWNERDEAD terminates without unlocking the
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* mutex, the next owner acquires the lock with an EOWNERDEAD return code.
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*/
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#if !defined(_UWIN)
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/*# include <process.h> */
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#endif
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#include "pthread.h"
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#include "implement.h"
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INLINE
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int
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ptw32_robust_mutex_inherit(pthread_mutex_t * mutex)
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{
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int result;
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pthread_mutex_t mx = *mutex;
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ptw32_robust_node_t* robust = mx->robustNode;
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switch ((LONG)PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG(
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(PTW32_INTERLOCKED_LONGPTR)&robust->stateInconsistent,
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(PTW32_INTERLOCKED_LONG)PTW32_ROBUST_INCONSISTENT,
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(PTW32_INTERLOCKED_LONG)-1 /* The terminating thread sets this */))
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{
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case -1L:
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result = EOWNERDEAD;
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break;
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case (LONG)PTW32_ROBUST_NOTRECOVERABLE:
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result = ENOTRECOVERABLE;
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break;
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default:
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result = 0;
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break;
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}
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return result;
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}
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/*
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* The next two internal support functions depend on only being
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* called by the thread that owns the robust mutex. This enables
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* us to avoid additional locks.
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* Any mutex currently in the thread's robust mutex list is held
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* by the thread, again eliminating the need for locks.
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* The forward/backward links allow the thread to unlock mutexes
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* in any order, not necessarily the reverse locking order.
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* This is all possible because it is an error if a thread that
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* does not own the [robust] mutex attempts to unlock it.
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*/
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INLINE
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void
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ptw32_robust_mutex_add(pthread_mutex_t* mutex, pthread_t self)
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{
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ptw32_robust_node_t** list;
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pthread_mutex_t mx = *mutex;
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ptw32_thread_t* tp = (ptw32_thread_t*)self.p;
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ptw32_robust_node_t* robust = mx->robustNode;
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list = &tp->robustMxList;
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mx->ownerThread = self;
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if (NULL == *list)
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{
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robust->prev = NULL;
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robust->next = NULL;
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*list = robust;
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}
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else
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{
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robust->prev = NULL;
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robust->next = *list;
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(*list)->prev = robust;
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*list = robust;
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}
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}
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INLINE
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void
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ptw32_robust_mutex_remove(pthread_mutex_t* mutex, ptw32_thread_t* otp)
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{
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ptw32_robust_node_t** list;
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pthread_mutex_t mx = *mutex;
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ptw32_robust_node_t* robust = mx->robustNode;
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list = &(((ptw32_thread_t*)mx->ownerThread.p)->robustMxList);
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mx->ownerThread.p = otp;
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if (robust->next != NULL)
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{
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robust->next->prev = robust->prev;
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}
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if (robust->prev != NULL)
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{
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robust->prev->next = robust->next;
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}
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if (*list == robust)
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{
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*list = robust->next;
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}
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}
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int
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pthread_mutex_consistent (pthread_mutex_t* mutex)
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{
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pthread_mutex_t mx = *mutex;
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int result = 0;
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/*
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* Let the system deal with invalid pointers.
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*/
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if (mx == NULL)
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{
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return EINVAL;
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}
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if (mx->kind >= 0
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|| (PTW32_INTERLOCKED_LONG)PTW32_ROBUST_INCONSISTENT != PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG(
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(PTW32_INTERLOCKED_LONGPTR)&mx->robustNode->stateInconsistent,
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(PTW32_INTERLOCKED_LONG)PTW32_ROBUST_CONSISTENT,
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(PTW32_INTERLOCKED_LONG)PTW32_ROBUST_INCONSISTENT))
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{
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result = EINVAL;
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}
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return (result);
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}
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