/*
* 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 .
* â– 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.
* â– 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.
* â– 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.
* â– 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.
* â– 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.
* â– 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.
*/
#if !defined(_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 ((LONG)PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG(
(PTW32_INTERLOCKED_LONGPTR)&robust->stateInconsistent,
(PTW32_INTERLOCKED_LONG)PTW32_ROBUST_INCONSISTENT,
(PTW32_INTERLOCKED_LONG)-1 /* 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
|| (PTW32_INTERLOCKED_LONG)PTW32_ROBUST_INCONSISTENT != PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG(
(PTW32_INTERLOCKED_LONGPTR)&mx->robustNode->stateInconsistent,
(PTW32_INTERLOCKED_LONG)PTW32_ROBUST_CONSISTENT,
(PTW32_INTERLOCKED_LONG)PTW32_ROBUST_INCONSISTENT))
{
result = EINVAL;
}
return (result);
}