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/*
* pthread_mutex_trylock.c
*
* Description:
* This translation unit implements mutual exclusion (mutex) primitives.
*
* --------------------------------------------------------------------------
*
* Pthreads4w - POSIX Threads Library for Win32
* Copyright(C) 1998 John E. Bossom
* Copyright(C) 1999-2018, Pthreads4w contributors
*
* Homepage: https://sourceforge.net/projects/pthreads4w/
*
* 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:
* https://sourceforge.net/p/pthreads4w/wiki/Contributors/
*
* This file is part of Pthreads4w.
*
* Pthreads4w is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Pthreads4w 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Pthreads4w. If not, see <http://www.gnu.org/licenses/>. *
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#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);
}
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