155 lines
4.4 KiB
C
155 lines
4.4 KiB
C
/*
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* pthread_mutex_trylock.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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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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#include "pthread.h"
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#include "implement.h"
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int
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pthread_mutex_trylock (pthread_mutex_t * mutex)
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{
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pthread_mutex_t mx;
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int kind;
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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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/*
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* We do a quick check to see if we need to do more work
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* to initialise a static mutex. We check
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* again inside the guarded section of ptw32_mutex_check_need_init()
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* to avoid race conditions.
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*/
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if (*mutex >= PTHREAD_ERRORCHECK_MUTEX_INITIALIZER)
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{
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if ((result = ptw32_mutex_check_need_init (mutex)) != 0)
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{
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return (result);
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}
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}
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mx = *mutex;
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kind = mx->kind;
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if (kind >= 0)
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{
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/* Non-robust */
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if (0 == (PTW32_INTERLOCKED_LONG) PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG (
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(PTW32_INTERLOCKED_LONGPTR) &mx->lock_idx,
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(PTW32_INTERLOCKED_LONG) 1,
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(PTW32_INTERLOCKED_LONG) 0))
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{
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if (kind != PTHREAD_MUTEX_NORMAL)
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{
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mx->recursive_count = 1;
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mx->ownerThread = pthread_self ();
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}
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}
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else
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{
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if (kind == PTHREAD_MUTEX_RECURSIVE &&
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pthread_equal (mx->ownerThread, pthread_self ()))
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{
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mx->recursive_count++;
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}
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else
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{
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result = EBUSY;
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}
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}
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}
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else
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{
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/*
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* Robust types
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* All types record the current owner thread.
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* The mutex is added to a per thread list when ownership is acquired.
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*/
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pthread_t self;
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ptw32_robust_state_t* statePtr = &mx->robustNode->stateInconsistent;
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if ((PTW32_INTERLOCKED_LONG)PTW32_ROBUST_NOTRECOVERABLE ==
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PTW32_INTERLOCKED_EXCHANGE_ADD_LONG(
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(PTW32_INTERLOCKED_LONGPTR)statePtr,
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(PTW32_INTERLOCKED_LONG)0))
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{
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return ENOTRECOVERABLE;
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}
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self = pthread_self();
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kind = -kind - 1; /* Convert to non-robust range */
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if (0 == (PTW32_INTERLOCKED_LONG) PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG (
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(PTW32_INTERLOCKED_LONGPTR) &mx->lock_idx,
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(PTW32_INTERLOCKED_LONG) 1,
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(PTW32_INTERLOCKED_LONG) 0))
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{
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if (kind != PTHREAD_MUTEX_NORMAL)
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{
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mx->recursive_count = 1;
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}
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ptw32_robust_mutex_add(mutex, self);
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}
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else
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{
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if (PTHREAD_MUTEX_RECURSIVE == kind &&
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pthread_equal (mx->ownerThread, pthread_self ()))
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{
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mx->recursive_count++;
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}
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else
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{
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if (EOWNERDEAD == (result = ptw32_robust_mutex_inherit(mutex)))
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{
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mx->recursive_count = 1;
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ptw32_robust_mutex_add(mutex, self);
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}
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else
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{
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if (0 == result)
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{
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result = EBUSY;
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}
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}
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}
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}
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}
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return (result);
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}
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