native_client_sdk/src/libraries/third_party/pthreads-win32/pthread_mutex_trylock.c

   1 /*
   2  * pthread_mutex_trylock.c
   3  *
   4  * Description:
   5  * This translation unit implements mutual exclusion (mutex) primitives.
   6  *
   7  * --------------------------------------------------------------------------
   8  *
   9  *      Pthreads-win32 - POSIX Threads Library for Win32
  10  *      Copyright(C) 1998 John E. Bossom
  11  *      Copyright(C) 1999,2005 Pthreads-win32 contributors
  12  *
  13  *      Contact Email: rpj@callisto.canberra.edu.au
  14  *
  15  *      The current list of contributors is contained
  16  *      in the file CONTRIBUTORS included with the source
  17  *      code distribution. The list can also be seen at the
  18  *      following World Wide Web location:
  19  *      http://sources.redhat.com/pthreads-win32/contributors.html
  20  *
  21  *      This library is free software; you can redistribute it and/or
  22  *      modify it under the terms of the GNU Lesser General Public
  23  *      License as published by the Free Software Foundation; either
  24  *      version 2 of the License, or (at your option) any later version.
  25  *
  26  *      This library is distributed in the hope that it will be useful,
  27  *      but WITHOUT ANY WARRANTY; without even the implied warranty of
  28  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  29  *      Lesser General Public License for more details.
  30  *
  31  *      You should have received a copy of the GNU Lesser General Public
  32  *      License along with this library in the file COPYING.LIB;
  33  *      if not, write to the Free Software Foundation, Inc.,
  34  *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  35  */
  36
  37 #include "pthread.h"
  38 #include "implement.h"
  39
  40
  41 int
  42 pthread_mutex_trylock (pthread_mutex_t * mutex)
  43 {
  44   pthread_mutex_t mx;
  45   int kind;
  46   int result = 0;
  47
  48   /*
  49    * Let the system deal with invalid pointers.
  50    */
  51
  52   /*
  53    * We do a quick check to see if we need to do more work
  54    * to initialise a static mutex. We check
  55    * again inside the guarded section of ptw32_mutex_check_need_init()
  56    * to avoid race conditions.
  57    */
  58   if (*mutex >= PTHREAD_ERRORCHECK_MUTEX_INITIALIZER)
  59     {
  60       if ((result = ptw32_mutex_check_need_init (mutex)) != 0)
  61         {
  62           return (result);
  63         }
  64     }
  65
  66   mx = *mutex;
  67   kind = mx->kind;
  68
  69   if (kind >= 0)
  70     {
  71       /* Non-robust */
  72       if (0 == (PTW32_INTERLOCKED_LONG) PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG (
  73                          (PTW32_INTERLOCKED_LONGPTR) &mx->lock_idx,
  74                          (PTW32_INTERLOCKED_LONG) 1,
  75                          (PTW32_INTERLOCKED_LONG) 0))
  76         {
  77           if (kind != PTHREAD_MUTEX_NORMAL)
  78             {
  79               mx->recursive_count = 1;
  80               mx->ownerThread = pthread_self ();
  81             }
  82         }
  83       else
  84         {
  85           if (kind == PTHREAD_MUTEX_RECURSIVE &&
  86               pthread_equal (mx->ownerThread, pthread_self ()))
  87             {
  88               mx->recursive_count++;
  89             }
  90           else
  91             {
  92               result = EBUSY;
  93             }
  94         }
  95     }
  96   else
  97     {
  98       /*
  99        * Robust types
 100        * All types record the current owner thread.
 101        * The mutex is added to a per thread list when ownership is acquired.
 102        */
 103       pthread_t self;
 104       ptw32_robust_state_t* statePtr = &mx->robustNode->stateInconsistent;
 105
 106       if ((PTW32_INTERLOCKED_LONG)PTW32_ROBUST_NOTRECOVERABLE ==
 107                   PTW32_INTERLOCKED_EXCHANGE_ADD_LONG(
 108                     (PTW32_INTERLOCKED_LONGPTR)statePtr,
 109                     (PTW32_INTERLOCKED_LONG)0))
 110         {
 111           return ENOTRECOVERABLE;
 112         }
 113
 114       self = pthread_self();
 115       kind = -kind - 1; /* Convert to non-robust range */
 116
 117       if (0 == (PTW32_INTERLOCKED_LONG) PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG (
 118                          (PTW32_INTERLOCKED_LONGPTR) &mx->lock_idx,
 119                          (PTW32_INTERLOCKED_LONG) 1,
 120                          (PTW32_INTERLOCKED_LONG) 0))
 121         {
 122           if (kind != PTHREAD_MUTEX_NORMAL)
 123             {
 124               mx->recursive_count = 1;
 125             }
 126           ptw32_robust_mutex_add(mutex, self);
 127         }
 128       else
 129         {
 130           if (PTHREAD_MUTEX_RECURSIVE == kind &&
 131               pthread_equal (mx->ownerThread, pthread_self ()))
 132             {
 133               mx->recursive_count++;
 134             }
 135           else
 136             {
 137               if (EOWNERDEAD == (result = ptw32_robust_mutex_inherit(mutex)))
 138                 {
 139                   mx->recursive_count = 1;
 140                   ptw32_robust_mutex_add(mutex, self);
 141                 }
 142               else
 143                 {
 144                   if (0 == result)
 145                     {
 146                       result = EBUSY;
 147                     }
 148                 }
 149             }
 150         }
 151     }
 152
 153   return (result);
 154 }