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      1 /*
      2  * w32_CancelableWait.c
      3  *
      4  * Description:
      5  * This translation unit implements miscellaneous thread functions.
      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 (at) 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 static INLINE int
     42 ptw32_cancelable_wait (HANDLE waitHandle, DWORD timeout)
     43      /*
     44       * -------------------------------------------------------------------
     45       * This provides an extra hook into the pthread_cancel
     46       * mechanism that will allow you to wait on a Windows handle and make it a
     47       * cancellation point. This function blocks until the given WIN32 handle is
     48       * signaled or pthread_cancel has been called. It is implemented using
     49       * WaitForMultipleObjects on 'waitHandle' and a manually reset WIN32
     50       * event used to implement pthread_cancel.
     51       *
     52       * Given this hook it would be possible to implement more of the cancellation
     53       * points.
     54       * -------------------------------------------------------------------
     55       */
     56 {
     57   int result;
     58   pthread_t self;
     59   ptw32_thread_t * sp;
     60   HANDLE handles[2];
     61   DWORD nHandles = 1;
     62   DWORD status;
     63 
     64   handles[0] = waitHandle;
     65 
     66   self = pthread_self();
     67   sp = (ptw32_thread_t *) self.p;
     68 
     69   if (sp != NULL)
     70     {
     71       /*
     72        * Get cancelEvent handle
     73        */
     74       if (sp->cancelState == PTHREAD_CANCEL_ENABLE)
     75 	{
     76 
     77 	  if ((handles[1] = sp->cancelEvent) != NULL)
     78 	    {
     79 	      nHandles++;
     80 	    }
     81 	}
     82     }
     83   else
     84     {
     85       handles[1] = NULL;
     86     }
     87 
     88   status = WaitForMultipleObjects (nHandles, handles, PTW32_FALSE, timeout);
     89 
     90   switch (status - WAIT_OBJECT_0)
     91     {
     92     case 0:
     93       /*
     94        * Got the handle.
     95        * In the event that both handles are signalled, the smallest index
     96        * value (us) is returned. As it has been arranged, this ensures that
     97        * we don't drop a signal that we should act on (i.e. semaphore,
     98        * mutex, or condition variable etc).
     99        */
    100       result = 0;
    101       break;
    102 
    103     case 1:
    104       /*
    105        * Got cancel request.
    106        * In the event that both handles are signaled, the cancel will
    107        * be ignored (see case 0 comment).
    108        */
    109       ResetEvent (handles[1]);
    110 
    111       if (sp != NULL)
    112 	{
    113           ptw32_mcs_local_node_t stateLock;
    114 	  /*
    115 	   * Should handle POSIX and implicit POSIX threads..
    116 	   * Make sure we haven't been async-canceled in the meantime.
    117 	   */
    118 	  ptw32_mcs_lock_acquire (&sp->stateLock, &stateLock);
    119 	  if (sp->state < PThreadStateCanceling)
    120 	    {
    121 	      sp->state = PThreadStateCanceling;
    122 	      sp->cancelState = PTHREAD_CANCEL_DISABLE;
    123 	      ptw32_mcs_lock_release (&stateLock);
    124 	      ptw32_throw (PTW32_EPS_CANCEL);
    125 
    126 	      /* Never reached */
    127 	    }
    128 	  ptw32_mcs_lock_release (&stateLock);
    129 	}
    130 
    131       /* Should never get to here. */
    132       result = EINVAL;
    133       break;
    134 
    135     default:
    136       if (status == WAIT_TIMEOUT)
    137 	{
    138 	  result = ETIMEDOUT;
    139 	}
    140       else
    141 	{
    142 	  result = EINVAL;
    143 	}
    144       break;
    145     }
    146 
    147   return (result);
    148 
    149 }				/* CancelableWait */
    150 
    151 int
    152 pthreadCancelableWait (HANDLE waitHandle)
    153 {
    154   return (ptw32_cancelable_wait (waitHandle, INFINITE));
    155 }
    156 
    157 int
    158 pthreadCancelableTimedWait (HANDLE waitHandle, DWORD timeout)
    159 {
    160   return (ptw32_cancelable_wait (waitHandle, timeout));
    161 }
    162