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pthread_timechange_handler_np.c    109 lines (100 with data), 3.9 kB

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/*
* pthread_timechange_handler_np.c
*
* Description:
* This translation unit implements miscellaneous thread functions.
*
* --------------------------------------------------------------------------
*
* 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
*/
#include "pthread.h"
#include "implement.h"
/*
* Notes on handling system time adjustments (especially negative ones).
* ---------------------------------------------------------------------
*
* This solution was suggested by Alexander Terekhov, but any errors
* in the implementation are mine - [Ross Johnson]
*
* 1) The problem: threads doing a timedwait on a CV may expect to timeout
* at a specific absolute time according to a system timer. If the
* system clock is adjusted backwards then those threads sleep longer than
* expected. Also, pthreads-win32 converts absolute times to intervals in
* order to make use of the underlying Win32, and so waiting threads may
* awake before their proper abstimes.
*
* 2) We aren't able to distinquish between threads on timed or untimed waits,
* so we wake them all at the time of the adjustment so that they can
* re-evaluate their conditions and re-compute their timeouts.
*
* 3) We rely on correctly written applications for this to work. Specifically,
* they must be able to deal properly with spurious wakeups. That is,
* they must re-test their condition upon wakeup and wait again if
* the condition is not satisfied.
*/
void *
pthread_timechange_handler_np (void *arg)
/*
* ------------------------------------------------------
* DOCPUBLIC
* Broadcasts all CVs to force re-evaluation and
* new timeouts if required.
*
* PARAMETERS
* NONE
*
*
* DESCRIPTION
* Broadcasts all CVs to force re-evaluation and
* new timeouts if required.
*
* This routine may be passed directly to pthread_create()
* as a new thread in order to run asynchronously.
*
*
* RESULTS
* 0 successfully broadcast all CVs
* EAGAIN Not all CVs were broadcast
*
* ------------------------------------------------------
*/
{
int result = 0;
pthread_cond_t cv;
ptw32_mcs_local_node_t node;
ptw32_mcs_lock_acquire(&ptw32_cond_list_lock, &node);
cv = ptw32_cond_list_head;
while (cv != NULL && 0 == result)
{
result = pthread_cond_broadcast (&cv);
cv = cv->next;
}
ptw32_mcs_lock_release(&node);
return (void *) (size_t) (result != 0 ? EAGAIN : 0);
}