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Diffstat (limited to 'pthread_timechange_handler_np.c')
| -rw-r--r-- | pthread_timechange_handler_np.c | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/pthread_timechange_handler_np.c b/pthread_timechange_handler_np.c new file mode 100644 index 0000000..b7d432b --- /dev/null +++ b/pthread_timechange_handler_np.c @@ -0,0 +1,108 @@ +/* + * 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) 1999,2002 Pthreads-win32 contributors + * + * Contact Email: rpj@ise.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; + + EnterCriticalSection(&ptw32_cond_list_lock); + + cv = ptw32_cond_list_head; + + while (cv != NULL && 0 == result) + { + result = pthread_cond_broadcast(&cv); + cv = cv->next; + } + + LeaveCriticalSection(&ptw32_cond_list_lock); + + return (void *)(result != 0 ? EAGAIN : 0); +} + |