/* * 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) 1999,2012 Pthreads-win32 contributors * * Homepage1: http://sourceware.org/pthreads-win32/ * Homepage2: http://sourceforge.net/projects/pthreads4w/ * * 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 */ #ifdef HAVE_CONFIG_H # include <config.h> #endif #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); }