1 /* 2 * pthread_timechange_handler_np.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 * Notes on handling system time adjustments (especially negative ones). 42 * --------------------------------------------------------------------- 43 * 44 * This solution was suggested by Alexander Terekhov, but any errors 45 * in the implementation are mine - [Ross Johnson] 46 * 47 * 1) The problem: threads doing a timedwait on a CV may expect to timeout 48 * at a specific absolute time according to a system timer. If the 49 * system clock is adjusted backwards then those threads sleep longer than 50 * expected. Also, pthreads-win32 converts absolute times to intervals in 51 * order to make use of the underlying Win32, and so waiting threads may 52 * awake before their proper abstimes. 53 * 54 * 2) We aren't able to distinquish between threads on timed or untimed waits, 55 * so we wake them all at the time of the adjustment so that they can 56 * re-evaluate their conditions and re-compute their timeouts. 57 * 58 * 3) We rely on correctly written applications for this to work. Specifically, 59 * they must be able to deal properly with spurious wakeups. That is, 60 * they must re-test their condition upon wakeup and wait again if 61 * the condition is not satisfied. 62 */ 63 64 void * 65 pthread_timechange_handler_np (void *arg) 66 /* 67 * ------------------------------------------------------ 68 * DOCPUBLIC 69 * Broadcasts all CVs to force re-evaluation and 70 * new timeouts if required. 71 * 72 * PARAMETERS 73 * NONE 74 * 75 * 76 * DESCRIPTION 77 * Broadcasts all CVs to force re-evaluation and 78 * new timeouts if required. 79 * 80 * This routine may be passed directly to pthread_create() 81 * as a new thread in order to run asynchronously. 82 * 83 * 84 * RESULTS 85 * 0 successfully broadcast all CVs 86 * EAGAIN Not all CVs were broadcast 87 * 88 * ------------------------------------------------------ 89 */ 90 { 91 int result = 0; 92 pthread_cond_t cv; 93 ptw32_mcs_local_node_t node; 94 95 ptw32_mcs_lock_acquire(&ptw32_cond_list_lock, &node); 96 97 cv = ptw32_cond_list_head; 98 99 while (cv != NULL && 0 == result) 100 { 101 result = pthread_cond_broadcast (&cv); 102 cv = cv->next; 103 } 104 105 ptw32_mcs_lock_release(&node); 106 107 return (void *) (size_t) (result != 0 ? EAGAIN : 0); 108 } 109
