From a416ab17ecf9f2cb0f1e3f7bd645a8d1ce690ca2 Mon Sep 17 00:00:00 2001 From: rpj Date: Mon, 18 Feb 2002 03:16:52 +0000 Subject: Major reorganisation of source code; new routine and tests added. --- condvar_signal.c | 355 ------------------------------------------------------- 1 file changed, 355 deletions(-) delete mode 100644 condvar_signal.c (limited to 'condvar_signal.c') diff --git a/condvar_signal.c b/condvar_signal.c deleted file mode 100644 index 604ef4d..0000000 --- a/condvar_signal.c +++ /dev/null @@ -1,355 +0,0 @@ -/* - * condvar_signal.c - * - * Description: - * This translation unit implements condition variables and their primitives. - * - * - * -------------------------------------------------------------------------- - * - * 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 - * - * ------------------------------------------------------------- - * Algorithm: - * The algorithm used in this implementation is that developed by - * Alexander Terekhov in colaboration with Louis Thomas. The bulk - * of the discussion is recorded in the file README.CV, which contains - * several generations of both colaborators original algorithms. The final - * algorithm used here is the one referred to as - * - * Algorithm 8a / IMPL_SEM,UNBLOCK_STRATEGY == UNBLOCK_ALL - * - * presented below in pseudo-code as it appeared: - * - * - * given: - * semBlockLock - bin.semaphore - * semBlockQueue - semaphore - * mtxExternal - mutex or CS - * mtxUnblockLock - mutex or CS - * nWaitersGone - int - * nWaitersBlocked - int - * nWaitersToUnblock - int - * - * wait( timeout ) { - * - * [auto: register int result ] // error checking omitted - * [auto: register int nSignalsWasLeft ] - * [auto: register int nWaitersWasGone ] - * - * sem_wait( semBlockLock ); - * nWaitersBlocked++; - * sem_post( semBlockLock ); - * - * unlock( mtxExternal ); - * bTimedOut = sem_wait( semBlockQueue,timeout ); - * - * lock( mtxUnblockLock ); - * if ( 0 != (nSignalsWasLeft = nWaitersToUnblock) ) { - * if ( bTimeout ) { // timeout (or canceled) - * if ( 0 != nWaitersBlocked ) { - * nWaitersBlocked--; - * } - * else { - * nWaitersGone++; // count spurious wakeups. - * } - * } - * if ( 0 == --nWaitersToUnblock ) { - * if ( 0 != nWaitersBlocked ) { - * sem_post( semBlockLock ); // open the gate. - * nSignalsWasLeft = 0; // do not open the gate - * // below again. - * } - * else if ( 0 != (nWaitersWasGone = nWaitersGone) ) { - * nWaitersGone = 0; - * } - * } - * } - * else if ( INT_MAX/2 == ++nWaitersGone ) { // timeout/canceled or - * // spurious semaphore :-) - * sem_wait( semBlockLock ); - * nWaitersBlocked -= nWaitersGone; // something is going on here - * // - test of timeouts? :-) - * sem_post( semBlockLock ); - * nWaitersGone = 0; - * } - * unlock( mtxUnblockLock ); - * - * if ( 1 == nSignalsWasLeft ) { - * if ( 0 != nWaitersWasGone ) { - * // sem_adjust( semBlockQueue,-nWaitersWasGone ); - * while ( nWaitersWasGone-- ) { - * sem_wait( semBlockQueue ); // better now than spurious later - * } - * } sem_post( semBlockLock ); // open the gate - * } - * - * lock( mtxExternal ); - * - * return ( bTimedOut ) ? ETIMEOUT : 0; - * } - * - * signal(bAll) { - * - * [auto: register int result ] - * [auto: register int nSignalsToIssue] - * - * lock( mtxUnblockLock ); - * - * if ( 0 != nWaitersToUnblock ) { // the gate is closed!!! - * if ( 0 == nWaitersBlocked ) { // NO-OP - * return unlock( mtxUnblockLock ); - * } - * if (bAll) { - * nWaitersToUnblock += nSignalsToIssue=nWaitersBlocked; - * nWaitersBlocked = 0; - * } - * else { - * nSignalsToIssue = 1; - * nWaitersToUnblock++; - * nWaitersBlocked--; - * } - * } - * else if ( nWaitersBlocked > nWaitersGone ) { // HARMLESS RACE CONDITION! - * sem_wait( semBlockLock ); // close the gate - * if ( 0 != nWaitersGone ) { - * nWaitersBlocked -= nWaitersGone; - * nWaitersGone = 0; - * } - * if (bAll) { - * nSignalsToIssue = nWaitersToUnblock = nWaitersBlocked; - * nWaitersBlocked = 0; - * } - * else { - * nSignalsToIssue = nWaitersToUnblock = 1; - * nWaitersBlocked--; - * } - * } - * else { // NO-OP - * return unlock( mtxUnblockLock ); - * } - * - * unlock( mtxUnblockLock ); - * sem_post( semBlockQueue,nSignalsToIssue ); - * return result; - * } - * ------------------------------------------------------------- - * - */ - -#include "pthread.h" -#include "implement.h" - - -static INLINE int -ptw32_cond_unblock (pthread_cond_t * cond, - int unblockAll) - /* - * Notes. - * - * Does not use the external mutex for synchronisation, - * therefore semBlockLock is needed. - * mtxUnblockLock is for LEVEL-2 synch. LEVEL-2 is the - * state where the external mutex is not necessarily locked by - * any thread, ie. between cond_wait unlocking and re-acquiring - * the lock after having been signaled or a timeout or - * cancellation. - * - * Uses the following CV elements: - * nWaitersBlocked - * nWaitersToUnblock - * nWaitersGone - * mtxUnblockLock - * semBlockLock - * semBlockQueue - */ -{ - int result; - pthread_cond_t cv; - int nSignalsToIssue; - - if (cond == NULL || *cond == NULL) - { - return EINVAL; - } - - cv = *cond; - - /* - * No-op if the CV is static and hasn't been initialised yet. - * Assuming that any race condition is harmless. - */ - if (cv == PTHREAD_COND_INITIALIZER) - { - return 0; - } - - if ((result = pthread_mutex_lock(&(cv->mtxUnblockLock))) != 0) - { - return result; - } - - if ( 0 != cv->nWaitersToUnblock ) - { - if ( 0 == cv->nWaitersBlocked ) - { - return pthread_mutex_unlock( &(cv->mtxUnblockLock) ); - } - if (unblockAll) - { - cv->nWaitersToUnblock += (nSignalsToIssue = cv->nWaitersBlocked); - cv->nWaitersBlocked = 0; - } - else - { - nSignalsToIssue = 1; - cv->nWaitersToUnblock++; - cv->nWaitersBlocked--; - } - } - else if ( cv->nWaitersBlocked > cv->nWaitersGone ) - { - if (sem_wait( &(cv->semBlockLock) ) != 0) - { - result = errno; - (void) pthread_mutex_unlock( &(cv->mtxUnblockLock) ); - return result; - } - if ( 0 != cv->nWaitersGone ) - { - cv->nWaitersBlocked -= cv->nWaitersGone; - cv->nWaitersGone = 0; - } - if (unblockAll) - { - nSignalsToIssue = cv->nWaitersToUnblock = cv->nWaitersBlocked; - cv->nWaitersBlocked = 0; - } - else - { - nSignalsToIssue = cv->nWaitersToUnblock = 1; - cv->nWaitersBlocked--; - } - } - else - { - return pthread_mutex_unlock( &(cv->mtxUnblockLock) ); - } - - if ((result = pthread_mutex_unlock( &(cv->mtxUnblockLock) )) == 0) - { - if (sem_post_multiple( &(cv->semBlockQueue), nSignalsToIssue ) != 0) - { - result = errno; - } - } - - return result; - -} /* ptw32_cond_unblock */ - -int -pthread_cond_signal (pthread_cond_t * cond) - /* - * ------------------------------------------------------ - * DOCPUBLIC - * This function signals a condition variable, waking - * one waiting thread. - * If SCHED_FIFO or SCHED_RR policy threads are waiting - * the highest priority waiter is awakened; otherwise, - * an unspecified waiter is awakened. - * - * PARAMETERS - * cond - * pointer to an instance of pthread_cond_t - * - * - * DESCRIPTION - * This function signals a condition variable, waking - * one waiting thread. - * If SCHED_FIFO or SCHED_RR policy threads are waiting - * the highest priority waiter is awakened; otherwise, - * an unspecified waiter is awakened. - * - * NOTES: - * - * 1) Use when any waiter can respond and only one need - * respond (all waiters being equal). - * - * RESULTS - * 0 successfully signaled condition, - * EINVAL 'cond' is invalid, - * - * ------------------------------------------------------ - */ -{ - /* - * The '0'(FALSE) unblockAll arg means unblock ONE waiter. - */ - return (ptw32_cond_unblock(cond, 0)); - -} /* pthread_cond_signal */ - -int -pthread_cond_broadcast (pthread_cond_t * cond) - /* - * ------------------------------------------------------ - * DOCPUBLIC - * This function broadcasts the condition variable, - * waking all current waiters. - * - * PARAMETERS - * cond - * pointer to an instance of pthread_cond_t - * - * - * DESCRIPTION - * This function signals a condition variable, waking - * all waiting threads. - * - * NOTES: - * - * 1) Use when more than one waiter may respond to - * predicate change or if any waiting thread may - * not be able to respond - * - * RESULTS - * 0 successfully signalled condition to all - * waiting threads, - * EINVAL 'cond' is invalid - * ENOSPC a required resource has been exhausted, - * - * ------------------------------------------------------ - */ -{ - /* - * The '1'(TRUE) unblockAll arg means unblock ALL waiters. - */ - return (ptw32_cond_unblock(cond, 1)); - -} /* pthread_cond_broadcast */ -- cgit v1.2.3