From 2ab3d99967d68c79351fe2a3df22c445447e3010 Mon Sep 17 00:00:00 2001 From: Michał Cichoń Date: Tue, 15 Nov 2011 22:28:48 +0100 Subject: Initial import. --- pthreads/src/ptw32_reuse.c | 151 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 151 insertions(+) create mode 100644 pthreads/src/ptw32_reuse.c (limited to 'pthreads/src/ptw32_reuse.c') diff --git a/pthreads/src/ptw32_reuse.c b/pthreads/src/ptw32_reuse.c new file mode 100644 index 0000000..7325857 --- /dev/null +++ b/pthreads/src/ptw32_reuse.c @@ -0,0 +1,151 @@ +/* + * ptw32_threadReuse.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" + + +/* + * How it works: + * A pthread_t is a struct (2x32 bit scalar types on IA-32, 2x64 bit on IA-64) + * which is normally passed/returned by value to/from pthreads routines. + * Applications are therefore storing a copy of the struct as it is at that + * time. + * + * The original pthread_t struct plus all copies of it contain the address of + * the thread state struct ptw32_thread_t_ (p), plus a reuse counter (x). Each + * ptw32_thread_t contains the original copy of it's pthread_t. + * Once malloced, a ptw32_thread_t_ struct is not freed until the process exits. + * + * The thread reuse stack is a simple LILO stack managed through a singly + * linked list element in the ptw32_thread_t. + * + * Each time a thread is destroyed, the ptw32_thread_t address is pushed onto the + * reuse stack after it's ptHandle's reuse counter has been incremented. + * + * The following can now be said from this: + * - two pthread_t's are identical if their ptw32_thread_t reference pointers + * are equal and their reuse counters are equal. That is, + * + * equal = (a.p == b.p && a.x == b.x) + * + * - a pthread_t copy refers to a destroyed thread if the reuse counter in + * the copy is not equal to the reuse counter in the original. + * + * threadDestroyed = (copy.x != ((ptw32_thread_t *)copy.p)->ptHandle.x) + * + */ + +/* + * Pop a clean pthread_t struct off the reuse stack. + */ +pthread_t +ptw32_threadReusePop (void) +{ + pthread_t t = {NULL, 0}; + ptw32_mcs_local_node_t node; + + ptw32_mcs_lock_acquire(&ptw32_thread_reuse_lock, &node); + + if (PTW32_THREAD_REUSE_EMPTY != ptw32_threadReuseTop) + { + ptw32_thread_t * tp; + + tp = ptw32_threadReuseTop; + + ptw32_threadReuseTop = tp->prevReuse; + + if (PTW32_THREAD_REUSE_EMPTY == ptw32_threadReuseTop) + { + ptw32_threadReuseBottom = PTW32_THREAD_REUSE_EMPTY; + } + + tp->prevReuse = NULL; + + t = tp->ptHandle; + } + + ptw32_mcs_lock_release(&node); + + return t; + +} + +/* + * Push a clean pthread_t struct onto the reuse stack. + * Must be re-initialised when reused. + * All object elements (mutexes, events etc) must have been either + * detroyed before this, or never initialised. + */ +void +ptw32_threadReusePush (pthread_t thread) +{ + ptw32_thread_t * tp = (ptw32_thread_t *) thread.p; + pthread_t t; + ptw32_mcs_local_node_t node; + + ptw32_mcs_lock_acquire(&ptw32_thread_reuse_lock, &node); + + t = tp->ptHandle; + memset(tp, 0, sizeof(ptw32_thread_t)); + + /* Must restore the original POSIX handle that we just wiped. */ + tp->ptHandle = t; + + /* Bump the reuse counter now */ +#if defined(PTW32_THREAD_ID_REUSE_INCREMENT) + tp->ptHandle.x += PTW32_THREAD_ID_REUSE_INCREMENT; +#else + tp->ptHandle.x++; +#endif + + tp->state = PThreadStateReuse; + + tp->prevReuse = PTW32_THREAD_REUSE_EMPTY; + + if (PTW32_THREAD_REUSE_EMPTY != ptw32_threadReuseBottom) + { + ptw32_threadReuseBottom->prevReuse = tp; + } + else + { + ptw32_threadReuseTop = tp; + } + + ptw32_threadReuseBottom = tp; + + ptw32_mcs_lock_release(&node); +} -- cgit v1.2.3