From ce4f3efd78c110c015c54eab05f201d1caac5f8d Mon Sep 17 00:00:00 2001 From: Guenter Bartsch Date: Sun, 20 Apr 2003 16:42:06 +0000 Subject: importing win32 contrib sources and msvc build environment CVS patchset: 4641 CVS date: 2003/04/20 16:42:06 --- win32/contrib/pthreads/rwlock.c | 616 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 616 insertions(+) create mode 100644 win32/contrib/pthreads/rwlock.c (limited to 'win32/contrib/pthreads/rwlock.c') diff --git a/win32/contrib/pthreads/rwlock.c b/win32/contrib/pthreads/rwlock.c new file mode 100644 index 000000000..2bb62f1e5 --- /dev/null +++ b/win32/contrib/pthreads/rwlock.c @@ -0,0 +1,616 @@ +/* + * rwlock.c + * + * Description: + * This translation unit implements read/write lock primitives. + * + * Pthreads-win32 - POSIX Threads Library for Win32 + * Copyright (C) 1998 + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Library 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 + * Library General Public License for more details. + * + * You should have received a copy of the GNU Library General Public + * License along with this library; if not, write to the Free + * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, + * MA 02111-1307, USA + */ + +#include +#include + +#include "pthread.h" +#include "implement.h" + +static INLINE int +ptw32_rwlock_check_need_init(pthread_rwlock_t *rwlock) +{ + int result = 0; + + /* + * The following guarded test is specifically for statically + * initialised rwlocks (via PTHREAD_RWLOCK_INITIALIZER). + * + * Note that by not providing this synchronisation we risk + * introducing race conditions into applications which are + * correctly written. + * + * Approach + * -------- + * We know that static rwlocks will not be PROCESS_SHARED + * so we can serialise access to internal state using + * Win32 Critical Sections rather than Win32 Mutexes. + * + * If using a single global lock slows applications down too much, + * multiple global locks could be created and hashed on some random + * value associated with each mutex, the pointer perhaps. At a guess, + * a good value for the optimal number of global locks might be + * the number of processors + 1. + * + */ + EnterCriticalSection(&ptw32_rwlock_test_init_lock); + + /* + * We got here possibly under race + * conditions. Check again inside the critical section + * and only initialise if the rwlock is valid (not been destroyed). + * If a static rwlock has been destroyed, the application can + * re-initialise it only by calling pthread_rwlock_init() + * explicitly. + */ + if (*rwlock == PTHREAD_RWLOCK_INITIALIZER) + { + result = pthread_rwlock_init(rwlock, NULL); + } + else if (*rwlock == NULL) + { + /* + * The rwlock has been destroyed while we were waiting to + * initialise it, so the operation that caused the + * auto-initialisation should fail. + */ + result = EINVAL; + } + + LeaveCriticalSection(&ptw32_rwlock_test_init_lock); + + return result; +} + +int +pthread_rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr) +{ + int result; + pthread_rwlock_t rwl = 0; + + if (rwlock == NULL) + { + return EINVAL; + } + + if (attr != NULL && *attr != NULL) + { + result = EINVAL; /* Not supported */ + goto DONE; + } + + rwl = (pthread_rwlock_t) calloc(1, sizeof(*rwl)); + + if (rwl == NULL) + { + result = ENOMEM; + goto DONE; + } + + rwl->nSharedAccessCount = 0; + rwl->nExclusiveAccessCount = 0; + rwl->nCompletedSharedAccessCount = 0; + + result = pthread_mutex_init(&rwl->mtxExclusiveAccess, NULL); + if (result != 0) + { + goto FAIL0; + } + + result = pthread_mutex_init(&rwl->mtxSharedAccessCompleted, NULL); + if (result != 0) + { + goto FAIL1; + } + + result = pthread_cond_init(&rwl->cndSharedAccessCompleted, NULL); + if (result != 0) + { + goto FAIL2; + } + + rwl->nMagic = PTW32_RWLOCK_MAGIC; + + result = 0; + goto DONE; + +FAIL2: + (void) pthread_mutex_destroy(&(rwl->mtxSharedAccessCompleted)); + +FAIL1: + (void) pthread_mutex_destroy(&(rwl->mtxExclusiveAccess)); + +FAIL0: + (void) free(rwl); + rwl = NULL; + +DONE: + *rwlock = rwl; + + return result; +} + +int +pthread_rwlock_destroy(pthread_rwlock_t *rwlock) +{ + pthread_rwlock_t rwl; + int result = 0, result1 = 0, result2 = 0; + + if (rwlock == NULL || *rwlock == NULL) + { + return EINVAL; + } + + if (*rwlock != PTHREAD_RWLOCK_INITIALIZER) + { + rwl = *rwlock; + + if (rwl->nMagic != PTW32_RWLOCK_MAGIC) + { + return EINVAL; + } + + if ((result = pthread_mutex_lock(&(rwl->mtxExclusiveAccess))) != 0) + { + return result; + } + + if ((result = pthread_mutex_lock(&(rwl->mtxSharedAccessCompleted))) != 0) + { + (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess)); + return result; + } + + /* + * Check whether any threads own/wait for the lock (wait for ex.access); + * report "BUSY" if so. + */ + if (rwl->nExclusiveAccessCount > 0 + || rwl->nSharedAccessCount > rwl->nCompletedSharedAccessCount) + { + result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted)); + result1 = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess)); + result2 = EBUSY; + } + else + { + rwl->nMagic = 0; + + if ((result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted))) != 0) + { + pthread_mutex_unlock(&rwl->mtxExclusiveAccess); + return result; + } + + if ((result = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess))) != 0) + { + return result; + } + + *rwlock = NULL; /* Invalidate rwlock before anything else */ + result = pthread_cond_destroy(&(rwl->cndSharedAccessCompleted)); + result1 = pthread_mutex_destroy(&(rwl->mtxSharedAccessCompleted)); + result2 = pthread_mutex_destroy(&(rwl->mtxExclusiveAccess)); + (void) free(rwl); + } + } + else + { + /* + * See notes in ptw32_rwlock_check_need_init() above also. + */ + EnterCriticalSection(&ptw32_rwlock_test_init_lock); + + /* + * Check again. + */ + if (*rwlock == PTHREAD_RWLOCK_INITIALIZER) + { + /* + * This is all we need to do to destroy a statically + * initialised rwlock that has not yet been used (initialised). + * If we get to here, another thread + * waiting to initialise this rwlock will get an EINVAL. + */ + *rwlock = NULL; + } + else + { + /* + * The rwlock has been initialised while we were waiting + * so assume it's in use. + */ + result = EBUSY; + } + + LeaveCriticalSection(&ptw32_rwlock_test_init_lock); + } + + return ((result != 0) ? result : ((result1 != 0) ? result1 : result2)); +} + +int +pthread_rwlock_rdlock(pthread_rwlock_t *rwlock) +{ + int result; + pthread_rwlock_t rwl; + + if (rwlock == NULL || *rwlock == NULL) + { + return EINVAL; + } + + /* + * We do a quick check to see if we need to do more work + * to initialise a static rwlock. We check + * again inside the guarded section of ptw32_rwlock_check_need_init() + * to avoid race conditions. + */ + if (*rwlock == PTHREAD_RWLOCK_INITIALIZER) + { + result = ptw32_rwlock_check_need_init(rwlock); + + if (result != 0 && result != EBUSY) + { + return result; + } + } + + rwl = *rwlock; + + if (rwl->nMagic != PTW32_RWLOCK_MAGIC) + { + return EINVAL; + } + + if ((result = pthread_mutex_lock(&(rwl->mtxExclusiveAccess))) != 0) + { + return result; + } + + if (++rwl->nSharedAccessCount == INT_MAX) + { + if ((result = pthread_mutex_lock(&(rwl->mtxSharedAccessCompleted))) != 0) + { + (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess)); + return result; + } + + rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount; + rwl->nCompletedSharedAccessCount = 0; + + if ((result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted))) != 0) + { + (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess)); + return result; + } + } + + return (pthread_mutex_unlock(&(rwl->mtxExclusiveAccess))); +} + +static void +ptw32_rwlock_cancelwrwait(void * arg) +{ + pthread_rwlock_t rwl = (pthread_rwlock_t) arg; + + rwl->nSharedAccessCount = -rwl->nCompletedSharedAccessCount; + rwl->nCompletedSharedAccessCount = 0; + + (void) pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted)); + (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess)); +} + +int +pthread_rwlock_wrlock(pthread_rwlock_t * rwlock) +{ + int result; + pthread_rwlock_t rwl; + + if (rwlock == NULL || *rwlock == NULL) + { + return EINVAL; + } + + /* + * We do a quick check to see if we need to do more work + * to initialise a static rwlock. We check + * again inside the guarded section of ptw32_rwlock_check_need_init() + * to avoid race conditions. + */ + if (*rwlock == PTHREAD_RWLOCK_INITIALIZER) + { + result = ptw32_rwlock_check_need_init(rwlock); + + if (result != 0 && result != EBUSY) + { + return result; + } + } + + rwl = *rwlock; + + if (rwl->nMagic != PTW32_RWLOCK_MAGIC) + { + return EINVAL; + } + + if ((result = pthread_mutex_lock(&(rwl->mtxExclusiveAccess))) != 0) + { + return result; + } + + if ((result = pthread_mutex_lock(&(rwl->mtxSharedAccessCompleted))) != 0) + { + (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess)); + return result; + } + + if (rwl->nExclusiveAccessCount == 0) + { + if (rwl->nCompletedSharedAccessCount > 0) + { + rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount; + rwl->nCompletedSharedAccessCount = 0; + } + + if (rwl->nSharedAccessCount > 0) + { + /* + * pthread_rwlock_wrlock() is not a cancelation point + * so temporarily prevent pthread_cond_wait() from being one. + */ + pthread_t self = pthread_self(); + int oldCancelState; + + rwl->nCompletedSharedAccessCount = -rwl->nSharedAccessCount; + + if (self->cancelType == PTHREAD_CANCEL_DEFERRED) + { + pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldCancelState); + } + + /* Could still be PTHREAD_CANCEL_ASYNCHRONOUS. */ + pthread_cleanup_push(ptw32_rwlock_cancelwrwait, (void*)rwl); + + do + { + result = pthread_cond_wait(&(rwl->cndSharedAccessCompleted), + &(rwl->mtxSharedAccessCompleted)); + } + while (result == 0 && rwl->nCompletedSharedAccessCount < 0); + + if (self->cancelType == PTHREAD_CANCEL_DEFERRED) + { + pthread_setcancelstate(oldCancelState, NULL); + } + + pthread_cleanup_pop ((result != 0) ? 1 : 0); + + if (result == 0) + { + rwl->nSharedAccessCount = 0; + } + } + } + + if (result == 0) + { + rwl->nExclusiveAccessCount++; + } + + return result; +} + +int +pthread_rwlock_unlock(pthread_rwlock_t * rwlock) +{ + int result, result1; + pthread_rwlock_t rwl; + + if (rwlock == NULL || *rwlock == NULL) + { + return(EINVAL); + } + + if (*rwlock == PTHREAD_RWLOCK_INITIALIZER) + { + /* + * Assume any race condition here is harmless. + */ + return 0; + } + + rwl = *rwlock; + + if (rwl->nMagic != PTW32_RWLOCK_MAGIC) + { + return EINVAL; + } + + if (rwl->nExclusiveAccessCount == 0) + { + if ((result = pthread_mutex_lock(&(rwl->mtxSharedAccessCompleted))) != 0) + { + return result; + } + + if (++rwl->nCompletedSharedAccessCount == 0) + { + result = pthread_cond_signal(&(rwl->cndSharedAccessCompleted)); + } + + result1 = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted)); + } + else + { + rwl->nExclusiveAccessCount--; + + result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted)); + result1 = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess)); + + } + + return ((result != 0) ? result : result1); +} + +int +pthread_rwlock_tryrdlock(pthread_rwlock_t * rwlock) +{ + int result; + pthread_rwlock_t rwl; + + if (rwlock == NULL || *rwlock == NULL) + { + return EINVAL; + } + + /* + * We do a quick check to see if we need to do more work + * to initialise a static rwlock. We check + * again inside the guarded section of ptw32_rwlock_check_need_init() + * to avoid race conditions. + */ + if (*rwlock == PTHREAD_RWLOCK_INITIALIZER) + { + result = ptw32_rwlock_check_need_init(rwlock); + + if (result != 0 && result != EBUSY) + { + return result; + } + } + + rwl = *rwlock; + + if (rwl->nMagic != PTW32_RWLOCK_MAGIC) + { + return EINVAL; + } + + if ((result = pthread_mutex_trylock(&(rwl->mtxExclusiveAccess))) != 0) + { + return result; + } + + if (++rwl->nSharedAccessCount == INT_MAX) + { + if ((result = pthread_mutex_lock(&(rwl->mtxSharedAccessCompleted))) != 0) + { + (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess)); + return result; + } + + rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount; + rwl->nCompletedSharedAccessCount = 0; + + if ((result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted))) != 0) + { + (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess)); + return result; + } + } + + return (pthread_mutex_unlock(&rwl->mtxExclusiveAccess)); +} + +int +pthread_rwlock_trywrlock(pthread_rwlock_t * rwlock) +{ + int result, result1; + pthread_rwlock_t rwl; + + if (rwlock == NULL || *rwlock == NULL) + { + return EINVAL; + } + + /* + * We do a quick check to see if we need to do more work + * to initialise a static rwlock. We check + * again inside the guarded section of ptw32_rwlock_check_need_init() + * to avoid race conditions. + */ + if (*rwlock == PTHREAD_RWLOCK_INITIALIZER) + { + result = ptw32_rwlock_check_need_init(rwlock); + + if (result != 0 && result != EBUSY) + { + return result; + } + } + + rwl = *rwlock; + + if (rwl->nMagic != PTW32_RWLOCK_MAGIC) + { + return EINVAL; + } + + if ((result = pthread_mutex_trylock(&(rwl->mtxExclusiveAccess))) != 0) + { + return result; + } + + if ((result = pthread_mutex_trylock(&(rwl->mtxSharedAccessCompleted))) != 0) + { + result1 = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess)); + return ((result1 != 0) ? result1 : result); + } + + if (rwl->nExclusiveAccessCount == 0) + { + if (rwl->nCompletedSharedAccessCount > 0) + { + rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount; + rwl->nCompletedSharedAccessCount = 0; + } + + if (rwl->nSharedAccessCount > 0) + { + if ((result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted))) != 0) + { + (void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess)); + return result; + } + + if ((result = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess))) == 0) + { + result = EBUSY; + } + } + else + { + rwl->nExclusiveAccessCount = 1; + } + } + else + { + result = EBUSY; + } + + return result; +} -- cgit v1.2.3