diff options
Diffstat (limited to 'barrier.c')
| -rw-r--r-- | barrier.c | 124 |
1 files changed, 13 insertions, 111 deletions
@@ -27,62 +27,6 @@ #include "implement.h" -static int -ptw32_barrier_check_need_init(pthread_barrier_t *barrier) -{ - int result = 0; - - /* - * The following guarded test is specifically for statically - * initialised barriers (via PTHREAD_BARRIER_INITIALIZER). - * - * Note that by not providing this synchronisation we risk - * introducing race conditions into applications which are - * correctly written. - * - * Approach - * -------- - * We know that static barriers 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 barrier, 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_barrier_test_init_lock); - - /* - * We got here possibly under race - * conditions. Check again inside the critical section - * and only initialise if the barrier is valid (not been destroyed). - * If a static barrier has been destroyed, the application can - * re-initialise it only by calling pthread_barrier_init() - * explicitly. - */ - if (*barrier == (pthread_barrier_t) PTW32_OBJECT_AUTO_INIT) - { - result = pthread_barrier_init(barrier, NULL); - } - else if (*barrier == NULL) - { - /* - * The barrier has been destroyed while we were waiting to - * initialise it, so the operation that caused the - * auto-initialisation should fail. - */ - result = EINVAL; - } - - LeaveCriticalSection(&ptw32_barrier_test_init_lock); - - return(result); -} - - int pthread_barrier_init(pthread_barrier_t * barrier, const pthread_barrierattr_t * attr, @@ -147,57 +91,23 @@ pthread_barrier_destroy(pthread_barrier_t *barrier) return EINVAL; } - if (*barrier != (pthread_barrier_t) PTW32_OBJECT_AUTO_INIT) - { - b = *barrier; + b = *barrier; - if (0 == pthread_mutex_trylock(&b->mtxExclusiveAccess)) - { - /* - * FIXME!!! - * The mutex isn't held by another thread but we could still - * be too late invalidating the barrier below since another thread - * may alredy have entered barrier_wait and the check for a valid - * *barrier != NULL. - */ - *barrier = NULL; - - (void) sem_destroy(&(b->semBarrierBreeched)); - (void) pthread_mutex_unlock(&(b->mtxExclusiveAccess)); - (void) pthread_mutex_destroy(&(b->mtxExclusiveAccess)); - (void) free(b); - } - } - else + if (0 == pthread_mutex_trylock(&b->mtxExclusiveAccess)) { /* - * See notes in ptw32_barrier_check_need_init() above also. - */ - EnterCriticalSection(&ptw32_barrier_test_init_lock); - - /* - * Check again. + * FIXME!!! + * The mutex isn't held by another thread but we could still + * be too late invalidating the barrier below since another thread + * may alredy have entered barrier_wait and the check for a valid + * *barrier != NULL. */ - if (*barrier == (pthread_barrier_t) PTW32_OBJECT_AUTO_INIT) - { - /* - * This is all we need to do to destroy a statically - * initialised barrier that has not yet been used (initialised). - * If we get to here, another thread - * waiting to initialise this barrier will get an EINVAL. - */ - *barrier = NULL; - } - else - { - /* - * The barrier has been initialised while we were waiting - * so assume it's in use. - */ - result = EBUSY; - } + *barrier = NULL; - LeaveCriticalSection(&ptw32_barrier_test_init_lock); + (void) sem_destroy(&(b->semBarrierBreeched)); + (void) pthread_mutex_unlock(&(b->mtxExclusiveAccess)); + (void) pthread_mutex_destroy(&(b->mtxExclusiveAccess)); + (void) free(b); } return(result); @@ -215,17 +125,10 @@ pthread_barrier_wait(pthread_barrier_t *barrier) return EINVAL; } - if (*barrier == (pthread_barrier_t) PTHREAD_OBJECT_AUTO_INIT) - { - if ((result = ptw32_barrier_check_need_init(barrier)) != 0) - { - return(result); - } - } - b = *barrier; result = pthread_mutex_lock(b->mtxExclusiveAccess); + if (0 == result) { if (0 == --(b->nCurrentBarrierHeight)) @@ -514,4 +417,3 @@ pthread_barrierattr_setpshared (pthread_barrierattr_t * attr, return (result); } /* pthread_barrierattr_setpshared */ - |