From cd3c708380761302fb5ffc6531d396f71b706b4f Mon Sep 17 00:00:00 2001
From: rpj
While pthread_once is not a cancellation point, -init_routine can be. The required effect on once_control -of a cancellation inside the init_routine is to leave it as if -pthread_once had not been called.
-If the init_routine is cancelled and there are threads -waiting on the once_control then Pthreads-w32 wakes one of -them so that it can re-compete along with any newly arriving threads -in the re-running of init_routine.
+init_routine can be. The effect on once_control of a +cancellation inside the init_routine is to leave it as if +pthread_once had not been called by the cancelled thread.pthread_once returns 0 on success, or an error code on failure.
diff --git a/private.c b/private.c index 51b5707..7e311b1 100644 --- a/private.c +++ b/private.c @@ -41,6 +41,7 @@ /* Must be first to define HAVE_INLINABLE_INTERLOCKED_CMPXCHG */ #include "ptw32_InterlockedCompareExchange.c" +#include "ptw32_MCS_lock.c" #include "ptw32_is_attr.c" #include "ptw32_processInitialize.c" #include "ptw32_processTerminate.c" diff --git a/pthread.h b/pthread.h index 00b81fe..eddbb53 100644 --- a/pthread.h +++ b/pthread.h @@ -652,14 +652,14 @@ enum { * ==================== * ==================== */ -#define PTHREAD_ONCE_INIT { 0, 0, 0, 0} +#define PTHREAD_ONCE_INIT { PTW32_FALSE, 0, 0, 0} struct pthread_once_t_ { - int state; /* indicates if user function has been executed */ - int reserved; - int numSemaphoreUsers; - HANDLE semaphore; + int done; /* indicates if user function has been executed */ + void * lock; + int reserved1; + int reserved2; }; diff --git a/pthread_kill.c b/pthread_kill.c index 5a795dd..7de3fe2 100644 --- a/pthread_kill.c +++ b/pthread_kill.c @@ -82,8 +82,7 @@ pthread_kill (pthread_t thread, int sig) if (NULL == tp || thread.x != tp->ptHandle.x - || NULL == tp->threadH - || THREAD_PRIORITY_ERROR_RETURN == GetThreadPriority (tp->threadH)) + || NULL == tp->threadH) { result = ESRCH; } diff --git a/pthread_once.c b/pthread_once.c index 39ddcce..aa09d99 100644 --- a/pthread_once.c +++ b/pthread_once.c @@ -39,147 +39,48 @@ static void PTW32_CDECL -ptw32_once_init_routine_cleanup(void * arg) +ptw32_once_on_init_cancel (void * arg) { - pthread_once_t * once_control = (pthread_once_t *) arg; - - (void) PTW32_INTERLOCKED_EXCHANGE((LPLONG)&once_control->state, (LONG)PTW32_ONCE_INIT); - - if (InterlockedExchangeAdd((LPLONG)&once_control->semaphore, 0L)) /* MBR fence */ - { - ReleaseSemaphore(once_control->semaphore, 1, NULL); - } + /* when the initting thread is cancelled we have to release the lock */ + ptw32_mcs_local_node_t *node = (ptw32_mcs_local_node_t *)arg; + ptw32_mcs_lock_release(node); } int pthread_once (pthread_once_t * once_control, void (*init_routine) (void)) - /* - * ------------------------------------------------------ - * DOCPUBLIC - * If any thread in a process with a once_control parameter - * makes a call to pthread_once(), the first call will summon - * the init_routine(), but subsequent calls will not. The - * once_control parameter determines whether the associated - * initialization routine has been called. The init_routine() - * is complete upon return of pthread_once(). - * This function guarantees that one and only one thread - * executes the initialization routine, init_routine when - * access is controlled by the pthread_once_t control - * key. - * - * pthread_once() is not a cancelation point, but the init_routine - * can be. If it's cancelled then the effect on the once_control is - * as if pthread_once had never been entered. - * - * - * PARAMETERS - * once_control - * pointer to an instance of pthread_once_t - * - * init_routine - * pointer to an initialization routine - * - * - * DESCRIPTION - * See above. - * - * RESULTS - * 0 success, - * EINVAL once_control or init_routine is NULL - * - * ------------------------------------------------------ - */ { - int result; - int state; - HANDLE sema; - if (once_control == NULL || init_routine == NULL) { - result = EINVAL; - goto FAIL0; + return EINVAL; } - else + + if (!InterlockedExchangeAdd((LPLONG)&once_control->done, 0)) /* MBR fence */ { - result = 0; - } + ptw32_mcs_local_node_t node; - while ((state = - PTW32_INTERLOCKED_COMPARE_EXCHANGE((PTW32_INTERLOCKED_LPLONG)&once_control->state, - (PTW32_INTERLOCKED_LONG)PTW32_ONCE_STARTED, - (PTW32_INTERLOCKED_LONG)PTW32_ONCE_INIT)) - != PTW32_ONCE_DONE) - { - if (PTW32_ONCE_INIT == state) - { + ptw32_mcs_lock_acquire((ptw32_mcs_lock_t *)&once_control->lock, &node); + + if (!InterlockedExchangeAdd((LPLONG)&once_control->done, 0L)) + { #ifdef _MSC_VER #pragma inline_depth(0) #endif - pthread_cleanup_push(ptw32_once_init_routine_cleanup, (void *) once_control); - (*init_routine)(); - pthread_cleanup_pop(0); + pthread_cleanup_push(ptw32_once_on_init_cancel, (void *)&node); + (*init_routine)(); + pthread_cleanup_pop(0); #ifdef _MSC_VER #pragma inline_depth() #endif - (void) PTW32_INTERLOCKED_EXCHANGE((LPLONG)&once_control->state, - (LONG)PTW32_ONCE_DONE); - - /* - * we didn't create the semaphore. - * it is only there if there is someone waiting. - */ - if (InterlockedExchangeAdd((LPLONG)&once_control->semaphore, 0L)) /* MBR fence */ - { - ReleaseSemaphore(once_control->semaphore, - once_control->numSemaphoreUsers, NULL); - } - } - else - { - InterlockedIncrement((LPLONG)&once_control->numSemaphoreUsers); - - if (!InterlockedExchangeAdd((LPLONG)&once_control->semaphore, 0L)) /* MBR fence */ - { - sema = CreateSemaphore(NULL, 0, INT_MAX, NULL); + (void) PTW32_INTERLOCKED_EXCHANGE((LPLONG)&once_control->done, (LONG)PTW32_TRUE); + } - if (PTW32_INTERLOCKED_COMPARE_EXCHANGE((PTW32_INTERLOCKED_LPLONG)&once_control->semaphore, - (PTW32_INTERLOCKED_LONG)sema, - (PTW32_INTERLOCKED_LONG)0)) - { - CloseHandle(sema); - } - } - - /* - * Check 'state' again in case the initting thread has finished or - * cancelled and left before seeing that there was a semaphore. - */ - if (InterlockedExchangeAdd((LPLONG)&once_control->state, 0L) == PTW32_ONCE_STARTED) - { - WaitForSingleObject(once_control->semaphore, INFINITE); - } - - if (0 == InterlockedDecrement((LPLONG)&once_control->numSemaphoreUsers)) - { - /* we were last */ - if ((sema = - (HANDLE) PTW32_INTERLOCKED_EXCHANGE((LPLONG)&once_control->semaphore, (LONG)0))) - { - CloseHandle(sema); - } - } - } + ptw32_mcs_lock_release(&node); } - /* - * ------------ - * Failure Code - * ------------ - */ -FAIL0: - return (result); -} /* pthread_once */ + return 0; + +} /* pthread_once */ diff --git a/ptw32_MCS_lock.c b/ptw32_MCS_lock.c new file mode 100644 index 0000000..478a059 --- /dev/null +++ b/ptw32_MCS_lock.c @@ -0,0 +1,210 @@ +/* + * ptw32_MCS_lock.c + * + * Description: + * This translation unit implements queue-based locks. + * + * -------------------------------------------------------------------------- + * + * 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 + */ + +/* + * About MCS locks: + * + * MCS locks are queue-based locks, where the queue nodes are local to the + * thread. The 'lock' is nothing more than a global pointer that points to + * the last node in the queue, or is NULL if the queue is empty. + * + * Originally designed for use as spin locks requiring no kernel resources + * for synchronisation or blocking, the implementation below has adapted + * the MCS spin lock for use as a general mutex that will suspend threads + * when there is lock contention. + * + * Because the queue nodes are thread-local, most of the memory read/write + * operations required to add or remove nodes from the queue do not trigger + * cache-coherence updates. + * + * Like 'named' mutexes, MCS locks consume system recourses transiently - + * they are able to acquire and free recourses automatically - but MCS + * locks do not require any unique 'name' to identify the lock to all + * threads using it. + * + * Usage of MCS locks: + * + * - you need a global ptw32_mcs_lock_t instance initialised to 0 or NULL. + * - you need a local thread-scope ptw32_mcs_local_node_t instance, which + * may serve several different locks but you need at least one node for + * every lock held concurrently by a thread. + * + * E.g.: + * + * ptw32_mcs_lock_t lock1 = 0; + * ptw32_mcs_lock_t lock2 = 0; + * + * void *mythread(void *arg) + * { + * ptw32_mcs_local_node_t node; + * + * ptw32_mcs_acquire (&lock1, &node); + * ptw32_mcs_release (&node); + * + * ptw32_mcs_acquire (&lock2, &node); + * ptw32_mcs_release (&node); + * { + * ptw32_mcs_local_node_t nodex; + * + * ptw32_mcs_acquire (&lock1, &node); + * ptw32_mcs_acquire (&lock2, &nodex); + * + * ptw32_mcs_release (&nodex); + * ptw32_mcs_release (&node); + * } + * return (void *)0; + * } + */ + +#include "implement.h" +#include "pthread.h" + +/* + * ptw32_mcs_flag_set -- notify another thread about an event. + * + * Set event if an event handle has been stored in the flag, and + * set flag to -1 otherwise. Note that -1 cannot be a valid handle value. + */ +INLINE void +ptw32_mcs_flag_set (LONG * flag) +{ + HANDLE e = (HANDLE)PTW32_INTERLOCKED_COMPARE_EXCHANGE( + (PTW32_INTERLOCKED_LPLONG)flag, + (PTW32_INTERLOCKED_LONG)-1, + (PTW32_INTERLOCKED_LONG)0); + if ((HANDLE)0 != e) + { + /* another thread has already stored an event handle in the flag */ + SetEvent(e); + } +} + +/* + * ptw32_mcs_flag_set -- wait for notification from another. + * + * Store an event handle in the flag and wait on it if the flag has not been + * set, and proceed without creating an event otherwise. + */ +INLINE void +ptw32_mcs_flag_wait (LONG * flag) +{ + if (0 == InterlockedExchangeAdd((LPLONG)flag, 0)) /* MBR fence */ + { + /* the flag is not set. create event. */ + + HANDLE e = CreateEvent(NULL, PTW32_FALSE, PTW32_FALSE, NULL); + + if (0 == PTW32_INTERLOCKED_COMPARE_EXCHANGE( + (PTW32_INTERLOCKED_LPLONG)flag, + (PTW32_INTERLOCKED_LONG)e, + (PTW32_INTERLOCKED_LONG)0)) + { + /* stored handle in the flag. wait on it now. */ + WaitForSingleObject(e, INFINITE); + } + + CloseHandle(e); + } +} + +/* + * ptw32_mcs_lock_acquire -- acquire an MCS lock. + * + * See: + * J. M. Mellor-Crummey and M. L. Scott. + * Algorithms for Scalable Synchronization on Shared-Memory Multiprocessors. + * ACM Transactions on Computer Systems, 9(1):21-65, Feb. 1991. + */ +INLINE void +ptw32_mcs_lock_acquire (ptw32_mcs_lock_t * lock, ptw32_mcs_local_node_t * node) +{ + ptw32_mcs_local_node_t *pred; + + node->lock = lock; + node->nextFlag = 0; + node->readyFlag = 0; + node->next = 0; /* initially, no successor */ + + /* queue for the lock */ + pred = (ptw32_mcs_local_node_t *)PTW32_INTERLOCKED_EXCHANGE((LPLONG)lock, + (LONG)node); + + if (0 != pred) + { + /* the lock was not free. link behind predecessor. */ + pred->next = node; + ptw32_mcs_flag_set(&pred->nextFlag); + ptw32_mcs_flag_wait(&node->readyFlag); + } +} + +/* + * ptw32_mcs_lock_release -- release an MCS lock. + * + * See: + * J. M. Mellor-Crummey and M. L. Scott. + * Algorithms for Scalable Synchronization on Shared-Memory Multiprocessors. + * ACM Transactions on Computer Systems, 9(1):21-65, Feb. 1991. + */ +INLINE void +ptw32_mcs_lock_release (ptw32_mcs_local_node_t * node) +{ + ptw32_mcs_lock_t *lock = node->lock; + ptw32_mcs_local_node_t *next = (ptw32_mcs_local_node_t *) + InterlockedExchangeAdd((LPLONG)&node->next, 0); /* MBR fence */ + + if (0 == next) + { + /* no known successor */ + + if (node == (ptw32_mcs_local_node_t *) + PTW32_INTERLOCKED_COMPARE_EXCHANGE((PTW32_INTERLOCKED_LPLONG)lock, + (PTW32_INTERLOCKED_LONG)0, + (PTW32_INTERLOCKED_LONG)node)) + { + /* no successor, lock is free now */ + return; + } + + /* wait for successor */ + ptw32_mcs_flag_wait(&node->nextFlag); + next = (ptw32_mcs_local_node_t *) + InterlockedExchangeAdd((LPLONG)&node->next, 0); /* MBR fence */ + } + + /* pass the lock */ + ptw32_mcs_flag_set(&next->readyFlag); +} diff --git a/ptw32_relmillisecs.c b/ptw32_relmillisecs.c index 7031148..f3e7b76 100644 --- a/ptw32_relmillisecs.c +++ b/ptw32_relmillisecs.c @@ -44,7 +44,7 @@ #endif -DWORD +INLINE DWORD ptw32_relmillisecs (const struct timespec * abstime) { const int64_t NANOSEC_PER_MILLISEC = 1000000; diff --git a/tests/Bmakefile b/tests/Bmakefile index b56c18f..c1c5805 100644 --- a/tests/Bmakefile +++ b/tests/Bmakefile @@ -91,7 +91,8 @@ PASSES= loadfree.pass \ mutex6s.pass mutex6es.pass mutex6rs.pass \ mutex7.pass mutex7n.pass mutex7e.pass mutex7r.pass \ mutex8.pass mutex8n.pass mutex8e.pass mutex8r.pass \ - count1.pass once1.pass once2.pass once3.pass once4.pass \ + count1.pass \ + once1.pass once2.pass once3.pass once4.pass \ self2.pass \ cancel1.pass cancel2.pass \ semaphore4.pass semaphore4t.pass \ diff --git a/tests/ChangeLog b/tests/ChangeLog index 9b00fa3..b3784e4 100644 --- a/tests/ChangeLog +++ b/tests/ChangeLog @@ -1,3 +1,8 @@ +2005-06-02 Ross Johnson