From 46ae637c4ef03a921d4a06baf99219c6149a7d20 Mon Sep 17 00:00:00 2001 From: rpj Date: Sun, 15 May 2005 15:28:24 +0000 Subject: '' --- pthread_join.c | 103 ++++++++------------------------------------------------- 1 file changed, 14 insertions(+), 89 deletions(-) (limited to 'pthread_join.c') diff --git a/pthread_join.c b/pthread_join.c index 56ed0ba..8237b6c 100644 --- a/pthread_join.c +++ b/pthread_join.c @@ -84,60 +84,10 @@ pthread_join (pthread_t thread, void **value_ptr) pthread_t self; ptw32_thread_t * tp = (ptw32_thread_t *) thread.p; - /* - * Possibilities for the target thread on entry to pthread_join(): - * - * 1) the target thread is detached, in which case it could be destroyed and - * it's thread id (struct) reused before we get the reuse lock; - * 2) the target thread is joinable, in which case it will not be destroyed - * until it has been joined, and it's thread id cannot be reused before we - * get access to it. - * - * Only (1) is a potential race condition. - * While (1) is possibly an application programming error, pthread_join is - * required to handle it with an error. - * If an application attempts to join a detached thread that exits before we - * get the reuse lock, it's thread struct could be reused for a new joinable - * thread before we get the reuse_lock and we will then be joining the wrong - * thread. - * - * To fix this properly would require a reuse count as part of the thread id - * so that we could confirm that we are working with the same thread. This - * option will require a major change to the API, forcing recompilation of - * applications that use the library. - * - * Cheaper alternatives that do not change the API are: - * - separate reuse stacks could be used for detached and joinable - * threads. Threads which detach themselves will not present a race condition - * because they will be placed on a different stack to that which provides - * reusable structs to new joinable threads. - * The problem with this solution is that, an application that creates - * joinable threads which then detach themselves can cause the detach reuse - * stack to grow indefinitely. - * - * - maintain a sufficiently large reuse pool and manage it as a FIFO - * queue. This would prevent the immediate reuse of thread structs, but this - * only provides a statistical safeguard, not a deterministic one. - * - * - include an entry point array at the start of each thread struct so that - * each reuse (modulo N) returns a different thread id (pointer to the thread - * struct). Offset 0 from this pointer will contain a validity field and an - * offset value field (subtracted from the pointer to obtain the address of - * thread struct). This option is similar to including a reuse counter with - * the thread id but maintains the thread id as a simple pointer. - * - * As at 03/11/2004, the reuse count option has been implemented. - */ - EnterCriticalSection (&ptw32_thread_reuse_lock); - /* - * The first test is the same as pthread_kill(thread, 0), duplicated here - * so that we can use the reuse_lock to ensure the thread isn't destroyed - * and reused before we've finished with the POSIX thread struct. - */ - if (tp == NULL - || NULL == tp->threadH - || THREAD_PRIORITY_ERROR_RETURN == GetThreadPriority (tp->threadH)) + + if (NULL == tp + || thread.x != tp->ptHandle.x) { result = ESRCH; } @@ -146,20 +96,24 @@ pthread_join (pthread_t thread, void **value_ptr) result = EINVAL; } else + { + result = 0; + } + + LeaveCriticalSection (&ptw32_thread_reuse_lock); + + if (result == 0) { /* * The target thread is joinable and can't be reused before we join it. */ - - LeaveCriticalSection (&ptw32_thread_reuse_lock); - self = pthread_self(); if (NULL == self.p) { result = ENOENT; } - else if (0 != pthread_equal (self, thread)) + else if (pthread_equal (self, thread)) { result = EDEADLK; } @@ -176,29 +130,6 @@ pthread_join (pthread_t thread, void **value_ptr) if (0 == result) { - -#if ! defined (__MINGW32__) || defined (__MSVCRT__) || defined (__DMC__) - - if (value_ptr != NULL - && !GetExitCodeThread (tp->threadH, (LPDWORD) value_ptr)) - { - result = ESRCH; - } - else - { - /* - * The result of making multiple simultaneous calls to - * pthread_join() specifying the same target is undefined. - */ - ptw32_threadDestroy (thread); - } - -#else /* __MINGW32__ && ! __MSVCRT__ */ - - /* - * If using CRTDLL, the thread may have exited, and endthread - * will have closed the handle. - */ if (value_ptr != NULL) { *value_ptr = tp->exitStatus; @@ -206,24 +137,18 @@ pthread_join (pthread_t thread, void **value_ptr) /* * The result of making multiple simultaneous calls to - * pthread_join() specifying the same target is undefined. + * pthread_join() or pthread_detach() specifying the same + * target is undefined. */ - ptw32_threadDestroy (thread); - -#endif /* __MINGW32__ && ! __MSVCRT__ */ - + result = pthread_detach (thread); } else { result = ESRCH; } } - - goto FAIL0; } - LeaveCriticalSection (&ptw32_thread_reuse_lock); -FAIL0: return (result); } /* pthread_join */ -- cgit v1.2.3