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Diffstat (limited to 'liblo/pthreads.2/pthread_cond_destroy.c')
| -rw-r--r-- | liblo/pthreads.2/pthread_cond_destroy.c | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/liblo/pthreads.2/pthread_cond_destroy.c b/liblo/pthreads.2/pthread_cond_destroy.c new file mode 100644 index 0000000..8d016af --- /dev/null +++ b/liblo/pthreads.2/pthread_cond_destroy.c @@ -0,0 +1,244 @@ +/*
+ * pthread_cond_destroy.c
+ *
+ * Description:
+ * This translation unit implements condition variables and their primitives.
+ *
+ *
+ * --------------------------------------------------------------------------
+ *
+ * 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"
+
+int
+pthread_cond_destroy (pthread_cond_t * cond)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * This function destroys a condition variable
+ *
+ *
+ * PARAMETERS
+ * cond
+ * pointer to an instance of pthread_cond_t
+ *
+ *
+ * DESCRIPTION
+ * This function destroys a condition variable.
+ *
+ * NOTES:
+ * 1) A condition variable can be destroyed
+ * immediately after all the threads that
+ * are blocked on it are awakened. e.g.
+ *
+ * struct list {
+ * pthread_mutex_t lm;
+ * ...
+ * }
+ *
+ * struct elt {
+ * key k;
+ * int busy;
+ * pthread_cond_t notbusy;
+ * ...
+ * }
+ *
+ *
+ * struct elt *
+ * list_find(struct list *lp, key k)
+ * {
+ * struct elt *ep;
+ *
+ * pthread_mutex_lock(&lp->lm);
+ * while ((ep = find_elt(l,k) != NULL) && ep->busy)
+ * pthread_cond_wait(&ep->notbusy, &lp->lm);
+ * if (ep != NULL)
+ * ep->busy = 1;
+ * pthread_mutex_unlock(&lp->lm);
+ * return(ep);
+ * }
+ *
+ * delete_elt(struct list *lp, struct elt *ep)
+ * {
+ * pthread_mutex_lock(&lp->lm);
+ * assert(ep->busy);
+ * ... remove ep from list ...
+ * ep->busy = 0;
+ * (A) pthread_cond_broadcast(&ep->notbusy);
+ * pthread_mutex_unlock(&lp->lm);
+ * (B) pthread_cond_destroy(&rp->notbusy);
+ * free(ep);
+ * }
+ *
+ * In this example, the condition variable
+ * and its list element may be freed (line B)
+ * immediately after all threads waiting for
+ * it are awakened (line A), since the mutex
+ * and the code ensure that no other thread
+ * can touch the element to be deleted.
+ *
+ * RESULTS
+ * 0 successfully released condition variable,
+ * EINVAL 'cond' is invalid,
+ * EBUSY 'cond' is in use,
+ *
+ * ------------------------------------------------------
+ */
+{
+ pthread_cond_t cv;
+ int result = 0, result1 = 0, result2 = 0;
+
+ /*
+ * Assuming any race condition here is harmless.
+ */
+ if (cond == NULL || *cond == NULL)
+ {
+ return EINVAL;
+ }
+
+ if (*cond != PTHREAD_COND_INITIALIZER)
+ {
+ EnterCriticalSection (&ptw32_cond_list_lock);
+
+ cv = *cond;
+
+ /*
+ * Close the gate; this will synchronize this thread with
+ * all already signaled waiters to let them retract their
+ * waiter status - SEE NOTE 1 ABOVE!!!
+ */
+ if (sem_wait (&(cv->semBlockLock)) != 0)
+ {
+ return errno;
+ }
+
+ /*
+ * !TRY! lock mtxUnblockLock; try will detect busy condition
+ * and will not cause a deadlock with respect to concurrent
+ * signal/broadcast.
+ */
+ if ((result = pthread_mutex_trylock (&(cv->mtxUnblockLock))) != 0)
+ {
+ (void) sem_post (&(cv->semBlockLock));
+ return result;
+ }
+
+ /*
+ * Check whether cv is still busy (still has waiters)
+ */
+ if (cv->nWaitersBlocked > cv->nWaitersGone)
+ {
+ if (sem_post (&(cv->semBlockLock)) != 0)
+ {
+ result = errno;
+ }
+ result1 = pthread_mutex_unlock (&(cv->mtxUnblockLock));
+ result2 = EBUSY;
+ }
+ else
+ {
+ /*
+ * Now it is safe to destroy
+ */
+ *cond = NULL;
+
+ if (sem_destroy (&(cv->semBlockLock)) != 0)
+ {
+ result = errno;
+ }
+ if (sem_destroy (&(cv->semBlockQueue)) != 0)
+ {
+ result1 = errno;
+ }
+ if ((result2 = pthread_mutex_unlock (&(cv->mtxUnblockLock))) == 0)
+ {
+ result2 = pthread_mutex_destroy (&(cv->mtxUnblockLock));
+ }
+
+ /* Unlink the CV from the list */
+
+ if (ptw32_cond_list_head == cv)
+ {
+ ptw32_cond_list_head = cv->next;
+ }
+ else
+ {
+ cv->prev->next = cv->next;
+ }
+
+ if (ptw32_cond_list_tail == cv)
+ {
+ ptw32_cond_list_tail = cv->prev;
+ }
+ else
+ {
+ cv->next->prev = cv->prev;
+ }
+
+ (void) free (cv);
+ }
+
+ LeaveCriticalSection (&ptw32_cond_list_lock);
+ }
+ else
+ {
+ /*
+ * See notes in ptw32_cond_check_need_init() above also.
+ */
+ EnterCriticalSection (&ptw32_cond_test_init_lock);
+
+ /*
+ * Check again.
+ */
+ if (*cond == PTHREAD_COND_INITIALIZER)
+ {
+ /*
+ * This is all we need to do to destroy a statically
+ * initialised cond that has not yet been used (initialised).
+ * If we get to here, another thread waiting to initialise
+ * this cond will get an EINVAL. That's OK.
+ */
+ *cond = NULL;
+ }
+ else
+ {
+ /*
+ * The cv has been initialised while we were waiting
+ * so assume it's in use.
+ */
+ result = EBUSY;
+ }
+
+ LeaveCriticalSection (&ptw32_cond_test_init_lock);
+ }
+
+ return ((result != 0) ? result : ((result1 != 0) ? result1 : result2));
+}
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