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authormarha <marha@users.sourceforge.net>2011-07-18 10:33:05 +0200
committermarha <marha@users.sourceforge.net>2011-07-18 10:33:05 +0200
commit88101146f2ec7d53ffb793e365f05097ffd35fd3 (patch)
treedb77eef572a00c62c8d9485c4786f682e20a2fd0 /pthreads/pthread_cond_destroy.c
parent772373ccc8da2b2019555228f4972cc0c5a885a4 (diff)
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cvs version of pthreads
Diffstat (limited to 'pthreads/pthread_cond_destroy.c')
-rw-r--r--pthreads/pthread_cond_destroy.c504
1 files changed, 253 insertions, 251 deletions
diff --git a/pthreads/pthread_cond_destroy.c b/pthreads/pthread_cond_destroy.c
index 34550f08d..40d4a0896 100644
--- a/pthreads/pthread_cond_destroy.c
+++ b/pthreads/pthread_cond_destroy.c
@@ -1,251 +1,253 @@
-/*
- * 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 (ptw32_semwait (&(cv->semBlockLock)) != 0) /* Non-cancelable */
- {
- result = errno;
- }
- else
- {
- /*
- * !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));
- }
- }
-
- if (result != 0)
- {
- LeaveCriticalSection (&ptw32_cond_list_lock);
- 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));
-}
+/*
+ * 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)
+ {
+ ptw32_mcs_local_node_t node;
+ ptw32_mcs_lock_acquire(&ptw32_cond_list_lock, &node);
+
+ 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 (ptw32_semwait (&(cv->semBlockLock)) != 0) /* Non-cancelable */
+ {
+ result = errno;
+ }
+ else
+ {
+ /*
+ * !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));
+ }
+ }
+
+ if (result != 0)
+ {
+ ptw32_mcs_lock_release(&node);
+ 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);
+ }
+
+ ptw32_mcs_lock_release(&node);
+ }
+ else
+ {
+ ptw32_mcs_local_node_t node;
+ /*
+ * See notes in ptw32_cond_check_need_init() above also.
+ */
+ ptw32_mcs_lock_acquire(&ptw32_cond_test_init_lock, &node);
+
+ /*
+ * 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;
+ }
+
+ ptw32_mcs_lock_release(&node);
+ }
+
+ return ((result != 0) ? result : ((result1 != 0) ? result1 : result2));
+}