summaryrefslogtreecommitdiff
path: root/pthreads/src/pthread_cond_signal.c
diff options
context:
space:
mode:
Diffstat (limited to 'pthreads/src/pthread_cond_signal.c')
-rw-r--r--pthreads/src/pthread_cond_signal.c231
1 files changed, 231 insertions, 0 deletions
diff --git a/pthreads/src/pthread_cond_signal.c b/pthreads/src/pthread_cond_signal.c
new file mode 100644
index 0000000..2b4f6d4
--- /dev/null
+++ b/pthreads/src/pthread_cond_signal.c
@@ -0,0 +1,231 @@
+/*
+ * pthread_cond_signal.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
+ *
+ * -------------------------------------------------------------
+ * Algorithm:
+ * See the comments at the top of pthread_cond_wait.c.
+ */
+
+#include "pthread.h"
+#include "implement.h"
+
+static INLINE int
+ptw32_cond_unblock (pthread_cond_t * cond, int unblockAll)
+ /*
+ * Notes.
+ *
+ * Does not use the external mutex for synchronisation,
+ * therefore semBlockLock is needed.
+ * mtxUnblockLock is for LEVEL-2 synch. LEVEL-2 is the
+ * state where the external mutex is not necessarily locked by
+ * any thread, ie. between cond_wait unlocking and re-acquiring
+ * the lock after having been signaled or a timeout or
+ * cancellation.
+ *
+ * Uses the following CV elements:
+ * nWaitersBlocked
+ * nWaitersToUnblock
+ * nWaitersGone
+ * mtxUnblockLock
+ * semBlockLock
+ * semBlockQueue
+ */
+{
+ int result;
+ pthread_cond_t cv;
+ int nSignalsToIssue;
+
+ if (cond == NULL || *cond == NULL)
+ {
+ return EINVAL;
+ }
+
+ cv = *cond;
+
+ /*
+ * No-op if the CV is static and hasn't been initialised yet.
+ * Assuming that any race condition is harmless.
+ */
+ if (cv == PTHREAD_COND_INITIALIZER)
+ {
+ return 0;
+ }
+
+ if ((result = pthread_mutex_lock (&(cv->mtxUnblockLock))) != 0)
+ {
+ return result;
+ }
+
+ if (0 != cv->nWaitersToUnblock)
+ {
+ if (0 == cv->nWaitersBlocked)
+ {
+ return pthread_mutex_unlock (&(cv->mtxUnblockLock));
+ }
+ if (unblockAll)
+ {
+ cv->nWaitersToUnblock += (nSignalsToIssue = cv->nWaitersBlocked);
+ cv->nWaitersBlocked = 0;
+ }
+ else
+ {
+ nSignalsToIssue = 1;
+ cv->nWaitersToUnblock++;
+ cv->nWaitersBlocked--;
+ }
+ }
+ else if (cv->nWaitersBlocked > cv->nWaitersGone)
+ {
+ /* Use the non-cancellable version of sem_wait() */
+ if (ptw32_semwait (&(cv->semBlockLock)) != 0)
+ {
+ result = errno;
+ (void) pthread_mutex_unlock (&(cv->mtxUnblockLock));
+ return result;
+ }
+ if (0 != cv->nWaitersGone)
+ {
+ cv->nWaitersBlocked -= cv->nWaitersGone;
+ cv->nWaitersGone = 0;
+ }
+ if (unblockAll)
+ {
+ nSignalsToIssue = cv->nWaitersToUnblock = cv->nWaitersBlocked;
+ cv->nWaitersBlocked = 0;
+ }
+ else
+ {
+ nSignalsToIssue = cv->nWaitersToUnblock = 1;
+ cv->nWaitersBlocked--;
+ }
+ }
+ else
+ {
+ return pthread_mutex_unlock (&(cv->mtxUnblockLock));
+ }
+
+ if ((result = pthread_mutex_unlock (&(cv->mtxUnblockLock))) == 0)
+ {
+ if (sem_post_multiple (&(cv->semBlockQueue), nSignalsToIssue) != 0)
+ {
+ result = errno;
+ }
+ }
+
+ return result;
+
+} /* ptw32_cond_unblock */
+
+int
+pthread_cond_signal (pthread_cond_t * cond)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * This function signals a condition variable, waking
+ * one waiting thread.
+ * If SCHED_FIFO or SCHED_RR policy threads are waiting
+ * the highest priority waiter is awakened; otherwise,
+ * an unspecified waiter is awakened.
+ *
+ * PARAMETERS
+ * cond
+ * pointer to an instance of pthread_cond_t
+ *
+ *
+ * DESCRIPTION
+ * This function signals a condition variable, waking
+ * one waiting thread.
+ * If SCHED_FIFO or SCHED_RR policy threads are waiting
+ * the highest priority waiter is awakened; otherwise,
+ * an unspecified waiter is awakened.
+ *
+ * NOTES:
+ *
+ * 1) Use when any waiter can respond and only one need
+ * respond (all waiters being equal).
+ *
+ * RESULTS
+ * 0 successfully signaled condition,
+ * EINVAL 'cond' is invalid,
+ *
+ * ------------------------------------------------------
+ */
+{
+ /*
+ * The '0'(FALSE) unblockAll arg means unblock ONE waiter.
+ */
+ return (ptw32_cond_unblock (cond, 0));
+
+} /* pthread_cond_signal */
+
+int
+pthread_cond_broadcast (pthread_cond_t * cond)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * This function broadcasts the condition variable,
+ * waking all current waiters.
+ *
+ * PARAMETERS
+ * cond
+ * pointer to an instance of pthread_cond_t
+ *
+ *
+ * DESCRIPTION
+ * This function signals a condition variable, waking
+ * all waiting threads.
+ *
+ * NOTES:
+ *
+ * 1) Use when more than one waiter may respond to
+ * predicate change or if any waiting thread may
+ * not be able to respond
+ *
+ * RESULTS
+ * 0 successfully signalled condition to all
+ * waiting threads,
+ * EINVAL 'cond' is invalid
+ * ENOSPC a required resource has been exhausted,
+ *
+ * ------------------------------------------------------
+ */
+{
+ /*
+ * The TRUE unblockAll arg means unblock ALL waiters.
+ */
+ return (ptw32_cond_unblock (cond, PTW32_TRUE));
+
+} /* pthread_cond_broadcast */