From a416ab17ecf9f2cb0f1e3f7bd645a8d1ce690ca2 Mon Sep 17 00:00:00 2001
From: rpj <rpj>
Date: Mon, 18 Feb 2002 03:16:52 +0000
Subject: Major reorganisation of source code; new routine and tests added.

---
 pthread_barrier_wait.c | 114 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 pthread_barrier_wait.c

(limited to 'pthread_barrier_wait.c')

diff --git a/pthread_barrier_wait.c b/pthread_barrier_wait.c
new file mode 100644
index 0000000..e06e87d
--- /dev/null
+++ b/pthread_barrier_wait.c
@@ -0,0 +1,114 @@
+/*
+ * pthread_barrier_wait.c
+ *
+ * Description:
+ * This translation unit implements barrier primitives.
+ *
+ * --------------------------------------------------------------------------
+ *
+ *      Pthreads-win32 - POSIX Threads Library for Win32
+ *      Copyright(C) 1998 John E. Bossom
+ *      Copyright(C) 1999,2002 Pthreads-win32 contributors
+ *
+ *      Contact Email: rpj@ise.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_barrier_wait(pthread_barrier_t *barrier)
+{
+  int result;
+  int step;
+  pthread_barrier_t b;
+
+  if (barrier == NULL || *barrier == (pthread_barrier_t) PTW32_OBJECT_INVALID)
+    {
+      return EINVAL;
+    }
+
+  b = *barrier;
+  step = b->iStep;
+
+  if (0 == InterlockedDecrement((long *) &(b->nCurrentBarrierHeight)))
+    {
+      /* Must be done before posting the semaphore. */
+      b->nCurrentBarrierHeight = b->nInitialBarrierHeight;
+
+      /*
+       * There is no race condition between the semaphore wait and post
+       * because we are using two alternating semas and all threads have
+       * entered barrier_wait and checked nCurrentBarrierHeight before this
+       * barrier's sema can be posted. Any threads that have not quite
+       * entered sem_wait below when the multiple_post has completed
+       * will nevertheless continue through the semaphore (barrier)
+       * and will not be left stranded.
+       */
+      result = (b->nInitialBarrierHeight > 1
+                ? sem_post_multiple(&(b->semBarrierBreeched[step]),
+                                    b->nInitialBarrierHeight - 1)
+                : 0);
+    }
+  else
+    {
+      BOOL switchCancelState;
+      int oldCancelState;
+      pthread_t self = pthread_self();
+
+      /*
+       * This routine is not a cancelation point, so temporarily
+       * prevent sem_wait() from being one.
+       * PTHREAD_CANCEL_ASYNCHRONOUS threads can still be canceled.
+       */
+      switchCancelState = (self->cancelType == PTHREAD_CANCEL_DEFERRED &&
+                           0 == pthread_setcancelstate(PTHREAD_CANCEL_DISABLE,
+                                                       &oldCancelState));
+
+      result = sem_wait(&(b->semBarrierBreeched[step]));
+
+      if (switchCancelState)
+        {
+          (void) pthread_setcancelstate(oldCancelState, NULL);
+        }
+    }
+
+  /*
+   * The first thread across will be the PTHREAD_BARRIER_SERIAL_THREAD.
+   * This also sets up the alternate semaphore as the next barrier.
+   */
+  if (0 == result)
+    {
+      result = ((PTW32_INTERLOCKED_LONG) step ==
+                ptw32_interlocked_compare_exchange((PTW32_INTERLOCKED_LPLONG) &(b->iStep),
+                                                   (PTW32_INTERLOCKED_LONG) (1L - step),
+                                                   (PTW32_INTERLOCKED_LONG) step)
+                ? PTHREAD_BARRIER_SERIAL_THREAD
+                : 0);
+    }
+
+  return(result);
+}
+
-- 
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