Add new pthread_* APIs

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@134 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 181 insertions, 0 deletions

diff --git a/nuttx/sched/pthread_barrierwait.c b/nuttx/sched/pthread_barrierwait.c
new file mode 100644
index 000000000..14cfa2eb3
--- /dev/null
+++ b/nuttx/sched/pthread_barrierwait.c
@@ -0,0 +1,181 @@
+/********************************************************************************
+ * pthread_barrierwait.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ********************************************************************************/
+
+/********************************************************************************
+ * Included Files
+ ********************************************************************************/
+
+#include <sys/types.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <sched.h>
+#include <errno.h>
+#include <debug.h>
+
+/********************************************************************************
+ * Definitions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Type Declarations
+ ********************************************************************************/
+
+/********************************************************************************
+ * Global Variables
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Variables
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Function Prototypes
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Function: pthread_barrier_wait
+ *
+ * Description:
+ *   The pthread_barrier_wait() function synchronizse participating threads at
+ *   the barrier referenced by 'barrier'.  The calling thread is blocked until
+ *   the required number of threads have called pthread_barrier_wait() specifying
+ *   the same 'barrier'.  When the required number of threads have called
+ *   pthread_barrier_wait() specifying the 'barrier', the constant
+ *   PTHREAD_BARRIER_SERIAL_THREAD will be returned to one unspecified thread
+ *   and zero will be returned to each of the remaining threads. At this point,
+ *   the barrier will be reset to the state it had as a result of the most recent
+ *   pthread_barrier_init() function that referenced it.
+ *
+ *   The constant PTHREAD_BARRIER_SERIAL_THREAD is defined in pthread.h and its
+ *   value must be distinct from any other value returned by pthread_barrier_wait().
+ *
+ *   The results are undefined if this function is called with an uninitialized
+ *   barrier.
+ *
+ *   If a signal is delivered to a thread blocked on a barrier, upon return from
+ *   the signal handler the thread will resume waiting at the barrier if the barrier
+ *   wait has not completed; otherwise, the thread will continue as normal from
+ *   the completed barrier wait. Until the thread in the signal handler returns
+ *   from it, it is unspecified whether other threads may proceed past the barrier
+ *   once they have all reached it.
+ *
+ *   A thread that has blocked on a barrier will not prevent any unblocked thread
+ *   that is eligible to use the same processing resources from eventually making
+ *   forward progress in its execution.  Eligibility for processing resources will
+ *   be determined by the scheduling policy.
+ *
+ * Parameters:
+ *   barrier - the barrier to wait on
+ *
+ * Return Value:
+ *   0 (OK) on success or EINVAL if the barrier is not valid.
+ *
+ * Assumptions:
+ *
+ ********************************************************************************/
+
+int pthread_barrier_wait(FAR pthread_barrier_t *barrier)
+{
+  int semcount;
+  int ret = OK;
+
+  if (!barrier)
+    {
+      return EINVAL;
+    }
+
+  /* Disable pre-emption throughout the following */
+
+  sched_lock();
+
+  /* Find out how many threads are already waiting at the barrier */
+
+  ret = sem_getvalue(&barrier->sem, &semcount);
+  if (ret != OK)
+    {
+      sched_unlock();
+      return EINVAL;
+    }
+
+  /* If the number of waiters would be equal to the count, then we are done */
+
+  if (1 - semcount >= barrier->count)
+    {
+      /* Free all of the waiting threads */
+
+      while (semcount < 0)
+        {
+          (void)sem_post(&barrier->sem);
+          (void)sem_getvalue(&barrier->sem, &semcount);
+        }
+
+      /* Then return PTHREAD_BARRIER_SERIAL_THREAD to the final thread */
+
+      sched_unlock();
+      return PTHREAD_BARRIER_SERIAL_THREAD;
+    }
+  else
+    {
+      /* Otherwise, this thread must wait as well */
+
+      while (sem_wait(&barrier->sem) != OK)
+        {
+          /* If the thread is awakened by a signal, just continue to wait */
+
+          int errornumber = *get_errno_ptr();
+          if (errornumber != EINTR)
+            {
+              /* If it is awakened by some other error, then there is a
+               * problem
+               */
+
+              sched_unlock();
+              return errornumber;
+            }
+        }
+
+      /* We will only get here when we are one of the N-1 threads that were
+       * waiting for the final thread at the barrier.  We just need to return
+       * zero.
+       */
+
+      sched_unlock();
+      return 0;
+    }
+}