NuttX RTOS

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 213 insertions, 0 deletions

diff --git a/nuttx/sched/pthread_join.c b/nuttx/sched/pthread_join.c
new file mode 100644
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+++ b/nuttx/sched/pthread_join.c
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+/************************************************************
+ * pthread_join.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 <unistd.h>
+#include <pthread.h>
+#include <errno.h>
+#include <debug.h>
+#include "os_internal.h"
+#include "pthread_internal.h"
+
+/************************************************************
+ * Definitions
+ ************************************************************/
+
+/************************************************************
+ * Private Type Declarations
+ ************************************************************/
+
+/************************************************************
+ * Global Variables
+ ************************************************************/
+
+/************************************************************
+ * Private Variables
+ ************************************************************/
+
+/************************************************************
+ * Private Functions
+ ************************************************************/
+
+/************************************************************
+ * Public Functions
+ ************************************************************/
+
+/************************************************************
+ * Function:  pthread_join
+ *
+ * Description:
+ *    A thread can await termination of another thread and
+ *    retrieve the return value of the thread.
+ *
+ * Parameters:
+ *   thread
+ *   pexit_value
+ *
+ * Return Value:
+ *   0 if successful.  Otherwise, one of the following error codes:
+ *       EINVAL  The value specified by thread does not refer to a
+ *               joinable thread.
+ *       ESRCH   No thread could be found corresponding to that
+ *               specified by the given thread ID.
+ *       EDEADLK A deadlock was detected or the value of thread
+ *               specifies the calling thread.
+ *
+ * Assumptions:
+ *
+ ************************************************************/
+
+int pthread_join(pthread_t thread, pthread_addr_t *pexit_value)
+{
+  join_t *pjoin;
+  int ret;
+
+  dbg("%s: thread=%d\n", __FUNCTION__, thread.pid);
+
+  /* First make sure that this is not an attempt to join to
+   * ourself.
+   */
+
+  if (thread.pid == getpid())
+    {
+      return EDEADLK;
+    }
+
+  /* Make sure no other task is mucking with the data structures
+   * while we are performing the following operations.  NOTE:
+   * we can be also sure that pthread_exit() will not execute
+   * because it will also attempt to get this semaphore.
+   */
+
+  (void)pthread_takesemaphore(&g_join_semaphore);
+
+  /* Find the join information associated with this thread.
+   * This can fail for one of three reasons:  (1) There is no
+   * thread associated with 'thread,' (2) the thread is a task
+   * and does not have join information, or (3) the thread
+   * was detached and has exitted.
+   */
+
+  pjoin = pthread_findjoininfo(thread.pid);
+  if (!pjoin)
+    {
+      /* Determine what kind of error to return */
+
+      _TCB *tcb = sched_gettcb(thread.pid);
+
+      dbg("%s: Could not find thread data\n", __FUNCTION__);
+
+      /* Case (1) or (3) -- we can't tell which.  Assume (3) */
+
+      if (!tcb)
+        {
+          ret = ESRCH;
+        }
+
+      /* The thread is still active but has no join info.  In that
+       * case, it must be a task and not a pthread.
+       */
+
+      else /* if ((tcb->flags & EDEADLK) == 0) */
+        {
+          ret = EINVAL;
+        }
+
+      (void)pthread_givesemaphore(&g_join_semaphore);
+    }
+  else if (pjoin->terminated)
+    {
+      dbg("%s: Thread has terminated\n", __FUNCTION__);
+
+      /* Get the thread exit value from the terminated thread. */
+
+      if (pexit_value)
+        {
+          dbg("%s: exit_value=0x%p\n", __FUNCTION__, pjoin->exit_value);
+          *pexit_value = pjoin->exit_value;
+        }
+
+      /* Then remove and deallocate the thread entry. */
+
+      (void)pthread_removejoininfo(thread.pid);
+      (void)pthread_givesemaphore(&g_join_semaphore);
+      sched_free(pjoin);
+      ret = OK;
+    }
+  else
+    {
+      dbg("%s: Thread is still running\n", __FUNCTION__);
+
+      /* Relinquish the data set semaphore, making certain that
+       * no task has the opportunity to run between the time
+       * we relinquish the data set semaphore and the time that
+       * we wait on the join semaphore.
+       */
+
+      sched_lock();
+      (void)pthread_givesemaphore(&g_join_semaphore);
+
+      /* Take the thread's join semaphore */
+
+      (void)pthread_takesemaphore(&pjoin->exit_sem);
+
+      /* Get the thread exit value */
+
+      if (pexit_value)
+        {
+          *pexit_value = pjoin->exit_value;
+          dbg("%s: exit_value=0x%p\n", __FUNCTION__, pjoin->exit_value);
+        }
+
+      /* Post the thread's join semaphore so that exitting thread
+       * will know that we have received the data.
+       */
+
+      (void)pthread_givesemaphore(&pjoin->data_sem);
+
+      /* Pre-emption is okay now. */
+
+      sched_unlock();
+
+      ret = OK;
+    }
+
+  dbg("%s: Returning %d\n", __FUNCTION__, ret);
+  return ret;
+}