/************************************************************
* pthread_completejoin.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 <errno.h>
#include <debug.h>
#include "os_internal.h"
#include "pthread_internal.h"
/************************************************************
* Definitions
************************************************************/
/************************************************************
* Private Type Declarations
************************************************************/
/************************************************************
* Global Variables
************************************************************/
/************************************************************
* Private Variables
************************************************************/
/************************************************************
* Private Functions
************************************************************/
/************************************************************
* Function: pthread_notifywaiters
*
* Description:
* Notify all other threads waiting in phread join for this
* thread's exit data. This must be done by the child
* at child thread destruction time.
*
************************************************************/
static boolean pthread_notifywaiters(FAR join_t *pjoin)
{
int ntasks_waiting;
int status;
dbg("pjoin=0x%p\n", pjoin);
/* Are any tasks waiting for our exit value? */
status = sem_getvalue(&pjoin->exit_sem, &ntasks_waiting);
if (status == OK && ntasks_waiting < 0)
{
/* Set the data semaphore so that this thread will be
* awakened when all waiting tasks receive the data
*/
(void)sem_init(&pjoin->data_sem, 0, (ntasks_waiting+1));
/* Post the semaphore to restart each thread that is waiting
* on the semaphore
*/
do
{
status = pthread_givesemaphore(&pjoin->exit_sem);
if (status == OK)
{
status = sem_getvalue(&pjoin->exit_sem, &ntasks_waiting);
}
}
while (ntasks_waiting < 0 && status == OK);
/* Now wait for all these restarted tasks to obtain the return
* value.
*/
(void)pthread_takesemaphore(&pjoin->data_sem);
return TRUE;
}
return FALSE;
}
/************************************************************
* Public Functions
************************************************************/
/************************************************************
* Function: pthread_completejoin
*
* Description:
* A thread has been terminated -- either by returning,
* calling pthread_exit(), or through pthread_cancel().
* In any event, we must complete any pending join events.
*
* Parameters:
* exit_value
*
* Returned Value:
* OK unless there is no join information associated with
* the pid. This could happen, for example, if a task
* started with task_create() calls pthread_exit().
*
* Assumptions:
*
************************************************************/
int pthread_completejoin(pid_t pid, FAR void *exit_value)
{
FAR join_t *pjoin;
dbg("process_id=%d exit_value=%p\n", pid, exit_value);
/* First, find thread's structure in the private data set. */
(void)pthread_takesemaphore(&g_join_semaphore);
pjoin = pthread_findjoininfo(pid);
if (!pjoin)
{
(void)pthread_givesemaphore(&g_join_semaphore);
return ERROR;
}
else
{
boolean waiters;
/* Save the return exit value in the thread structure. */
pjoin->terminated = TRUE;
pjoin->exit_value = exit_value;
/* Notify waiters of the availability of the exit value */
waiters = pthread_notifywaiters(pjoin);
/* If there are no waiters and if the thread is marked as detached.
* then discard the join information now. Otherwise, the pthread
* join logic will call pthread_destroyjoin() when all of the threads
* have sampled the exit value.
*/
if (!waiters && pjoin->detached)
{
pthread_destroyjoin(pjoin);
}
/* Giving the following semaphore will allow the waiters
* to call pthread_destroyjoin.
*/
(void)pthread_givesemaphore(&g_join_semaphore);
}
return OK;
}
/************************************************************
* Function: pthread_destroyjoin
*
* Description:
* This is called from pthread_completejoin if the join
* info was detached or from pthread_join when the last
* waiting thread has received the thread exit info.
*
* Or it may never be called if the join info was never
* detached or if no thread ever calls pthread_join. In
* case, there is a memory leak!
*
* Assumptions:
* The caller holds g_join_semaphore
*
************************************************************/
void pthread_destroyjoin(FAR join_t *pjoin)
{
dbg("pjoin=0x%p\n", pjoin);
/* Remove the join info from the set of joins */
(void)pthread_removejoininfo((pid_t)pjoin->thread);
/* Destroy its semaphores */
(void)sem_destroy(&pjoin->data_sem);
(void)sem_destroy(&pjoin->exit_sem);
/* And deallocate the pjoin structure */
sched_free(pjoin);
}
