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Diffstat (limited to 'nuttx/sched/pthread_completejoin.c')
| -rw-r--r-- | nuttx/sched/pthread_completejoin.c | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/nuttx/sched/pthread_completejoin.c b/nuttx/sched/pthread_completejoin.c new file mode 100644 index 000000000..7c5191034 --- /dev/null +++ b/nuttx/sched/pthread_completejoin.c @@ -0,0 +1,231 @@ +/************************************************************************ + * sched/pthread_completejoin.c + * + * Copyright (C) 2007, 2009, 2011 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <gnutt@nuttx.org> + * + * 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 NuttX 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 <nuttx/config.h> + +#include <sys/types.h> +#include <stdbool.h> +#include <pthread.h> +#include <errno.h> +#include <debug.h> + +#include "os_internal.h" +#include "pthread_internal.h" + +/************************************************************************ + * Pre-processor Definitions + ************************************************************************/ + +/************************************************************************ + * Private Type Declarations + ************************************************************************/ + +/************************************************************************ + * Global Variables + ************************************************************************/ + +/************************************************************************ + * Private Variables + ************************************************************************/ + +/************************************************************************ + * Private Functions + ************************************************************************/ + +/************************************************************************ + * Name: 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 bool pthread_notifywaiters(FAR join_t *pjoin) +{ + int ntasks_waiting; + int status; + + svdbg("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 + ************************************************************************/ + +/************************************************************************ + * Name: 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; + + svdbg("pid=%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) + { + sdbg("Could not find join info, pid=%d\n", pid); + (void)pthread_givesemaphore(&g_join_semaphore); + return ERROR; + } + else + { + bool 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; +} + +/************************************************************************ + * Name: 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) +{ + sdbg("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); +} + |