/****************************************************************************
* examples/ostest/prioinherit.c
*
* Copyright (C) 2009 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 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 <sys/types.h>
#include <stdio.h>
#include <unistd.h>
#include <semaphore.h>
#include <pthread.h>
#include "ostest.h"
#if defined(CONFIG_PRIORITY_INHERITANCE) && !defined(CONFIG_DISABLE_SIGNALS) && !defined(CONFIG_DISABLE_PTHREAD)
/****************************************************************************
* Definitions
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
static sem_t g_sem;
static volatile int g_middle = 0;
/****************************************************************************
* Name: highpri_thread
****************************************************************************/
static void *highpri_thread(void *parameter)
{
int ret;
printf("highpri_thread: Thread %d started\n");
ret = sem_wait(&g_sem);
if (ret != 0)
{
printf("highpri_thread: sem_take failed: %d\n", ret);
}
else if (g_middle == 1)
{
printf("highpri_thread: Success midpri_thread is still running!\n");
}
else
{
printf("highpri_thread: ERROR -- midpri_thread has already exited!\n");
}
sem_post(&g_sem);
printf("medpri_thread: Okay... I'm done!\n");
fflush(stdout);
return NULL;
}
/****************************************************************************
* Name: medpri_thread
****************************************************************************/
static void *medpri_thread(void *parameter)
{
volatile long i;
printf("medpri_thread: Thread %d started ... I won't let go of the CPU!\n");
g_middle = 1;
for (i = 0; i < 0x7ffffff; i++);
printf("medpri_thread: Okay... I'm done!\n");
fflush(stdout);
return NULL;
}
/****************************************************************************
* Name: lowpri_thread
****************************************************************************/
static void *lowpri_thread(void *parameter)
{
void *retval = (void*)-1;
int ret;
printf("lowpri_thread: Thread %d started\n");
ret = sem_wait(&g_sem);
if (ret != 0)
{
printf("lowpri_thread: sem_take failed: %d\n", ret);
}
else
{
/* Hang on to the thread until the middle priority thread runs */
while (g_middle == 0)
{
printf("lowpri_thread: Waiting for the midle pri task to run\n");
printf("lowpri_thread: I still have the semaphore\n");
sleep(1);
}
/* The middle priority task is running, let go of the semaphore */
if (g_middle == 1)
{
/* Good.. the middle priority task is still running but we got priority! */
retval = NULL;
}
else
{
printf("lowpri_thread: ERROR the middle priority task has already exitted!\n");
}
}
printf("lowpri_thread: Letting go of the semaphore\n");
sem_post(&g_sem);
printf("lowpri_thread: Okay... I'm done!\n");
fflush(stdout);
return retval;
}
#endif /* CONFIG_PRIORITY_INHERITANCE && !CONFIG_DISABLE_SIGNALS && !CONFIG_DISABLE_PTHREAD */
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: priority_inheritance
****************************************************************************/
void priority_inheritance(void)
{
#if defined(CONFIG_PRIORITY_INHERITANCE) && !defined(CONFIG_DISABLE_SIGNALS) && !defined(CONFIG_DISABLE_PTHREAD)
pthread_t lowpri;
pthread_t medpri;
pthread_t highpri;
pthread_addr_t result;
pthread_attr_t attr;
struct sched_param sparam;
int my_pri;
int max_pri;
int mid_pri;
int min_pri;
int status;
printf("priority_inheritance: Started\n");
status = sched_getparam (getpid(), &sparam);
if (status != 0)
{
printf("priority_inheritance: sched_getparam failed\n");
sparam.sched_priority = PTHREAD_DEFAULT_PRIORITY;
}
my_pri = sparam.sched_priority;
max_pri = sched_get_priority_max(SCHED_FIFO);
min_pri = sched_get_priority_min(SCHED_FIFO);
mid_pri = my_pri - 1;
sem_init(&g_sem, 0, 1);
/* Start the low priority task */
printf("priority_inheritance: Starting lowpri_thread at %d\n", min_pri);
status = pthread_attr_init(&attr);
if (status != 0)
{
printf("priority_inheritance: pthread_attr_init failed, status=%d\n", status);
}
sparam.sched_priority = min_pri;
status = pthread_attr_setschedparam(&attr,& sparam);
if (status != OK)
{
printf("priority_inheritance: pthread_attr_setschedparam failed, status=%d\n", status);
}
else
{
printf("priority_inheritance: Set lowpri_thread priority to %d\n", sparam.sched_priority);
}
status = pthread_create(&lowpri, &attr, lowpri_thread, NULL);
if (status != 0)
{
printf("priority_inheritance: pthread_create failed, status=%d\n", status);
}
printf("priority_inheritance: Waiting...\n");
sleep(5);
/* Start the medium priority task */
printf("priority_inheritance: Starting medpri_thread at %d\n", mid_pri);
status = pthread_attr_init(&attr);
if (status != 0)
{
printf("priority_inheritance: pthread_attr_init failed, status=%d\n", status);
}
sparam.sched_priority = mid_pri;
status = pthread_attr_setschedparam(&attr,& sparam);
if (status != OK)
{
printf("priority_inheritance: pthread_attr_setschedparam failed, status=%d\n", status);
}
else
{
printf("priority_inheritance: Set medpri_thread priority to %d\n", sparam.sched_priority);
}
status = pthread_create(&medpri, &attr, medpri_thread, NULL);
if (status != 0)
{
printf("priority_inheritance: pthread_create failed, status=%d\n", status);
}
/* Start the high priority task */
printf("priority_inheritance: Starting highpri_thread at %d\n", max_pri);
status = pthread_attr_init(&attr);
if (status != 0)
{
printf("priority_inheritance: pthread_attr_init failed, status=%d\n", status);
}
sparam.sched_priority = max_pri;
status = pthread_attr_setschedparam(&attr,& sparam);
if (status != OK)
{
printf("priority_inheritance: pthread_attr_setschedparam failed, status=%d\n", status);
}
else
{
printf("priority_inheritance: Set highpri_thread priority to %d\n", sparam.sched_priority);
}
status = pthread_create(&medpri, &attr, highpri_thread, NULL);
if (status != 0)
{
printf("priority_inheritance: pthread_create failed, status=%d\n", status);
}
/* Wait for all thread instances to complete */
printf("priority_inheritance: Waiting for highpri_thread to complete\n");
(void)pthread_join(highpri, &result);
printf("priority_inheritance: Waiting for medpri_thread to complete\n");
(void)pthread_join(medpri, &result);
printf("priority_inheritance: Waiting for lowpri_thread to complete\n");
(void)pthread_join(lowpri, &result);
printf("priority_inheritance: Finished\n");
sem_destroy(&g_sem);
fflush(stdout);
#endif /* CONFIG_PRIORITY_INHERITANCE && !CONFIG_DISABLE_SIGNALS && !CONFIG_DISABLE_PTHREAD */
}