/***********************************************************************
* sem.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.
*
***********************************************************************/
#include <sys/types.h>
#include <stdio.h>
#include <pthread.h>
#include <semaphore.h>
#include <sched.h>
#include "ostest.h"
#ifndef NULL
# define NULL (void*)0
#endif
static sem_t sem;
static void *waiter_func(void *parameter)
{
int id = (int)parameter;
int status;
int value;
printf("%s: Thread %d Started\n", __FUNCTION__, id);
/* Take the semaphore */
status = sem_getvalue(&sem, &value);
if (status < 0)
{
printf("%s: ERROR thread %d could not get semaphore value\n", __FUNCTION__, id);
}
else
{
printf("%s: Thread %d initial semaphore value = %d\n", __FUNCTION__, id, value);
}
printf("%s: Thread %d aiting on semaphore\n", __FUNCTION__, id);
status = sem_wait(&sem);
if (status != 0)
{
printf("%s: ERROR thread %d sem_wait failed\n", __FUNCTION__, id);
}
printf("%s: Thread %d awakened\n", __FUNCTION__, id);
status = sem_getvalue(&sem, &value);
if (status < 0)
{
printf("%s: ERROR thread %d could not get semaphore value\n", __FUNCTION__, id);
}
else
{
printf("%s: Thread %d new semaphore value = %d\n", __FUNCTION__, id, value);
}
printf("%s: Thread %d done\n", __FUNCTION__, id);
return NULL;
}
static void *poster_func(void *parameter)
{
int id = (int)parameter;
int status;
int value;
printf("%s: Thread %d started\n", __FUNCTION__, id);
/* Take the semaphore */
do
{
status = sem_getvalue(&sem, &value);
if (status < 0)
{
printf("%s: ERROR thread %d could not get semaphore value\n", __FUNCTION__, id);
}
else
{
printf("%s: Thread %d semaphore value = %d\n", __FUNCTION__, id, value);
}
if (value < 0)
{
printf("%s: Thread %d posting semaphore\n", __FUNCTION__, id);
status = sem_post(&sem);
if (status != 0)
{
printf("%s: ERROR thread %d sem_wait failed\n", __FUNCTION__, id);
}
pthread_yield();
status = sem_getvalue(&sem, &value);
if (status < 0)
{
printf("%s: ERROR thread %d could not get semaphore value\n", __FUNCTION__, id);
}
else
{
printf("%s: Thread %d new semaphore value = %d\n", __FUNCTION__, id, value);
}
}
}
while (value < 0);
printf("%s: Thread %d done\n", __FUNCTION__, id);
return NULL;
}
void sem_test(void)
{
pthread_t waiter_thread1;
pthread_t waiter_thread2;
pthread_t poster_thread;
struct sched_param sparam;
int prio_min;
int prio_max;
int prio_mid;
pthread_attr_t attr;
int status;
printf("%s: Initializing semaphore to 0\n", __FUNCTION__);
sem_init(&sem, 0, 0);
/* Start two waiter thread instances */
printf("%s: Starting waiter thread 1\n", __FUNCTION__);
status = pthread_attr_init(&attr);
if (status != OK)
{
printf("%s: pthread_attr_init failed, status=%d\n", __FUNCTION__, status);
}
prio_min = sched_get_priority_min(SCHED_FIFO);
prio_max = sched_get_priority_max(SCHED_FIFO);
prio_mid = (prio_min + prio_max) / 2;
sparam.sched_priority = (prio_mid + prio_max) / 2;
status = pthread_attr_setschedparam(&attr,&sparam);
if (status != OK)
{
printf("%s: pthread_attr_setschedparam failed, status=%d\n", __FUNCTION__, status);
}
else
{
printf("%s: Set thread 1 priority to %d\n", __FUNCTION__, sparam.sched_priority);
}
status = pthread_create(&waiter_thread1, &attr, waiter_func, (void*)1);
if (status != 0)
{
printf("%s: Error in thread 1 creation, status=%d\n", __FUNCTION__, status);
}
printf("%s: Starting waiter thread 2\n", __FUNCTION__);
status = pthread_attr_init(&attr);
if (status != 0)
{
printf("%s: pthread_attr_init failed, status=%d\n", __FUNCTION__, status);
}
sparam.sched_priority = prio_mid;
status = pthread_attr_setschedparam(&attr,&sparam);
if (status != OK)
{
printf("%s: pthread_attr_setschedparam failed, status=%d\n", __FUNCTION__, status);
}
else
{
printf("%s: Set thread 2 priority to %d\n", __FUNCTION__, sparam.sched_priority);
}
status = pthread_create(&waiter_thread2, &attr, waiter_func, (void*)2);
if (status != 0)
{
printf("%s: Error in thread 2 creation, status=%d\n", __FUNCTION__, status);
}
printf("%s: Starting poster thread 3\n", __FUNCTION__);
status = pthread_attr_init(&attr);
if (status != 0)
{
printf("%s: pthread_attr_init failed, status=%d\n", __FUNCTION__, status);
}
sparam.sched_priority = (prio_min + prio_mid) / 2;
status = pthread_attr_setschedparam(&attr,&sparam);
if (status != OK)
{
printf("%s: pthread_attr_setschedparam failed, status=%d\n", __FUNCTION__, status);
}
else
{
printf("%s: Set thread 3 priority to %d\n", __FUNCTION__, sparam.sched_priority);
}
status = pthread_create(&poster_thread, &attr, poster_func, (void*)3);
if (status != 0)
{
printf("%s: Error in thread 3 creation, status=%d\n", __FUNCTION__, status);
}
pthread_join(waiter_thread1, NULL);
pthread_join(waiter_thread2, NULL);
pthread_join(poster_thread, NULL);
}
