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nuttx-bb/nuttx/examples/ostest/cond.c

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/***********************************************************************
* cond.c
*
* Copyright (C) 2007, 2008 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.
*
***********************************************************************/
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
#include "ostest.h"
#ifndef NULL
# define NULL (void*)0
#endif
static volatile enum { RUNNING, MUTEX_WAIT, COND_WAIT} waiter_state;
static pthread_mutex_t mutex;
static pthread_cond_t cond;
static volatile int data_available = 0;
static int waiter_nloops = 0;
static int waiter_waits = 0;
static int waiter_nerrors = 0;
static int signaler_nloops = 0;
static int signaler_already = 0;
static int signaler_state = 0;
static int signaler_nerrors = 0;
static void *thread_waiter(void *parameter)
{
int status;
printf("waiter_thread: Started\n");
for(;;)
{
/* Take the mutex */
waiter_state = MUTEX_WAIT;
status = pthread_mutex_lock(&mutex);
waiter_state = RUNNING;
if (status != 0)
{
printf("waiter_thread: ERROR pthread_mutex_lock failed, status=%d\n", status);
waiter_nerrors++;
}
/* Check if data is available -- if data is not available then
* wait for it
*/
if (!data_available)
{
/* We are higher priority than the signaler thread so the
* only time that the signaler thread will have a chance to run is when
* we are waiting for the condition variable. In this case, pthread_cond_wait
* will automatically release the mutex for the signaler (then re-acquire
* the mutex before returning.
*/
waiter_state = COND_WAIT;
status = pthread_cond_wait(&cond, &mutex);
waiter_state = RUNNING;
if (status != 0)
{
printf("waiter_thread: ERROR pthread_cond_wait failed, status=%d\n", status);
waiter_nerrors++;
}
waiter_waits++;
}
/* Now data should be available */
if (!data_available)
{
printf("waiter_thread: ERROR data not available after wait\n");
waiter_nerrors++;
}
/* Clear data available */
data_available = 0;
/* Release the mutex */
status = pthread_mutex_unlock(&mutex);
if (status != 0)
{
printf("waiter_thread: ERROR waiter: pthread_mutex_unlock failed, status=%d\n", status);
waiter_nerrors++;
}
waiter_nloops++;
}
return NULL;
}
static void *thread_signaler(void *parameter)
{
int status;
int i;
printf("thread_signaler: Started\n");
for (i = 0; i < 32; i++)
{
/* Take the mutex. The waiter is higher priority and should
* run until it waits for the condition. So, at this point
* signaler should be waiting for the condition.
*/
status = pthread_mutex_lock(&mutex);
if (status != 0)
{
printf("thread_signaler: ERROR pthread_mutex_lock failed, status=%d\n", status);
signaler_nerrors++;
}
/* Verify the state */
if (waiter_state != COND_WAIT)
{
printf("thread_signaler: ERROR waiter state = %d != COND_WAITING\n", waiter_state);
signaler_state++;
}
if (data_available)
{
printf("thread_signaler: ERROR data already available, waiter_state=%d\n", waiter_state);
signaler_already++;
}
/* Set data available and signal the waiter */
data_available = 1;
status = pthread_cond_signal(&cond);
if (status != 0)
{
printf("thread_signaler: ERROR pthread_cond_signal failed, status=%d\n", status);
signaler_nerrors++;
}
/* Release the mutex */
status = pthread_mutex_unlock(&mutex);
if (status != 0)
{
printf("thread_signaler: ERROR pthread_mutex_unlock failed, status=%d\n", status);
signaler_nerrors++;
}
signaler_nloops++;
}
printf("thread_signaler: Terminating\n");
pthread_exit(NULL);
return NULL; /* Non-reachable -- needed for some compilers */
}
void cond_test(void)
{
pthread_t waiter;
pthread_t signaler;
pthread_attr_t attr;
#ifdef SDCC
pthread_addr_t result;
#endif
struct sched_param sparam;
int prio_min;
int prio_max;
int prio_mid;
int status;
/* Initialize the mutex */
printf("cond_test: Initializing mutex\n");
status = pthread_mutex_init(&mutex, NULL);
if (status != 0)
{
printf("cond_test: ERROR pthread_mutex_init failed, status=%d\n", status);
}
/* Initialize the condition variable */
printf("cond_test: Initializing cond\n");
status = pthread_cond_init(&cond, NULL);
if (status != 0)
{
printf("cond_test: ERROR pthread_condinit failed, status=%d\n", status);
}
/* Start the waiter thread at higher priority */
printf("cond_test: Starting waiter\n");
status = pthread_attr_init(&attr);
if (status != 0)
{
printf("cond_test: pthread_attr_init failed, status=%d\n", 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;
status = pthread_attr_setschedparam(&attr,&sparam);
if (status != OK)
{
printf("cond_test: pthread_attr_setschedparam failed, status=%d\n", status);
}
else
{
printf("cond_test: Set thread 1 priority to %d\n", sparam.sched_priority);
}
status = pthread_create(&waiter, &attr, thread_waiter, NULL);
if (status != 0)
{
printf("cond_test: pthread_create failed, status=%d\n", status);
}
printf("cond_test: Starting signaler\n");
status = pthread_attr_init(&attr);
if (status != 0)
{
printf("cond_test: pthread_attr_init failed, status=%d\n", status);
}
sparam.sched_priority = (prio_min + prio_mid) / 2;
status = pthread_attr_setschedparam(&attr,&sparam);
if (status != OK)
{
printf("cond_test: pthread_attr_setschedparam failed, status=%d\n", status);
}
else
{
printf("cond_test: Set thread 2 priority to %d\n", sparam.sched_priority);
}
status = pthread_create(&signaler, &attr, thread_signaler, NULL);
if (status != 0)
{
printf("cond_test: pthread_create failed, status=%d\n", status);
}
/* Wait for the threads to stop */
#ifdef SDCC
pthread_join(signaler, &result);
#else
pthread_join(signaler, NULL);
#endif
printf("cond_test: signaler terminated, now cancel the waiter\n");
pthread_detach(waiter);
pthread_cancel(waiter);
printf("cond_test: \tWaiter\tSignaler\n");
printf("cond_test: Loops\t%d\t%d\n", waiter_nloops, signaler_nloops);
printf("cond_test: Errors\t%d\t%d\n", waiter_nerrors, signaler_nerrors);
printf("cond_test:\n");
printf("cond_test: %d times, waiter did not have to wait for data\n", waiter_nloops - waiter_waits);
printf("cond_test: %d times, data was already available when the signaler run\n", signaler_already);
printf("cond_test: %d times, the waiter was in an unexpected state when the signaler ran\n", signaler_state);
}
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