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/* Example code to demonstrate behavior of multi-core, threaded application
*
* Written by: Mike Anderson
* The PTR Group, Inc.
* mike@theptrgroup.com
*
* License: GPLv2
*
*/
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <signal.h>
#ifndef TRUE
#define TRUE 1
#define FALSE 0
#endif
pthread_mutex_t mutex_fix; /* protect the critical region */
pthread_t looperThId;
pthread_t conflictThId;
volatile int value1;
volatile int value2;
volatile int counter = 0;
volatile int bTimeToExit = FALSE;
int bUseMutex = FALSE; /* The "s" option */
/* Conflict thread */
void *conflictTh(void *arg)
{
int same;
unsigned long loopCount = 0;
struct timespec sleep_time = {
.tv_sec = 0,
.tv_nsec = 7 * 1000 * 1000,
};
while (!bTimeToExit) {
if (bUseMutex) {
// Acquire mutex using pthread_mutex_lock(3p)
}
same = (value1 == value2);
if (!same)
printf("\nHey! value1 = %d, value2 = %d\n", value1,
value2);
loopCount++;
if ((loopCount % 1000) == 0) {
printf("\nConflict thread Counter = %lu \n", loopCount);
fflush(stdout);
counter = 0;
}
if (bUseMutex) {
// Release mutex using pthread_mutex_unlock(3p);
}
/* Sleep for 7ms */
nanosleep(&sleep_time, NULL);
}
return NULL;
}
/* Main loop thread */
void *looperTh(void *arg)
{
int counterTemp;
struct timespec sleep_time = {
.tv_sec = 0,
.tv_nsec = 13 * 1000 * 1000,
};
/* give the conflict thread a chance to start */
sleep(1);
while (!bTimeToExit) {
if (bUseMutex) {
// Acquire mutex using pthread_mutex_lock(3p)
}
value1 = counter;
value2 = counter;
counterTemp = counter++;
if (bUseMutex) {
// Release mutex using pthread_mutex_unlock(3p);
}
if ((counterTemp % 1000000) == 0) {
printf("Main loop counter = %d \r", counterTemp);
fflush(stdout);
/* Sleep for 13ms */
nanosleep(&sleep_time, NULL);
}
}
return NULL;
}
/* Ctrl-C Signal Handler */
void gotCtrlC(int sig)
{
printf("\nGot Ctrl-C! Shutting down...\n");
bTimeToExit = TRUE;
}
void print_usage(char *program)
{
fprintf(stderr, "Usage: %s [options]\n%s", program,
"-h This help\n"
"-s (Use mutex to enforce synchronization)\n");
}
void parse_options(int argc, char *argv[])
{
int c;
opterr = 0; /* get opt stuff */
while ((c = getopt(argc, argv, "hs")) != -1) {
switch (c) {
case 's':
bUseMutex = TRUE;
break;
case '?':
if (isprint(optopt))
fprintf(stderr, "Unknown option '-%c'.\n",
optopt);
else
fprintf(stderr,
"Unknown option character '\\x%x'.\n",
optopt);
/*FALLTHRU*/
case 'h':
default:
print_usage(argv[0]);
exit(EXIT_SUCCESS);
}
}
printf("Options in effect:\n");
if (bUseMutex)
printf(" Thread synchronization using mutexes is in effect \n");
else
printf(" Mutex-based thread synchronization is off \n");
}
int main(int argc, char *argv[])
{
int res;
/* Parse the command line arguments */
parse_options(argc, argv);
printf("\nUse ^C to exit application...\n");
/* Set up the ^C signal handler so we can shut down cleanly */
(void)signal(SIGINT, gotCtrlC);
/* Go ahead and initialize the mutex in case we need it */
// Initialize the mutex using pthread_mutex_init(3p)
if (res != 0) {
perror("Mutex initialization failed");
exit(EXIT_FAILURE);
}
/* Create the main loop thread */
res = pthread_create(&looperThId, NULL, looperTh, NULL);
if (res != 0) {
perror("Main loop thread creation failed");
exit(EXIT_FAILURE);
}
/* Create the conflict thread */
res = pthread_create(&conflictThId, NULL, conflictTh, NULL);
if (res != 0) {
perror("Conflict thread creation failed");
exit(EXIT_FAILURE);
}
printf("\nMain is waiting for threads to finish...\n");
res = pthread_join(conflictThId, NULL);
if (res != 0) {
perror("Thread join with conflictTh() failed");
exit(EXIT_FAILURE);
}
res = pthread_join(looperThId, NULL);
if (res != 0) {
perror("Thread join with looperTh() failed");
exit(EXIT_FAILURE);
}
printf("Threads joined -- exiting main\n");
// Destroy the mutex using pthread_mutex_destroy(3p);
return EXIT_SUCCESS;
}
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