44 lines
1.0 KiB
C
44 lines
1.0 KiB
C
|
#include <stdio.h>
|
||
|
|
#include <pthread.h>
|
||
|
|
#include <semaphore.h>
|
||
|
|
#include <fcntl.h>
|
||
|
|
|
||
|
|
int counter = 0; // shared resource
|
||
|
|
sem_t *semaphore; // semaphore declaration
|
||
|
|
|
||
|
|
void* increment(void* arg) {
|
||
|
|
for (int i = 0; i < 100000; i++) {
|
||
|
|
sem_wait(semaphore); // lock
|
||
|
|
counter++; // critical section
|
||
|
|
sem_post(semaphore); // unlock
|
||
|
|
}
|
||
|
|
return NULL;
|
||
|
|
}
|
||
|
|
|
||
|
|
int main() {
|
||
|
|
pthread_t t1, t2, t3, t4;
|
||
|
|
|
||
|
|
// MacOS specific semaphore definition.
|
||
|
|
semaphore = sem_open("/mysem", O_CREAT, 0644, 1);
|
||
|
|
if (semaphore == SEM_FAILED) {
|
||
|
|
perror("sem_open failed");
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
pthread_create(&t1, NULL, increment, NULL);
|
||
|
|
pthread_create(&t2, NULL, increment, NULL);
|
||
|
|
pthread_create(&t3, NULL, increment, NULL);
|
||
|
|
pthread_create(&t4, NULL, increment, NULL);
|
||
|
|
pthread_join(t1, NULL);
|
||
|
|
pthread_join(t2, NULL);
|
||
|
|
pthread_join(t3, NULL);
|
||
|
|
pthread_join(t4, NULL);
|
||
|
|
|
||
|
|
sem_close(semaphore);
|
||
|
|
sem_unlink("/mysem");
|
||
|
|
|
||
|
|
printf("Final Counter Value (with semaphores): %d\n", counter);
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|