Newer
Older
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
#include <pthread.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#define NB_THREADS 2
#define MAX_INCREMENT 10000
int lock;
int counter;
void init_lock(int *lock_ptr) { __sync_val_compare_and_swap(lock_ptr, 0, 0); }
void acquire_lock(int *lock_ptr) {
__sync_val_compare_and_swap(lock_ptr, *lock_ptr, 1);
}
void release_lock(int *lock_ptr) {
__sync_val_compare_and_swap(lock_ptr, *lock_ptr, 0);
}
void *routine(void *arg) {
int *counter = (int *)arg;
acquire_lock(&lock);
for (int i = 0; i < MAX_INCREMENT; i++) {
(*counter)++;
}
release_lock(&lock);
return NULL;
}
int main(void) {
pthread_t threads[NB_THREADS];
init_lock(&lock);
for (int i = 0; i < NB_THREADS; i++) {
if (pthread_create(&threads[i], NULL, routine, &counter) == -1) {
perror("pthread_create");
}
}
for (int i = 0; i < NB_THREADS; i++) {
if (pthread_join(threads[i], NULL)) {
perror("pthread_join");
}
}
fprintf(stdout, "Value of counter = %d\n", counter);
return EXIT_SUCCESS;
}