bart | cb48672 | 2014-05-18 19:32:26 +0000 | [diff] [blame] | 1 | /** |
| 2 | * @file annotate_sem.c |
| 3 | * |
| 4 | * @brief Multithreaded test program that triggers various access patterns |
| 5 | * without triggering any race conditions using a binary semaphore |
| 6 | * implemented via busy-waiting. Annotations are used to tell DRD |
| 7 | * which higher-level semaphore operations are being performed. |
| 8 | */ |
| 9 | |
| 10 | #include <assert.h> |
| 11 | #include <pthread.h> |
| 12 | #include <stdio.h> |
| 13 | #include "../../config.h" |
| 14 | #include "../../drd/drd.h" |
| 15 | |
| 16 | #define THREADS 10 |
| 17 | #define ITERATIONS 1000 |
| 18 | |
| 19 | typedef struct { |
| 20 | volatile unsigned value; |
| 21 | } sem_t; |
| 22 | |
| 23 | static sem_t s_sem; |
| 24 | static unsigned int s_counter; |
| 25 | |
| 26 | static void sem_init(sem_t *p, unsigned value) |
| 27 | { |
| 28 | DRD_IGNORE_VAR(*p); |
| 29 | p->value = value; |
| 30 | ANNOTATE_SEM_INIT_PRE(p, value); |
| 31 | } |
| 32 | |
| 33 | static void sem_destroy(sem_t *p) |
| 34 | { |
| 35 | ANNOTATE_SEM_DESTROY_POST(p); |
| 36 | } |
| 37 | |
| 38 | static void sem_wait(sem_t *p) |
| 39 | { |
| 40 | unsigned old, new; |
| 41 | struct timespec ts = { 0, 0 }; |
| 42 | |
| 43 | ANNOTATE_SEM_WAIT_PRE(p); |
| 44 | do { |
| 45 | old = p->value; |
| 46 | new = old - 1; |
| 47 | nanosleep(&ts, NULL); |
| 48 | ts.tv_nsec = 1; |
| 49 | } while (!old || !__sync_bool_compare_and_swap(&p->value, old, new)); |
| 50 | ANNOTATE_SEM_WAIT_POST(p); |
| 51 | } |
| 52 | |
| 53 | static void sem_post(sem_t *p) |
| 54 | { |
| 55 | ANNOTATE_SEM_POST_PRE(p); |
| 56 | __sync_fetch_and_add(&p->value, 1); |
| 57 | } |
| 58 | |
| 59 | static void *thread_func(void *arg) |
| 60 | { |
| 61 | unsigned int i; |
| 62 | unsigned int sum = 0; |
| 63 | |
| 64 | for (i = 0; i < ITERATIONS; i++) { |
| 65 | sem_wait(&s_sem); |
| 66 | sum += s_counter; |
| 67 | sem_post(&s_sem); |
| 68 | |
| 69 | sem_wait(&s_sem); |
| 70 | s_counter++; |
| 71 | sem_post(&s_sem); |
| 72 | } |
| 73 | |
| 74 | return 0; |
| 75 | } |
| 76 | |
| 77 | int main(int argc, const char *argv[]) |
| 78 | { |
| 79 | pthread_t tid[THREADS]; |
| 80 | unsigned int i; |
| 81 | |
| 82 | sem_init(&s_sem, 1); |
| 83 | for (i = 0; i < THREADS; i++) |
| 84 | pthread_create(&tid[i], 0, thread_func, 0); |
| 85 | |
| 86 | for (i = 0; i < THREADS; i++) |
| 87 | pthread_join(tid[i], 0); |
| 88 | |
| 89 | assert(s_counter == THREADS * ITERATIONS); |
| 90 | assert(s_sem.value == 1); |
| 91 | sem_destroy(&s_sem); |
| 92 | |
| 93 | fprintf(stderr, "Finished.\n"); |
| 94 | |
| 95 | return 0; |
| 96 | } |