Commit | Line | Data |
---|---|---|
6b2a29ce JB |
1 | #include <unistd.h> |
2 | #include <stdio.h> | |
3 | #include <semaphore.h> | |
4 | ||
5 | static int db = 42; | |
6 | static int NbL = 0; | |
7 | sem_t mutex; | |
8 | sem_t redact; | |
9 | ||
10 | static void *lecteur(void *arg) | |
11 | { | |
12 | while (1) { | |
13 | sem_wait(&mutex); | |
14 | if (NbL == 0) | |
15 | sem_wait(&redact); | |
16 | NbL++; | |
17 | sem_post(&mutex); | |
18 | // lecture de la base | |
19 | sleep(1); | |
20 | printf("lecteur bd=%d\n", db); | |
21 | // fin de l’accès à la base | |
22 | sem_wait(&mutex); | |
23 | NbL--; | |
24 | if (NbL == 0) | |
25 | sem_post(&redact); | |
26 | sem_post(&mutex); | |
27 | } | |
28 | } | |
29 | ||
30 | static void *redacteur(void *arg) | |
31 | { | |
32 | while (1) { | |
33 | sem_wait(&redact); | |
34 | // modifier les données de la base | |
35 | db++; | |
36 | printf("redacteur bd=%d\n", db); | |
37 | sleep(2); | |
38 | sem_post(&redact); | |
39 | } | |
40 | } | |
41 | ||
42 | int main() | |
43 | { | |
44 | ||
45 | } |