Difference between revisions of "Python"
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| − | * [[multiprocess.Lock replacement using SYSV]] |
+ | * [[multiprocess.Lock replacement using SYSV]] |
| − | <nowiki> |
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| − | #include <sys/types.h> |
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| − | #include <sys/ipc.h> |
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| − | #include <sys/sem.h> |
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| − | #include <stdlib.h> |
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| − | #include <stdio.h> |
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| − | |||
| − | int acquire(int semid){ |
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| − | struct sembuf sops[2]; |
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| − | |||
| − | sops[0].sem_num = 0; |
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| − | sops[0].sem_op = -1; |
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| − | sops[0].sem_flg = SEM_UNDO; |
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| − | |||
| − | if (semop(semid, sops, 1) == -1) { |
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| − | perror("acquire"); |
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| − | exit(1); |
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| − | } |
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| − | } |
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| − | |||
| − | int release(int semid){ |
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| − | struct sembuf sops[2]; |
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| − | |||
| − | sops[0].sem_num = 0; /* Operate on semaphore 0 */ |
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| − | sops[0].sem_op = 1; /* Wait for value to equal 0 */ |
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| − | sops[0].sem_flg = SEM_UNDO; |
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| − | |||
| − | if (semop(semid, sops, 1) == -1) { |
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| − | perror("release"); |
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| − | exit(1); |
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| − | } |
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| − | } |
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| − | |||
| − | void p(int semid, int i){ |
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| − | int j; |
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| − | |||
| − | acquire(semid); |
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| − | for(j=0; j<10; j++){ |
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| − | printf("%i\n",i); |
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| − | sleep(1); |
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| − | } |
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| − | release(semid); |
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| − | } |
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| − | |||
| − | int main(int argc, char **argv){ |
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| − | key_t key; |
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| − | int semid; |
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| − | int wait_status; |
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| − | union semun { |
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| − | int val; /* Value for SETVAL */ |
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| − | struct semid_ds *buf; /* Buffer for IPC_STAT, IPC_SET */ |
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| − | unsigned short *array; /* Array for GETALL, SETALL */ |
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| − | struct seminfo *__buf; /* Buffer for IPC_INFO |
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| − | (Linux-specific) */ |
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| − | }; |
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| − | int v; |
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| − | union semun su; |
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| − | |||
| − | //key=ftok("l-.l", 0x55); |
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| − | //printf("key=%i\n",key); |
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| − | key=IPC_PRIVATE; |
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| − | semid=semget(key, 1, IPC_CREAT|0666); |
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| − | printf("semid=%i\n",semid); |
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| − | su.val=1; |
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| − | v=semctl(semid, 0, SETVAL, su); |
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| − | if(v==-1){ |
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| − | perror("semctl0"); |
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| − | exit(1); |
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| − | } |
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| − | |||
| − | v=semctl(semid, 0, GETVAL); |
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| − | if(v==-1){ |
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| − | perror("semctl1"); |
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| − | exit(1); |
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| − | } |
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| − | printf("val after set: v=%i\n", v); |
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| − | |||
| − | if(fork()){ |
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| − | p(semid, 1); |
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| − | wait(&wait_status); |
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| − | } else { |
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| − | p(semid, 2); |
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| − | } |
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| − | |||
| − | } |
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| − | |||
| − | </nowiki> |
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