Difference between revisions of "Python"
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| + | * [[multiprocess.Lock replacement using SYSV]] |
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| − | <nowiki> |
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| + | * [[Converting Gregorian dates to day numbers]] |
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| − | import ctypes |
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| − | import os |
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| − | import sys |
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| − | |||
| − | IPC_CREAT=00001000 |
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| − | # man shm_overview |
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| − | # for f in `find /lib/lib* -type f `; do nm -D $f|grep sem_open && echo found in library: $f; done |
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| − | locksUsed=0 |
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| − | class Lock: |
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| − | def __init__(self): |
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| − | #http://www.dailyfreecode.com/code/create-shared-memory-print-id-shared-2183.aspx |
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| − | global locksUsed |
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| − | self.fname="/tmp/Py-Lock%4i"%locksUsed |
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| − | |||
| − | self.libc = ctypes.cdll.LoadLibrary("/lib/libc.so.6") |
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| − | self.librt = ctypes.cdll.LoadLibrary("/lib/librt.so.1") |
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| − | |||
| − | f=open(self.fname,"w") |
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| − | f.write("0") |
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| − | f.close() |
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| − | self.key=self.libc.ftok(fname, 0x55) |
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| − | print "ftok returned:", self.key |
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| − | r=self.libc.semget(self.key, 1, IPC_CREAT|0666) |
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| − | print "semget returned: ",r |
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| − | |||
| − | si=self.librt.sem_init(self.mem, 1, 1) |
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| − | print "sem_init returned:", si |
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| − | locksUsed+=1 |
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| − | |||
| − | def acquire(self): |
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| − | self.librt.sem_wait(self.sm) |
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| − | |||
| − | def release(self): |
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| − | self.librt.sem_post(self.sm) |
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| − | |||
| − | #class Lock_POSIX: |
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| − | # def __init__(self): |
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| − | # global locksUsed |
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| − | # self.librt = ctypes.cdll.LoadLibrary("/lib/libpthread.so.0") |
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| − | # |
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| − | # try: |
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| − | # self.librt.sem_unlink("/PyLock%4i"%locksUsed) |
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| − | # except: |
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| − | # pass |
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| − | # self.sm=self.librt.sem_open("/PyLock%4i"%locksUsed, os.O_RDWR|os.O_CREAT, 0x1ff, 1) |
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| − | # if sm==0: |
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| − | # print "sem_open returned:", self.sm |
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| − | # sys.exit() |
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| − | # #si=self.librt.sem_init(self.sm, 1, 1) |
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| − | # print "sem_init returned:", si |
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| − | # if self.sm>=0: |
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| − | # locksUsed+=1 |
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| − | # |
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| − | # def acquire(self): |
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| − | # self.librt.sem_wait(self.sm) |
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| − | # |
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| − | # def release(self): |
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| − | # self.librt.sem_post(self.sm) |
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| − | |||
| − | if __name__== "__main__": |
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| − | import time |
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| − | import random |
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| − | from multiprocessing import Process |
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| − | l=Lock() |
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| − | def fight(i): |
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| − | for j in range(10): |
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| − | l.acquire() |
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| − | for k in range(10): |
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| − | print i |
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| − | time.sleep(random.random()/30.) |
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| − | print |
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| − | l.release() |
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| − | |||
| − | Process(target=fight, args=(1,)).start() |
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| − | Process(target=fight, args=(2,)).start() |
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| − | Process(target=fight, args=(3,)).start() |
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| − | Process(target=fight, args=(4,)).start() |
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| − | |||
| − | </nowiki> |
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| − | |||
| − | |||
| − | <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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| − | |||
| − | key=ftok("l-.l", 0x55); |
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| − | printf("key=%i\n",key); |
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| − | semid=semget(key, 1, IPC_CREAT|0666); |
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| − | printf("semid=%i\n",semid); |
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| − | release(semid); |
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| − | printf("after first release"); |
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| − | |||
| − | printf("semid=%i\n", semid); |
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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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