相同机器进程间通信-信号量

来源：互联网发布：java运行时异常编辑：程序博客网时间：2024/06/08 16:37

高效的进程间通信
共享内存 — 实时性最好

信号量

#include "io.h"#include <sys/sem.h>int init(int semnums, int value){    key_t key = ftok("/etc", 100);    int semid = -1;    semid = semget(key, semnums, 0600 | IPC_CREAT | IPC_EXCL);    if (semid < 0) {        /*已经存在*/        semid = semget(key, semnums, 0600);        if (semid < 0) exit(0);        return semid;    }    union semun {        int val;        struct semid_ds* buf;        unsigned short * array;    } va;    va.array = (unsigned short *)calloc(semnums, sizeof(unsigned short));    int i = 0;    for (i  = 0; i < semnums; i++) {        va.array[i] = value;    }    semctl(semid, semnums, SETALL, va);    free(va.array);    va.array = NULL;    return semid;}void D(int semid){    semctl(semid, 0, IPC_RMID);}int P(int semid, int nums, int val)/*-,dierge参数是第几个*/{    struct sembuf buf[1] = {        {nums, -val, SEM_UNDO}    };    if (semop(semid, buf, 1) < 0) {        fprintf(stderr, "semop + error:%s\n", strerror(errno));        return -1;    }    return 0;}int V(int semid, int nums, int val)/*+*/{    struct sembuf buf[1] = {        {0, +val, SEM_UNDO}    };    if (semop(semid, buf, sizeof(buf) / sizeof(struct(sembuf))) < 0) {        fprintf(stderr, "semop - error:%s\n", strerror(errno));        return -1;    }    return 0;}void display(int semid, int nums){    union semun {        int val;        struct semid_ds* buf;        unsigned short* array;    } buffer;    buffer.array = (unsigned short *) calloc (nums, sizeof(unsigned short));    semctl(semid, nums, GETALL, buffer);    int i = 0;    for (i = 0; i < nums; i++) {        printf("%d ", buffer.array[i]);    }    printf("\n");    free(buffer.array);    buffer.array = NULL;    semctl(semid, nums, GETALL, buffer);}int main(int argc, char const *argv[]){    int sid = init(10, 1);    display(sid, 10);    P(sid, 4, 1);    display(sid, 10);    P(sid, 4, 1);    D(sid);    return 0;}

阅读全文

0 0