IPC-信号灯

IPC-信号灯之生产者消费者

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有亲缘关系生产者消费者

子进程生成，父进程消费

#include<stdio.h>#include<sys/types.h>#include<sys/ipc.h>#include<sys/sem.h>#include<stdlib.h>union semun{    int val;    struct semid_ds *buf;    unsigned short *array;    struct seminfo *__buf;};int main(void){    int semid = semget(0, 1, 0666|IPC_CREAT);// 0为IPC_PRIVATE表示该信号灯集在父子进程间，1表示信号灯集有1个信号灯    if(-1 == semid)    {        perror("semget");        exit(EXIT_FAILURE);    }    union semun sm;    sm.val = 5;     // sm.val表示某个信号灯的起始资源数量    if(-1 == semctl(semid, 0, SETVAL, sm))  // 将sm写到下标为0的信号灯（semid所标识的信号灯集）中    {        perror("semctl");        exit(EXIT_FAILURE);    }    if(fork() == 0) // 子进程为生产者    {        struct sembuf sop;        sop.sem_num = 0;    // 下标为0的信号灯        sop.sem_op = 1;     // V操作        sop.sem_flg = 0;    // 0代表资源不足则阻塞        while(1)        {            sleep(3);            if(-1 == semop(semid, &sop, 1)) // 1表示sembuf数组（sop）大小为1            {                perror("semop");                exit(EXIT_FAILURE);            }            printf("V  资源数量：%d\n", semctl(semid, 0, GETVAL, sm));        }        return 0;    }    // 消费者    struct sembuf sop;    sop.sem_num = 0;    sop.sem_op = -1;    sop.sem_flg = 0;    while(1)    {        if(-1 == semop(semid, &sop, 1))        {            perror("semop");            exit(EXIT_FAILURE);        }        printf("P  资源数量：%d\n", semctl(semid, 0, GETVAL));        sleep(1);    }    return 0;}

无亲缘关系

问题描述：一个仓库能装下10个产品。仓库装满之后，生产者停止生产，等待仓库非满；仓库空之后，消费者停止消费，等待仓库非空

producer.c

#include<stdio.h>#include<stdlib.h>#include<sys/types.h>#include<sys/sem.h>#include<sys/ipc.h>//生产者消费者之间设置相同且唯一的KEY,以便获取相同的semid，最好用ftok获取，以便保证唯一性#define KEY 1234union semun{    int val;    struct semid_ds *buf;    unsigned short *array;    struct seminfo *__buf;};int createSemSet(int nsems, int semflg){    int semid;    semid = semget(KEY, nsems, semflg);    if(-1 == semid)    {        perror("semget");        exit(EXIT_FAILURE);    }    return semid;}int semctlSetall(int semid){    unsigned short arr[2];    arr[0] = 0;     // 仓库初始库存    arr[1] = 10;    // 仓库剩余空间    union semun sm;    sm.array = arr;    int returnValue = semctl(semid, 0, SETALL, sm);    if(-1 == returnValue)    {        perror("semctl SETALL");        exit(EXIT_FAILURE);    }    return returnValue;}void init2Sembuf(struct sembuf *sops){    sops[0].sem_num = 0;    sops[0].sem_op = 1; // V操作    sops[0].sem_flg = 0;// 资源不足则阻塞    sops[1].sem_num = 1;    sops[1].sem_op = -1;// P操作    sops[1].sem_flg = 0;}int main(void){    int semid;    semid = createSemSet(2, IPC_CREAT|0666);    semctlSetall(semid);    struct sembuf sops[2];    init2Sembuf(sops);    while(1)    {        printf("--productor number is %d, space number is %d\n", semctl(semid, 0, GETVAL), semctl(semid, 1, GETVAL));        sleep(2);        if(-1 == semop(semid, sops, 2))        {            perror("semop");            exit(EXIT_FAILURE);        }        printf("productor number is %d, space number is %d\n", semctl(semid, 0, GETVAL), semctl(semid, 1, GETVAL));    }    return 0;}

customer.c

#include<stdio.h>#include<stdlib.h>#include<sys/types.h>#include<sys/sem.h>#include<sys/ipc.h>#define KEY 1234int createSemSet(int nsems, int semflg){    int semid;    semid = semget(KEY, nsems, semflg);    if(-1 == semid)    {        perror("semget");        exit(EXIT_FAILURE);    }    return semid;}void init2Sembuf(struct sembuf *sops){    sops[0].sem_num = 0;    sops[0].sem_op = -1;    sops[0].sem_flg = 0;    sops[1].sem_num = 1;    sops[1].sem_op = 1;    sops[1].sem_flg = 0;}int main(void){    int semid;    semid = createSemSet(2, IPC_CREAT|0666);    struct sembuf sops[2];    init2Sembuf(sops);    while(1)    {        printf("--productor number is %d, space number is %d\n", semctl(semid, 0, GETVAL), semctl(semid, 1, GETVAL));        sleep(1);        if(-1 == semop(semid, sops, 2))        {            perror("semop");            exit(EXIT_FAILURE);        }        printf("productor number is %d, space number is %d\n", semctl(semid, 0, GETVAL), semctl(semid, 1, GETVAL));    }    return 0;}