将poll程序改为epoll实现

原实例在APUE（第三版）17.2 UNIX域套接字

1、使用UNIX与套接字轮询XSI消息队列（poll版，原版）

#include "apue.h"#include #include #include #include #define NQ                 3               //队列的数量#define MAXMSZ             512             //消息的最大长度#define KEY                        0x123   //消息队列的第一个key值struct threadinfo {        int qid;        int fd;};struct mymesg {        long mtype;        char mtext[MAXMSZ];};void *helper(void *arg){        int n;        struct mymesg m;        struct threadinfo *tip = arg;        for (;;) {                printf("helper qid %d, fd %d, tid %u\n", tip->qid, tip->fd, (unsigned)pthread_self());                memset(&m, 0, sizeof(m));                if ((n = msgrcv(tip->qid, &m, MAXMSZ, 0, MSG_NOERROR)) < 0) {                        err_sys("msgrcv error");                }                if (write(tip->fd, m.mtext, n) < 0) {                        err_sys("write error");                }        }}int main(){        int i, n, err;        int fd[2];        int qid[NQ];        struct pollfd pfd[NQ];        struct threadinfo ti[NQ];        pthread_t tid[NQ];        char buf[MAXMSZ];        for (i = 0; i < NQ; ++i) {                if ((qid[i] = msgget((KEY+i), IPC_CREAT|0666)) < 0) {     //创建一个新队列                        err_sys("msgget error");                }                printf("queue %d ID is %d\n", i, qid[i]);                if (socketpair(AF_UNIX, SOCK_DGRAM, 0, fd) < 0) { //创建UNXI域套接字（fd管道）                        err_sys("socketpair error");                }                printf("fd[0]:%d\n", fd[0]);                printf("fd[1]:%d\n", fd[1]);                pfd[i].fd = fd[0];                pfd[i].events = POLLIN;                ti[i].qid = qid[i];                ti[i].fd = fd[1];                if ((err = pthread_create(&tid[i], NULL, helper, &ti[i])) != 0) {  //创建线程                        err_exit(err, "pthread_create error");                }        }        for (;;) {                if (poll(pfd, NQ, -1) < 0) {   //等待事件发生                        err_sys("poll error");                }                for (i = 0; i < NQ; ++i) {                        //printf("i:%d\n", i);                        if (pfd[i].revents & POLLIN) {                                if ((n = read(pfd[i].fd, buf, sizeof(buf))) < 0) {                                        err_sys("read error");                                }                                buf[n] = 0;                                printf("queue %d id %d, message %s\n", i, qid[i], buf);                        }                }        }        exit(0);}

编译命令：

gcc pollmsg.c -o pollmsg -lapue -lpthread -std=c99

2、使用UNIX与套接字轮询XSI消息队列（epoll版，改版）

#include "apue.h"#include #include #include #include #define NQ                 3               //队列的数量#define MAXMSZ             512             //消息的最大长度#define KEY                        0x123   //消息队列的第一个key值#define FDSIZE             1000#define EPOLLEVENTS        100struct threadinfo {        int qid;        int fd;};struct mymesg {        long mtype;        char mtext[MAXMSZ];};void *helper(void *arg){        int n;        struct mymesg m;        struct threadinfo *tip = arg;        for (;;) {                printf("helper qid %d, fd %d, tid %u\n", tip->qid, tip->fd, (unsigned)pthread_self());                memset(&m, 0, sizeof(m));                if ((n = msgrcv(tip->qid, &m, MAXMSZ, 0, MSG_NOERROR)) < 0) {                        err_sys("msgrcv error");                }                if (write(tip->fd, m.mtext, n) < 0) {                        err_sys("write error");                }        }}int main(){        int i, n, err;        int fd[2];        int qid[NQ];        int epollfd;        struct epoll_event events[EPOLLEVENTS];        struct threadinfo ti[NQ];        pthread_t tid[NQ];        char buf[MAXMSZ];        epollfd = epoll_create(FDSIZE);       //创建epoll文件描述符        for (i = 0; i < NQ; ++i) {                if ((qid[i] = msgget((KEY+i), IPC_CREAT|0666)) < 0) {     //创建一个新队列                        err_sys("msgget error");                }                printf("queue %d ID is %d\n", i, qid[i]);                if (socketpair(AF_UNIX, SOCK_DGRAM, 0, fd) < 0) { //创建UNXI域套接字（fd管道）                        err_sys("socketpair error");                }                struct epoll_event ev;                ev.events = EPOLLIN;                ev.data.fd = fd[0];                epoll_ctl(epollfd, EPOLL_CTL_ADD, fd[0], &ev);       //注册fd[0]到epoll                ti[i].qid = qid[i];                ti[i].fd = fd[1];                if ((err = pthread_create(&tid[i], NULL, helper, &ti[i])) != 0) {  //创建线程                        err_exit(err, "pthread_create error");                }               }        for (;;) {                int occurred;                if ((occurred = epoll_wait(epollfd, events, EPOLLEVENTS, -1)) < 0) {    //等待事件发生                        err_sys("epoll error");                }                if (occurred == 0) {                        err_sys("epoll timeout");                }                for (i = 0; i < occurred; ++i) {                        if (events[i].events & EPOLLIN) {                                if ((n = read(events[i].data.fd, buf, sizeof(buf))) < 0) {                                        err_sys("read error");                                }                                buf[n] = 0;                                printf("main thread %u, message %s\n", (unsigned)pthread_self(), buf);                        }                }        }        exit(0);}

编译命令：

gcc epollmsg.c -o epollmsg -lapue -lpthread -std=c99

3、给XSI消息队列发送消息（测试程序，原版）

#include "apue.h"#include #define MAXMSZ 512struct mymesg {        long mtype;        char mtext[MAXMSZ];};int main(int argc, char *argv[]){        key_t key;        long qid;        size_t nbytes;        struct mymesg m;        if (argc != 3) {                fprintf(stderr, "usage: sendmsg KEY message\n");                exit(1);        }        key = strtol(argv[1], NULL, 0);        //printf("key:0xX\n", (unsigned )key);        if ((qid = msgget(key, 0)) < 0) { //打开一个现有队列                err_sys("can't open queue key %s", argv[1]);        }        memset(&m, 0, sizeof(m));        strncpy(m.mtext, argv[2], MAXMSZ - 1);        nbytes = strlen(m.mtext);        m.mtype = 1;        //printf("qid:%ld\n", qid);        if (msgsnd(qid, &m, nbytes, 0) < 0) { //发送消息给指定消息队列                err_sys("can't send message");        }        exit(0);}

编译命令：

gcc sendmsg.c -o sendmsg -lapue -std=c99

相关阅读：

1、select、poll、epoll之间的区别总结[整理]

2、poll函数的使用，原文

3、APUE读书笔记

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