#include  <unistd.h>#include  <sys/types.h>       /* basic system data types */#include  <sys/socket.h>      /* basic socket definitions */#include  <netinet/in.h>      /* sockaddr_in{} and other Internet defns */#include  <arpa/inet.h>       /* inet(3) functions */#include <sys/epoll.h> /* epoll function */#include <fcntl.h>     /* nonblocking */#include <sys/resource.h> /*setrlimit */#include <stdlib.h>#include <errno.h>#include <stdio.h>#include <string.h>#define MAXEPOLLSIZE 10000#define MAXLINE 10240int handle(int connfd);int setnonblocking(int sockfd){    if (fcntl(sockfd, F_SETFL, fcntl(sockfd, F_GETFD, 0)|O_NONBLOCK) == -1) {        return -1;    }    return 0;}int main(int argc, char **argv){    int  servPort = 6888;    int listenq = 1024;    int listenfd, connfd, kdpfd, nfds, n, nread, curfds,acceptCount = 0;    struct sockaddr_in servaddr, cliaddr;    socklen_t socklen = sizeof(struct sockaddr_in);    struct epoll_event ev;    struct epoll_event events[MAXEPOLLSIZE];    struct rlimit rt;    char buf[MAXLINE];    /* 设置每个进程允许打开的最大文件数 */    rt.rlim_max = rt.rlim_cur = MAXEPOLLSIZE;    if (setrlimit(RLIMIT_NOFILE, &rt) == -1)     {        perror("setrlimit error");        return -1;    }    bzero(&servaddr, sizeof(servaddr));    servaddr.sin_family = AF_INET;     servaddr.sin_addr.s_addr = htonl (INADDR_ANY);    servaddr.sin_port = htons (servPort);    listenfd = socket(AF_INET, SOCK_STREAM, 0);     if (listenfd == -1) {        perror("can‘t create socket file");        return -1;    }    int opt = 1;    setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));    if (setnonblocking(listenfd) < 0) {        perror("setnonblock error");    }    if (bind(listenfd, (struct sockaddr *) &servaddr, sizeof(struct sockaddr)) == -1)     {        perror("bind error");        return -1;    }     if (listen(listenfd, listenq) == -1)     {        perror("listen error");        return -1;    }    /* 创建 epoll 句柄，把监听 socket 加入到 epoll 集合里 */    kdpfd = epoll_create(MAXEPOLLSIZE);    ev.events = EPOLLIN | EPOLLET;    ev.data.fd = listenfd;    if (epoll_ctl(kdpfd, EPOLL_CTL_ADD, listenfd, &ev) < 0)     {        fprintf(stderr, "epoll set insertion error: fd=%d\n", listenfd);        return -1;    }    curfds = 1;    printf("epollserver startup,port %d, max connection is %d, backlog is %d\n", servPort, MAXEPOLLSIZE, listenq);    for (;;) {        /* 等待有事件发生 */        nfds = epoll_wait(kdpfd, events, curfds, -1);        if (nfds == -1)        {            perror("epoll_wait");            continue;        }        /* 处理所有事件 */        for (n = 0; n < nfds; ++n)        {            if (events[n].data.fd == listenfd)             {                connfd = accept(listenfd, (struct sockaddr *)&cliaddr,&socklen);                if (connfd < 0)                 {                    perror("accept error");                    continue;                }                sprintf(buf, "accept form %s:%d\n", inet_ntoa(cliaddr.sin_addr), cliaddr.sin_port);                printf("%d:%s", ++acceptCount, buf);                if (curfds >= MAXEPOLLSIZE) {                    fprintf(stderr, "too many connection, more than %d\n", MAXEPOLLSIZE);                    close(connfd);                    continue;                }                 if (setnonblocking(connfd) < 0) {                    perror("setnonblocking error");                }                ev.events = EPOLLIN | EPOLLET;                ev.data.fd = connfd;                if (epoll_ctl(kdpfd, EPOLL_CTL_ADD, connfd, &ev) < 0)                {                    fprintf(stderr, "add socket ‘%d‘ to epoll failed: %s\n", connfd, strerror(errno));                    return -1;                }                curfds++;                continue;            }             // 处理客户端请求            if (handle(events[n].data.fd) < 0) {                epoll_ctl(kdpfd, EPOLL_CTL_DEL, events[n].data.fd,&ev);                curfds--;            }        }    }    close(listenfd);    return 0;}int handle(int connfd) {    int nread;    char buf[MAXLINE];    nread = read(connfd, buf, MAXLINE);//读取客户端socket流    if (nread == 0) {        printf("client close the connection\n");        close(connfd);        return -1;    }     if (nread < 0) {        perror("read error");        close(connfd);        return -1;    }        write(connfd, buf, nread);//响应客户端      return 0;}