本章节是用基本的Linux基本函数加上epoll调用编写一个完整的服务器和客户端例子，可在Linux上运行，客户端和服务端的功能如下:
客户端从标准输入读入一行，发送到服务端
服务端从网络读取一行，然后输出到客户端
客户端收到服务端的响应，输出这一行到标准输出
服务端
代码如下:
#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 10240 int 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; }
下载和编译
下载地址
编译和启动服务端
gcc epollserver.c -o epollserver ./epollserver
至于客户端可以参考本文的Linux/Unix服务端和客户端Socket编程入门实例的echoclient例子下载编译。
