Linux IO多路复用之epoll网络编程_Linux

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前言

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;
}

编译

编译和启动服务端

gcc epollserver.c -o epollserver
./epollserver

总结

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