本文是用基本的linux基本函數(shù)加上epoll調(diào)用編寫一個完整的服務(wù)器和客戶端例子，可在linux上運行，客戶端和服務(wù)端的功能如下:
客戶端從標準輸入讀入一行，發(fā)送到服務(wù)端服務(wù)端從網(wǎng)絡(luò)讀取一行，然后輸出到客戶端客戶端收到服務(wù)端的響應(yīng)，輸出這一行到標準輸出服務(wù)端
代碼如下:
#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];
/* 設(shè)置每個進程允許打開的最大文件數(shù) */
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;
}
/* 創(chuàng)建 epoll 句柄，把監(jiān)聽 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 (;;) {
/* 等待有事件發(fā)生 */
nfds = epoll_wait(kdpfd, events, curfds, -1);
if (nfds == -1)
{
perror(epoll_wait);
continue;
}
/* 處理所有事件 */
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;
}
// 處理客戶端請求
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);//讀取客戶端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);//響應(yīng)客戶端
return 0;
}編譯
編譯和啟動服務(wù)端
gcc epollserver.c -o epollserver
./epollserver