epoll的server端：

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include<string.h>
 4 #include<unistd.h>
 5 #include<errno.h>
 6 #include<pthread.h>
 7 #include<ctype.h>
 8 #include<sys/socket.h>
 9 #include<sys/epoll.h>
10 #include<arpa/inet.h>
11
 
 
12 #define SERV_PORT 9527
13 #define MAXLINE 8192
14 #define OPEN_MAX 5000
15 
16 int main(int argc,char *argv[])
17 {
18     int listenfd = 0,connfd = 0,sockfd,i;
19     int n,num = 0;
20     ssize_t nready,efd,res;
21     char buf[MAXLINE], str[INET_ADDRSTRLEN];
22     socklen_t clilen;
23 
24     struct
 
 sockaddr_in cliaddr,servaddr;
25 
26     listenfd = socket(AF_INET,SOCK_STREAM,0);
27     int opt = 1;
28     setsockopt(listenfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt));  //埠複用
29     memset(&servaddr,0,sizeof(servaddr));
30     servaddr.sin_family = AF_INET;
31     servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
 
32     servaddr.sin_port = htons(SERV_PORT);
33     bind(listenfd,(struct sockaddr *)&servaddr, sizeof(servaddr));
34     listen(listenfd,20);
35 
36     efd = epoll_create(OPEN_MAX);    //建立epoll模型，efd指向紅黑樹根節點
37 
38     struct epoll_event tep, ep[OPEN_MAX];       //tep:epoll_ctl引數，ep[]:epoll_wait引數;
39     tep.events = EPOLLIN;
40     tep.data.fd = listenfd;                     //指定listenfd的監聽事件為“讀”
41 
42     res = epoll_ctl(efd, EPOLL_CTL_ADD, listenfd, &tep); //將listenfd及對應的結構體設定到樹上，efd可找到該樹
43 
44     for(;;){
45         //epoll為server阻塞監聽事件，ep為struct epoll_event型別陣列，OPEN_MAX為陣列容量，-1表示永久阻塞
46         nready = epoll_wait(efd,ep,OPEN_MAX,-1);
47 
48         for(i=0;i<nready;i++){
49             if(!(ep[i].events & EPOLLIN))
50                 continue;
51             if(ep[i].data.fd == listenfd){      //判斷滿足事件的fd是不是lfd
52                 clilen = sizeof(cliaddr);
53                 connfd = accept(listenfd,(struct sockaddr *)&cliaddr,&clilen); //接受連線
54 
55                 tep.events = EPOLLIN; 
56                 tep.data.fd = connfd;
57 
58                 res = epoll_ctl(efd,EPOLL_CTL_ADD,connfd,&tep);  //加入紅黑樹
59             }else{                      //不是lfd
60                 sockfd = ep[i].data.fd;
61                 n = read(sockfd,buf,MAXLINE);
62 
63                 if(n == 0){                                            //讀到0，說明客戶端關閉連線
64                     res = epoll_ctl(efd, EPOLL_CTL_DEL, sockfd, NULL); //將該檔案描述符從紅黑樹摘除
65                     close(sockfd);                                     //關閉與該客戶端的連線
66                 }
67                 else if(n < 0){        //出錯
68                     res = epoll_ctl(efd, EPOLL_CTL_DEL, sockfd, NULL); //摘除節點
69                     close(sockfd);
70                 }
71                 else{                  //讀到了位元組數
72                     for(i=0;i<n;i++)
73                        buf[i] = toupper(buf[i]);
74 
75                     write(STDOUT_FILENO,buf,n);
76                     write(sockfd,buf,n);
77                 }
78             }
79         }
80     }
81     close(listenfd);
82     return 0;
83 }