基于epoll的echo服务器源代码

#include "unp.h"
#include <sys/epoll.h>

int epoll_create(int);
int epoll_ctl(int,int,int,struct epoll_event *);
int epoll_wait(int,struct epoll_event *,int,int);

int
main(int argc, char **argv)
{
    int            i, listenfd, connfd, sockfd;
    int            epfd;    //epoll instance file describer
    int            nready;  //the nummber of event needed to be processed
    ssize_t        n;
    char        buf[MAXLINE];
    socklen_t    clilen;
    struct        epoll_event ev;                //ev for register event
    struct        epoll_event events[20];        //event[] for transmite event needed to be processed
    struct        sockaddr_in cliaddr,servaddr;

    listenfd = socket(AF_INET, SOCK_STREAM, 0);  //creat listen socket

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family     = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(SERV_PORT);

    Bind(listenfd, (SA *)&servaddr,sizeof(servaddr));

    Listen(listenfd, LISTENQ);

    epfd=epoll_create(256);         //creat epoll instance,size is 256
    ev.data.fd=listenfd;            //set ev users data fd as listen
    ev.events=EPOLLIN|EPOLLET;      //set epoll event is fd readable of ET
    if(epoll_ctl(epfd,EPOLL_CTL_ADD,listenfd,&ev) < 0){
        err_sys("epoll register fialed");
        return -1;
    }
    for(;;){

        nready=epoll_wait(epfd,events,20,500);              //wait for epoll events
        for(i=0;i<nready;++i){
            if(events[i].data.fd == listenfd){              //connect event
                clilen = sizeof(cliaddr);
                connfd = Accept(listenfd,(SA*)&cliaddr, &clilen);
                ev.data.fd = connfd;
                ev.events = EPOLLIN|EPOLLET;
                epoll_ctl(epfd,EPOLL_CTL_ADD,connfd,&ev);
            }

            else if(events[i].events&EPOLLIN){               //input event
                if((sockfd = events[i].data.fd) < 0)//no valid sockfd
                    continue;
                if((n = Read(sockfd, buf, MAXLINE)) < 0){    //read socket
                    if(errno == ECONNRESET) {                //connect error
                        Close(sockfd);
                        events[i].data.fd = -1;
                    }else
                        err_sys("read error");
                }else if (n == 0) {                          //read error
                    Close(sockfd);
                    events[i].data.fd = -1;
                }
                ev.data.fd=sockfd;
                ev.events=EPOLLOUT|EPOLLET;
                epoll_ctl(epfd,EPOLL_CTL_MOD,sockfd,&ev);
            }
            else if(events[i].events&EPOLLOUT){              //output event
                sockfd = events[i].data.fd;
                Write(sockfd, buf, n);
                ev.data.fd=sockfd;
                ev.events=EPOLLIN|EPOLLET;
                epoll_ctl(epfd,EPOLL_CTL_MOD,sockfd,&ev);
            }
        }
    }
}