epoll_test.cc

介绍epoll

#include <iostream>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>

#define MAXLINE   10
#define OPEN_MAX  100
#define LISTENQ   20
#define SERV_PORT 5555
#define INFTIM    1000


void setnonblocking(int sock)
{
     int opts;
     opts=fcntl(sock,F_GETFL);

     if(opts<0)
     {
          perror("fcntl(sock,GETFL)");
          exit(1);
     }

     opts = opts | O_NONBLOCK;
     if(fcntl(sock,F_SETFL,opts)<0)
     {
          perror("fcntl(sock,SETFL,opts)");
          exit(1);
     }    
}

int main(int argc, char *argv[])
{
     int i, maxi, listenfd, connfd, sockfd,epfd,nfds;
     ssize_t n;
     char line[MAXLINE];
     socklen_t clilen;

     //声明epoll_event结构体的变量,ev用于注册事件,数组用于回传要处理的事件
     struct epoll_event ev,events[20];

     //生成用于处理accept的epoll专用的文件描述符
     epfd=epoll_create(256);

     struct sockaddr_in clientaddr;
     struct sockaddr_in serveraddr;
     listenfd = socket(AF_INET, SOCK_STREAM, 0);

     //把socket设置为非阻塞方式
     setnonblocking(listenfd);

     //设置与要处理的事件相关的文件描述符
     ev.data.fd=listenfd;

     //设置要处理的事件类型
     ev.events=EPOLLIN|EPOLLET;

     //注册epoll事件
     epoll_ctl(epfd,EPOLL_CTL_ADD,listenfd,&ev);


     bzero(&serveraddr, sizeof(serveraddr));
     serveraddr.sin_family = AF_INET;

     char *local_addr = "192.168.100.75";
     inet_aton(local_addr, &(serveraddr.sin_addr));//htons(SERV_PORT);
     serveraddr.sin_port = htons(SERV_PORT);
     bind(listenfd, (sockaddr *)&serveraddr, sizeof(serveraddr));
     listen(listenfd, LISTENQ);

     maxi = 0; 
     for ( ; ; ) 
	 {
          //等待epoll事件的发生
          nfds=epoll_wait(epfd,events,20,500);

          //处理所发生的所有事件      
          for(i = 0;i < nfds; ++i)
          {
               if(events[i].data.fd==listenfd)
               {
                    connfd = accept(listenfd,(sockaddr *)&clientaddr, &clilen);
                    if(connfd<0)
					{
                         perror("connfd<0");
                         exit(1);
                    }

                    setnonblocking(connfd);

                    char *str = inet_ntoa(clientaddr.sin_addr);
                    std::cout<<"connect from "<<str<<std::endl;

                    //设置用于读操作的文件描述符
                    ev.data.fd = connfd;

                    //设置用于注测的读操作事件
                    ev.events = EPOLLIN | EPOLLET;

                    //注册ev
                    epoll_ctl(epfd, EPOLL_CTL_ADD, connfd, &ev);
               }
               else if(events[i].events & EPOLLIN)
               {
                    if ( (sockfd = events[i].data.fd) < 0)
				    {
						continue;
				    }

                    if ( (n = read(sockfd, line, MAXLINE)) < 0) 
					{
                         if (errno == ECONNRESET) 
						 {
                              close(sockfd);
                              events[i].data.fd = -1;
                         }
						 else
						 {
                              std::cout<<"readline error"<<std::endl;
						 }
                    }
					else if (n == 0) 
					{
                         close(sockfd);
                         events[i].data.fd = -1;
                    }

                    //设置用于写操作的文件描述符
                    ev.data.fd=sockfd;

                    //设置用于注测的写操作事件
                    ev.events = EPOLLOUT | EPOLLET;

                    //修改sockfd上要处理的事件为EPOLLOUT
                    epoll_ctl(epfd, EPOLL_CTL_MOD, sockfd, &ev);
               }
               else if(events[i].events&EPOLLOUT)
               {    
                    sockfd = events[i].data.fd;
                    write(sockfd, line, n);

                    //设置用于读操作的文件描述符
                    ev.data.fd=sockfd;

                    //设置用于注测的读操作事件
                    ev.events=EPOLLIN|EPOLLET;

                    //修改sockfd上要处理的事件为EPOLIN
                    epoll_ctl(epfd,EPOLL_CTL_MOD,sockfd,&ev);
               }
          }
     }
}