epoll_create, epoll_ctl和epoll_wait

参考代码

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

 using namespace std;

 #define MAXLINE 5
 #define OPEN_MAX 100
 #define LISTENQ 20
 #define SERV_PORT 5000
 #define INFTIM 1000

 void setnonblocking(int sock)
 {
     int opts;
     opts=fcntl(sock,F_GETFL);
     if(opts<)
     {
         perror("fcntl(sock,GETFL)");
         exit();
     }
     opts = opts|O_NONBLOCK;
     if(fcntl(sock,F_SETFL,opts)<)
     {
         perror("fcntl(sock,SETFL,opts)");
         exit();
     }
 }

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

     if (  == argc )
     {
         if( (portnumber = atoi(argv[])) <  )
         {
             fprintf(stderr,"Usage:%s portnumber/a/n",argv[]);
             return ;
         }
     }
     else
     {
         fprintf(stderr,"Usage:%s portnumber/a/n",argv[]);
         return ;
     }

     //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[];
     //生成用于处理accept的epoll专用的文件描述符

     epfd=epoll_create();
     struct sockaddr_in clientaddr;
     struct sockaddr_in serveraddr;
     listenfd = socket(AF_INET, SOCK_STREAM, );
     //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;
     //ev.events=EPOLLIN;

     //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="127.0.0.1";
     inet_aton(local_addr,&(serveraddr.sin_addr));//htons(portnumber);

     serveraddr.sin_port=htons(portnumber);
     bind(listenfd,(sockaddr *)&serveraddr, sizeof(serveraddr));
     listen(listenfd, LISTENQ);
     maxi = ;
     for ( ; ; ) {
         //等待epoll事件的发生

         nfds=epoll_wait(epfd,events,,);
         //处理所发生的所有事件

         for(i=;i<nfds;++i)
         {
             if(events[i].data.fd==listenfd)//如果新监测到一个SOCKET用户连接到了绑定的SOCKET端口，建立新的连接。

             {
                 connfd = accept(listenfd,(sockaddr *)&clientaddr, &clilen);
                 if(connfd<){
                     perror("connfd<0");
                     exit();
                 }
                 //setnonblocking(connfd);

                 char *str = inet_ntoa(clientaddr.sin_addr);
                 cout << "accapt a connection from " << str << 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;
                 //ev.events=EPOLLIN;

                 //注册ev

                 epoll_ctl(epfd,EPOLL_CTL_ADD,connfd,&ev);
             }
             else if(events[i].events&EPOLLIN)//如果是已经连接的用户，并且收到数据，那么进行读入。

             {
                 cout << "EPOLLIN" << endl;
                 if ( (sockfd = events[i].data.fd) < )
                     continue;
                 if ( (n = read(sockfd, line, MAXLINE)) < ) {
                     if (errno == ECONNRESET) {
                         close(sockfd);
                         events[i].data.fd = -;
                     } else
                         std::cout<<"readline error"<<std::endl;
                 } else if (n == ) {
                     close(sockfd);
                     events[i].data.fd = -;
                 }
                 line[n] = '/0';
                 cout << "read " << line << endl;
                 //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) // 如果有数据发送

             {
                 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);
             }
         }
     }
     return ;
 }

 //
 // a simple echo server using epoll in linux
 //
 // 2009-11-05
 // 2013-03-22:修改了几个问题，1是/n格式问题，2是去掉了原代码不小心加上的ET模式;
 // 本来只是简单的示意程序，决定还是加上 recv/send时的buffer偏移
 // by sparkling
 //
 #include <sys/socket.h>
 #include <sys/epoll.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <stdio.h>
 #include <errno.h>
 #include <iostream>
 using namespace std;
 #define MAX_EVENTS 500
 struct myevent_s
 {
     int fd;
     void (*call_back)(int fd, int events, void *arg);
     int events;
     void *arg;
     int status; // 1: in epoll wait list, 0 not in
     char buff[]; // recv data buffer
     int len, s_offset;
     long last_active; // last active time
 };
 // set event
 void EventSet(myevent_s *ev, int fd, void (*call_back)(int, int, void*), void *arg)
 {
     ev->fd = fd;
     ev->call_back = call_back;
     ev->events = ;
     ev->arg = arg;
     ev->status = ;
     bzero(ev->buff, sizeof(ev->buff));
     ev->s_offset = ;
     ev->len = ;
     ev->last_active = time(NULL);
 }
 // add/mod an event to epoll
 void EventAdd(int epollFd, int events, myevent_s *ev)
 {
     struct epoll_event epv = {, {}};
     int op;
     epv.data.ptr = ev;
     epv.events = ev->events = events;
     if(ev->status == ){  

         op = EPOLL_CTL_MOD;
     }
     else{
         op = EPOLL_CTL_ADD;
         ev->status = ;
     }
     if(epoll_ctl(epollFd, op, ev->fd, &epv) < )
         printf("Event Add failed[fd=%d], evnets[%d]\n", ev->fd, events);
     else
         printf("Event Add OK[fd=%d], op=%d, evnets[%0X]\n", ev->fd, op, events);
 }
 // delete an event from epoll
 void EventDel(int epollFd, myevent_s *ev)
 {
     struct epoll_event epv = {, {}};
     if(ev->status != ) return;
     epv.data.ptr = ev;
     ev->status = ;
     epoll_ctl(epollFd, EPOLL_CTL_DEL, ev->fd, &epv);
 }
 int g_epollFd;
 myevent_s g_Events[MAX_EVENTS+]; // g_Events[MAX_EVENTS] is used by listen fd
 void RecvData(int fd, int events, void *arg);
 void SendData(int fd, int events, void *arg);
 // accept new connections from clients
 void AcceptConn(int fd, int events, void *arg)
 {
     struct sockaddr_in sin;
     socklen_t len = sizeof(struct sockaddr_in);
     int nfd, i;
     // accept
     if((nfd = accept(fd, (struct sockaddr*)&sin, &len)) == -)
     {
         if(errno != EAGAIN && errno != EINTR)
         {
         }
         printf("%s: accept, %d", __func__, errno);
         return;
     }
     do
     {
         for(i = ; i < MAX_EVENTS; i++)
         {
             if(g_Events[i].status == )
             {
                 break;
             }
         }
         if(i == MAX_EVENTS)
         {
             printf("%s:max connection limit[%d].", __func__, MAX_EVENTS);
             break;
         }
         // set nonblocking
         int iret = ;
         if((iret = fcntl(nfd, F_SETFL, O_NONBLOCK)) < )
         {
             printf("%s: fcntl nonblocking failed:%d", __func__, iret);
             break;
         }
         // add a read event for receive data
         EventSet(&g_Events[i], nfd, RecvData, &g_Events[i]);
         EventAdd(g_epollFd, EPOLLIN, &g_Events[i]);
     }while();
     printf("new conn[%s:%d][time:%d], pos[%d]\n", inet_ntoa(sin.sin_addr),
             ntohs(sin.sin_port), g_Events[i].last_active, i);
 }
 // receive data
 void RecvData(int fd, int events, void *arg)
 {
     struct myevent_s *ev = (struct myevent_s*)arg;
     int len;
     // receive data
     len = recv(fd, ev->buff+ev->len, sizeof(ev->buff)--ev->len, );
     EventDel(g_epollFd, ev);
     if(len > )
     {
         ev->len += len;
         ev->buff[len] = '\0';
         printf("C[%d]:%s\n", fd, ev->buff);
         // change to send event
         EventSet(ev, fd, SendData, ev);
         EventAdd(g_epollFd, EPOLLOUT, ev);
     }
     else if(len == )
     {
         close(ev->fd);
         printf("[fd=%d] pos[%d], closed gracefully.\n", fd, ev-g_Events);
     }
     else
     {
         close(ev->fd);
         printf("recv[fd=%d] error[%d]:%s\n", fd, errno, strerror(errno));
     }
 }
 // send data
 void SendData(int fd, int events, void *arg)
 {
     struct myevent_s *ev = (struct myevent_s*)arg;
     int len;
     // send data
     len = send(fd, ev->buff + ev->s_offset, ev->len - ev->s_offset, );
     if(len > )
     {
         printf("send[fd=%d], [%d<->%d]%s\n", fd, len, ev->len, ev->buff);
         ev->s_offset += len;
         if(ev->s_offset == ev->len)
         {
             // change to receive event
             EventDel(g_epollFd, ev);
             EventSet(ev, fd, RecvData, ev);
             EventAdd(g_epollFd, EPOLLIN, ev);
         }
     }
     else
     {
         close(ev->fd);
         EventDel(g_epollFd, ev);
         printf("send[fd=%d] error[%d]\n", fd, errno);
     }
 }
 void InitListenSocket(int epollFd, short port)
 {
     int listenFd = socket(AF_INET, SOCK_STREAM, );
     fcntl(listenFd, F_SETFL, O_NONBLOCK); // set non-blocking
     printf("server listen fd=%d\n", listenFd);
     EventSet(&g_Events[MAX_EVENTS], listenFd, AcceptConn, &g_Events[MAX_EVENTS]);
     // add listen socket
     EventAdd(epollFd, EPOLLIN, &g_Events[MAX_EVENTS]);
     // bind & listen
     sockaddr_in sin;
     bzero(&sin, sizeof(sin));
     sin.sin_family = AF_INET;
     sin.sin_addr.s_addr = INADDR_ANY;
     sin.sin_port = htons(port);
     bind(listenFd, (const sockaddr*)&sin, sizeof(sin));
     listen(listenFd, );
 }
 int main(int argc, char **argv)
 {
     unsigned short port = ; // default port
     if(argc == ){
         port = atoi(argv[]);
     }
     // create epoll
     g_epollFd = epoll_create(MAX_EVENTS);
     if(g_epollFd <= ) printf("create epoll failed.%d\n", g_epollFd);
     // create & bind listen socket, and add to epoll, set non-blocking
     InitListenSocket(g_epollFd, port);
     // event loop
     struct epoll_event events[MAX_EVENTS];
     printf("server running:port[%d]\n", port);
     int checkPos = ;
     while(){
         // a simple timeout check here, every time 100, better to use a mini-heap, and add timer event
         long now = time(NULL);
         for(int i = ; i < ; i++, checkPos++) // doesn't check listen fd
         {
             if(checkPos == MAX_EVENTS) checkPos = ; // recycle
             if(g_Events[checkPos].status != ) continue;
             long duration = now - g_Events[checkPos].last_active;
             if(duration >= ) // 60s timeout
             {
                 close(g_Events[checkPos].fd);
                 printf("[fd=%d] timeout[%d--%d].\n", g_Events[checkPos].fd, g_Events[checkPos].last_active, now);
                 EventDel(g_epollFd, &g_Events[checkPos]);
             }
         }
         // wait for events to happen
         int fds = epoll_wait(g_epollFd, events, MAX_EVENTS, );
         if(fds < ){
             printf("epoll_wait error, exit\n");
             break;
         }
         for(int i = ; i < fds; i++){
             myevent_s *ev = (struct myevent_s*)events[i].data.ptr;
             if((events[i].events&EPOLLIN)&&(ev->events&EPOLLIN)) // read event
             {
                 ev->call_back(ev->fd, events[i].events, ev->arg);
             }
             if((events[i].events&EPOLLOUT)&&(ev->events&EPOLLOUT)) // write event
             {
                 ev->call_back(ev->fd, events[i].events, ev->arg);
             }
         }
     }
     // free resource
     return ;
 }   

参考资料

epoll相关资料整理

epoll_create函数实现源码分析

epoll_create epoll_ctl epoll_wait close epoll和select的简单比较

epoll使用详解（精髓）

epoll源码分析

epoll_create函数实现源码分析

学习使用epoll