epoll用法

// // a simple echo server using epoll in linux// // 2009-11-05// 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 500struct 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[128]; // recv data buffer    int len;    long last_active; // last active time};// set eventvoid EventSet(myevent_s *ev, int fd, void (*call_back)(int, int, void*), void *arg){    ev->fd = fd;    ev->call_back = call_back;    ev->events = 0;    ev->arg = arg;    ev->status = 0;    ev->last_active = time(NULL);}// add/mod an event to epollvoid EventAdd(int epollFd, int events, myevent_s *ev){    struct epoll_event epv = {0, {0}};    int op;    epv.data.ptr = ev;    epv.events = ev->events = events;    if(ev->status == 1){        op = EPOLL_CTL_MOD;    }    else{        op = EPOLL_CTL_ADD;        ev->status = 1;    }    if(epoll_ctl(epollFd, op, ev->fd, &epv) < 0)        printf("Event Add failed[fd=%d]/n", ev->fd);    else        printf("Event Add OK[fd=%d]/n", ev->fd);}// delete an event from epollvoid EventDel(int epollFd, myevent_s *ev){    struct epoll_event epv = {0, {0}};    if(ev->status != 1) return;    epv.data.ptr = ev;    ev->status = 0;    epoll_ctl(epollFd, EPOLL_CTL_DEL, ev->fd, &epv);}int g_epollFd;myevent_s g_Events[MAX_EVENTS+1]; // g_Events[MAX_EVENTS] is used by listen fdvoid RecvData(int fd, int events, void *arg);void SendData(int fd, int events, void *arg);// accept new connections from clientsvoid 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)) == -1)    {        if(errno != EAGAIN && errno != EINTR)        {            printf("%s: bad accept", __func__);        }        return;    }    do    {        for(i = 0; i < MAX_EVENTS; i++)        {            if(g_Events[i].status == 0)            {                break;            }        }        if(i == MAX_EVENTS)        {            printf("%s:max connection limit[%d].", __func__, MAX_EVENTS);            break;        }        // set nonblocking        if(fcntl(nfd, F_SETFL, O_NONBLOCK) < 0) break;        // add a read event for receive data        EventSet(&g_Events[i], nfd, RecvData, &g_Events[i]);        EventAdd(g_epollFd, EPOLLIN|EPOLLET, &g_Events[i]);        printf("new conn[%s:%d][time:%d]/n", inet_ntoa(sin.sin_addr), ntohs(sin.sin_port), g_Events[i].last_active);    }while(0);}// receive datavoid RecvData(int fd, int events, void *arg){    struct myevent_s *ev = (struct myevent_s*)arg;    int len;    // receive data    len = recv(fd, ev->buff, sizeof(ev->buff)-1, 0);     EventDel(g_epollFd, ev);    if(len > 0)    {        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|EPOLLET, ev);    }    else if(len == 0)    {        close(ev->fd);        printf("[fd=%d] closed gracefully./n", fd);    }    else    {        close(ev->fd);        printf("recv[fd=%d] error[%d]:%s/n", fd, errno, strerror(errno));    }}// send datavoid 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->len, 0);    ev->len = 0;    EventDel(g_epollFd, ev);    if(len > 0)    {        // change to receive event        EventSet(ev, fd, RecvData, ev);        EventAdd(g_epollFd, EPOLLIN|EPOLLET, ev);    }    else    {        close(ev->fd);        printf("recv[fd=%d] error[%d]/n", fd, errno);    }}void InitListenSocket(int epollFd, short port){    int listenFd = socket(AF_INET, SOCK_STREAM, 0);    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|EPOLLET, &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, 5);}int main(int argc, char **argv){    short port = 12345; // default port    if(argc == 2){        port = atoi(argv[1]);    }    // create epoll    g_epollFd = epoll_create(MAX_EVENTS);    if(g_epollFd <= 0) 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 = 0;    while(1){        // 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 = 0; i < 100; i++, checkPos++) // doesn't check listen fd        {            if(checkPos == MAX_EVENTS) checkPos = 0; // recycle            if(g_Events[checkPos].status != 1) continue;            long duration = now - g_Events[checkPos].last_active;            if(duration >= 60) // 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, 1000);        if(fds < 0){            printf("epoll_wait error, exit/n");            break;        }        for(int i = 0; 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 0;}