使用范例：

epoll最多的用途就是socket编程，可以大大提高服务器的性能，此处我们实现一个简单的http服务器。 #define MAXFDS 128

#define EVENTS 100

#define PORT 8080

#define MAXEPOLLSIZE 1024*10

typedef enum

{

false,

true

}bool;

/***************定义处理socket的回调函数类型***********/

typedef int (*socket_pro)(int fd,void *data);

/***************定义回调函数的用户数据***********/

typedef struct userdata

{

int fd;

socket_pro cb;

}userdata_t;

static int epfd;//epoll句柄

/***************发送一个文件数据的函数***********/

static void cws_client_request (int connfd,void *data)

{

struct epoll_event ev = {0};

char buffer[1024*8] = {0};

int ret;

char *requestPath = NULL;

char tmpPath[512] = {"./www/"};

int pagesize = 0;

ret = recv (connfd, buffer, sizeof (buffer) -1, 0);

if (ret > 0)

{

if (strncmp (buffer, "GET ", 4) != 0)

{

printf("bad request.\n");

}

if (strncmp (buffer, "GET /", 5) == 0)

{

if (strncmp (buffer, "GET / ", 6) == 0)

{

strcat(tmpPath, "/index.html");

requestPath = tmpPath;

}

else

{

requestPath = buffer+5;

char * pos = strstr(buffer+5, " ");

strncat(tmpPath, requestPath, pos - requestPath);

requestPath = tmpPath;

}

}

char * badRequest = (char *)"Error 404 Not Found.";

char * httpStatus200 = (char *)"HTTP/1.0 200 OK\r\nContent-Type:text/html\r\n\r\n";

FILE * fp = fopen(requestPath, "r");

FILE * connfp = fdopen(connfd, "w");

if ( connfp == NULL )

{

perror("fdopen error");//cout <

}

if (fp == NULL)

{

setlinebuf(connfp);

fwrite(badRequest, strlen(badRequest), 1, connfp);

fclose(connfp);

}

else

{

setlinebuf(connfp);

//fwrite(httpStatus200, strlen(httpStatus200), 1, connfp);

//fflush(connfp);

while ((ret = fread (buffer, 1, sizeof(buffer) -1, fp)) > 0)

{

fwrite(buffer, 1, ret, connfp);

pagesize += ret;

fflush(connfp);

}

printf("pagesize:%d\n",pagesize);//cout <

fclose(fp);

}

}

//1

close(connfd);

epoll_ctl (epfd, EPOLL_CTL_DEL, connfd, &ev);

}

/***************处理已经连接socket函数***********/

static int __process_data_fd(int fd,void *data)

{

struct epoll_event *ev = (struct epoll_event *)data;

cws_client_request(fd,ev);

free(data);

return;

}

/***************处理监听socket函数***********/

static int __process_listen_fd(int fd,void *data)

{

struct sockaddr_in caddr = {0};

struct epoll_event ev = {0};

int len = sizeof (caddr);

int cfd = accept (fd, (struct sockaddr *) &caddr, (socklen_t *) & len);

if (-1 == cfd)

{

perror("accpet error");//cout << "server has an error, now accept a socket fd" <

break;

}

setNonBlock (cfd);

userdata_t *cb_data = malloc(sizeof(userdata_t));

cb_data->fd = cfd;

cb_data->cb = __process_data_fd;

ev.data.ptr = cfd;

ev.events = EPOLLIN | EPOLLET;

epoll_ctl (epfd, EPOLL_CTL_ADD, cfd, &ev);

return 0;

}

/***************设置描述符为非阻塞***********/

static bool setNonBlock (int fd)

{

int flags = fcntl (fd, F_GETFL, 0);

flags |= O_NONBLOCK;

if (-1 == fcntl (fd, F_SETFL, flags))

{

return false;

}

return true;

}

/***************主函数***********/

int main (int argc, char *argv[])

{

int listen_fd, nfds;

int on = 1;

char buffer[512];

struct sockaddr_in saddr, caddr;

struct epoll_event ev, events[EVENTS];

signal(SIGPIPE, SIG_IGN);

if (fork())

{

exit(0);

}

if (-1 == (listen_fd = socket(AF_INET, SOCK_STREAM, 0)))

{

perror("socket error");//cout << "create socket error!" << endl;

return -1;

}

epfd = epoll_create (MAXFDS);

setsockopt (listen_fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof (on));

bzero (&saddr, sizeof (saddr));

saddr.sin_family = AF_INET;

saddr.sin_port = htons ((short) (PORT));

saddr.sin_addr.s_addr = INADDR_ANY;

if (-1 == bind(listen_fd, (struct sockaddr *) &saddr, sizeof (saddr)))

{

perror("bind error");//cout << " cann't bind socket on server " << endl;

return -1;

}

if (-1 == listen (listen_fd, 32))

{

perror("listen error");//cout << "listen error" << endl;

return -1;

}

userdata_t *cb_data = (userdata_t *)malloc(sizeof(userdata_t));

cb_data->fd = listen_fd;

cb_data->cb = __process_listen_fd;

ev.data.ptr = cb_data;

ev.events = EPOLLIN|EPOLLET;

epoll_ctl (epfd, EPOLL_CTL_ADD, listen_fd, &ev);

for (;;)

{

int i;

nfds = epoll_wait (epfd, events, MAXFDS, -1);

for (i = 0; i < nfds; ++i)

{

userdata_t *cb_data = (userdata_t *)events[i].data.ptr;

cb_data.cb(cb_data.fd,cb_data);

}

}

if (listen_fd > 0)

{

shutdown (listen_fd, SHUT_RDWR);

close (listen_fd);

}

return 0;

}