/
epoll_example.c
231 lines (200 loc) · 6.11 KB
/
epoll_example.c
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//refer: http://blog.csdn.net/vonzhoufz/article/details/37662581
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/epoll.h>
#include <errno.h>
#include <libgen.h>
#define MAXEVENTS 1024
#define BUF_SIZE 10
//set this descriptor non blocking
static int setnonblocking(int sfd)
{
int flags, s;
flags = fcntl(sfd, F_GETFL, 0);
if (flags == -1) {
perror ("fcntl");
return -1;
}
flags |= O_NONBLOCK;
s = fcntl(sfd, F_SETFL, flags);
if (s == -1) {
perror ("fcntl");
return -1;
}
return 0;
}
static int create_and_bind (char *port)
{
struct addrinfo hints;
struct addrinfo *result, *rp;
int s, sfd;
memset (&hints, 0, sizeof (struct addrinfo));
hints.ai_family = AF_UNSPEC; //IPv4 IPv6通用
hints.ai_socktype = SOCK_STREAM; /* We want a TCP socket */
hints.ai_flags = AI_PASSIVE; //监听套接字;
//根据暗示得到所有可用的addrinfo
s = getaddrinfo (NULL, port, &hints, &result);
if (s != 0){
fprintf (stderr, "getaddrinfo: %s\n", gai_strerror (s));
return -1;
}
//use the first addr to create socket
for (rp = result; rp != NULL; rp = rp->ai_next) {
sfd = socket (rp->ai_family, rp->ai_socktype, rp->ai_protocol);
if (sfd == -1)
continue;
s = bind (sfd, rp->ai_addr, rp->ai_addrlen);
if (s == 0) {
//bind success
break;
}
close (sfd);//if bind failed we close this socket
}
if (rp == NULL) {
fprintf (stderr, "Could not bind\n");
return -1;
}
freeaddrinfo (result);
return sfd;
}
// add EPOLLIN event of fd to the epollfd
void addfd(int epollfd, int fd, int enable_et)
{
struct epoll_event event;
event.data.fd = fd;
event.events = EPOLLIN;
if(enable_et) event.events |= EPOLLET;
epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &event);
setnonblocking(fd);
}
//the level-trigger logic
void lt(struct epoll_event *events, int number, int epollfd, int listenfd)
{
char buf[BUF_SIZE];
int i;
for(i = 0; i < number; i++)
{
int sockfd = events[i].data.fd;
//new client connection
if(sockfd == listenfd){
struct sockaddr_in client_addr;
socklen_t client_addrlen = sizeof(client_addr);
int connfd = accept(listenfd, (struct sockaddr *)&client_addr, &client_addrlen);
if(connfd < 0){
perror("accept failed..");
exit(-1);
}
//register this event
addfd(epollfd, connfd, 0);
}else if(events[i].events & EPOLLIN){
//if there exists data unreaded , this code will invoke
printf("sockefd %d read event trigger once\n", sockfd);
int ret = recv(sockfd, buf, BUF_SIZE, 0);
if(ret <= 0){
printf("some read error or client closed.\n");
close(sockfd); // will unregister
continue;
}
printf("get %d bytes from client: %s\n", ret, buf);
}else{
// what we are not interested
printf("something else happened\n");
}
}
}
//the edge-trigger logic
void et(struct epoll_event *events, int number, int epollfd, int listenfd)
{
char buf[BUF_SIZE];
int i;
for(i = 0; i < number; i++)
{
int sockfd = events[i].data.fd;
//new client connection
if(sockfd == listenfd){
struct sockaddr_in client_addr;
socklen_t client_addrlen = sizeof(client_addr);
int connfd = accept(listenfd, (struct sockaddr *)&client_addr, &client_addrlen);
if(connfd < 0){
perror("accept failed..");
exit(-1);
}
//register this event and set edge trigger mode
addfd(epollfd, connfd, 1);
}else if(events[i].events & EPOLLIN){
//in this mode , we should read all the data out once
printf("sockefd %d read event trigger once\n", sockfd);
while(1)
{
memset(buf, 0, sizeof(buf));
int ret = recv(sockfd, buf, BUF_SIZE, 0);
if(ret < 0){
//for the nonblocking IO,the following errors indicate the read complete
if(errno == EAGAIN || errno == EWOULDBLOCK){
printf("read later\n");
break;
}
printf("some other error\n");
close(sockfd); // will unregister
break;
}else if(ret == 0){
printf("client closed.\n");
close(sockfd);
break;
}else{
printf("get %d bytes from client: %s\n", ret, buf);
}
}
}else{
// what we are not interested
printf("something else happened\n");
}
}
}
int main (int argc, char *argv[])
{
int sfd, s;
int efd;
struct epoll_event event;
struct epoll_event events[MAXEVENTS];
if (argc < 2){
fprintf (stderr, "Usage: %s [port]\n", basename(argv[0]));
exit (EXIT_FAILURE);
}
// const char *ip = argv[1];
// int port = atoi(argv[2]);
sfd = create_and_bind (argv[1]);
if (sfd == -1) abort ();
//listen for connection coming
s = listen (sfd, SOMAXCONN);
if (s == -1) {
perror ("listen");
abort ();
}
//create a epoll object
efd = epoll_create1 (0);
if (efd == -1) {
perror ("epoll_create");
abort ();
}
//add the listen socket to the event poll
addfd(efd, sfd, 1);
while(1)
{
int ret = epoll_wait(efd, events, MAXEVENTS, -1);
if(ret < 0){
printf("epoll wait failture..\n");
break;
}
//et(events, ret, efd, sfd);
lt(events, ret, efd, sfd);
}
close (sfd);
return EXIT_SUCCESS;
}