epoll示范

一.server端

#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 <stdlib.h>
#include <errno.h>
#include <string.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 < 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 listenfd = socket(AF_INET, SOCK_STREAM, 0);	//创建socket
	setnonblocking(listenfd);	//socket设置为非阻塞方式
	
	struct epoll_event ev; //ev用于注册事件
	struct epoll_event events[20];	//events用于回传要处理的事件
	ev.data.fd = listenfd;	//设置与要处理的事件相关的文件描述符
	ev.events = EPOLLIN|EPOLLET;	//设置要处理的事件类型
	
	int epfd = epoll_create(256);	//生成用于处理accept的epoll专用的文件描述符
	epoll_ctl(epfd, EPOLL_CTL_ADD, listenfd, &ev);	//注册epoll事件
	
	struct sockaddr_in clientaddr;
	struct sockaddr_in serveraddr;
	bzero(&serveraddr, sizeof(serveraddr));
	serveraddr.sin_family = AF_INET;
	char *local_addr = "127.0.0.1";
    inet_aton(local_addr, &(serveraddr.sin_addr));
    serveraddr.sin_port = htons(SERV_PORT);
	bind(listenfd, (sockaddr *)&serveraddr, sizeof(serveraddr));
	listen(listenfd, LISTENQ);
	
	int sockfd;
	ssize_t n;
    char buf[MAXLINE];
    socklen_t clilen;
	
	while(1)
	{
		int nfds = epoll_wait(epfd, events, 20, 500);	//等待epoll事件的发生
		for (int i = 0; i < nfds; i++)
		{
			if (events[i].data.fd == listenfd)
			{
				int connfd = accept(listenfd, (sockaddr *)&clientaddr, &clilen);
				if(connfd < 0)
				{
                    perror("connfd<0");
                    exit(1);
                }
				
				char *str = inet_ntoa(clientaddr.sin_addr);
				printf("accapt a connection from: %s\n", str);
				
				setnonblocking(connfd);	//socket设置为非阻塞方式
				ev.data.fd = connfd;	//设置用于读操作的文件描述符
				ev.events = EPOLLIN|EPOLLET;	//设置用于注册的读操作事件
				epoll_ctl(epfd, EPOLL_CTL_ADD, connfd, &ev);	//注册ev	
			}
			else if (events[i].events & EPOLLIN)
			{
				if ((sockfd = events[i].data.fd) < 0)
				{
					continue;
				}
				
				if ((n = read(sockfd, buf, MAXLINE)) < 0)
				{
					if (errno == ECONNRESET)
					{
						close(sockfd);
						events[i].data.fd = -1;
					}
				}
				else if (n == 0)
				{
					close(sockfd);
                    events[i].data.fd = -1;
				}
				
				buf[n] = '\0';
				ev.data.fd = sockfd;	//设置用于写操作的文件描述符
				ev.events = EPOLLOUT|EPOLLET;	////设置用于注册的写操作事件
				epoll_ctl(epfd, EPOLL_CTL_MOD, sockfd, &ev);	//修改sockfd上要处理的事件为EPOLLOUT
				
				printf("recv data:%s\n", buf);
			}
			else if (events[i].events&EPOLLOUT)
            {   
				if ((sockfd = events[i].data.fd) < 0)
				{
					continue;
				}
				
				write(sockfd, buf, n);
				ev.data.fd = sockfd;	//设置用于读操作的文件描述符
				ev.events = EPOLLIN|EPOLLET;	//设置用于注册的读操作事件
				epoll_ctl(epfd, EPOLL_CTL_MOD, sockfd, &ev);	////修改sockfd上要处理的事件为EPOLIN
				
				printf("send data:%s\n", buf);
            }	
		}
	}
	
	return 0;
}

二.client端

#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 <stdlib.h>
#include <errno.h>
#include <string.h>

using namespace std;

#define SERV_PORT 5000
#define MAXLINE 5
#define MESSAGE "hello"

int main()
{
	char buf[MAXLINE];
	
	int sockfd = socket(AF_INET, SOCK_STREAM, 0);
	
	struct sockaddr_in serveraddr;
	bzero(&serveraddr, sizeof(serveraddr));
	serveraddr.sin_family = AF_INET;
	char *local_addr = "127.0.0.1";
    inet_aton(local_addr, &(serveraddr.sin_addr));
    serveraddr.sin_port = htons(SERV_PORT);
	
	if (0 != connect(sockfd, (sockaddr *)&serveraddr, sizeof(serveraddr)))
    {
        printf("connected failed");
        return 1;
    }
	
	write(sockfd, MESSAGE, sizeof(MESSAGE));
    int count = read(sockfd, buf, MAXLINE);

    printf("Response from server: %s\n",buf);

    close(sockfd);
    return 0;
}