APUE中关于I/O复用没有epoll的讲解,Linux高性能服务器中的讲解比较中肯,写个聊天室练习一下。
基于C/S模型的高并发聊天室项目,在linux环境下开发,主要功能包括用户上线通知、用户离线通知和用户群聊等基本功能。
基于Socket套接字和epoll机制开发了系统的客户端和服务器端;服务端为了提高并发量采用epoll监视网络接口;客户端采用epoll方式分别监视网络socket接口和pipe的读端,进行网络socket接口和本地STDIN和STDOUT的交互。
关于LT与ET:
服务器预设LT模式,可以切换ET模式。
整体架构如下:
客户机:
建立pipe,然后进行fork,父子进程之间通信用的是pipe,
子进程直接和标准输入交互,关闭pipe的读端fd0;当stdin读入的buffer和“EXIT”比较,然后在决定是否关闭,将buffer write到pipe的写端,写入pipe_fd[1]
父进程的epoll句柄监控pipe的读pipe_fd[0]和socket的套接字的写
如果检测到socket套接字则recv消息到buffer,然后从stdin输出给用户
如果检测到pipe的写入,则读入buffer,在send到服务器
服务器:TCP
监听socket套接字
如果是listen则进行accept得到confd然后将confd加入到保持链接的链表中,并调用broadcast函数进行广播,广播给所有链接保持链表中的在线用户,发送welcome消息。
Broadcast函数:
Recv(cilentfd)若返回0则表示此客户端链接断开,从链表中删除此链接描述符,并循环告知所有在线用户此此用户下线。
否则检查链表的长度,若长度为1,则表示只有一个用户,告知用户聊天室只有一个,
然后将此用户的消息循环send到链表中的在线用户。
功能测试:
Epoll_helper.h
#ifndef EPOLL_HELPER_H_INCLUDED
#define EPOLL_HELPER_H_INCLUDED
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
using namespace std;
// clients_list save all the clients's socket
list clients_list;
/********************** macro defintion **************************/
// server ip
#define SERVER_IP "127.0.0.1"
// server port
#define SERVER_PORT 8888
//epoll size
#define EPOLL_SIZE 5000
//message buffer size
#define BUF_SIZE 0xFFFF
#define SERVER_WELCOME "Welcome you join to the chat room! Your chat ID is: Client #%d"
#define SERVER_MESSAGE "ClientID %d say >> %s"
// exit
#define EXIT "EXIT"
#define CAUTION "There is only one int the char room!"
/********************** some function **************************/
/**
* @param sockfd: socket descriptor
* @return 0
**/
int setnonblocking(int sockfd)
{
fcntl(sockfd, F_SETFL, fcntl(sockfd, F_GETFD, 0)| O_NONBLOCK);
return 0;
}
/**
epollfd: epoll handle
socket descriptor
enable_et : enable_et = true, epoll use ET; otherwise LT
**/
void addfd( int epollfd, int fd, bool enable_et )
{
struct epoll_event ev;
ev.data.fd = fd;
ev.events = EPOLLIN;
if( enable_et )
ev.events = EPOLLIN | EPOLLET;
epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev);
setnonblocking(fd);
printf("fd added to epoll!\n\n");
}
/**
* @param clientfd: socket descriptor
* @return : len
**/
int sendBroadcastmessage(int clientfd)
{
// buf[BUF_SIZE] receive new chat message
// message[BUF_SIZE] save format message
char buf[BUF_SIZE], message[BUF_SIZE];
bzero(buf, BUF_SIZE);
bzero(message, BUF_SIZE);
// receive message
printf("read from client(clientID = %d)\n", clientfd);
int len = recv(clientfd, buf, BUF_SIZE, 0);
if(len == 0) // len = 0 means the client closed connection
{
close(clientfd);
clients_list.remove(clientfd); //server remove the client
printf("ClientID = %d closed.\n now there are %d client in the char room\n", clientfd, (int)clients_list.size());
}
else //broadcast message
{
if(clients_list.size() == 1) { // this means There is only one int the char room
send(clientfd, CAUTION, strlen(CAUTION), 0);
return len;
}
// format message to broadcast
sprintf(message, SERVER_MESSAGE, clientfd, buf);
list::iterator it;
for(it = clients_list.begin(); it != clients_list.end(); ++it) {
if(*it != clientfd){
if( send(*it, message, BUF_SIZE, 0) < 0 ) { perror("error"); exit(-1);}
}
}
}
return len;
}
#endif // UTILITY_H_INCLUDED
TCP_epoll_client.cpp
#include "Epoll_helper.h"
int main(int argc, char *argv[])
{
//用户连接的服务器 IP + port
struct sockaddr_in serverAddr;
serverAddr.sin_family = PF_INET;
serverAddr.sin_port = htons(SERVER_PORT);
serverAddr.sin_addr.s_addr = inet_addr(SERVER_IP);
// 创建socket
int sock = socket(AF_INET, SOCK_STREAM, 0);
if(sock < 0)
{
perror("sock error");
exit(-1);
}
// 连接服务端
if(connect(sock, (struct sockaddr *)&serverAddr, sizeof(serverAddr)) < 0) {
perror("connect error");
exit(-1);
}
// 创建管道,其中fd[0]用于父进程读,fd[1]用于子进程写
int pipe_fd[2];
if(pipe(pipe_fd) < 0)
{
perror("pipe error");
exit(-1);
}
// 创建epoll
int epfd = epoll_create(EPOLL_SIZE);
if(epfd < 0)
{
perror("epfd error");
exit(-1);
}
static struct epoll_event events[2];
//将sock和管道读端描述符都添加到内核事件表中
addfd(epfd, sock, true);
addfd(epfd, pipe_fd[0], true);
// 表示客户端是否正常工作
bool isClientwork = true;
// 聊天信息缓冲区
char message[BUF_SIZE];
// Fork
int pid = fork();
if(pid < 0)
{
perror("fork error");
exit(-1);
}
else if(pid == 0) // 子进程
{
//子进程负责写入管道,因此先关闭读端
close(pipe_fd[0]);
printf("Please input 'exit' to exit the chat room\n");
while(isClientwork){
bzero(&message, BUF_SIZE);
fgets(message, BUF_SIZE, stdin);
// 客户输出exit,退出
if(strncasecmp(message, EXIT, strlen(EXIT)) == 0){
isClientwork = 0;
}
// 子进程将信息写入管道
else {
if( write(pipe_fd[1], message, strlen(message) - 1 ) < 0 )
{ perror("fork error"); exit(-1); }
}
}
}
else //pid > 0 父进程
{
//父进程负责读管道数据,因此先关闭写端
close(pipe_fd[1]);
// 主循环(epoll_wait)
while(isClientwork) {
int epoll_events_count = epoll_wait( epfd, events, 2, -1 );
//处理就绪事件
for(int i = 0; i < epoll_events_count ; ++i)
{
bzero(&message, BUF_SIZE);
//服务端发来消息
if(events[i].data.fd == sock)
{
//接受服务端消息
int ret = recv(sock, message, BUF_SIZE, 0);
// ret= 0 服务端关闭
if(ret == 0) {
printf("Server closed connection: %d\n", sock);
close(sock);
isClientwork = 0;
}
else printf("%s\n", message);
}
//子进程写入事件发生,父进程处理并发送服务端
else {
//父进程从管道中读取数据
int ret = read(events[i].data.fd, message, BUF_SIZE);
// ret = 0
if(ret == 0) isClientwork = 0;
else{ // 将信息发送给服务端
send(sock, message, BUF_SIZE, 0);
}
}
}//for
}//while
}
if(pid){
//关闭父进程和sock
close(pipe_fd[0]);
close(sock);
}else{
//关闭子进程
close(pipe_fd[1]);
}
return 0;
}
TCP_epoll_server.cpp
#include "Epoll_helper.h"
int main(int argc, char *argv[])
{
//服务器IP + port
struct sockaddr_in serverAddr;
serverAddr.sin_family = PF_INET;
serverAddr.sin_port = htons(SERVER_PORT);
serverAddr.sin_addr.s_addr = inet_addr(SERVER_IP);
//创建监听socket
int listener = socket(AF_INET, SOCK_STREAM, 0);
if(listener < 0)
{
perror("listener");
exit(-1);
}
printf("listen socket created \n");
//绑定地址
if( bind(listener, (struct sockaddr *)&serverAddr, sizeof(serverAddr)) < 0) {
perror("bind error");
exit(-1);
}
//监听
int ret = listen(listener, 5);
if(ret < 0)
{
perror("listen error");
exit(-1);
}
printf("Start to listen: %s\n", SERVER_IP);
//在内核中创建事件表
int epfd = epoll_create(EPOLL_SIZE);
if(epfd < 0)
{
perror("epfd error");
exit(-1);
}
printf("epoll created, epollfd = %d\n", epfd);
static struct epoll_event events[EPOLL_SIZE];
//往内核事件表里添加事件
addfd(epfd, listener, true);
//主循环
while(1)
{
//epoll_events_count表示就绪事件的数目
int epoll_events_count = epoll_wait(epfd, events, EPOLL_SIZE, -1);
if(epoll_events_count < 0) {
perror("epoll failure");
break;
}
printf("epoll_events_count = %d\n", epoll_events_count);
//处理这epoll_events_count个就绪事件
for(int i = 0; i < epoll_events_count; ++i)
{
int sockfd = events[i].data.fd;
//新用户连接
if(sockfd == listener)
{
struct sockaddr_in client_address;
socklen_t client_addrLength = sizeof(struct sockaddr_in);
int clientfd = accept( listener, ( struct sockaddr* )&client_address, &client_addrLength );
printf("client connection from: %s : % d(IP : port), clientfd = %d \n",
inet_ntoa(client_address.sin_addr),
ntohs(client_address.sin_port),
clientfd);
addfd(epfd, clientfd, true);////把这个新的客户端添加到内核事件列表
// 服务端用list保存用户连接
clients_list.push_back(clientfd);
printf("Add new clientfd = %d to epoll\n", clientfd);
printf("Now there are %d clients int the chat room\n", (int)clients_list.size());
// 服务端发送欢迎信息
printf("welcome message\n");
char message[BUF_SIZE];
bzero(message, BUF_SIZE);
sprintf(message, SERVER_WELCOME, clientfd);
int ret = send(clientfd, message, BUF_SIZE, 0);
if(ret < 0) { perror("send error"); exit(-1); }
}
//客户端唤醒//处理用户发来的消息,并广播,使其他用户收到信息
else
{
int ret = sendBroadcastmessage(sockfd);
if(ret < 0) { perror("error");exit(-1); }
}
}
}
close(listener); //关闭socket
close(epfd); //关闭内核 不在监控这些注册事件是否发生
return 0;
}
参考:Linux 高性能服务器编程
https://www.cnblogs.com/-Lei/archive/2012/09/12/2681475.html