Linux C : select简介和epoll 实现

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include
#define MAX 1024
#define SERVER_IP "127.0.0.1"
#define SERVER_HOST "localhost"
// #define SERVER_PORT 1234
int server_init(int port){
	printf("=============server init========\n");
	printf("1. create a TCP socket\n");
	//sock的文件描述符	
  int mysock = socket (AF_INET,SOCK_STREAM,0);
	if(mysock < 0){
		printf("socket call failed\n"); return -1;
	}
	printf("2. fill server_addr with host_ip and port number \n");
	int opt =1; unsigned int len = sizeof(opt);
	setsockopt(mysock,SOL_SOCKET,SO_REUSEADDR,&opt,len);
	setsockopt(mysock,SOL_SOCKET,SO_KEEPALIVE,&opt,len);
	struct sockaddr_in server_addr ;
	server_addr .sin_family = AF_INET;
	server_addr .sin_port   =  htons(port);
	server_addr .sin_addr.s_addr = htonl(INADDR_ANY);
	printf("3.  bind socket to server address \n");
	int r =bind (mysock ,(struct sockaddr *) & server_addr  ,sizeof (server_addr ));
	if( r<0){
		printf("bind call failed\n"); exit(3);
	}
	printf("	hostname =%s, port = %d \n", SERVER_HOST ,port);
	listen(mysock , 5 );
	printf("============init done ===========\n");
	return mysock;
}
 
int main (int argc, char *argv[]){
	if(argc !=2){
	   printf("usage:./tcpepoll port\n");
	   return 1;	
	}
	//char line [MAX];
	int listensocket=server_init(atoi(argv[1]));
	printf("listensocket=%d\n",listensocket);
	if(listensocket < 0){
	   printf("listensocket failed \n");
	}
	char buffer[1024];
	memset(buffer,0,sizeof(buffer));
//create a fd 	
	int epollfd=epoll_create(1); 
//add a listen event
	struct epoll_event ev;
	ev.data.fd=listensocket;
	ev.events=EPOLLIN;
	epoll_ctl(epollfd,EPOLL_CTL_ADD,listensocket,&ev);
	
	while (1){
	   struct epoll_event events[MAX];
	  // waiting event occurt
	   int infds=epoll_wait(epollfd,events,MAX,-1);
	   if(infds <0 ){
	   	printf("epoll wait failed \n");break;
	   }
	   if(infds ==0){
			printf("epoll wait timeout \n");continue;	
	   }
		for(int ii=0; ii
			if( (events[ii].data.fd == listensocket) &&
	      (events[ii].events & EPOLLIN)){
	      	
				//如果监听的socket有事件，那么说明有客户端程序连接上来
				struct sockaddr_in client;
				socklen_t len = sizeof(client);
				printf("accepting \n");
				int clientsock = accept(listensocket,(struct  sockaddr*)&client,&len);
				if(clientsock < 0){
					printf("accept() fail\n"); continue;
				}
				//把监听到的socket加入到epoll中去管理
				memset(&ev,0,sizeof(struct epoll_event));
				ev.data.fd=clientsock;
				ev.events=EPOLLIN;
				epoll_ctl(epollfd,EPOLL_CTL_ADD,clientsock,&ev);
				printf("clientsock=%d success \n",clientsock);
				continue;
			}else if(events[ii].events & EPOLLIN){
				//如果是客户端socket有事件
				char buffer[1024];
				memset(buffer,0,sizeof(buffer));
				//读取客户端数据
				ssize_t  isize = read(events[ii].data.fd,buffer,sizeof(buffer));
				if(isize <= 0){
					//已断开的连接从epoll中删除
					memset(&ev,0,sizeof(struct epoll_event));
					ev.events = EPOLLIN;
					ev.data.fd = events[ii].data.fd;
					epoll_ctl(epollfd,EPOLL_CTL_DEL,events[ii].data.fd,&ev);
					close(events[ii].data.fd);
					continue;
				}
				printf("recv(eventfd=%d,size=%ld): %s \n",events[ii].data.fd,isize,buffer);
				//把收到的保温发回客户端
				write(events[ii].data.fd,buffer,strlen(buffer));
			}
    }
  }
  close(epollfd);
  return 0 ;
}

#include 
#include 
#include 
#include 
#include 
#include 
#include
 
#define MAX 256
#define SERVER_HOST "localhost"
#define SERVER_PORT 1234
 
 
struct sockaddr_in server_addr ;
int sock,r;   
 
int client_init(){
	printf("=============client init========\n");
	printf("1. create a TCP socket\n");
	sock = socket (AF_INET,SOCK_STREAM,0);
	if(sock < 0){
		printf("socket call failed\n"); exit(1);
	}
	printf("2. fill server_addr with host_ip and port number \n");
	
	server_addr .sin_family = AF_INET;
	server_addr .sin_port   =  htons(SERVER_PORT);
	server_addr .sin_addr.s_addr = htonl(INADDR_ANY);
	printf("3.  connecting to server \n");
	r = connect (sock ,(struct sockaddr *) & server_addr  ,sizeof (server_addr ));	
	if( r<0){
		printf("bind call failed\n"); exit(3);
	}
	printf("	hostname =%s, port = %d \n", SERVER_HOST ,SERVER_PORT);
	printf("============client init done ===========\n");
	return 0;
}
 
int main (){
	char line [MAX] , ans[MAX];
	int n; 
	client_init();
	printf(" ********processing loop *******************");
	while (1){
		printf("put a line... \n");
		bzero(line ,MAX);
		fgets(line,MAX,stdin);
		line[strlen(line) - 1] = 0;
		if(line[0] ==0) exit(0);
		n=write(sock,line,MAX);
		printf("client : wrote n =%d bytes ; line %s :\n", n , line);
		n =read(sock ,ans,MAX);	
		printf("client : read n =%d bytes ; line %s :\n", n , line);
	}
 
}