多路复用I/O模型select() 模型 代码实现

多路复用I/O:  socket编程之select(),poll(),epoll()

代码：

client.c

 #include <stdio.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
 #include <netinet/in.h>
 #include <sys/socket.h>
 #include <sys/select.h>
 #include <arpa/inet.h>
 #include <assert.h>
 #define maxn 1100
 #define IP  "127.0.0.1"
 #define PORT 45178
 #define MAXLINE 1024
 #define LISTENQ 5
 #define SIZE 10
 #define BACKLOG 2
 int main()
 {
     int sockfd;
     if((sockfd = socket(AF_INET,SOCK_STREAM,)) == -)
     {
         printf("socket error!\n");
         exit();
     }
     struct sockaddr_in server;
     bzero(&server,sizeof(server));
     server.sin_family = AF_INET;
     server.sin_port = htons(PORT);
     inet_pton(AF_INET,IP,&server.sin_addr);
     char buf[maxn];
     int connfd;
     connfd = connect(sockfd,(struct sockaddr*)&server,sizeof(server));
     if(connfd < )
     {
         printf("connect failure!\n");
         return -;
     }
     printf("client send to server\n");
     printf("please input something\n");
     scanf("%s",buf);
     write(sockfd,buf,maxn);
     char recvbuf[maxn];
     char sendbuf[maxn];
     fd_set readfd;
     int maxnum = ;
     struct timeval T_time;
     int n;
     int sel_fd;
     while()
     {
         FD_ZERO(&readfd);
         FD_SET(sockfd,&readfd);
         maxnum = sockfd;
         T_time.tv_sec = ;
         T_time.tv_usec = ;
         sel_fd = select(maxnum + ,&readfd,NULL,NULL,&T_time);
         if(sel_fd < )
         {
             continue;
         }
         else if(sel_fd == -)
         {
             printf("select error!\n");
             return;
         }
         if(FD_ISSET(sockfd,&readfd))
         {
             n = read(sockfd,recvbuf,maxn);
             if(n <= )
             {
                 printf("server is closed!\n");
                 close(sockfd);
                 FD_CLR(sockfd,&readfd);
                 return;
             }
             printf("recv message is %s\n", recvbuf);
             sleep();
             write(sockfd,buf,strlen(buf) + );
         }
     }
     close(sockfd);
     return ;
 }

server.c

 #include <stdio.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
 #include <netinet/in.h>
 #include <sys/socket.h>
 #include <sys/select.h>
 #include <arpa/inet.h>
 #include <assert.h>
 #define maxn 1100
 #define PORT 45178
 #define IP "127.0.0.1"
 #define MAXLINE 1024
 #define LISTENQ 5
 #define SIZE 10
 #define BACKLOG 2
 typedef struct server_context_st
 {
        int cli_num;        /*客户端个数*/
         int cli_fds[SIZE];   /*客户端的个数*/
       fd_set allfds;      /*句柄集合*/
         int maxfd;          /*句柄最大值*/
 } server_context_st;

 static int  init();
 static void deal_maxfd(int sockfd);
 static int accept_client(int sockfd);
 static void recv_client_msg(fd_set *readfd);
 static void submit_client_msg(int temp,char buf[]);
 static server_context_st *server_client = NULL;
 int Max(int a,int b);
 int Max(int a,int b)
 {
     return a>b?a:b;
 }
 static int server_init()
 {
     server_client = (server_context_st *)malloc(sizeof(server_context_st));
     if(server_client == NULL)
     {
         return -;
     }
     memset(server_client,,sizeof(server_context_st));
     int i=;
     for(;i<SIZE;i++)
     {
         server_client->cli_fds[i] = -;
     }
     return ;
 }
 static int  init()
 {

     int sockfd;
     if((sockfd = socket(AF_INET,SOCK_STREAM,)) == -)
     {
         printf("socket error!\n");
         exit();
     }
     int listenfd;
     struct sockaddr_in server;
     bzero(&server,sizeof(server));
     server.sin_family = AF_INET;
     server.sin_port = htons(PORT);
     inet_pton(AF_INET,IP,&server.sin_addr);
     if(bind(sockfd,(struct sockaddr*)&server,sizeof(struct sockaddr)) == -)
     {
         perror("bind error:");
         return -;
     }
     listen(sockfd,BACKLOG);
     return sockfd;
 }
 static void deal_maxfd(int sockfd)
 {
     fd_set *readfd = &server_client->allfds;
     int sel_fd = ;
     int clifd = -;
     struct timeval T_time;
     while()
     {
         FD_ZERO(readfd);
         FD_SET(sockfd,readfd);
         server_client->maxfd = sockfd;
         T_time.tv_sec = ;
         T_time.tv_usec = ;

         int i;
         for(i=;i<server_client->cli_num;i++)
         {
             clifd = server_client->cli_fds[i];
             FD_SET(clifd,readfd);
             server_client->maxfd =  Max(clifd,server_client->maxfd);
         }
         //retval = select(s_srv_ctx->maxfd + 1, readfds, NULL, NULL, &tv);
         sel_fd  = select(server_client->maxfd+,readfd,NULL,NULL,&T_time);
         if(sel_fd == )
         {
             printf("time out!\n");
             continue;
         }
         else if(sel_fd == -)
         {
             printf("something error!\n");
             return ;
         }
         if(FD_ISSET(sockfd,readfd))
         {
             /*监听客户端请求*/
             accept_client(sockfd);
         }
         else
         {
             /*接受处理客户端消息*/
             recv_client_msg(readfd);
         }
     }
 }
 static int accept_client(int sockfd)
 {
     struct sockaddr_in server_c;
     socklen_t len;
     len = sizeof (server_c);
     int afd = -;
     Loop:
     printf("waiting ............................\n");
     afd = accept(sockfd,(struct sockaddr*)&server_c,&len);
     if(afd == -)
     {
         if(errno == EINTR)
         {
             goto Loop;
         }
         else
         {
              fprintf(stderr, "accept fail,error:%s\n", strerror(errno));
             return -;
         }
     }
     printf("accept successful!\n");
     int i=;
     for(i=;i<SIZE;i++)
     {
         if(server_client->cli_fds[i] < )
         {
             server_client->cli_fds[i] = afd;
             server_client->cli_num ++;
             break;
         }
     }
     if(i == SIZE)
     {
         printf("too many client to accept!\n");
         return -;
     }
 }
 static void recv_client_msg(fd_set *readfd)
 {
     int i=;
     int temp;
     char buf[maxn];
     for(i=;i<server_client->cli_num;i++)
     {
         temp = server_client->cli_fds[i];
         if(temp < )
         {
             continue;
         }
         if(FD_ISSET(temp,readfd))
         {
             int n = read(temp,buf,maxn);
             if(n <= )
             {
                 FD_CLR(temp,&server_client->allfds);
                 close(temp);
                 server_client->cli_fds[i] = -;
                 continue;
             }
             submit_client_msg(temp,buf);
         }
     }
 }
 static void submit_client_msg(int temp,char buf[])
 {
     assert(buf);
     printf("receive message is %s\n",buf);
     write(temp,buf,strlen(buf)+);
     return ;
 }
 int main()
 {
     if(server_init() == -)
     {
         printf("init error\n");
         return -;
     }
     int sockfd;
     sockfd = init();
     deal_maxfd(sockfd);
     close(sockfd);
     return ;
 }

结果：