多进程服务端

1. 利用信号回收子进程例子(利用子进程结束后向父进程发送SIGCHLD信号来回收子进程

   #include <me.h>
   
   //子进程结束信号
   void read_childproc(int signo)
   {
     int status;
     pid_t id = waitpid(-1,&status,WNOHANG);
     if (WIFEXITED(status))
     {
       printf("Removed proc id: %d \n",id);
       printf("Child send: %d \n",WEXITSTATUS(status));
     }
   }
   
   int main(int argc,char *argv[])
   {
     pid_t pid;
     struct sigaction act;
     act.sa_handler = read_childproc;
     sigemptyset(&act.sa_mask);//信号处理函数执行时期的信号屏蔽字 
     act.sa_flags = 0;
     sigaction(SIGCHLD,&act,0);
     
     pid = fork();
     if (pid == 0)
     {
       puts("Hi! I'm child process.");
       sleep(10);
       return 12;
     }
     else 
     {
       printf("Child proc id: %d \n",pid);
       pid = fork();
       if (pid == 0)//第二个子进程 
       {
         puts("Hi! I'm child process");
         sleep(10);
         exit(24);
       }
       else//主进程 
       {
         int i;
         printf("Child proc id: %d \n",pid);
         for (i=0; i<5; i++)
         {
           puts("wait...");
           sleep(5);
         }
       }
     }
     return 0;
   }

2. 通过多个进程来实现并发(

   由父进程来监听连接请求,多个子进程来处理逻辑 ,因为fork后文件描述符也被复制一份到子进程,因为一个端口对应一个套接字,而此时文件描述符多了1份,

   1. 让唯一的父进程处理连接请求,那么去掉fork前连接成功的客户端socket fd,

   2. 多个子进程只需要负责数据,不需要监听,那么关闭监听的socket fd

   #include <me.h>
   
   #define BUF_SIZE 30
   
   void read_childproc(int);
   
   int main(int argc,char *argv[])
   {
     int serv_sock,clnt_sock;
     struct sockaddr_in serv_adr,clnt_adr;
     pid_t pid;
     struct sigaction act;
     int str_len,state;
     socklen_t adr_sz;
     char buf[BUF_SIZE];
     if (argc != 2)
     {
       printf("Usage : %s <port> \n",argv[0]);
       exit(1);
     }
   
     //注册信号处理函数 
     act.sa_handler = read_childproc;
     sigemptyset(&act.sa_mask);
     act.sa_flags = 0;
     state = sigaction(SIGCHLD,&act,0);
     if (state == -1)
       error_handle("sigaction error")
   
     serv_sock = socket(AF_INET,SOCK_STREAM,0);
     memset(&serv_adr,0,sizeof(serv_adr));
     serv_adr.sin_family = AF_INET;
     serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
     serv_adr.sin_port = htons(atoi(argv[1]));
     
     if (bind(serv_sock,(struct sockaddr*)&serv_adr,sizeof(serv_adr)) == -1)
       error_handle("bind() error")
   
     if (listen(serv_sock,5) == -1)
       error_handle("listen() error")
   
     while(1)
     {
       adr_sz = sizeof(clnt_adr);
       clnt_sock = accept(serv_sock,(struct sockaddr*)&clnt_adr,&adr_sz);
       if (clnt_sock == -1)
         continue;
       else 
         puts("new client connected...");
       pid = fork();
       if (pid == -1)//连接成功,但是fork失败 
       {
         close(clnt_sock);
         continue;
       }
   
       if (pid == 0)
       {
         close(serv_sock); //子进程不需要监听相应端口,所以此进程关闭该复制的套接字 
         while((str_len = read(clnt_sock,buf,BUF_SIZE)) != 0)
           write(clnt_sock,buf,str_len);
         close(clnt_sock);
         puts("client disconnected...");
         return 0;
       }
       else 
       {
         //父进程用不到此套接字(因为已经交给子进程来处理了)
         close(clnt_sock);
       }
     }
     close(serv_sock);//父进程结束,服务器端套接字关闭
     return 0;
   }
   
   void read_childproc(int signo)
   {
     pid_t pid;
     int status;
     pid = waitpid(-1,&status,WNOHANG);//不阻塞回收子进程 
     printf("removed proc id: %d \n",pid);
   }

3. 分割IO程序,开子进程让2个进程分别In和out

   普通回声服务器客户端(写了之后在读:

   #include <me.h>
   
   #define BUF_SIZE 1024
   int main(int argc,char *argv[])
   {
     int sock;
     char message[BUF_SIZE];
     int str_len;
     struct sockaddr_in serv_adr;
     
     if (argc != 3)
     {
       printf("Usage : %s <IP> <port>\n",argv[0]);
       exit(1);
     }
   
     sock = socket(AF_INET,SOCK_STREAM,0);
     if (sock == -1)
       error_handle("socket() error");
     
     memset(&serv_adr,0,sizeof(serv_adr));
     serv_adr.sin_family       = AF_INET;
     serv_adr.sin_addr.s_addr  = inet_addr(argv[1]);
     serv_adr.sin_port         = htons(atoi(argv[2]));
   
     if (connect(sock,(struct sockaddr*)&serv_adr,sizeof(serv_adr)) == -1)
       error_handle("connect() error")
     else 
       puts("connected...");
   
     //已经连接上了服务器
     while(1)
     {
       fputs("Input message(Q to quit): ",stdout);
       fgets(message,BUF_SIZE,stdin);
   
       if (!strcmp(message,"q\n") || !strcmp(message,"Q\n"))
         break;
   
       write(sock,message,strlen(message));
       str_len = read(sock,message,BUF_SIZE-1);
       message[str_len] = 0;
       printf("Message from server: %s",message);
     }
     close(sock);
     return 0;
   }

   ---

   开子进程同时读和写:

   #include <me.h>
   #define BUF_SIZE 30 
   
   void read_routine(int,char*);
   void write_routine(int,char*);
   
   int main(int argc,char *argv[])
   {
     int sock;
     pid_t pid;
     char buf[BUF_SIZE];
     struct sockaddr_in serv_adr;
     if (argc != 3)
     {
       printf("Usage : %s <IP> <port> \n",argv[0]);
       exit(1);
     }
   
     sock = socket(AF_INET,SOCK_STREAM,0);
     memset(&serv_adr,0,sizeof(serv_adr));
     serv_adr.sin_family = AF_INET;
     serv_adr.sin_addr.s_addr = inet_addr(argv[1]);
     serv_adr.sin_port = htons(atoi(argv[2]));
   
     if (connect(sock,(struct sockaddr*)&serv_adr,sizeof(serv_adr)) == -1)
       error_handle("connect() error");
     //IO分割
     pid = fork();
     if (pid == 0)
     {
       write_routine(sock,buf);    
     }
     else 
     {
       read_routine(sock,buf);
     }
     close(sock);
     return 0;
   }
   
   void read_routine(int sock,char *buf)
   {
     while(1)
     {
       int str_len = read(sock,buf,BUF_SIZE);
       if (str_len == 0)
         return ;
       buf[str_len] = 0;
       printf("Message from server: %s",buf);
     }
   }
   
   void write_routine(int sock,char *buf)
   {
     while(1)
     {
       fgets(buf,BUF_SIZE,stdin);
       if (!strcmp(buf,"q\n") || !strcmp(buf,"Q\n"))
       {
         shutdown(sock,SHUT_WR);
         return ;
       }
       write(sock,buf,strlen(buf));
     }
   }

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