linux TCP客户端增加接收截止延迟

  if ( connect(sock, (struct sockaddr*)&addr, sizeof(addr)) != -1 )
  {
      printf("connect ok\n");
      if((sockLen=send(sock,"connect ok",strlen("connect ok"),0))==-1)
      {
          printf("send error\n");
          goto innererror;
      }
      while(1)
      {
          fd_set readfds;
          tv.tv_sec = 0;                 //设置超时时间
          tv.tv_usec = 50000;
          FD_ZERO(&readfds);
          FD_SET(sock,&readfds);
          ret = select(sock+1,&readfds,NULL,NULL,&tv);
          if(FD_ISSET(sock,&readfds))     //检测sock中有无数据
          {
             if((sockLen=recv(sock,chCmd,sizeof(chCmd),0))>0)
             {
                printf("chCmd=%s\n",chCmd);
                gpio.port = E;
                gpio.num = 0;
                gpio.data = 1;
                write(fd_gpio,&gpio,sizeof(struct gpio_config));   //485串口发送
                write(fd_uart[GPRS_PORT485],chCmd,strlen(chCmd));  //将获取数据发送到主机
              }
              else if(!sockLen)
             {
                printf("%d client close",sockLen);
                goto innererror;
             }
          }
          else  //网络无数据时检测485串口有无数据
         {
             bzero(string,1024);
             gpio.port = E;
             gpio.num = 0;
             gpio.data = 0;
             write(fd_gpio,&gpio,sizeof(struct gpio_config));   //485串口接收
             tcflush(fd_uart[GPRS_PORT485],TCIOFLUSH);
             read_datas_tty(fd_uart[GPRS_PORT485],string,0,200000);
             if(strlen(string) != 0)
             {
                if((sockLen=send(sock,string,strlen(string),0))==-1)
                {
                   printf("send error\n");
                }
             }
         }
      }
  }