GRS系统总结2

今天只写一个问题。

tcp字节流接收问题，tcp是以流的形式发送到应用层的，比如1000个字节为单位，我们每次希望recv 1000个字节，但是它是以流的形式，也就是说也许这次只到了800个字节，因此我们只收到800个字节，那么下一次我们再去尝试读流中字节时，又到了1000个字节，怎么办呢？  会默认去把前面剩下的200个字节读完，然后读这一次的800个字节， 最后发现socket还可用 就继续读剩下的200 个字节。

 

 1000   800   1000  200

 1000。。1000。。1000。。

 

 

可以设一个标志位来让每次在读完了1000个字节后再进行某个操作。

 

 

/*监听服务器socket，是否有消息发来*/
            int ret = select(sockfd+1,&grs_readset,NULL,NULL,grs_timeout);    
            if (ret == -1)
            {                
                break;
            }else if(ret == 0)
            {                
                break;
            }else /*有消息发来*/
            {    
                if (FD_ISSET(sockfd,&grs_readset))
                {    
                    if (!over_flag)
                    {
                        if ((recvbytes=recv(sockfd, (char *)resvmsg+totalbytes, sizeof(grs_session_info_c)-totalbytes,0)) ==-1)
                        {
                            perror("recv");
                            break;
                        }
                        totalbytes += recvbytes;
                    }else
                    if ((totalbytes=recv(sockfd, (char *)resvmsg, sizeof(grs_session_info_c),0)) ==-1)
                    {
                        perror("recv");
                        break;
                    }
                    GRUC_DBG("recvbytes = %d\r\n", recvbytes);
                    
                    if (totalbytes == sizeof(grs_session_info_c))
                    {    
                        over_flag = 1;
                        totalbytes = 0;                        
                        //notify GUI there is msg from server!                

                        grs_session_info sinfo;
                        sessionInfoC2Qt(*resvmsg,&sinfo);
                         
                        gpGuiCltObj->notifyRecvMsg(sinfo);
                    }else if(totalbytes <= 0)
                    {                                                
                        FD_CLR(sockfd,&allreadset);                    
                        needStop = 1;             //服务器断开连接，让客户端停止            

                        break;
                    }else
                    {
                        over_flag = 0;                        
                    }
                    FD_SET(sockfd,&allreadset); /*用allreadset保存，每次执行select会把以前的洗掉*/
                }
            }