qt - QT QTcpSocket miss some data after start write data to server

Question

I get sine wave from server though TCP and plot it. Everything seems to be fine until I start sending something back at c>1000. After one byte sent, I still get data but the waveform of sine wave is changed. I'm sure that there are some missed data but I can't find bugs in my code. The transmission rate is about 1M bps.

The question is

1. When I write something to server, how it effects to socket?

2. Why the socket miss some data?

3. How can I fix it?

   ssTcpClient::ssTcpClient(QObject *parent) :
   QObject(parent)
   {
       socket = new QTcpSocket(this);
       connect(socket, SIGNAL(connected()),
               this, SLOT(on_connected()));
       connect(socket, SIGNAL(disconnected()),
               this, SLOT(on_disconnected()));
   }
   
   void ssTcpClient::on_connected()
   {
       qDebug() << "Client: Connection established.";
       connect(socket, SIGNAL(readyRead()),
               this, SLOT(on_readyRead()));
       in = new QDataStream(socket);
   }
   
   void ssTcpClient::on_readyRead(){
       static quint32 c = 0;
       qDebug() << "c" << c++;
   
       QVector<quint8> data;
       quint8 buf;
       while(socket->bytesAvailable()>0){
           //read data to buffer
           *in >> buf;
           data.append(buf);
       }
       //process data
       emit data_read(data);
   
       //if there are over 1000 data then send something back
       if(c>1000){
           char msg[10];
           msg[0] = 'c';
           socket->write(msg,1);
           socket->flush();
       }
   
   }
   

Answer 1

您不能依赖 TCP 流量来完成，数据以无法确定的块的形式到达。

您正在使用QDataStream从套接字读取数据。这是一个非常糟糕的主意，因为QDataStream假设您拥有完整的数据集。如果没有足够的数据，它将默默地失败。

我建议您修改您的数据源，以便它首先发送一个字节数，或者它发送某种终止序列，您可以注意它告诉您已收到足够的处理。