// asyncsocket.h
class AsyncSocket
{
public:
    void send(const QByteArray &msg);

public slots:
    void readyRead();

private:
    QTcpSocket *socket;
};

// asyncsocket.cpp
void AsyncSocket::send(const QByteArray &msg)
{
    if (socket->state() == QAbstractSocket::ConnectedState)
        socket->write(msg, msg.size());
}

void AsyncSocket::readyRead()
{
    qDebug() << "slot readyRead" << socket->bytesAvailable();
}

----- button clicked ------
slot readyRead 1460
slot readyRead 3508
slot readyRead 3900
----- button clicked ------
slot readyRead 2048
slot readyRead 3508
slot readyRead 3900
----- button clicked ------
slot readyRead 2048
slot readyRead 3900
----- button clicked ------
slot readyRead 1460
slot readyRead 2048
slot readyRead 3508
slot readyRead 3900

#  |     Source    |  Destination  | Prot| len  | Info
25 | 192.168.51.57 | 192.168.51.63 | TCP | 3954 | 50597 → 9025 [PSH, ACK] Seq=1 Ack=1 Win=64240 Len=3900

27 | 192.168.51.63 | 192.168.51.57 | TCP | 1514 | 9025 → 50597 [ACK] Seq=1 Ack=3901 Win=7300 Len=1460
28 | 192.168.51.63 | 192.168.51.57 | TCP |  642 | 9025 → 50597 [PSH, ACK] Seq=1461 Ack=3901 Win=7300 Len=588
30 | 192.168.51.63 | 192.168.51.57 | TCP | 1514 | 9025 → 50597 [ACK] Seq=2049 Ack=3901 Win=7300 Len=1460
31 | 192.168.51.63 | 192.168.51.57 | TCP |  446 | 9025 → 50597 [PSH, ACK] Seq=3509 Ack=3901 Win=7300 Len=392