[Solved] QTcpSocket connection data received is empty after certain limit

[Abin]

HI,

I am trying to send data between server and client using qtcpsocket connection. When I send small size data everything is fine. But when size increases the data read from tcpsocket goes empty :(.

// data to be sent

@int ClientService::syncMasters(SyncMaster syncMasterData)
{
qDebug() << Q_FUNC_INFO << "Invoked";

int syncStatus = -1;

if(enableConnection())
{
    qDebug() << Q_FUNC_INFO << "connection enabled";
    //  typecast to ensure cross platform compatibility
    const qint32 mode_int = static_cast<qint32>(SYNC_MASTERS_QUERY);
    QByteArray block;
    QDataStream outputStream(&block, QIODevice::WriteOnly);
    outputStream.setVersion(QDataStream::Qt_4_0);
    outputStream << (quint16)0;
    outputStream << mode_int;       // saying query mode to server

    // group master data
    outputStream << syncMasterData.groupMasterList.count();
    qDebug() <<  "groupmaster count" <<
                                syncMasterData.groupMasterList.count();

    foreach (GroupMaster groupMasterItem, syncMasterData.groupMasterList)
    {
        outputStream << groupMasterItem.groupCode;
        outputStream << groupMasterItem.groupDescription;
        outputStream << groupMasterItem.kotPrinterNo;
        outputStream << groupMasterItem.image;
        outputStream << groupMasterItem.sortId;
    }

    // subgroup master data
    outputStream << syncMasterData.subGroupMasterList.count();
    qDebug() << Q_FUNC_INFO << "subgroupmaster count" <<
                                syncMasterData.subGroupMasterList.count();

    foreach (SubGroupMaster subGroupMasterItem,
                            syncMasterData.subGroupMasterList)
    {
        outputStream << subGroupMasterItem.groupCode;
        outputStream << subGroupMasterItem.subGroupCode;
        outputStream << subGroupMasterItem.subGroupDescription;

    }

    // item master data
    outputStream << syncMasterData.itemMasterList.count();
    qDebug() << Q_FUNC_INFO << "item master count" <<
                                syncMasterData.itemMasterList.count();

    foreach (ItemMaster ItemMasterItem, syncMasterData.itemMasterList)
    {
        outputStream << ItemMasterItem.itemCode;
        outputStream << ItemMasterItem.itemName;
        outputStream << ItemMasterItem.groupCode;
        outputStream << ItemMasterItem.subGroupCode;
        outputStream << ItemMasterItem.imagePath;
        outputStream << ItemMasterItem.productId;
        outputStream << ItemMasterItem.itemPriceType;
        outputStream << ItemMasterItem.itemPrice;
        outputStream << ItemMasterItem.kotPrinterNumber;
        outputStream << ItemMasterItem.sortId;
    }

    // side item master data
    outputStream << syncMasterData.sideItemMasterList.count();
    .
    .
    . ... // similar data is sent
    
    outputStream.device()->seek(0);
    outputStream << (quint16)(block.size() - sizeof(quint16));

    if(sendToServer(block))
    {
        qDebug() << Q_FUNC_INFO << "query sent to server successfully";

        if (waitForServerResponse())
        {
            qDebug() << Q_FUNC_INFO << "read set status from server";

            QDataStream inputStream(&m_socket);
            inputStream.setVersion(QDataStream::Qt_4_0);
            inputStream >> syncStatus;
        }
    }

    disableConnection();
}

qDebug() << Q_FUNC_INFO << "Exits" << syncStatus;
return syncStatus;

}@

// read is also similar

@void ServerFunctionThread::syncMasters()
{
qDebug() << Q_FUNC_INFO << "Invoked";

SyncMaster syncMasterData;

int groupCount      = 0,
subGroupCount   = 0,
itemCount       = 0,
sideItemCount   = 0,
priceCount      = 0;

QDataStream inputStream(&tcpSocket);
inputStream.setVersion(QDataStream::Qt_4_0);

// group master data reception
inputStream >> groupCount;
qDebug() << Q_FUNC_INFO << "group master Count" << groupCount;

while (groupCount--)
{
    GroupMaster groupMasterItem;
    inputStream >> groupMasterItem.groupCode;
    inputStream >> groupMasterItem.groupDescription;
    inputStream >> groupMasterItem.kotPrinterNo;
    inputStream >> groupMasterItem.image;
    inputStream >> groupMasterItem.sortId;

    syncMasterData.groupMasterList.append(groupMasterItem);

    qDebug() << Q_FUNC_INFO <<
    "code"      << groupMasterItem.groupCode         <<
    "desc"      << groupMasterItem.groupDescription  <<
    "kot "      << groupMasterItem.kotPrinterNo      <<
    "image"     << groupMasterItem.image             <<
    "sort id"   << groupMasterItem.sortId;

}@

.

Can someone help me to know if there a size limit to the data written into QDataStream...
Because from my logs connection is still alive and i get response. But data received is empty after few data is read.

[Abin]

// enabling connection
@bool ClientService::enableConnection()
{
const int iTimeout = 5 * 1000;
m_socket.connectToHost(settings.getServerIP(), PORT);
if (!m_socket.waitForConnected(iTimeout))
{
emit error();
qDebug() << m_socket.errorString();
return false;
}
return true;
}

// send data to server once all data is written into QDataStream
bool ClientService::sendToServer(QByteArray block)
{
bool sendStatus = false;
if (QTcpSocket::ConnectedState == m_socket.state())
{
if (-1 != m_socket.write(block))
{
m_socket.waitForBytesWritten();
sendStatus = true;
}
else
{}
}
else
{}
if (!sendStatus)
{
emit error();
}
return sendStatus;
}

// wait until response is received from server

bool ClientService::waitForServerResponse()
{
qDebug() << "Invoked";
const int iTimeout = 5 * 1000;
while (m_socket.bytesAvailable() < (int)sizeof(quint16))
{
if (!m_socket.waitForReadyRead(iTimeout))
{
emit error();
qDebug() << m_socket.errorString();
return false;
}
}

quint16 blockSize;
QDataStream inputStream(&m_socket);
inputStream.setVersion(QDataStream::Qt_4_0);
inputStream >> blockSize;

while (m_socket.bytesAvailable() < blockSize)
{
if (!m_socket.waitForReadyRead(iTimeout))
{
emit error();
qDebug() << m_socket.errorString();
return false;
}
}

return true;
}@

// disable the connection once response is received

@void ClientService::disableConnection()
{
qDebug() << "Invoked";
m_socket.disconnectFromHost();
qDebug() << "Exits";
return;
}@

[SGaist]

Hi,

The thing I see is that you use your socket as a QByteArray which it's not. You should rather read the content of your socket when data arrived in a QByteArray, then once your byte array is of the proper size parse it.

Hope it helps

[Abin]

Thanks SGaist,

I use QByteArray to create data that has to be send through socket. And at time to send I write this QByteArray to the socket. I follow this as found from qt examples...

The issue is resolved now. :)

The data size passed from client to server caused the issue. Since I used quint16 when the size of data becomes more the server doesn't get to know the exact incoming data size. So I changed the type to quint32. And the issue is resolved.

@outputStream << (quint32)0;@

// and end

@outputStream.device()->seek(0);
outputStream << (quint32)(block.size() - sizeof(quint32));@

and server side also waits for data size received in quint32