QTcpSocket readyRead and buffer size

[pdoria]

Hi all,

Does anyone know the size at which the buffer is filled when readyRead signal is emitted?

Thanks in advance.
Pedro Doria Meunier.

[seveninches]

As soon as there is something in the buffer (even if it's a single byte). Look in bool QAbstractSocketPrivate::_q_canReadNotification() in src/network/qabstractsocket.cp

[pdoria]

Txs for your answer.

I've got a situation here where I cannot determine whether it's the device tx scheme or the size of the socket read buffer than come into play...

The thing is:
The device reports n Bytes to be read (the physical thing).
and the readyRead gets fired at 255 bytes.

So when I try to parse the data I'm n bytes short.
Dirty solution:
In the method connected to the readyRead signal I compare the tcpSocket.bytesAvailable() to the # of bytes the device says it wants to transmit.
In a nutshell:

if (totalBytes < dataLength)
{
	tcpSocket.waitForReadyRead(5000);
}

if (totalBytes < dataLength)
{
	tcpSocket.waitForReadyRead(5000);
}

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Bottom line (and question ):
Is there anyway to wait until n Bytes are available in the buffer instead of n milliseconds?

Thanks in advance.
Pedro Doria Meunier.

[aamer4yu]

TCP is a stream based protocol... you will get data... but no fixed length.

to read N bytes... u can connect the readyRead to a slot, and have a static buffer there. When the bytes read equals N bytes, u can call some member function to process the N bytes.

MySocket::OnReadyRead()
{
static buffer[1024];
buffer = readAll();
if(buffer.lenght()  >= m_N)
{
processNbytes(buffer);
buffer.clear();
}
}

MySocket::OnReadyRead()
{
static buffer[1024];
buffer = readAll();
if(buffer.lenght()  >= m_N)
{
processNbytes(buffer);
buffer.clear();
}
}

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[Bitto]

It's 1000000 times better to just leave the data in the socket, and return. The next time this signal is fired, you'll probably have enough. So:

void MyClass::slotConnectedToReadyRead()
{
    // Bad:
    static QByteArray data; // static data is bad
    data += readAll(); // unnecessary copy
    if (data.size() < 256)
        return;
 
    // Good:
    if (bytesAvailable() < 256)
        return;
    QByteArray data = read(256); // local variable is good
}

void MyClass::slotConnectedToReadyRead()
{
    // Bad:
    static QByteArray data; // static data is bad
    data += readAll(); // unnecessary copy
    if (data.size() < 256)
        return;

    // Good:
    if (bytesAvailable() < 256)
        return;
    QByteArray data = read(256); // local variable is good
}

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