How to limit TCP writes to particular size and then block untlil the data is read

[wysota]

One last query: is there anything similar to QAbstractSocket::setReadBufferSize( qint64 size ) for WriteBufferSize(..) ?

No, I can't see an equivalent but you can implement it by subclassing QTcpSocket and reimplementing write related virtual methods.

Then i can precisely control how much memory consumption i want befor Socket blocks on further writes.

Not entirely. Remember that the operating system has buffers of its own.