Socket Reading causes CPU to max out

Hi,

Ok, so im trying to asynchronously read data from a QTcpSocket, in a slot connected to its readyRead() signal.

Every time the signal gets emitted, I readAll() and append it to a QByteArray buffer, after each readAll() call, I check to see if the buffer has the termination bytes in to know if I have all my data so I can stop.

With 3mb of data coming down, it works fine but CPU usage is way to high and im after a solution if possible.

Code:

---

void nclient::readSocket() // connected to QTcpSocket::readyRead()
{
     buffer.append(client->readAll());  // put available bytes into buffer  
...
// buffer testing logic to find if all data has been received
}

---

Its defiantly the readAll() calls that are maxing out the CPU and not my checking code, I can only assume its down to the large volumes of readyRead() signals, I think its 1 per packet and there's obviously 1000s of packets for a 3mb transmission...

I don't know the size of the data in advance, so I cant enforce a minimum bytesAvailable size before reading data, all I know is how the stream ends.

I would be really grateful if anyone can point me in the right direction, basically so I can download the stream without resource hogging and stop when I find the ending bytes.

Thanks,

Jack

I'd rather think this is append() that is eating all your cpu power, not readAll().

Hmm thanks alot, assuming the append() call is what's sucking up resources, could you recommend a more efficient approach to keeping a buffer maintained in memory?

Why assume when you can check it out? Surround the calls with QTime::elapsed and you'll be certain.

If you append to a large buffer, the buffer has to be reallocated and the data has to be copied to a new buffer which takes time. Either allocate some space in advance or store the data in several buffers.