gistfile1.cpp

#include <QNetworkAccessManager>
#include <QEventLoop>
#include <QUrl>
#include <QDebug>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QObject>
#include <QCoreApplication>
#include <QTimer>
int main(int argc, char**argv) {
		QCoreApplication app(argc,argv);
		QNetworkAccessManager *manager = new QNetworkAccessManager();
                  QNetworkReply* reply = manager->get(QNetworkRequest(QUrl("http://ipv4.download.thinkbroadband.com/5MB.zip")));
	
                  int buffersize = 1024*1024*1; //1MB
                  reply->setReadBufferSize(buffersize);
	
		QObject::connect(reply, &QNetworkReply::metaDataChanged, [reply,buffersize](){reply->setReadBufferSize(buffersize); qDebug() << buffersize;});

                  QEventLoop loop;
		QTimer::singleShot(15*1000,[&loop](){ loop.quit();});
                  loop.exec();

                  qDebug() << "Bytes available:" << reply->bytesAvailable() << "Buffer Size:" << buffersize;
}