- Qt 5.5
- Qt Network
- Torrent Example
- ratecontroller.cpp Example File
- Qt 5.5.1 Reference Documentation

# ratecontroller.cpp Example File

torrent/ratecontroller.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
    **
    ** "Redistribution and use in source and binary forms, with or without
    ** modification, are permitted provided that the following conditions are
    ** met:
    **   * Redistributions of source code must retain the above copyright
    **     notice, this list of conditions and the following disclaimer.
    **   * Redistributions in binary form must reproduce the above copyright
    **     notice, this list of conditions and the following disclaimer in
    **     the documentation and/or other materials provided with the
    **     distribution.
    **   * Neither the name of The Qt Company Ltd nor the names of its
    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
    **
    **
    ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
    **
    ** $QT_END_LICENSE$
    **
    ****************************************************************************/

    #include "peerwireclient.h"
    #include "ratecontroller.h"

    #include <QtCore>

    Q_GLOBAL_STATIC(RateController, rateController)

    RateController *RateController::instance()
    {
        return rateController();
    }

    void RateController::addSocket(PeerWireClient *socket)
    {
        connect(socket, SIGNAL(readyToTransfer()), this, SLOT(scheduleTransfer()));
        socket->setReadBufferSize(downLimit * 4);
        sockets << socket;
        scheduleTransfer();
    }

    void RateController::removeSocket(PeerWireClient *socket)
    {
        disconnect(socket, SIGNAL(readyToTransfer()), this, SLOT(scheduleTransfer()));
        socket->setReadBufferSize(0);
        sockets.remove(socket);
    }

    void RateController::setDownloadLimit(int bytesPerSecond)
    {
        downLimit = bytesPerSecond;
        foreach (PeerWireClient *socket, sockets)
            socket->setReadBufferSize(downLimit * 4);
    }

    void RateController::scheduleTransfer()
    {
        if (transferScheduled)
            return;
        transferScheduled = true;
        QTimer::singleShot(50, this, SLOT(transfer()));
    }

    void RateController::transfer()
    {
        transferScheduled = false;
        if (sockets.isEmpty())
            return;

        int msecs = 1000;
        if (!stopWatch.isNull())
            msecs = qMin(msecs, stopWatch.elapsed());

        qint64 bytesToWrite = (upLimit * msecs) / 1000;
        qint64 bytesToRead = (downLimit * msecs) / 1000;
        if (bytesToWrite == 0 && bytesToRead == 0) {
            scheduleTransfer();
            return;
        }

        QSet<PeerWireClient *> pendingSockets;
        foreach (PeerWireClient *client, sockets) {
            if (client->canTransferMore())
                pendingSockets << client;
        }
        if (pendingSockets.isEmpty())
            return;

        stopWatch.start();

        bool canTransferMore;
        do {
            canTransferMore = false;
            qint64 writeChunk = qMax<qint64>(1, bytesToWrite / pendingSockets.size());
            qint64 readChunk = qMax<qint64>(1, bytesToRead / pendingSockets.size());

            QSetIterator<PeerWireClient *> it(pendingSockets);
            while (it.hasNext() && (bytesToWrite > 0 || bytesToRead > 0)) {
                PeerWireClient *socket = it.next();
                if (socket->state() != QAbstractSocket::ConnectedState) {
                    pendingSockets.remove(socket);
                    continue;
                }

                bool dataTransferred = false;
                qint64 available = qMin<qint64>(socket->socketBytesAvailable(), readChunk);
                if (available > 0) {
                    qint64 readBytes = socket->readFromSocket(qMin<qint64>(available, bytesToRead));
                    if (readBytes > 0) {
                        bytesToRead -= readBytes;
                        dataTransferred = true;
                    }
                }

                if (upLimit * 2 > socket->bytesToWrite()) {
                    qint64 chunkSize = qMin<qint64>(writeChunk, bytesToWrite);
                    qint64 toWrite = qMin(upLimit * 2 - socket->bytesToWrite(), chunkSize);
                    if (toWrite > 0) {
                        qint64 writtenBytes = socket->writeToSocket(toWrite);
                        if (writtenBytes > 0) {
                            bytesToWrite -= writtenBytes;
                            dataTransferred = true;
                        }
                    }
                }

                if (dataTransferred && socket->canTransferMore())
                    canTransferMore = true;
                else
                    pendingSockets.remove(socket);
            }
        } while (canTransferMore && (bytesToWrite > 0 || bytesToRead > 0) && !pendingSockets.isEmpty());

        if (canTransferMore || bytesToWrite == 0 || bytesToRead == 0)
            scheduleTransfer();
    }