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#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();

}