qpacketprotocol.cpp

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#include "private/qpacketprotocol_p.h"

#include <QBuffer>
#include <QElapsedTimer>

QT_BEGIN_NAMESPACE

#define MAX_PACKET_SIZE 0x7FFFFFFF

class QPacketProtocolPrivate : public QObject
{
Q_OBJECT
public:
    QPacketProtocolPrivate(QPacketProtocol * parent, QIODevice * _dev)
    : QObject(parent), inProgressSize(-1), maxPacketSize(MAX_PACKET_SIZE),
      waitingForPacket(false), dev(_dev)
    {
        Q_ASSERT(4 == sizeof(qint32));

        QObject::connect(this, SIGNAL(readyRead()),
                         parent, SIGNAL(readyRead()));
        QObject::connect(this, SIGNAL(packetWritten()),
                         parent, SIGNAL(packetWritten()));
        QObject::connect(this, SIGNAL(invalidPacket()),
                         parent, SIGNAL(invalidPacket()));
        QObject::connect(dev, SIGNAL(readyRead()),
                         this, SLOT(readyToRead()));
        QObject::connect(dev, SIGNAL(aboutToClose()),
                         this, SLOT(aboutToClose()));
        QObject::connect(dev, SIGNAL(bytesWritten(qint64)),
                         this, SLOT(bytesWritten(qint64)));
    }

Q_SIGNALS:
    void readyRead();
    void packetWritten();
    void invalidPacket();

public Q_SLOTS:
    void aboutToClose()
    {
        inProgress.clear();
        sendingPackets.clear();
        inProgressSize = -1;
    }

    void bytesWritten(qint64 bytes)
    {
        Q_ASSERT(!sendingPackets.isEmpty());

        while(bytes) {
            if(sendingPackets.at(0) > bytes) {
                sendingPackets[0] -= bytes;
                bytes = 0;
            } else {
                bytes -= sendingPackets.at(0);
                sendingPackets.removeFirst();
                emit packetWritten();
            }
        }
    }

    void readyToRead()
    {
        bool gotPackets = false;
        while (true) {
            // Get size header (if not in progress)
            if (-1 == inProgressSize) {
                // We need a size header of sizeof(qint32)
                if (sizeof(qint32) > (uint)dev->bytesAvailable()) {
                    if (gotPackets)
                        emit readyRead();
                    return; // no more data available
                }

                // Read size header
                int read = dev->read((char *)&inProgressSize, sizeof(qint32));
                Q_ASSERT(read == sizeof(qint32));
                Q_UNUSED(read);

                // Check sizing constraints
                if (inProgressSize > maxPacketSize) {
                    QObject::disconnect(dev, SIGNAL(readyRead()),
                                        this, SLOT(readyToRead()));
                    QObject::disconnect(dev, SIGNAL(aboutToClose()),
                                        this, SLOT(aboutToClose()));
                    QObject::disconnect(dev, SIGNAL(bytesWritten(qint64)),
                                        this, SLOT(bytesWritten(qint64)));
                    dev = 0;
                    emit invalidPacket();
                    return;
                }

                inProgressSize -= sizeof(qint32);
            } else {
                inProgress.append(dev->read(inProgressSize - inProgress.size()));

                if (inProgressSize == inProgress.size()) {
                    // Packet has arrived!
                    packets.append(inProgress);
                    inProgressSize = -1;
                    inProgress.clear();

                    waitingForPacket = false;
                    gotPackets = true;
                } else {
                    if (gotPackets)
                        emit readyRead();
                    return; // packet in progress is not yet complete
                }
            }
        }
    }

public:
    QList<qint64> sendingPackets;
    QList<QByteArray> packets;
    QByteArray inProgress;
    qint32 inProgressSize;
    qint32 maxPacketSize;
    bool waitingForPacket;
    QIODevice * dev;
};

QPacketProtocol::QPacketProtocol(QIODevice * dev, QObject * parent)
: QObject(parent), d(new QPacketProtocolPrivate(this, dev))
{
    Q_ASSERT(dev);
}

QPacketProtocol::~QPacketProtocol()
{
}

qint32 QPacketProtocol::maximumPacketSize() const
{
    return d->maxPacketSize;
}

qint32 QPacketProtocol::setMaximumPacketSize(qint32 max)
{
    if(max > (signed)sizeof(qint32))
        d->maxPacketSize = max;
    return d->maxPacketSize;
}

QPacketAutoSend QPacketProtocol::send()
{
    return QPacketAutoSend(this);
}

void QPacketProtocol::send(const QPacket & p)
{
    if(p.b.isEmpty())
        return; // We don't send empty packets

    qint64 sendSize = p.b.size() + sizeof(qint32);

    d->sendingPackets.append(sendSize);
    qint32 sendSize32 = sendSize;
    qint64 writeBytes = d->dev->write((char *)&sendSize32, sizeof(qint32));
    Q_ASSERT(writeBytes == sizeof(qint32));
    writeBytes = d->dev->write(p.b);
    Q_ASSERT(writeBytes == p.b.size());
}

qint64 QPacketProtocol::packetsAvailable() const
{
    return d->packets.count();
}

void QPacketProtocol::clear()
{
    d->packets.clear();
}

QPacket QPacketProtocol::read()
{
    if(0 == d->packets.count())
        return QPacket();

    QPacket rv(d->packets.at(0));
    d->packets.removeFirst();
    return rv;
}

/*
   Returns the difference between msecs and elapsed. If msecs is -1,
   however, -1 is returned.
*/
static int qt_timeout_value(int msecs, int elapsed)
{
    if (msecs == -1)
        return -1;

    int timeout = msecs - elapsed;
    return timeout < 0 ? 0 : timeout;
}

bool QPacketProtocol::waitForReadyRead(int msecs)
{
    if (!d->packets.isEmpty())
        return true;

    QElapsedTimer stopWatch;
    stopWatch.start();

    d->waitingForPacket = true;
    do {
        if (!d->dev->waitForReadyRead(msecs))
            return false;
        if (!d->waitingForPacket)
            return true;
        msecs = qt_timeout_value(msecs, stopWatch.elapsed());
    } while (true);
}

QIODevice * QPacketProtocol::device()
{
    return d->dev;
}

QPacket::QPacket()
: QDataStream(), buf(0)
{
    buf = new QBuffer(&b);
    buf->open(QIODevice::WriteOnly);
    setDevice(buf);
    setVersion(QDataStream::Qt_4_7);
}

QPacket::~QPacket()
{
    if(buf) {
        delete buf;
        buf = 0;
    }
}

QPacket::QPacket(const QPacket & other)
: QDataStream(), b(other.b), buf(0)
{
    buf = new QBuffer(&b);
    buf->open(other.buf->openMode());
    setDevice(buf);
}

QPacket::QPacket(const QByteArray & ba)
: QDataStream(), b(ba), buf(0)
{
    buf = new QBuffer(&b);
    buf->open(QIODevice::ReadOnly);
    setDevice(buf);
}

bool QPacket::isEmpty() const
{
    return b.isEmpty();
}

QByteArray QPacket::data() const
{
    return b;
}

void QPacket::clear()
{
    QBuffer::OpenMode oldMode = buf->openMode();
    buf->close();
    b.clear();
    buf->setBuffer(&b); // reset QBuffer internals with new size of b.
    buf->open(oldMode);
}

QPacketAutoSend::QPacketAutoSend(QPacketProtocol * _p)
: QPacket(), p(_p)
{
}

QPacketAutoSend::~QPacketAutoSend()
{
    if(!b.isEmpty())
        p->send(*this);
}

QT_END_NAMESPACE

#include <qpacketprotocol.moc>