TrafficDataSource_Udp.h

/***************************************************************************
 *   Copyright (C) 2021-2026 by Stefan Kebekus                             *
 *   stefan.kebekus@gmail.com                                              *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 3 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/
 
#pragma once
 
#include <QElapsedTimer>
#include <QPointer>
#include <QUdpSocket>
 
#include "traffic/TrafficDataSource_AbstractSocket.h"
 
#include <optional>
 
using namespace Qt::Literals::StringLiterals;
 
 
namespace Traffic {

class TrafficDataSource_Udp : public TrafficDataSource_AbstractSocket {
    Q_OBJECT
 
public:
    TrafficDataSource_Udp(bool isCanonical, quint16 port, QObject *parent = nullptr);
 
    // Standard destructor
    ~TrafficDataSource_Udp() override;
 
 
 
    //
    // Properties
    //

    Q_PROPERTY(quint16 port READ port CONSTANT)
 
 
 
    //
    // Getter Methods
    //
 
    
    [[nodiscard]] QString dataFormat() const override { return u"GDL90, XGPS"_s; }

    [[nodiscard]] QString icon() const override { return u"/icons/material/ic_wifi.svg"_s; }

    [[nodiscard]] auto sourceName() const -> QString override
    {
        return tr("UDP connection to port %1").arg(m_port);
    }

    [[nodiscard]] quint16 port() const
    {
        return m_port;
    }
 
 
public slots:
    void connectToTrafficReceiver() override;

    void disconnectFromTrafficReceiver() override;
 
private slots:
    // Read messages from the socket datagrams and passes them on for
    // processing: XGPS/XTRA datagrams are routed to processXGPSString, all
    // other messages are passed on to processGDLMessage.
    void onReadyRead();
 
private:
    Q_DISABLE_COPY_MOVE(TrafficDataSource_Udp)
 
    QPointer<QUdpSocket> m_socket;
    quint16 m_port;
 
    // The same datagram is often delivered on several network interfaces. To
    // sort out these duplicates, we store the hashes of recently received
    // datagrams together with their arrival time in a circular array. A
    // datagram counts as a duplicate only if an identical one arrived within
    // the last duplicateWindowMs milliseconds. Without the time limit,
    // legitimately recurring datagrams (e.g. XGPS reports from a stationary
    // source, which carry no timestamp) would be suppressed forever.
    // The cache is cleared on every (re)connect. The nextHashIndex points to
    // the next array entry that will be re-written.
    struct DatagramRecord
    {
        size_t hash = 0;
        qint64 arrivalMs = 0;
    };
    static constexpr qint64 duplicateWindowMs = 500;
    QVector<std::optional<DatagramRecord>> receivedDatagrams = QVector<std::optional<DatagramRecord>>(512, std::nullopt);
    qsizetype nextHashIndex = 0;
    QElapsedTimer m_arrivalClock;
 
};
 
} // namespace Traffic