DriftingDateTime.h

#ifndef DRIFTINGDATETIME_H
#define DRIFTINGDATETIME_H
 
#include "TwoPhaseSignal.h"
 
#include <QDateTime>
#include <QMutex>
#include <QPointer>

class DriftingDateTimeSingleton : public TwoPhaseSignal {
    Q_OBJECT
 
  private:
    // As this is a subclass of QObject,
    // it lives in a thread: Whatever thread
    // first called getSingleton().
    DriftingDateTimeSingleton();
    qint64 driftMS;
    mutable QMutex mutex;
 
    static QPointer<DriftingDateTimeSingleton> singleton;
 
  private:
    void setDriftInner(qint64 ms);
 
  public:
    static DriftingDateTimeSingleton &getSingleton();

    qint64 drift() const;

    inline QDateTime currentDateTimeUtc() const {
        return QDateTime::currentDateTimeUtc().addMSecs(drift());
    }

    inline QDateTime currentDateTimeLocal() const {
        return QDateTime::currentDateTime().addMSecs(drift());
    }

    inline qint64 currentMSecsSinceEpoch() const {
        return QDateTime::currentMSecsSinceEpoch() + drift();
    }

    inline qint64 currentSecsSinceEpoch() const {
        return currentMSecsSinceEpoch() / 1000;
    }
 
  public slots:
    void setDrift(qint64 ms);
    void onPlumbingCompleted() const;
 
  signals:
    void driftChanged(qint64 new_drift) const;
};

namespace DriftingDateTime {
inline qint64 drift() {
    return DriftingDateTimeSingleton::getSingleton().drift();
}

inline void setDrift(qint64 ms) {
    DriftingDateTimeSingleton::getSingleton().setDrift(ms);
}
 
inline QDateTime currentDateTimeUtc() {
    return DriftingDateTimeSingleton::getSingleton().currentDateTimeUtc();
}
 
inline QDateTime currentDateTimeLocal() {
    return DriftingDateTimeSingleton::getSingleton().currentDateTimeLocal();
}
 
inline qint64 currentMSecsSinceEpoch() {
    return DriftingDateTimeSingleton::getSingleton().currentMSecsSinceEpoch();
}
 
inline qint64 currentSecsSinceEpoch() {
    return DriftingDateTimeSingleton::getSingleton().currentSecsSinceEpoch();
}
}; // namespace DriftingDateTime
 
#endif // DRIFTINGDATETIME_H