/****************************************************************************
**
** Copyright (C) 2021 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt VS Tools.
**
** $QT_BEGIN_LICENSE:GPL-EXCEPT$
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** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
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** GNU General Public License Usage
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** General Public License version 3 as published by the Free Software
** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
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using System.Diagnostics;

namespace QtVsTools
{
    public class Timestamp : Concurrent<Timestamp>
    {
        long LastTimestamp { get; set; }
        long GetStrictMonotonicTimestamp()
        {
            lock (CriticalSection) {
                long t = Stopwatch.GetTimestamp();
                if (t <= LastTimestamp)
                    t = LastTimestamp + 1;
                return (LastTimestamp = t);
            }
        }

        static Timestamp _Instance;
        static Timestamp Instance =>
            StaticThreadSafeInit(() => _Instance, () => _Instance = new Timestamp());

        public static long Next()
        {
            return Instance.GetStrictMonotonicTimestamp();
        }
    }
}