Timer.h

//	This file is part of the continued Journey MMORPG client
//	Copyright (C) 2015-2019  Daniel Allendorf, Ryan Payton
//
//	This program is free software: you can redistribute it and/or modify
//	it under the terms of the GNU Affero 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 Affero General Public License for more details.
//
//	You should have received a copy of the GNU Affero General Public License
//	along with this program.  If not, see <https://www.gnu.org/licenses/>.
#pragma once

#include <chrono>
#include <cstdint>

#include "Template/Singleton.h"

namespace ms {
// Small class for measuring elapsed time between game loops.
class Timer : public Singleton<Timer> {
public:
    Timer() { start(); }

    ~Timer() override = default;

    // Start the timer by setting the last measurement to now.
    void start() { point = clock::now(); }

    // Return time elapsed since the last measurement.
    int64_t stop() {
        clock::time_point last = point;
        point = clock::now();

        auto duration =
            std::chrono::duration_cast<std::chrono::microseconds>(point - last);
        return duration.count();
    }

private:
    using clock = std::chrono::high_resolution_clock;

    clock::time_point point;
};

// Small class for measuring elapsed time given a specific start time.
class ContinuousTimer : public Singleton<ContinuousTimer> {
public:
    using point = std::chrono::time_point<std::chrono::steady_clock>;

    ContinuousTimer() { start(); }

    ~ContinuousTimer() override = default;

    // Return now from the clock to be used to calculate elapsed time later.
    point start() { return clock::now(); }

    // Return time elapsed since the last measurement provided.
    int64_t stop(point last) {
        auto now = clock::now();

        auto duration =
            std::chrono::duration_cast<std::chrono::microseconds>(now - last);
        return duration.count();
    }

private:
    using clock = std::chrono::steady_clock;
};
}  // namespace ms