Timer.h

/*
╔══════════════════════════════════════════════════════════════════════════════╗
║                       SIMPLY POWERFUL TOOLKIT (SPTK)                         ║
╟──────────────────────────────────────────────────────────────────────────────╢
║  copyright            © 1999-2022 Alexey Parshin. All rights reserved.       ║
║  email                alexeyp@gmail.com                                      ║
╚══════════════════════════════════════════════════════════════════════════════╝
┌──────────────────────────────────────────────────────────────────────────────┐
│   This library is free software; you can redistribute it and/or modify it    │
│   under the terms of the GNU Library General Public License as published by  │
│   the Free Software Foundation; either version 2 of the License, or (at your │
│   option) any later version.                                                 │
│                                                                              │
│   This library 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 Library   │
│   General Public License for more details.                                   │
│                                                                              │
│   You should have received a copy of the GNU Library General Public License  │
│   along with this library; if not, write to the Free Software Foundation,    │
│   Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.               │
│                                                                              │
│   Please report all bugs and problems to alexeyp@gmail.com.                  │
└──────────────────────────────────────────────────────────────────────────────┘
*/
 
#pragma once
 
#include "Semaphore.h"
#include "Thread.h"
 
#include <functional>
#include <set>
 
namespace sptk {
 
class TimerThread;
 
class SP_EXPORT Timer
{
public:
    struct EventId {
        uint64_t serial {++Timer::nextSerial}; 
        DateTime when;                         
        explicit EventId(const DateTime& when);
    };
 
    class EventData
    {
        friend class Timer;
 
    public:
        using Callback = std::function<void()>;
 
        EventData(const EventData& other) = delete;
 
        const EventId& getId() const;
 
        EventData& operator=(const EventData& other) = delete;
 
        EventData(const DateTime& timestamp, const Callback& eventCallback, std::chrono::milliseconds repeatEvery,
                  int repeatCount = -1);
 
        const DateTime& getWhen() const
        {
            return m_id.when;
        }
 
        bool shift(std::chrono::milliseconds interval)
        {
            if (m_repeatCount == 0)
            {
                return false;
            }
 
            if (m_repeatCount > 0)
            {
                m_id.when = m_id.when + interval;
                --m_repeatCount;
                return true;
            }
 
            // Repeat count < 0 - infinite repeats
            m_id.when = m_id.when + interval;
            return true;
        }
 
        const std::chrono::milliseconds& getInterval() const
        {
            return m_repeatInterval;
        }
 
        int getRepeatCount() const
        {
            return m_repeatCount;
        }
 
        bool fire();
 
    private:
        EventId m_id;                               
        Callback m_callback;                        
        std::chrono::milliseconds m_repeatInterval; 
        int m_repeatCount {0};                      
    };
 
    using Event = std::shared_ptr<EventData>;
 
    Timer() = default;
 
    Timer(const Timer& other) = delete;
 
    virtual ~Timer();
 
    Event fireAt(const DateTime& timestamp, const EventData::Callback& eventCallback);
 
    Event repeat(std::chrono::milliseconds interval, const EventData::Callback& eventCallback, int repeatCount = -1);
 
    void cancel(const Event& event);
 
    void cancel();
 
protected:
    void unlink(const Event& event); 
 
private:
    mutable std::mutex m_mutex; 
    std::set<Event> m_events;   
 
    static std::atomic<uint64_t> nextSerial; 
    static std::mutex timerThreadMutex;
    static std::shared_ptr<TimerThread> timerThread;
 
    std::set<Timer::Event> moveOutEvents();
 
    static void checkTimerThreadRunning();
};
 
} // namespace sptk