timer.h

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#if !defined(FLOW_TIMER_H)
     #define FLOW_TIMER_H

#include <atomic>
#include <chrono>
#include <condition_variable>
#include <functional>
#include <map>
#include <mutex>
#include <thread>
#include <vector>


namespace flow
{

class timer
{
    std::atomic<bool> d_stop_a;

protected:
    typedef std::map<size_t, const std::function<void ()>> listeners_t; 
    listeners_t d_listeners;    
    size_t d_next_index;        

    std::mutex d_listeners_m;   

public:
    timer() : d_stop_a(false), d_next_index(0) {}

    virtual ~timer() {}

    virtual bool stopped() const
    {
        return d_stop_a;
    }

    virtual void stop()
    {
        d_stop_a = true;
    }

    virtual size_t listen(const std::function<void ()>& listener)
    {
        std::lock_guard<std::mutex> lg(d_listeners_m);
        d_listeners.insert(std::make_pair(d_next_index, listener));
        return d_next_index++;
    }

    virtual void ignore(const size_t token)
    {
        std::lock_guard<std::mutex> lg(d_listeners_m);
        d_listeners.erase(token);
    }

    virtual void operator()() = 0;
};

class monotonous_timer : public timer
{
    std::chrono::milliseconds d_interval;

    std::condition_variable d_stopped_cv;
    std::mutex d_stopped_m;

public:
    template<typename Duration>
    monotonous_timer(const Duration& interval) : d_interval(std::chrono::duration_cast<std::chrono::milliseconds>(interval)) {}

    virtual ~monotonous_timer() {}

    virtual void stop()
    {
        timer::stop();

        d_stopped_cv.notify_one();
    }

    virtual void operator()()
    {
        while(!stopped())
        {
            {
                std::lock_guard<std::mutex> lg(d_listeners_m);
                for(auto& listener : d_listeners)
                {
                    listener.second();
                }
            }
            
            // Wait until time has expired OR timer is stopped.
            std::unique_lock<std::mutex> l_stopped(d_stopped_m);
            d_stopped_cv.wait_for(l_stopped, d_interval);
        }
    }
};

}

#endif

/*
    (C) Copyright Thierry Seegers 2010-2012. Distributed under the following license:

    Boost Software License - Version 1.0 - August 17th, 2003

    Permission is hereby granted, free of charge, to any person or organization
    obtaining a copy of the software and accompanying documentation covered by
    this license (the "Software") to use, reproduce, display, distribute,
    execute, and transmit the Software, and to prepare derivative works of the
    Software, and to permit third-parties to whom the Software is furnished to
    do so, all subject to the following:

    The copyright notices in the Software and this entire statement, including
    the above license grant, this restriction and the following disclaimer,
    must be included in all copies of the Software, in whole or in part, and
    all derivative works of the Software, unless such copies or derivative
    works are solely in the form of machine-executable object code generated by
    a source language processor.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
    SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
    FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
    ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.
*/