library/cpp/messagebus/misc/granup.h


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#pragma once

#include <util/datetime/base.h>
#include <util/system/guard.h>
#include <util/system/mutex.h>
#include <util/system/spinlock.h>

namespace NBus {
    template <typename TItem, typename TLocker = TSpinLock>
    class TGranUp {
    public:
        TGranUp(TDuration gran)
            : Gran(gran)
            , Next(TInstant::MicroSeconds(0))
        { 
        } 

        template <typename TFunctor> 
        void Update(TFunctor functor, TInstant now, bool force = false) { 
            if (force || now > Next) 
                Set(functor(), now);
        }

        void Update(const TItem& item, TInstant now, bool force = false) { 
            if (force || now > Next) 
                Set(item, now);
        }

        TItem Get() const noexcept { 
            TGuard<TLocker> guard(Lock); 

            return Item;
        }

    protected:
        void Set(const TItem& item, TInstant now) { 
            TGuard<TLocker> guard(Lock); 

            Item = item;

            Next = now + Gran;
        }

    private:
        const TDuration Gran;
        TLocker Lock; 
        TItem Item; 
        TInstant Next; 
    };
}