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#pragma once 
 
#include <util/generic/buffer.h> 
#include <util/generic/deque.h> 
#include <util/generic/noncopyable.h> 
#include <util/generic/strbuf.h> 
#include <util/system/tls.h> 
#include <util/thread/singleton.h> 
 
namespace NCodecs { 
    template <class TItem> 
    struct TClear { 
        void operator()(TItem& item) const { 
            item.Clear(); 
        } 
    }; 
 
    template <class TItem, class TCleaner = TClear<TItem>>
    class TTlsCache { 
        using TSelf = TTlsCache<TItem, TCleaner>; 
 
        struct TItemHolder: public TIntrusiveListItem<TItemHolder> {
            TItemHolder(TSelf& factory) 
                : Factory(factory) 
            {
            }
 
            void Release() { 
                Factory.Release(*this); 
            } 
 
            TSelf& Factory; 
            TItem Item; 
        }; 
 
        class TItemGuard { 
        public: 
            explicit TItemGuard(TSelf& fact) 
                : Holder(fact.Acquire()) 
            {
            }
 
            TItemGuard(TItemGuard&& other) noexcept {
                *this = std::move(other); 
            } 
 
            TItemGuard& operator=(TItemGuard&& other) noexcept {
                if (&other != this) { 
                    std::swap(Holder, other.Holder); 
                } 
                return *this; 
            } 
 
            ~TItemGuard() { 
                if (Holder) { 
                    Holder->Release(); 
                } 
            } 
 
            TItem& Get() & { 
                Y_ASSERT(Holder); 
                return Holder->Item; 
            } 
 
            TItem& Get() && = delete; 
 
        private: 
            TItemHolder* Holder = nullptr; 
        }; 
 
    public: 
        TItemGuard Item() { 
            return TItemGuard(*this); 
        } 
 
        static TSelf& TlsInstance() { 
            return *FastTlsSingleton<TSelf>(); 
        } 
 
    private: 
        TItemHolder* Acquire() { 
            if (Free.Empty()) { 
                return new TItemHolder(*this); 
            } else { 
                return Free.PopBack(); 
            } 
        } 
 
        void Release(TItemHolder& item) { 
            Cleaner(item.Item); 
            Free.PushBack(&item); 
        } 
 
    private: 
        TIntrusiveListWithAutoDelete<TItemHolder, TDelete> Free; 
        TCleaner Cleaner; 
    }; 
 
    using TBufferTlsCache = TTlsCache<TBuffer>; 
}