ClickHouse/base/poco/Foundation/include/Poco/UniqueAccessExpireLRUCache.h

//
// UniqueAccessExpireLRUCache.h
//
// Library: Foundation
// Package: Cache
// Module:  UniqueAccessExpireLRUCache
//
// Definition of the UniqueAccessExpireLRUCache class.
//
// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_UniqueAccessExpireLRUCache_INCLUDED
#define Foundation_UniqueAccessExpireLRUCache_INCLUDED


#include "Poco/AbstractCache.h"
#include "Poco/LRUStrategy.h"
#include "Poco/StrategyCollection.h"
#include "Poco/UniqueAccessExpireStrategy.h"


namespace Poco
{


template <class TKey, class TValue, class TMutex = FastMutex, class TEventMutex = FastMutex>
class UniqueAccessExpireLRUCache : public AbstractCache<TKey, TValue, StrategyCollection<TKey, TValue>, TMutex, TEventMutex>
/// A UniqueAccessExpireLRUCache combines LRU caching and time based per entry expire caching.
/// One can define for each cache entry a separate timepoint
/// but also limit the size of the cache (per default: 1024).
/// Each TValue object must thus offer the following method:
///
///    const Poco::Timespan& getTimeout() const;
///
/// which returns the relative timespan for how long the entry should be valid without being accessed!
/// The absolute expire timepoint is calculated as now() + getTimeout().
/// Accessing an object will update this absolute expire timepoint.
/// You can use the Poco::AccessExpirationDecorator to add the getExpiration
/// method to values that do not have a getExpiration function.
{
public:
    UniqueAccessExpireLRUCache(long cacheSize = 1024)
        : AbstractCache<TKey, TValue, StrategyCollection<TKey, TValue>, TMutex, TEventMutex>(StrategyCollection<TKey, TValue>())
    {
        this->_strategy.pushBack(new LRUStrategy<TKey, TValue>(cacheSize));
        this->_strategy.pushBack(new UniqueAccessExpireStrategy<TKey, TValue>());
    }

    ~UniqueAccessExpireLRUCache() { }

private:
    UniqueAccessExpireLRUCache(const UniqueAccessExpireLRUCache & aCache);
    UniqueAccessExpireLRUCache & operator=(const UniqueAccessExpireLRUCache & aCache);
};


} // namespace Poco


#endif // Foundation_UniqueAccessExpireLRUCache_INCLUDED