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

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


#ifndef Foundation_AccessExpireCache_INCLUDED
#define Foundation_AccessExpireCache_INCLUDED


#include "Poco/AbstractCache.h"
#include "Poco/AccessExpireStrategy.h"


namespace Poco
{


template <class TKey, class TValue, class TMutex = FastMutex, class TEventMutex = FastMutex>
class AccessExpireCache : public AbstractCache<TKey, TValue, AccessExpireStrategy<TKey, TValue>, TMutex, TEventMutex>
/// An AccessExpireCache caches entries for a fixed time period (per default 10 minutes).
/// Entries expire when they are not accessed with get() during this time period. Each access resets
/// the start time for expiration.
/// Be careful when using an AccessExpireCache. A cache is often used
/// like cache.has(x) followed by cache.get x). Note that it could happen
/// that the "has" call works, then the current execution thread gets descheduled, time passes,
/// the entry gets invalid, thus leading to an empty SharedPtr being returned
/// when "get" is invoked.
{
public:
    AccessExpireCache(Timestamp::TimeDiff expire = 600000)
        : AbstractCache<TKey, TValue, AccessExpireStrategy<TKey, TValue>, TMutex, TEventMutex>(AccessExpireStrategy<TKey, TValue>(expire))
    {
    }

    ~AccessExpireCache() { }

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


} // namespace Poco


#endif // Foundation_AccessExpireCache_INCLUDED