poco/Foundation/include/Poco/AccessExpireCache.h

//
// AccessExpireCache.h
//
// $Id: //poco/svn/Foundation/include/Poco/AccessExpireCache.h#2 $
//
// Library: Foundation
// Package: Cache
// Module:  AccessExpireCache
//
// Definition of the AccessExpireCache class.
//
// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// 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.
//


#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