llkeyusetracker.h

/** 
 * @file llkeyusetracker.h
 * @brief Declaration of the LLKeyUseTracker class.
 *
 * $LicenseInfo:firstyear=2003&license=viewergpl$
 * 
 * Copyright (c) 2003-2009, Linden Research, Inc.
 * 
 * Second Life Viewer Source Code
 * The source code in this file ("Source Code") is provided by Linden Lab
 * to you under the terms of the GNU General Public License, version 2.0
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 * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
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#ifndef LL_KEYUSETRACKER_H
#define LL_KEYUSETRACKER_H

// This is a generic cache for an arbitrary data type indexed against an
// arbitrary key type. The cache length is determined by expiration time
// tince against last use and set size. The age of elements and the size
// of the cache are queryable.
//
// This is implemented as a list, which makes search O(n). If you reuse this
// for something with a large dataset, consider reimplementing with a Boost
// multimap based on both a map(key) and priority queue(last_use).

template <class TKey, class TData>
class KeyUseTrackerNodeImpl
{
public:
	U64 mLastUse;
	U32 mUseCount;
	TKey mKey;
	TData mData;

	KeyUseTrackerNodeImpl( TKey k, TData d ) :
		mLastUse(0),
		mUseCount(0),
		mKey( k ),
		mData( d )
	{
	}
};


template <class TKey, class TData>
class LLKeyUseTracker
{
	typedef KeyUseTrackerNodeImpl<TKey,TData> TKeyUseTrackerNode;
	typedef std::list<TKeyUseTrackerNode *> TKeyList;
	TKeyList mKeyList;
	U64 mMemUsecs;