// Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies).

// All rights reserved.

// This component and the accompanying materials are made available

// under the terms of "Eclipse Public License v1.0"

// which accompanies this distribution, and is available

// at the URL "http://www.eclipse.org/legal/epl-v10.html".

//

// Initial Contributors:

// Nokia Corporation - initial contribution.

//

// Contributors:

//

// Description:

//

/**

 @file

 @internalComponent

*/

#ifndef __RESOLVERCACHE_H__

#define __RESOLVERCACHE_H__

#include <e32base.h>

#include <ecom/implementationproxy.h>

#include "callback.h"

class CResolver;

class CRegistryData;

class CRegistryResolveTransaction;

/** class TCounterTicks keep track of time an entry will remain in cache. */

class TCounterTicks

	{

public:

	inline TCounterTicks(TUint aTicks = 0);

	inline TUint ElapsedSinceThis(TUint aEndTick) const;

public:

	TUint iTicks;

	};

/** Bit mask indicating special conditions of cache entries */

enum TCacheEntryFlags

	{

	EEntryFlagsNone 		 = 0,

	EEntryIsOnReadWriteDrive = 0x1

	};

/** An entry in ECOM's custom resolver cache */

class RResolverCacheEntry

	{

public:

	RResolverCacheEntry();

	RResolverCacheEntry(const TUid aResolverUid,

						RLibrary aLib,

						TProxyNewLPtr	aNewL,

						TUint32 aFlags);

	void Close();

	static TInt CompareUid(const RResolverCacheEntry& aEntry1, const RResolverCacheEntry& aEntry2);

	TBool ThisIsOlder(const RResolverCacheEntry& aOther, TUint aCurrTick) const;

public:

	/** Timestamp, when the resolver is last accessed */

	TCounterTicks iLastUse;

	/** An extension of iLastUse. Serves as tie breaker when 2 entries

	 have the same timestamp. */

	TInt iLruRank;

	/** TUid of the custom resolver */

	TUid  iResolverUid;

	/** Function ptr to instantiate the custom resolver */

	TProxyNewLPtr iNewLFuncPtr;

	/** RLibraray object holding a handle on the resolver DLL */

	RLibrary iLibrary;

	/** Special conditions about the cache entry. */

	TUint32 iFlags;

	};

/** Handles caching custom resolvers */

class CCustomResolverCache : public CTimer

	{

public:

	static CCustomResolverCache* NewL(TUint32 aCacheSize, TUint32 aCacheTimeout);

	virtual ~CCustomResolverCache();

	TInt CacheResolver(const TUid aResolverUid,

						RLibrary aLib,

						TProxyNewLPtr aNewL,

						TUint32 aFlags);

	TBool CacheLookup(const TUid aResolverUid, TProxyNewLPtr& aNewLFuncPtr);

	TBool CachingEnabled() const; 

	TBool Remove(const TUid aResolverUid);

	void RemoveItemsWithFlags(TUint32 aMask);

private:

	CCustomResolverCache(TUint32 aCacheSize);

	void ConstructL(TUint32 aCacheTimeout);

	void RunL(); // implement the CActive pure virtual

	TInt FindResolver(const TUid aResolverUid) const;

	void Remove(TInt aIndex);

	void EvictLeastRecentlyUsed();

	void SetLastUseTime(RResolverCacheEntry& aEntry);

private:

	/** list of cached resolvers */

	RArray<RResolverCacheEntry> iResolvers;

	/** max. number of entries allowed in iResolvers */

	TUint32 iMaxCacheSize;

	/** Store the system tick period as member data to avoid

	having to invoke HAL::Get() repeatedly. */

	TInt 	iSystemTickPeriod;

	/** cache timeout value. Unit is number of system ticks */

	TUint	iEntryTimeToLive;

	/** Keep track of youngest timestamp of cache entries. Use to

	detect if two entries have same timestamp. */

	TUint	iMostRecentTimestamp;

#ifdef __ECOMSERVER_TESTING__

	// For unit testing purpose. The test harness installs a callback

	// here to detect when the cache timer fires. 

	TCallBackWithArg iTimerExpireCB;

#endif

	// the test bed state accessor

	friend class CCustomResolverCacheTest;

	};

#endif