// 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