// Copyright (c) 2004-2009 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:

 //

 #include "srvrepos_noc.h"

 #include "cachemgr.h"

 #include <bsul/bsul.h>

 #define UNUSED_VAR(a) a = a

 _LIT(KCacheLit, "CoarseGrainedCache");

 _LIT(KDefaultCacheSizeLit, "size");

 _LIT(KDefaultEvictionTimeoutLit, "timeout");

 CRepositoryCacheManager* CRepositoryCacheManager::NewLC(RFs& aFs)

 	{

 	CRepositoryCacheManager* self = new(ELeave) CRepositoryCacheManager;

 	CleanupStack::PushL(self);

 	self->ConstructL(aFs);

 	return self;

 	}

 CRepositoryCacheManager::~CRepositoryCacheManager()

 	{

 	DisableCache(ETrue);

 	}

 void CRepositoryCacheManager::ConstructL(RFs& aFs)

 	{

 	CTimer::ConstructL();

 	BSUL::CIniFile16* iniFile = NULL;

 	TInt res = KErrNone;

 	TBuf<KMaxFileName> iniFileName;

 	iniFileName.Copy( *TServerResources::iInstallDirectory );

 	iniFileName.Append( KCacheMgrIniFile );	

 	TRAP(res, iniFile = BSUL::CIniFile16::NewL(aFs, iniFileName, ETrue));

 	if(res==KErrNotFound)

 		{

 		// if RomDirectory exists

 		if (TServerResources::iRomDirectory)

 			{

 			iniFileName.Copy( *TServerResources::iRomDirectory );

 			iniFileName.Append( KCacheMgrIniFile );	

 			TRAP(res, iniFile = BSUL::CIniFile16::NewL(aFs, iniFileName, ETrue));

 			}

 		if(res==KErrNotFound)

 			{

 			__CENTREP_TRACE1("CENTREP: Central Repository Cache Parameters ini file %S not found. Default values will be used.", &KCacheMgrIniFile);

 			return;

 			}

 		}

 	if (res != KErrNone)

 		{

 		User::Leave(res);

 		}

 	CleanupStack::PushL(iniFile);

 	TBuf<20> buffer;

 	TPtrC ptr(buffer);

 	// find the value

 	res = iniFile->FindVar(KCacheLit(), KDefaultCacheSizeLit(), ptr);

 	TLex lex(ptr);

 	TBool valueFound = EFalse;

 	// if the value can't be found or can't be converted into a positive integer, use the default

 	if (res != KErrNone || lex.Val(iCacheSize) != KErrNone || iCacheSize < 0)	

 		{

 		iCacheSize = KDefaultCacheSize;

 		}

 	else

 		{

 		valueFound = ETrue;			

 		}

 	// if the value can be found, convert it

 	if (iniFile->FindVar(KCacheLit(), KDefaultEvictionTimeoutLit(), ptr) == KErrNone)

 		{

 		TInt tempTimeout;

 		lex.Assign(ptr);

 		// if the value can be converted into a positive integer, assign it to iDefaultTimeout.

 		if (lex.Val(tempTimeout) == KErrNone && tempTimeout >= 0)

 			{

 			iDefaultTimeout = tempTimeout;

 			valueFound = ETrue;

 			}

 		}

 #ifdef _DEBUG

 	// in Debug mode, if the Cache ini file exists either in install directory or 

 	// rom directory but does not contains the correct section "CoarseGrainedCache"

 	// nor any key of "size" and "timeout", the server panics.

 	if(! valueFound)

 	{

 	Panic(ECacheIniFileCorrupted);

 	}

 #else

 	UNUSED_VAR(valueFound);

 #endif		

 	CleanupStack::PopAndDestroy(iniFile);

 	}

 void CRepositoryCacheManager::EnableCache(TInt aDefaultTimeout, TInt aCacheSize)

 	{

 	if (aDefaultTimeout>0)

 		{

 		iDefaultTimeout = aDefaultTimeout;

 		}

 	if (aCacheSize>0)

 		{

 		iCacheSize = aCacheSize;

 		}

 	EnableCache();

 	}

 void CRepositoryCacheManager::EnableCache()

 	{

 	// If disabled, enable

 	if (!iEnabled)

 		{

 		iEnabled = ETrue;

 		__CENTREP_TRACE2("CENTREP: Cache Enabled. Size:%d Default Timeout:%d", iCacheSize, iDefaultTimeout.Int());

 		}

 	}

 void CRepositoryCacheManager::DisableCache(TBool aFullFlush)

 	{

 	// If enabled, disable

 	if (iEnabled)

 		{

 		// cancel any outstanding timer

 		Cancel();

 		FlushCache(aFullFlush);

 		iEnabled = EFalse;

 		__CENTREP_TRACE("CENTREP: Cache Disabled");

 		}

 	}

 void CRepositoryCacheManager::RescheduleTimer(const TTime& aTimeInUTC)

 	{

 	TTime now;

 	now.UniversalTime();

 	//Get the 64bit time interval between now and the cache timeout

 	TTimeIntervalMicroSeconds interval64 = aTimeInUTC.MicroSecondsFrom(now);

 	TTimeIntervalMicroSeconds32 interval32(iDefaultTimeout);

 	//If the interval is positive, i.e. the timeout is in the future, convert 

 	//this interval to a 32 bit value, otherwise use the default timeout

 	if(interval64 > 0)

 		{

 		//If the interval value is less than the maximum 32 bit value cast

 		//interval to 32 bit value, otherwise the interval is too large for 

 		//a 32 bit value so just set the interval to the max 32 bit value

 		const TInt64 KMax32BitValue(KMaxTInt32);

 		interval32 = (interval64 <= KMax32BitValue) ? 

 				static_cast<TTimeIntervalMicroSeconds32>(interval64.Int64()): KMaxTInt32;

 		}

 	//Reschedule the timer

 	After(interval32);

 	}

 void CRepositoryCacheManager::RemoveIdleRepository(CSharedRepository* aRepository)

 	{

 	if (iEnabled)

 		{

 		TInt i;

 		TInt count=iIdleRepositories.Count();

 		for(i=count-1; i>=0; i--)

 			{

 			if(iIdleRepositories[i].iSharedRepository==aRepository)

 				{

 				break;

 				}

 			}

 		// Idle repository might not be found in the list if multiple clients try to open the same 

 		// repository at the same time. First client will remove it and second one will not find it

 		if(i>=0)

 			{

 			__CENTREP_TRACE1("CENTREP: Cache Hit when opening repository %x", aRepository->Uid().iUid);

 			iTotalCacheUsage -= iIdleRepositories[i].iSharedRepository->Size();		

 			iIdleRepositories.Remove(i);

 			// If this was the first repository on the list, it means its timer is still ticking. 

 			// We have to stop it and ...

 			if (i==0)

 				{

 				Cancel();

 				// if there's still other repositories in the list, reschedule the timer with the

 				// new top-of-the-list  

 				if (iIdleRepositories.Count())

 					{

 					RescheduleTimer(iIdleRepositories[0].iCacheTime);

 					}

 				}

 			}

 		else

 			{

 			__CENTREP_TRACE1("CENTREP: Cache Miss when opening repository %x", aRepository->Uid().iUid);

 			}

 		}

 	}

 #ifdef CACHE_OOM_TESTABILITY

   	// This code is only for tesing and doesn't go into MCL

 	// Hence hide the leave in a macro instead of making StartEvictionL

 #define TEST_CODE_LEAVE(x) User::Leave(x)

 #endif	

 TBool CRepositoryCacheManager::StartEviction(CSharedRepository*& aRepository)

 	{

 	// find the item in the cache and remove it if it exists to reset the timer

 	RemoveIdleRepository(aRepository);

 	TInt64 lastTop = 0;

 	if (iIdleRepositories.Count())

 		{

 		lastTop = iIdleRepositories[0].iCacheTime.Int64();

 		}

 	// Execute the forced eviction algorithm only if it will make sense

 	// The eviction makes sense if:

 	// - there's anything in the cache to evict

 	// - the repository we're trying to cache can fit in the cache after evictions

 	if (iIdleRepositories.Count() && (aRepository->Size() < iCacheSize))

 		{

 		// Check to see if current cache size + the current repository size is overshooting the limit

 		if (iTotalCacheUsage + aRepository->Size() > iCacheSize)

 			{

 			// Forced eviction

 			__CENTREP_TRACE3("CENTREP: Cache Size Exceeded: Current(%d)+Size(%d)>Cache(%d)", iTotalCacheUsage, aRepository->Size(), iCacheSize);

 			// Sort in the forced eviction order

 			TLinearOrder<TRepositoryCacheInfo> forcedSortOrder(CRepositoryCacheManager::ForcedEvictionSortOrder);

 			iIdleRepositories.Sort(forcedSortOrder);

 			// Evict one by one until there's enough cache space or we run out of idle reps

 			do

 				{

 				__CENTREP_TRACE1("CENTREP: Forced Eviction of repository %x", iIdleRepositories[0].iSharedRepository->Uid().iUid);			

 				iTotalCacheUsage -= iIdleRepositories[0].iSharedRepository->Size();

 				Evict(0);

 				iIdleRepositories.Remove(0);		

 				} while (iIdleRepositories.Count() && (iTotalCacheUsage + aRepository->Size() > iCacheSize));

 #ifdef CENTREP_TRACE			

 			if (!iIdleRepositories.Count())

 				{

 				__CENTREP_TRACE("CENREP: Cache Emptied by Forced Eviction");

 				}

 #endif				

 			// Re-sort to timer order for normal operation

 			TLinearOrder<TRepositoryCacheInfo> timerSortOrder(CRepositoryCacheManager::TimerEvictionSortOrder);

 			iIdleRepositories.Sort(timerSortOrder);

 			};

 		}

 	// See if there's enough space now

 	if (iTotalCacheUsage + aRepository->Size() > iCacheSize)

 		{

 		return EFalse;

 		}

 	// Create new item for the cache and insert it in the list

 	TRepositoryCacheInfo repInfo;

 	repInfo.iCacheTime.UniversalTime();

 	repInfo.iCacheTime += TTimeIntervalMicroSeconds32(iDefaultTimeout);

 	repInfo.iSharedRepository = aRepository;

 	TLinearOrder<TRepositoryCacheInfo> timerSortOrder(CRepositoryCacheManager::TimerEvictionSortOrder);

 	// With the same timeout value assigned to all repositories, no two repositories can have the same 

 	// timeout theoretically, so InsertInOrder is sufficient. But in practice, because of the poor 

 	// resolution of the NTickCount() function used by TTime::UniversalTime(), InsertInOrderAllowRepeats 

 	// should be used instead of InsertInOrder to allow for duplicate timer values caused by two 

 	// repositories cached in quick succession (<1ms)

 	TInt err = iIdleRepositories.InsertInOrderAllowRepeats(repInfo, timerSortOrder);

 #ifdef CACHE_OOM_TESTABILITY

   	// This code is only for tesing and doesn't go into MCL

   	if (err == KErrNoMemory)	

   		{

   		TServerResources::iObserver->RemoveOpenRepository(aRepository);

   		aRepository = NULL;

   		// Should Leave here for the OOM tests to successfully complete. 

 		TEST_CODE_LEAVE(err);

   		}

 #endif	

 	if (err!=KErrNone)

 		{

 		return EFalse;

 		}

 	iTotalCacheUsage += repInfo.iSharedRepository->Size();

 	// Only reset timer if necessary. This operation takes time and doing it every time reduces performance considerably

 	if (lastTop != iIdleRepositories[0].iCacheTime.Int64())

 		{

 		// reset timer to the new top-of-the-list

 		Cancel();

 		RescheduleTimer(iIdleRepositories[0].iCacheTime);

 		}

 	return ETrue;

 	}

 void CRepositoryCacheManager::FlushCache(TBool aFullFlush)

 	{

 	// iterate through idle repositories (loaded in memory, scheduled to be evicted)

 	TInt idleRepCount = iIdleRepositories.Count();

 	for(TInt repCount = idleRepCount - 1; repCount >= 0 ; repCount--)	

 		{

 		// check if there are any observers listening (to see if any client is connected to this repository)

 		if (aFullFlush || (TServerResources::iObserver->FindConnectedRepository(iIdleRepositories[repCount].iSharedRepository->Uid())==KErrNotFound))

 			{

 			// if the client has already been disconnected, unload from memory

 			Evict(repCount);

 			}

 		}

 	// this whole iteration and search above can be replaced by a simple reference counter variable check,

 	// if the server is redesigned using a resource manager type pattern with CSharedRepository object as a resource

 	// empty the list

 	iIdleRepositories.Reset();

 	iTotalCacheUsage = 0;

 	__CENTREP_TRACE1("CENTREP: Cache Flush: %d repositories flushed", idleRepCount);

 	}

 // Evict removes items from iOpenRepositories list, not from iIdleRepositories list

 void CRepositoryCacheManager::Evict(TInt aIdleRepIndex)

 	{

 	// find,remove and delete the idle repositories' pointers in the open repositories list 

 	TServerResources::iObserver->RemoveOpenRepository(iIdleRepositories[aIdleRepIndex].iSharedRepository);

 	}

 void CRepositoryCacheManager::RunL()

 	{

 	TTime now;

 	now.UniversalTime();

 	TInt count = iIdleRepositories.Count();

 	// repositories that are involved in active transactions are not idle.

 	// this checks to make sure that we're not trying to reclaim memory that

 	// is actually still currently in use.

 	for (TInt i = 0;i < count;i++)

 		{

 		if (iIdleRepositories[i].iCacheTime > now)

 			{

 			break;

 			}

 		if (iIdleRepositories[i].iSharedRepository->IsTransactionActive())

 			{

 			__CENTREP_TRACE1("CRepositoryCacheManager::RunL - rescheduling UID 0x%x, in active transaction",

 					iIdleRepositories[i].iSharedRepository->Uid().iUid);

 			StartEviction(iIdleRepositories[i].iSharedRepository);

 			return;

 			}

 		}

 	// Try to evict all the repositories which have expired. There might be more than one repository

 	// destined to expire at the same time, or there are more than one repository with expiry times

 	// between the scheduled expiry time and now (which theoretically should have been the same, but maybe

 	// because of other procesor activity, the timer Active Object just got late a bit)

 	while((iIdleRepositories.Count()) && (iIdleRepositories[0].iCacheTime<=now))

 		{

 		__CENTREP_TRACE1("CENTREP: Normal Eviction of repository %x", iIdleRepositories[0].iSharedRepository->Uid().iUid);			

 		// Always remove from the top of the sorted list

 		iTotalCacheUsage -= iIdleRepositories[0].iSharedRepository->Size();		

 		Evict(0);

 		iIdleRepositories.Remove(0);		

 		};

 	// reschedule to run again at the expiry date of next repository on the list, if any

 	if (iIdleRepositories.Count())

 		{

 		RescheduleTimer(iIdleRepositories[0].iCacheTime);

 		}

 	else

 		{

 		__CENTREP_TRACE("CENTREP: Cache Empty/Timer Disabled");			

 		}

 	}

 TInt CRepositoryCacheManager::ForcedEvictionSortOrder(const TRepositoryCacheInfo &aRepository1, const TRepositoryCacheInfo &aRepository2)

 	{

 /*

    The code in the comments below is the original simple-to-read version of the algebraically

    simplified production code. 

 	TTime now;

 	now.UniversalTime();

 	// we calculate the ages of the repositories by taking the difference between now and when

 	// they were last became idle. When refactoring, the calculation of the absolute ages will be 

 	// eleminated and the age difference between the repositories will be used in the formula instead

 	TTimeIntervalMicroSeconds age1 = now.MicroSecondsFrom(aRepository1.iCacheTime);

 	TTimeIntervalMicroSeconds age2 = now.MicroSecondsFrom(aRepository2.iCacheTime);

 	// then divide the resulting numbers by conversion constant to get a number in a compatible unit

 	// to the size. This operation reduces the microsecond-based values to having an approx. max

 	// of 100K units

 	TInt t1 = age1.Int64()/KTimeoutToSizeConversion;

 	TInt t2 = age2.Int64()/KTimeoutToSizeConversion;

 	// the resulting normalized time difference values are added to the size of the repository

 	// resulting in an implicit %50 weight in the overall importance value 

 	// An approx. maximum size of a repository is assumed to be around 100K

 	TInt importance1 = t1+aRepository1.iSharedRepository->Size();

 	TInt importance2 = t2+aRepository2.iSharedRepository->Size();

 	// the difference between the importances of the repositories determine the sorting order

 	return static_cast<TInt>(importance1-importance2);

 */	

 	//	after refactoring, the resulting formula is this one

 	return static_cast<TInt>(((aRepository1.iCacheTime.Int64()-aRepository2.iCacheTime.Int64())/KTimeoutToSizeConversion)+(aRepository1.iSharedRepository->Size()-aRepository2.iSharedRepository->Size()));	

 	}

 TInt CRepositoryCacheManager::TimerEvictionSortOrder(const TRepositoryCacheInfo &aRepository1, const TRepositoryCacheInfo &aRepository2)

 	{

 	return static_cast<TInt>(aRepository1.iCacheTime.Int64()-aRepository2.iCacheTime.Int64());

 	}