// 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());

	}