// 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:

 // This file holds the class methods for the CFbTopMBMCache

 // 

 //

 #include "FBSMBMC.H"

 //

 //Constructor for CFbTopMBMCache objects with both forward and backward cache size

 //The forward(backward) cache size determines the number of stream ids after(before)

 //the current loaded bitmap ids to be stored in the cache

 //e.g Loading a bitmap with id=20 from a 40 bitmaps mbm file will load the cache(10,10)

 //with stream ids from 30-39(10 backward) and 40-49(10 forward)

 CFbTopStreamIdCache::CFbTopStreamIdCache(TInt aForwardSize, TInt aBackwardSize, TInt aMaxFilestores)

 	:CBase(),

 	iEntries(aMaxFilestores),

 	iForwardCacheSize(aForwardSize),

 	iBackwardCacheSize(aBackwardSize),

 	iMaxCacheFilestores(aMaxFilestores)

 	{

 	}

 //

 //Destructor of CFbTopMBMCache objects

 CFbTopStreamIdCache::~CFbTopStreamIdCache()

 	{

 	FlushCache();

 	}

 //Function to reset all the internal state of the class

 void CFbTopStreamIdCache::FlushCache()

 	{

 	CloseFileStores();

 	iEntries.Reset();

 	User::Free(iBuffer);

 	iBuffer = NULL;

 	}

 //Function to get the most recently used filestore stored in the cache

 CShiftedFileStore* CFbTopStreamIdCache::MruFileStore()

 	{

 	return iEntries[0]->FileStore();

 	}

 //Function to get the stream id for a bitmap id from a mbm file with certain offset.

 //It also fills up the cache with the stream ids for different bitmap from the same

 //mbm file and the number of stream ids stored depend on the initial setting of the

 //cache size. Also associates each resource with a client handle to improve the

 //performance of cleaning up.

 TStreamId CFbTopStreamIdCache::GetStreamIdL(RFile& aFile,const TDesC& aFilename,TInt32 aId,TUint aFileOffset, TInt aSessionHandle)

 	{

 	if (aId < 0)

 		{

 		User::Leave(KErrEof);

 		}

 	RCacheEntry *entry = FindCacheEntry(aFilename, aFileOffset);

 	if (entry == NULL)

 		{

 		entry = AddCacheEntryL(aFilename, aFileOffset);

 		}

 	entry->CreateFileStoreL(aFile, aSessionHandle);

 	return entry->GetStreamIdL(aId, iForwardCacheSize, iBackwardCacheSize);

 	}

 /**

 The overloaded version of GetStreamIdL which works with file session instead of file handle.

 */

 TStreamId CFbTopStreamIdCache::GetStreamIdL(RFs& aFs, const TDesC& aFileName,TInt32 aId,TUint aFileOffset, TInt aSessionHandle)

 	{

 	if (aId < 0)

 		{

 		User::Leave(KErrEof);

 		}

 	RCacheEntry *entry = FindCacheEntry(aFileName, aFileOffset);

 	if (entry == NULL)

 		{

 		entry = AddCacheEntryL(aFileName, aFileOffset);

 		}

 	entry->CreateFileStoreL(aFs, aFileName, aSessionHandle);

 	return entry->GetStreamIdL(aId, iForwardCacheSize, iBackwardCacheSize);

 	}

 void CFbTopStreamIdCache::CloseFileStores(TInt aSessionHandle)

 	{

 	TInt n = iEntries.Count();

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

 		{

 		if (!aSessionHandle || aSessionHandle == iEntries[i]->SessionHandle())

 			iEntries[i]->CloseFileStore();

 		}

  	}

 CFbTopStreamIdCache::RCacheEntry* CFbTopStreamIdCache::AddCacheEntryL(const TDesC& aFilename, TUint aFileOffset)

 	{

 	RCacheEntry *entry;

 	TInt n = iEntries.Count();

 	if (n < iMaxCacheFilestores)

 		{

 		TInt size = RCacheEntry::KBaseSize + (iForwardCacheSize + iBackwardCacheSize) * sizeof(TStreamId);

 		if (iBuffer == NULL)

 			iBuffer = static_cast<TUint8*>(User::AllocL(iMaxCacheFilestores * size));

 		entry = reinterpret_cast<RCacheEntry*>(iBuffer + n * size);

 		}

 	else

 		{

 		entry = iEntries[--n];

 		entry->CloseFileStore();

 		iEntries.Remove(n);

 		}

 	iEntries.InsertL(entry, 0);

 	return new(entry) RCacheEntry(aFilename, aFileOffset);

 	}

 CFbTopStreamIdCache::RCacheEntry* CFbTopStreamIdCache::FindCacheEntry(const TDesC& aFilename, TUint aFileOffset)

 	{

 	TInt n = iEntries.Count();

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

 		{

 		RCacheEntry *entry = iEntries[i];

 		if (entry->SameFile(aFilename, aFileOffset))

 			{

 			if (i > 0)

 				{

 				iEntries.Remove(i); // Keep least-recently-used order

 				iEntries.Insert(entry, 0); // Cannot fail

 				}

 			return entry;

 			}

 		}

 	return NULL;

 	}

 const TInt CFbTopStreamIdCache::RCacheEntry::KBaseSize = _FOFF(CFbTopStreamIdCache::RCacheEntry, iStreamIdCache);

 CFbTopStreamIdCache::RCacheEntry::RCacheEntry(const TDesC& aFilename, TUint aFileOffset)

 :	iFilename(aFilename),

 	iFileOffset(aFileOffset),

 	iFilestore(NULL),

 	iLastId(KErrNotFound),

 	iStreamIdCount(0),

 	iSessionHandle(0)

 	{

 	}

 TBool CFbTopStreamIdCache::RCacheEntry::SameFile(const TDesC& aFilename, TUint aFileOffset)

 	{

 	return !aFilename.Compare(iFilename) && aFileOffset == iFileOffset;

 	}

 TStreamId CFbTopStreamIdCache::RCacheEntry::GetStreamIdL(TInt32 aId, TInt aForwardSize, TInt aBackwardSize)

 	{

 	if (iLastId >= 0 && aId >= iLastId - aBackwardSize && aId < iLastId + aForwardSize)

 		{

 		TInt startindex = iLastId < aBackwardSize ? 0 : iLastId - aBackwardSize;

 		// ensure aId exists in the MBM file

 		// cache size previously set using the number of bitmaps

 		if (aId - startindex >= iStreamIdCount)

 			User::Leave(KErrEof);

 		return iStreamIdCache[aId - startindex];

 		}

 	//Flush the cache array

 	iLastId = KErrNotFound;

 	iStreamIdCount = 0;

 	//Extracting the header stream parameters numbitmaps and the stream ids

 	TStreamId bmpstreamid(iFilestore->Root().Value() + iFileOffset);

 	RStoreReadStream readstream;

 	readstream.OpenLC(*iFilestore, bmpstreamid);

 	TInt numbitmaps = readstream.ReadInt32L();

 	if (aId >= numbitmaps)

 		User::Leave(KErrEof);

 	TInt endcount = aId + aForwardSize;

 	//if endcount is greater than the numbitmaps we need to truncate it so we

 	//never overread and cause panic.

 	if (endcount > numbitmaps)

 		endcount = numbitmaps;

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

 		{

 		bmpstreamid.InternalizeL(readstream);

 		bmpstreamid=TStreamId(bmpstreamid.Value() + iFileOffset);

 		if (count >= aId - aBackwardSize)

 			iStreamIdCache[iStreamIdCount++] = bmpstreamid;

 		}

 	//get the stream id of the requested bitmap id

 	TInt startindex = aId < aBackwardSize ? 0 : aId - aBackwardSize;

 	bmpstreamid = iStreamIdCache[aId - startindex];

 	CleanupStack::PopAndDestroy();

 	// iLastId is updated just before returning to ensure that for error cases

 	// the cache is not used in subsequent calls to this method.

 	iLastId = aId;

 	return bmpstreamid;

 	}

 CShiftedFileStore* CFbTopStreamIdCache::RCacheEntry::FileStore()

 	{

 	return iFilestore;

 	}

 TInt CFbTopStreamIdCache::RCacheEntry::SessionHandle() const

 	{

 	return iSessionHandle;

 	}

 void CFbTopStreamIdCache::RCacheEntry::CloseFileStore()

 	{

 	delete iFilestore;

 	iFilestore = NULL;

 	iSessionHandle = 0;

  	}

 /**

 It creates a file store if is not there i.e. if iFileStore is NULL.

 @param  aFile the mbm or rsc file handle

 @param  aSessionHandle the associated client session handle

 */

 void CFbTopStreamIdCache::RCacheEntry::CreateFileStoreL(RFile& aFile, TInt aSessionHandle)

 	{

 	if (iFilestore == NULL)

 		{

 		iFilestore = CShiftedFileStore::FromL(aFile, iFileOffset);

 		iSessionHandle = aSessionHandle;

 		}

 	}

 /**

 It creates a file store if is not there i.e. if iFileStore is NULL.

 @param  aFs the associated file session handle

 @param  aFileName the mbm or rsc file name

 @param  aSessionHandle the associated client session handle

 */

 void CFbTopStreamIdCache::RCacheEntry::CreateFileStoreL(RFs& aFs, const TDesC& aFileName, TInt aSessionHandle)

 	{

 	if (iFilestore == NULL)

 		{

 		RFile file;

 		User::LeaveIfError(file.Open(aFs,aFileName,EFileShareReadersOnly));

 		iFilestore = CShiftedFileStore::FromL(file, iFileOffset);

 		iSessionHandle = aSessionHandle;

 		}

 	}