userlibandfileserver/fileserver/sfat/sl_dir_cache.cpp
changeset 9 96e5fb8b040d
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/userlibandfileserver/fileserver/sfat/sl_dir_cache.cpp	Thu Dec 17 09:24:54 2009 +0200
@@ -0,0 +1,1236 @@
+// 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 the License "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:
+// f32\sfat\sl_dir_cache.cpp
+//
+//
+
+//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+//!!
+//!! WARNING!! DO NOT edit this file !! '\sfat' component is obsolete and is not being used. '\sfat32'replaces it
+//!!
+//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+
+#include "sl_std.h"
+#include "sl_dir_cache.h"
+
+//======================================================================
+TDynamicDirCachePage::~TDynamicDirCachePage()
+    {
+    }
+
+/**
+The static cache page creation function.
+Cache page objects are not supposed to be created on the stack, so this factory function is required.
+*/
+TDynamicDirCachePage* TDynamicDirCachePage::NewL(CDynamicDirCache* aOwnerCache, TInt64 aStartMedPos, TUint8* aStartRamAddr)
+    {
+    return new(ELeave) TDynamicDirCachePage(aOwnerCache, aStartMedPos, aStartRamAddr);
+    }
+
+/**
+Cache page constructor.
+@param  aOwnerCache pointer of the cache that owns this page
+@param  aStartMedPos    the start address on the media that this page caches
+@param  aStartRamAddr   the start address in the ram that this page content lives
+*/
+TDynamicDirCachePage::TDynamicDirCachePage(CDynamicDirCache* aOwnerCache, TInt64 aStartMedPos, TUint8* aStartRamAddr)
+:iStartMedPos(aStartMedPos),
+iStartRamAddr(aStartRamAddr),
+iOwnerCache(aOwnerCache),
+iValid(EFalse),
+iLocked(EFalse)
+    {
+//  __PRINT3(_L("TDynamicDirCachePage::TDynamicDirCachePage(aStartMedPos=%lx, aStartRamAddr=0x%X, aPageSize=%u)"), aStartMedPos, aStartRamAddr, PageSizeInBytes());
+    iType = EUnknown;
+    }
+
+/////////////////////////////// class CDynamicDirCache::TLookupEntry ///////////////////////////
+/**
+Required by RHashSet<TLookupEntry> to identify individual hash set entries.
+@see    RHashSet
+*/
+TBool IdentityFunction(const TLookupEntry& aEntry1, const TLookupEntry& aEntry2)
+    {
+    // only check starting med pos for hash searching
+    return aEntry1.iPos == aEntry2.iPos;
+    }
+/**
+Required by RHashSet<TLookupEntry> to generate hash value.
+@see    RHashSet
+*/
+TUint32 HashFunction(const TLookupEntry& aEntry)
+    {
+    return (DefaultHash::Integer(I64HIGH(aEntry.iPos)) + DefaultHash::Integer(I64LOW(aEntry.iPos)));
+    }
+
+/////////////////////////////// class CDynamicDirCache ///////////////////////////
+CDynamicDirCache::~CDynamicDirCache()
+    {
+//  __PRINT(_L("CDynamicDirCache::~CDynamicDirCache()"));
+
+    // we should never decommit locked pages
+    while (!iLockedQ.IsEmpty())
+        {
+        TDynamicDirCachePage* page = iLockedQ.Last();
+        DeQueue(page);      // remove from queue
+        LookupTblRemove(page->StartPos());  // remove from lookuptable
+        delete page;
+        }
+    ASSERT(iLockedQCount == 0);
+
+    while (!iUnlockedQ.IsEmpty())
+        {
+        TDynamicDirCachePage* page = iUnlockedQ.Last();
+        DeQueue(page);      // remove from queue
+        LookupTblRemove(page->StartPos());  // remove from lookuptable
+        DecommitPage(page); // inform cache client to decommit page memory
+        delete page;
+        }
+    ASSERT(iUnlockedQCount == 0);
+
+    delete iActivePage;
+
+    ASSERT(iLookupTable.Count() == 0);
+    iLookupTable.Close();
+    if (iCacheMemoryClient)
+        iCacheMemoryClient->Reset();
+    }
+
+/**
+Constructor of CDynamicDirCache.
+@param  aDrive  local drive interface to read/write media
+@param  aMinPageNum the minimum page number for the cache, includes iActive page and locked pages.
+@param  aMaxPageNum the maximum page number for the cache, includes iActive page, locked pages and unlocked pages.
+@param  aPageSizeInBytesLog2    the log2 value of page size in bytes, assumes page size is always a power of two
+*/
+CDynamicDirCache::CDynamicDirCache(TFatDriveInterface& aDrive, TUint32 aMinPageNum, TUint32 aMaxPageNum, TUint32 aPageSizeInBytesLog2)
+:iPageSizeLog2(aPageSizeInBytesLog2),
+iMinSizeInPages(aMinPageNum),
+iMaxSizeInPages(aMaxPageNum),
+iDrive(aDrive),
+iLockedQ(_FOFF(TDynamicDirCachePage, iLink)),
+iUnlockedQ(_FOFF(TDynamicDirCachePage, iLink)),
+iLockedQCount(0),
+iUnlockedQCount(0),
+iHashFunction(HashFunction),
+iIdentityFunction(IdentityFunction),
+iLookupTable(iHashFunction, iIdentityFunction)
+    {
+    iPageSizeInBytes = 1 << aPageSizeInBytesLog2;
+    iCacheDisabled = EFalse;
+    iMinCacheSizeInBytes = aMinPageNum << aPageSizeInBytesLog2;
+    iMaxCacheSizeInBytes = aMaxPageNum << aPageSizeInBytesLog2;
+    ASSERT(iPageSizeInBytes && iPageSizeInBytes <= iMinCacheSizeInBytes && iMinCacheSizeInBytes <= iMaxCacheSizeInBytes);
+    // initial value, will be reset from outside
+    iCacheBasePos = 0;
+    }
+
+/**
+Second phase constructor of CDynamicDirCache.
+@param  aClientName the identification of cache memeory client this cache connects
+*/
+void CDynamicDirCache::ConstructL(const TDesC& aClientName)
+    {
+//    __PRINT3(_L("CDynamicDirCache::ConstructL(Min=%u, Max=%u, page=%u)"), iMinCacheSizeInBytes, iMaxCacheSizeInBytes, iPageSizeInBytes);
+    CCacheMemoryManager* manager = CCacheMemoryManagerFactory::CacheMemoryManager();
+    if (manager)
+        {
+        // client will register itself onto cache memory manager when created
+        // note this operation may leave under OOM condition
+        iCacheMemoryClient = manager->ConnectClientL(aClientName, iMinSizeInPages * PageSizeInSegs(), iMaxSizeInPages * PageSizeInSegs());
+        }
+    else
+        {
+        User::Leave(KErrNotSupported);
+        }
+
+    ASSERT(iCacheMemoryClient);
+    if (!iCacheMemoryClient)
+        {
+        User::Leave(KErrNoMemory);
+        }
+
+    // reserve active page
+    iActivePage = AllocateAndLockNewPageL(0);
+    ASSERT(iActivePage);
+    if (!iActivePage)
+        {
+        User::Leave(KErrNoMemory);
+        }
+    iActivePage->SetPageType(TDynamicDirCachePage::EActivePage);
+    }
+
+/**
+Static factory function of CDynamicDirCache
+*/
+CDynamicDirCache* CDynamicDirCache::NewL(TFatDriveInterface& aDrive, TUint32 aMinPageNum, TUint32 aMaxPageNum, TUint32 aPageSizeLog2, const TDesC& aClientName)
+    {
+//    __PRINT3(_L("CDynamicDirCache::NewL(MinPageNum=%u, MaxPageNum=%u, page=%u)"), aMinPageNum, aMaxPageNum, 1<<aPageSizeLog2);
+    CDynamicDirCache* pSelf = new (ELeave) CDynamicDirCache(aDrive, aMinPageNum, aMaxPageNum, aPageSizeLog2);
+    CleanupStack::PushL(pSelf);
+    pSelf->ConstructL(aClientName);
+    CleanupStack::Pop();
+    return pSelf;
+    }
+
+/**
+Insert an unlocked page into the last position of the locked queue, may squeeze the original last page into
+the unlocked queue.
+This function is used on last visited but 'unlocked' pages to avoid excessive lock/unlock calls to cache memory
+manager as contiguous entry reading/writing often happens on the same page.
+@param  aPage   the page to be inserted.
+@pre    the page type of aPage should only be TDynamicDirCachePage::EUnknown
+*/
+void CDynamicDirCache::MakePageLastLocked(TDynamicDirCachePage* aPage)
+    {
+    // this function should not be called on active pages
+    ASSERT(aPage->iType == TDynamicDirCachePage::EUnknown);
+
+    if (iLockedQ.IsEmpty())
+        {
+        // if locked queue is empty, add it onto the locked queue directly
+        AddFirstOntoQueue(aPage, TDynamicDirCachePage::ELocked);
+        }
+    else
+        {
+        // otherwise, we squeeze for the last position on locked queue
+        while (iLockedQCount + 1 >= iMinSizeInPages)
+            {
+            TDynamicDirCachePage* last = iLockedQ.Last();
+            DeQueue(last);
+            UnlockPage(last);
+            AddFirstOntoQueue(last, TDynamicDirCachePage::EUnlocked);
+            }
+
+        // iLockedQCount + 1 < iMinSizeInPages
+        iLockedQ.AddLast(*aPage);
+        aPage->SetPageType(TDynamicDirCachePage::ELocked);
+        iLockedQCount++;
+        }
+    }
+
+/**
+Read data from a single page. If the page is not found or not valid anymore, read media onto iActive page
+first.
+@param  aPos    the starting position of the media address to be read.
+@param  aLength the length of the content to be read.
+@param  aDes    the descriptor to contain the content.
+@pre    aLength should be no more than page size.
+*/
+void CDynamicDirCache::ReadDataFromSinglePageL(TInt64 aPos, TInt aLength, TDes8& aDes)
+    {
+    //-- the data section is in the cache page entirely, take data directly from the cache
+    TDynamicDirCachePage* pPage = FindPageByPos(aPos);
+    if (pPage)
+        {
+        // lock page before reading,
+        if (LockPage(pPage) != NULL)
+            {
+            // read data
+            aDes.Copy(pPage->PtrInPage(aPos), aLength);
+
+            // if page is from unlocked queue, insert it onto the last page of the locked
+            //  queue. this is to avoid excessive locking and unlocking operations that is
+            //  highly likely to happen for following reads.
+            if (pPage->PageType() == TDynamicDirCachePage::EUnlocked)
+                {
+                DeQueue(pPage);
+                MakePageLastLocked(pPage);
+                }
+            }
+        else    // page locking failed
+            {
+            ASSERT(pPage->PageType() == TDynamicDirCachePage::EUnlocked);
+            DeQueue(pPage);
+            LookupTblRemove(pPage->StartPos());
+            DecommitPage(pPage);
+            delete pPage;
+            pPage = NULL;
+            }
+        }
+
+    if (!pPage)
+        {
+        // if page not found or page data not valid anymore, use active page to read data in
+        pPage = UpdateActivePageL(aPos);
+        // read data
+        aDes.Copy(pPage->PtrInPage(aPos), aLength);
+        }
+
+    }
+
+//====================================================================
+/**
+Implementation of pure virtual function.
+@see    MWTCacheInterface::ReadL()
+*/
+void CDynamicDirCache::ReadL(TInt64 aPos, TInt aLength, TDes8& aDes)
+    {
+#ifdef _DEBUG
+    if(iCacheDisabled)
+        {
+        // cache is disabled for debug purposes
+        __PRINT(_L("CDynamicDirCache disabled"));
+        User::LeaveIfError(iDrive.ReadNonCritical(aPos, aLength, aDes));
+        return;
+        }
+#endif //_DEBUG
+
+    aDes.Zero();
+    const TUint32 PageSz = iPageSizeInBytes;//-- cache page size
+
+    TInt64 pageStartMedPos = CalcPageStartPos(aPos);
+    const TUint32 bytesToPageEnd = (TUint32)(pageStartMedPos + PageSz - aPos); //-- number of bytes from aPos to the end of the page
+
+//    __PRINT5(_L("CDynamicDirCache::ReadL: aPos=%lx, aLength=%x, page:%lx, pageSz:%x, bytesToPageEnd=%x"), aPos, aLength, pageStartMedPos, PageSz, bytesToPageEnd);
+    // if all data needed is on a single page
+    if((TUint32)aLength <= bytesToPageEnd)
+        {
+        ReadDataFromSinglePageL(aPos, aLength, aDes);
+        }
+    // or data to be read cross cache page boundary or probably we have more than 1 page to read
+    else
+        {
+        __PRINT(_L("CDynamicDirCache::ReadL() CROSS PAGE!"));
+        TUint32 dataLen(aLength);   //-- current data length
+        TInt64  currMediaPos(aPos); //-- current media position
+
+        //-- 1. read data that are already in the current page
+        ReadDataFromSinglePageL(currMediaPos, bytesToPageEnd, aDes);
+        dataLen -= bytesToPageEnd;
+        currMediaPos += bytesToPageEnd;
+
+        TPtr8 dataNext = aDes.MidTPtr(aDes.Length());
+
+        //-- 2. read whole pages of data
+        while (dataLen >= PageSz)
+            {
+            //-- find out if currMediaPos is in cache. If not, find a spare page and read data there
+            ReadDataFromSinglePageL(currMediaPos, PageSz, dataNext);
+            currMediaPos += PageSz;
+            dataLen -= PageSz;
+            dataNext = dataNext.MidTPtr(dataNext.Length());
+            }
+
+        //-- 3. read the rest of the data
+        if(dataLen > 0)
+            {
+            ReadDataFromSinglePageL(currMediaPos, dataLen, dataNext);
+            }
+        } //else((TUint32)aLength <= bytesToPageEnd)
+    }
+
+/**
+Write data through a single page. If the page is not found or not valid anymore, read media onto iActive page
+first, then write data through iActive page.
+@param  aPos    the starting position of the media address to be write.
+@param  aData   the starting address that the writing content lives in the ram.
+@param  aDataLen    the length of the content to be written.
+@pre    aDataLen    should be no more than page size.
+*/
+void CDynamicDirCache::WriteDataOntoSinglePageL(TInt64 aPos, const TUint8* aData, TUint32 aDataLen)
+    {
+    ASSERT(aDataLen <= iPageSizeInBytes);
+    //-- the data section is in the cache page entirely, take data directly from the cache
+    TDynamicDirCachePage* pPage = FindPageByPos(aPos);
+    if (pPage)
+        {
+        // lock page before writing,
+        if (LockPage(pPage) != NULL)
+            {
+            //-- update cache
+            Mem::Copy(pPage->PtrInPage(aPos), aData, aDataLen);
+            }
+        else
+            {
+            ASSERT(pPage->PageType() == TDynamicDirCachePage::EUnlocked);
+            DeQueue(pPage);
+            LookupTblRemove(pPage->StartPos());
+            DecommitPage(pPage);
+            delete pPage;
+            pPage = NULL;
+            }
+        }
+
+    // if page not found or page data not valid anymore, use active page to read data in
+    if (!pPage)
+        {
+        pPage = UpdateActivePageL(aPos);
+        //-- update cache
+        Mem::Copy(pPage->PtrInPage(aPos), aData, aDataLen);
+        }
+
+    // make sure the page is unlocked after use
+    if (pPage->PageType() == TDynamicDirCachePage::EUnlocked)
+        {
+        UnlockPage(pPage);
+        }
+
+    // always make writting events MRU
+    MakePageMRU(aPos);
+    return;
+    }
+
+/**
+Implementation of pure virtual function.
+@see    MWTCacheInterface::WriteL()
+*/
+void CDynamicDirCache::WriteL(TInt64 aPos,const TDesC8& aDes)
+    {
+#ifdef _DEBUG
+    if(iCacheDisabled)
+        {
+        // cache is disabled for debug purposes
+        __PRINT(_L("CDynamicDirCache disabled"));
+        User::LeaveIfError(iDrive.WriteCritical(aPos,aDes));
+        return;
+        }
+#endif //_DEBUG
+
+    TUint32 dataLen = aDes.Size();
+    const TUint8* pData   = aDes.Ptr();
+    const TUint32 PageSz  = iPageSizeInBytes; //-- cache page size
+
+    TInt64 pageStartMedPos = CalcPageStartPos(aPos);
+    TUint32 bytesToPageEnd = (TUint32)(pageStartMedPos + PageSz - aPos);
+
+//    __PRINT5(_L("CDynamicDirCache::WriteL: aPos=%lx, aLength=%x, page:%lx, pageSz:%x, bytesToPageEnd=%x"), aPos, dataLen, pageStartMedPos, PageSz, bytesToPageEnd);
+
+    if(dataLen <= bytesToPageEnd)
+        {
+        WriteDataOntoSinglePageL(aPos, pData, dataLen);
+        }
+    else
+        {
+        __PRINT(_L("CDynamicDirCache::WriteL() CROSS PAGE!"));
+
+        //-- Data to be written cross cache page boundary or probably we have more than 1 page to write
+        TInt64  currMediaPos(aPos);
+
+        //-- 1. update the current page
+        WriteDataOntoSinglePageL(currMediaPos, pData, bytesToPageEnd);
+
+        pData += bytesToPageEnd;
+        currMediaPos += bytesToPageEnd;
+        dataLen -= bytesToPageEnd;
+
+        //-- 2. write whole pages of data to the cache
+        while (dataLen >= PageSz)
+            {
+            WriteDataOntoSinglePageL(currMediaPos, pData, PageSz);
+
+            pData += PageSz;
+            currMediaPos += PageSz;
+            dataLen -= PageSz;
+            }
+
+        //-- 3. write the rest of the data
+        if(dataLen > 0)
+            {
+            WriteDataOntoSinglePageL(currMediaPos, pData, dataLen);
+            }
+        }// else(dataLen <= bytesToPageEnd)
+
+
+    //-- write data to the media
+    const TInt nErr = iDrive.WriteCritical(aPos,aDes);
+    if(nErr != KErrNone)
+        {//-- some serious problem occured during writing, invalidate cache.
+        InvalidateCache();
+        User::Leave(nErr);
+        }
+    }
+
+/**
+Implementation of pure virtual function.
+@see    MWTCacheInterface::InvalidateCache()
+*/
+void CDynamicDirCache::InvalidateCache(void)
+    {
+    __PRINT2(_L("CDynamicDirCache::InvalidateCache(locked=%d, unlocked=%d)"), iLockedQCount, iUnlockedQCount);
+    // we should never decommit locked pages as they needs to be reserved anyway
+    // the overhead of unnecessary page committing operations
+    while(!iLockedQ.IsEmpty())
+        {
+        TDynamicDirCachePage* page = iLockedQ.Last();
+        DeQueue(page);                      // remove from queue
+        LookupTblRemove(page->StartPos());  // remove from lookuptable
+        delete page;
+        }
+    ASSERT(iLockedQCount == 0);
+
+    // however we should decommit unlocked pages here
+    while (!iUnlockedQ.IsEmpty())
+        {
+        TDynamicDirCachePage* page = iUnlockedQ.Last();
+        DeQueue(page);                      // remove from queue
+        LookupTblRemove(page->StartPos());  // remove from lookuptable
+        DecommitPage(page);                 // inform cache client to decommit page memory
+        delete page;
+        }
+    ASSERT(iUnlockedQCount == 0);
+
+    ASSERT(iLookupTable.Count() == 0);
+    iLookupTable.Close();
+
+    ASSERT(iCacheMemoryClient);
+
+    // initialize cache state.
+    // Note that once the client is reset, all pages lose connection with the client
+    //  including the active page. So we will need to reset and re-allocate active page
+    //  properly.
+    if (iCacheMemoryClient)
+        iCacheMemoryClient->Reset();
+
+    // reset and re-allocate active page
+    ResetPagePos(iActivePage);              // reset start media position (0), invalidate page content
+    TUint8* startRamAddr = iCacheMemoryClient->AllocateAndLockSegments(PageSizeInSegs());
+    // this should always succeed as the client has just been reset and there are always reserved pages
+    ASSERT(startRamAddr);
+    iActivePage->SetStartPtr(startRamAddr); // set RAM address
+    }
+
+
+/** this method isn't implemented*/
+void CDynamicDirCache::InvalidateCachePage(TUint64 /*aPos*/)
+    {
+    ASSERT(0);
+    }
+
+
+/**
+Implementation of pure virtual function.
+@see    MWTCacheInterface::PosCached()
+*/
+TUint32 CDynamicDirCache::PosCached(const TInt64& aPos, TInt64& aCachedPosStart)
+    {
+    const TInt64 pageStartMedPos = CalcPageStartPos(aPos);
+
+    // only search the page in lookup table
+    // NOTE: we don't count the active page into acount here,
+    // this is to avoid pulling next pages recursively
+    TDynamicDirCachePage* pPage = LookupTblFind(pageStartMedPos);
+
+    // then check if page is still valid if page is on Unlocked Page Queue
+    if (pPage && pPage->PageType() == TDynamicDirCachePage::EUnlocked)
+        {
+        if (LockPage(pPage) != NULL)
+            {
+//          __PRINT1(_L("CDynamicDirCache::PosCached: page(0x%lx) found on Unlocked Queue!"), aPos);
+            // have to unlock it before returning, otherwise there will be memory leak
+            UnlockPage(pPage);
+            aCachedPosStart = pPage->StartPos();
+            return pPage->PageSizeInBytes();
+            }
+        else    // if the unlocked page is not valid anymore, remove it
+            {
+            DeQueue(pPage);
+            LookupTblRemove(pPage->StartPos());
+            DecommitPage(pPage);
+            delete pPage;
+            pPage = NULL;
+            }
+        }
+    // otherwise if page is already locked or valid active page
+    else if (pPage)
+        {
+        __PRINT1(_L("CDynamicDirCache::PosCached: page(0x%lx) on Locked Queue!"), aPos);
+        aCachedPosStart = pPage->StartPos();
+        return pPage->PageSizeInBytes();
+        }
+
+    // page is not found or not valid anymore
+    return 0;
+    }
+
+/**
+Implementation of pure virtual function.
+@see    MWTCacheInterface::CacheSizeInBytes()
+*/
+TUint32 CDynamicDirCache::CacheSizeInBytes()  const
+    {
+    return iMaxCacheSizeInBytes;
+    }
+
+/**
+Implementation of pure virtual function.
+@see    MWTCacheInterface::Control()
+*/
+TInt CDynamicDirCache::Control(TUint32 aFunction, TUint32 aParam1, TAny* aParam2)
+    {
+    TInt r = KErrNotSupported;
+#ifdef _DEBUG
+    (void)aParam2;
+    switch(aFunction)
+        {
+        // disable / enable cache, for debug
+        // if aParam1 != 0 cache will be disabled, enabled otherwise
+        case EDisableCache:
+            iCacheDisabled = aParam1 ? 1 : 0;
+            r = KErrNone;
+        break;
+
+        // dump cache, for debug
+        case EDumpCache:
+            {
+            RFs fs;
+            fs.Connect();
+            const TUint32 debugRegister = DebugRegister();
+            fs.SetDebugRegister(debugRegister|KFSYS);
+            Dump();
+            fs.SetDebugRegister(debugRegister);
+            fs.Close();
+            break;
+            }
+        case ECacheInfo:
+            {
+            RFs fs;
+            fs.Connect();
+            const TUint32 debugRegister = DebugRegister();
+            fs.SetDebugRegister(debugRegister|KFSYS);
+            Info();
+            fs.SetDebugRegister(debugRegister);
+            fs.Close();
+            break;
+            }
+
+        default:
+            __PRINT1(_L("CDynamicDirCache::Control() invalid function: %d"), aFunction);
+            ASSERT(0);
+        break;
+        }
+
+#else
+    (void)aFunction; //-- supress warnings
+    (void)aParam1;
+    (void)aParam2;
+    User::Invariant(); //-- don't call this method in release build
+#endif //_DEBUG
+
+    return r;
+    }
+
+/**
+Implementation of pure virtual function.
+@see    MWTCacheInterface::SetCacheBasePos()
+*/
+void CDynamicDirCache::SetCacheBasePos(TInt64 aBasePos)
+    {
+    iCacheBasePos = aBasePos;
+    }
+
+/**
+Implementation of pure virtual function.
+@see    MWTCacheInterface::SetCacheBasePos()
+*/
+TUint32 CDynamicDirCache::PageSizeInBytesLog2() const
+    {
+    return iPageSizeLog2;
+    }
+
+/**
+Implementation of pure virtual function.
+@see    MWTCacheInterface::MakePageMRU()
+*/
+void CDynamicDirCache::MakePageMRU(TInt64 aPos)
+    {
+    __PRINT1(_L("MakePageMRU (%lx)"), aPos);
+//  __PRINT4(_L("Current Cache State: iLockedQCount=%d, iUnlockedQCount=%d, iLookupTbl=%d, iMaxSizeInPages=%d"), iLockedQCount, iUnlockedQCount, iLookupTable.Count(), iMaxSizeInPages);
+    // check the MRU page first, if it is already the MRU page, we can return immediately
+    TInt64 pageStartMedPos = CalcPageStartPos(aPos);
+    if (!iLockedQ.IsEmpty())
+        {
+        if (iLockedQ.First()->StartPos() == pageStartMedPos)
+            {
+            return;
+            }
+        }
+
+    TDynamicDirCachePage* pPage = FindPageByPos(aPos);
+    if (pPage)
+        {
+        ASSERT(pPage->IsValid());
+        // lock page before make it MRU
+        if (pPage->PageType() == TDynamicDirCachePage::EUnlocked)
+            {
+            ASSERT(!pPage->IsLocked());
+            if (LockPage(pPage) == NULL)
+                {
+                DeQueue(pPage);
+                LookupTblRemove(pPage->StartPos());
+                DecommitPage(pPage);
+                delete pPage;
+                pPage = NULL;
+                }
+            }
+        else
+            {
+            // error checking: page should either be locked or active
+            ASSERT(LockPage(pPage) != NULL);
+            }
+        }
+
+    // if page not found or page data not valid anymore, use active page to read data
+    if (!pPage)
+        {
+        TRAPD(err, pPage = UpdateActivePageL(aPos));
+        if (err != KErrNone)
+            {
+            // problem occurred reading active page, return immediately.
+            return;
+            }
+        }
+
+    // by now, the page is either locked or active page
+    ASSERT(pPage && pPage->IsValid() && pPage->IsLocked());
+
+    switch (pPage->PageType())
+        {
+        // if the page is the active page, we will need to find a new active page for replacement
+        case TDynamicDirCachePage::EActivePage:
+            {
+            TDynamicDirCachePage* newAP = NULL;
+            // if there is more cache room available, try to create a new page first
+            if (!CacheIsFull())
+                {
+                // allocate and lock a new page
+                TRAPD(err, newAP = AllocateAndLockNewPageL(0));
+                // if any error ocurrs, return immediately
+                if (err != KErrNone)
+                    {
+                    // unlock the page that was originally unlocked before leave
+                    if (pPage->PageType() == TDynamicDirCachePage::EUnlocked)
+                        {
+                        UnlockPage(pPage);
+                        }
+                    return;
+                    }
+
+                if (newAP)
+                    {
+                    // replace the active page with the new page
+                    newAP->SetPageType(TDynamicDirCachePage::EActivePage);
+                    iActivePage = newAP;
+                    }
+                }
+
+            // if cache has grown to its max size, or new page allocation failed
+            if (!newAP)
+                {
+                // try to lock the LRU page on the unlocked page queque first
+                if (!iUnlockedQ.IsEmpty())
+                    {
+                    newAP = iUnlockedQ.Last();
+                    ASSERT(newAP->IsValid());
+                    if (LockPage(newAP) != NULL)
+                        {
+                        // deque, reset pos, set new type
+                        DeQueue(newAP);
+                        LookupTblRemove(newAP->StartPos());
+                        ResetPagePos(newAP);
+                        newAP->SetPageType(TDynamicDirCachePage::EActivePage);
+                        // replace active page
+                        iActivePage = newAP;
+                        }
+                    // if falied locking the LRU page from unclocked queque,
+                    // delete it
+                    else
+                        {
+                        DeQueue(newAP);
+                        LookupTblRemove(newAP->StartPos());
+                        DecommitPage(newAP);
+                        delete newAP;
+                        newAP = NULL;
+                        }
+                    }
+                }
+
+            // if still have not found new active page
+            // grab the LRU page from Locked Page Queue for active page
+            if (!newAP)
+                {
+                ASSERT(!iLockedQ.IsEmpty());
+                newAP = iLockedQ.Last();
+                // deque, reset pos, set new type
+                DeQueue(newAP);
+                LookupTblRemove(newAP->StartPos());
+                ResetPagePos(newAP);
+                newAP->SetPageType(TDynamicDirCachePage::EActivePage);
+                // replace active page
+                iActivePage = newAP;
+                }
+
+            // we should always be able to find a locked page for active page
+            ASSERT(newAP != NULL);
+
+            // make original page (i.e. former active page) MRU
+            // add onto locked queue
+            AddFirstOntoQueue(pPage, TDynamicDirCachePage::ELocked);
+            // add onto lookuptbl, as active page is not on lookup tbl originally
+            LookupTblAdd(pPage);
+            // check cache limit
+            CheckThresholds();
+            return;
+            }
+        case TDynamicDirCachePage::EUnlocked:
+            {
+            // if page was originally on Unlocked Page Queque, remove it from Unlocked Page Queue, add it
+            // to the Locked Page Queue and make it MRU
+            DeQueue(pPage);
+            AddFirstOntoQueue(pPage, TDynamicDirCachePage::ELocked);
+            // check cache limit
+            CheckThresholds();
+            return;
+            }
+        case TDynamicDirCachePage::ELocked:
+            {
+            // otherwise the page was on Locked Page Queue, make it MRU
+            // no need to check cache limit
+            if (pPage != iLockedQ.First())
+                {
+                DeQueue(pPage);
+                AddFirstOntoQueue(pPage, TDynamicDirCachePage::ELocked);
+                return;
+                }
+            break;
+            }
+        default:
+            ASSERT(0);
+        }
+    }
+
+//====================================================================
+/**
+Internal query function, to check if aPos is cached or not. iActive page is included in searching.
+*/
+TDynamicDirCachePage* CDynamicDirCache::FindPageByPos(TInt64 aPos)
+    {
+    __PRINT1(_L("CDynamicDirCache::FindPageByPos(aPos=%lx)"), aPos);
+    // align the page position
+    TInt64 pageStartMedPos = CalcPageStartPos(aPos);
+
+    if ((iActivePage->StartPos() == pageStartMedPos))
+        {
+        ASSERT(iActivePage->IsValid());
+        return iActivePage;
+        }
+
+    // search in lookup table
+    return LookupTblFind(pageStartMedPos);
+    }
+
+/**
+read a page length data into iActive page and return iActive page if read is successful.
+*/
+TDynamicDirCachePage* CDynamicDirCache::UpdateActivePageL(TInt64 aPos)
+    {
+    // align the page position
+    TInt64 pageStartMedPos = CalcPageStartPos(aPos);
+
+    if (iActivePage->StartPos() == pageStartMedPos && iActivePage->IsValid())
+        {
+        return iActivePage;
+        }
+
+    __PRINT2(_L("CDynamicDirCache::UpdateActivePageL(aPos=%lx, active=%lx)"), aPos, iActivePage->StartPos());
+
+    // set start med pos value, no other effects, only available to active page
+    iActivePage->SetPos(pageStartMedPos);
+
+    // read data, make active page valid
+    TUint8* data = iActivePage->PtrInPage(iActivePage->iStartMedPos);
+    TPtr8 dataPtr(data, iPageSizeInBytes);
+    const TInt nErr = iDrive.ReadNonCritical(iActivePage->iStartMedPos, iPageSizeInBytes, dataPtr);
+    if(nErr !=KErrNone)
+        {
+        // some serious problem occured during reading, invalidate cache.
+        InvalidateCache();
+        User::Leave(nErr);
+        }
+    iActivePage->SetValid(ETrue);
+
+    return iActivePage;
+    }
+
+/**
+Check if the number of (locked pages + iActive page) and unlocked pages have exceeded minimum allowed page
+number and maximum allowed page number respectively.
+*/
+void CDynamicDirCache::CheckThresholds()
+    {
+    while (iLockedQCount + 1 > iMinSizeInPages)
+        {
+        TDynamicDirCachePage* movePage = iLockedQ.Last();
+        UnlockPage(movePage);
+        DeQueue(movePage);
+        TInt err = LookupTblRemove(movePage->StartPos());
+        ASSERT(err == KErrNone);
+
+        // if it is a valid page, add onto unlocked queue
+        if (movePage->StartPos() != 0)
+            {
+            ASSERT(movePage->IsValid());
+            AddFirstOntoQueue(movePage, TDynamicDirCachePage::EUnlocked);
+            err = LookupTblAdd(movePage);
+            ASSERT(err == KErrNone);
+            }
+        else // reserved page, delete
+            {
+            DecommitPage(movePage);
+            delete movePage;
+            }
+        }
+
+    // if unlocked queue exceeds limit, delete LRU page
+    // note: all pages on unlocked queue should be valid
+    while (iUnlockedQCount > iMaxSizeInPages - iMinSizeInPages)
+        {
+        TDynamicDirCachePage* removePage = iUnlockedQ.Last();
+        ASSERT(removePage->StartPos() != 0 && removePage->IsValid());
+        DeQueue(removePage);
+        LookupTblRemove(removePage->StartPos());
+        DecommitPage(removePage);
+        delete removePage;
+        }
+    }
+
+/**
+Try to create a new page and lock the page content when it is created. This function should only be called
+when creating iActive page or making a page MRU (which might result in page evictions).
+@return the pointer of the newly created page, or NULL if allocation failed.
+@param  aStartMedPos    the starting media address of the page to be created.
+@pre    aStartMedPos should not already be existing in the cache.
+*/
+TDynamicDirCachePage* CDynamicDirCache::AllocateAndLockNewPageL(TInt64 aStartMedPos)
+    {
+    __PRINT1(_L("CDynamicDirCache::AllocateAndLockNewPageL(aStartMedPos=%lx)"), aStartMedPos);
+
+    TUint8* startRamAddr = iCacheMemoryClient->AllocateAndLockSegments(PageSizeInSegs());
+    if (startRamAddr)
+        {
+        // create new page and return
+        TDynamicDirCachePage* pPage = TDynamicDirCachePage::NewL(this, aStartMedPos, startRamAddr);
+        pPage->SetLocked(ETrue);
+        pPage->SetValid(EFalse);
+        return pPage;
+        }
+
+    return NULL;
+    }
+
+#ifdef _DEBUG
+/**
+Dump cache information, only enabled in debug mode.
+@see CDynamicDirCache::Control()
+*/
+void CDynamicDirCache::Info() const
+    {
+    __PRINT(_L("======== CDynamicDirCache::Info ========="));
+    const TUint32 SegmentSizeInBytesLog2 = CCacheMemoryManagerFactory::CacheMemoryManager()->SegmentSizeInBytesLog2();
+    // page size
+    __PRINT1(_L("=== Pages size:               [%d Bytes]"), iPageSizeInBytes);
+    __PRINT1(_L("=== Segment size:             [%d Bytes]"), 1 << SegmentSizeInBytesLog2);
+
+    // data size:
+    __PRINT1(_L("=== Min data size:            [%d Bytes]"), iMinSizeInPages << iPageSizeLog2);
+    __PRINT1(_L("=== Max data size:            [%d Bytes]"), iMaxSizeInPages << iPageSizeLog2);
+
+    // memory size:
+    const TUint32 pageMemSizeLog2 = iPageSizeLog2 > SegmentSizeInBytesLog2 ? iPageSizeLog2 : SegmentSizeInBytesLog2;
+    __PRINT1(_L("=== Min memory size:          [%d Bytes]"), iMinSizeInPages << pageMemSizeLog2);
+    __PRINT1(_L("=== Max memory size:          [%d Bytes]"), iMaxSizeInPages << pageMemSizeLog2);
+
+    // reserved pages
+    __PRINT1(_L("=== Number of pages reserved: [%d]"), iMinSizeInPages);
+    __PRINT1(_L("=== Reserved memory:          [%d Bytes]"), (iMinSizeInPages * PageSizeInSegs()) << SegmentSizeInBytesLog2);
+    // locked page num
+    __PRINT1(_L("=== Number of pages locked:   [%d]"), iLockedQCount);
+    __PRINT1(_L("=== Locked memory:            [%d Bytes]"), (iLockedQCount * PageSizeInSegs()) << SegmentSizeInBytesLog2);
+    // unlocked page num
+    __PRINT1(_L("=== Number of pages unlocked: [%d]"), iUnlockedQCount);
+    __PRINT1(_L("=== Unlocked memory:          [%d Bytes]"), (iUnlockedQCount * PageSizeInSegs()) << SegmentSizeInBytesLog2);
+    }
+
+/**
+Dump cache content, only enabled in debug mode.
+@see CDynamicDirCache::Control()
+*/
+void CDynamicDirCache::Dump()
+    {
+    __PRINT(_L("======== CDynamicDirCache::Dump ========="));
+    if (!iLockedQ.IsEmpty())
+        {
+        TDblQueIter<TDynamicDirCachePage> q(iLockedQ);
+        q.SetToFirst();
+        TInt i = 0;
+        while((TDynamicDirCachePage*)q)
+            {
+            TDynamicDirCachePage* pP = q++;
+            __PRINT3(_L("=== CDynamicDirCache::iLockedQ\t[%4d](pos=%lx, size=%d)"), i++, pP->StartPos(), pP->PageSizeInBytes());
+            }
+        }
+    if (!iUnlockedQ.IsEmpty())
+        {
+        TDblQueIter<TDynamicDirCachePage> q(iUnlockedQ);
+        q.SetToFirst();
+        TInt i = 0;
+        while((TDynamicDirCachePage*)q)
+            {
+            TDynamicDirCachePage* pP = q++;
+            __PRINT3(_L("=== CDynamicDirCache::iUnlockedQ\t[%4d](pos=%lx, size=%u)"), i++, pP->StartPos(), pP->PageSizeInBytes());
+            }
+        }
+    __PRINT2(_L("=== CDynamicDirCache::iActivePage\t[*](pos=%lx, size=%u)"), iActivePage->StartPos(), iActivePage->PageSizeInBytes());
+
+    if (iLookupTable.Count())
+        {
+        TInt i = 0;
+        THashSetIter<TLookupEntry> iter(iLookupTable);
+        TLookupEntry* pEntry;
+        pEntry = (TLookupEntry*) iter.Next();
+        while(pEntry)
+            {
+            TDynamicDirCachePage* pP = pEntry->iPage;
+            __PRINT3(_L("=== CDynamicDirCache::iLookupTable\t[%4d](pos=%lx, size=%u)"), i++, pP->StartPos(), pP->PageSizeInBytes());
+            pEntry = (TLookupEntry*) iter.Next();
+            };
+        }
+    __PRINT(_L("===========================================\n"));
+    }
+#endif //_DEBUG
+
+/**
+Lock an unlocked page, or do nothing if the page is already locked.
+@return TUint8* pointer of the page to be locked, if locking is successful, otherwise return NULL.
+@param  aPage   the pointer of the page to be locked.
+*/
+TUint8* CDynamicDirCache::LockPage(TDynamicDirCachePage* aPage)
+    {
+    ASSERT(aPage != NULL);
+    if (aPage->IsLocked())
+        return aPage->StartPtr();
+
+    TInt r = iCacheMemoryClient->LockSegments(aPage->StartPtr(), PageSizeInSegs());
+    if (r == KErrNone)
+        {
+        aPage->SetLocked(ETrue);
+        return aPage->StartPtr();
+        }
+
+    return NULL;
+    }
+
+/**
+Unlock a locked page.
+@return TInt    KErrNone if unlocking was successful, otherwise system-wide error code.
+@param  aPage   the pointer of the page to be unlocked.
+*/
+TInt CDynamicDirCache::UnlockPage(TDynamicDirCachePage* aPage)
+    {
+    ASSERT(aPage != NULL);
+    __PRINT1(_L("CDynamicDirCache::UnlockPage(%lx)"), aPage->StartPos());
+    TInt r = iCacheMemoryClient->UnlockSegments(aPage->StartPtr(), PageSizeInSegs());
+    if (r == KErrNone)
+        {
+        aPage->SetLocked(EFalse);
+        }
+    return r;
+    }
+
+/**
+Decommit a locked or unlocked page.
+@return TInt    KErrNone if decommition was successful, otherwise system-wide error code.
+@param  aPage   the pointer of the page to be decommitted.
+*/
+TInt CDynamicDirCache::DecommitPage(TDynamicDirCachePage* aPage)
+    {
+    ASSERT(aPage != NULL);
+    __PRINT1(_L("CDynamicDirCache::DecommitPage(%lx)"), aPage->StartPos());
+    if (aPage)
+        {
+        TInt r = iCacheMemoryClient->DecommitSegments(aPage->StartPtr(), PageSizeInSegs());
+        if (r == KErrNone)
+            {
+            aPage->SetLocked(EFalse);
+            aPage->SetValid(EFalse);
+            }
+        return r;
+        }
+    return KErrArgument;
+    }
+
+/////////////////////////// aluxiliary functions //////////////////////////////////
+/**
+Calculate the page size in segments. Segment size is the size of the kernel memory unit that cache memory manager manages.
+We are making assumption here about the page size: page size should always be either less than segment size
+or multiple times of segment size
+@return TUint32 the page size in segments.
+*/
+TUint32 CDynamicDirCache::PageSizeInSegs() const
+    {
+    // initialize cache memory manager as all file systems have mounted by now
+    ASSERT(CCacheMemoryManagerFactory::CacheMemoryManager());
+    const TUint32 SegmentSizeInBytesLog2 = CCacheMemoryManagerFactory::CacheMemoryManager()->SegmentSizeInBytesLog2();
+
+    // Page size should be non-zero
+    ASSERT(iPageSizeInBytes);
+
+    TUint32 segs = iPageSizeInBytes >> SegmentSizeInBytesLog2;
+    return segs > 0 ? segs : 1;
+    }
+
+/**
+Deque the page from locked queue or unlocked queue. All pages are managed through these two queues, expect iActive
+page.
+@param  aPage   the pointer of the page to be dequeued
+@return TInt    KErrArgument if aPage is invalid, otherwise KErrNone.
+*/
+TInt CDynamicDirCache::DeQueue(TDynamicDirCachePage* aPage)
+    {
+    ASSERT(aPage);
+    if (!aPage)
+        return KErrArgument;
+
+    if (aPage->iType == TDynamicDirCachePage::ELocked)
+        {
+        aPage->Deque();
+        aPage->SetPageType(TDynamicDirCachePage::EUnknown);
+        --iLockedQCount;
+        }
+    else if (aPage->iType == TDynamicDirCachePage::EUnlocked)
+        {
+        aPage->Deque();
+        aPage->SetPageType(TDynamicDirCachePage::EUnknown);
+        --iUnlockedQCount;
+        }
+    else
+        {
+        ASSERT(0);
+        return KErrArgument;
+        }
+    return KErrNone;
+    }
+
+/**
+Insert a page to the first position of locked queue or unlocked queue.
+@param  aPage   the pointer of the page to be inserted.
+@param  aType   the type of the queue to be inserted.
+@return TInt    KErrArgument if aPage is invalid, otherwise KErrNone.
+*/
+TInt CDynamicDirCache::AddFirstOntoQueue(TDynamicDirCachePage* aPage, TDynamicDirCachePage::TPageType aType)
+    {
+    ASSERT(aPage);
+    if (!aPage)
+        return KErrArgument;
+
+    // page must be dequed first or it is active page
+    if (aPage->iType != TDynamicDirCachePage::EActivePage && aPage->iType != TDynamicDirCachePage::EUnknown)
+        {
+        ASSERT(0);
+        return KErrArgument;
+        }
+
+    if (aType == TDynamicDirCachePage::ELocked)
+        {
+        iLockedQ.AddFirst(*aPage);
+        aPage->SetPageType(TDynamicDirCachePage::ELocked);
+        ++iLockedQCount;
+        }
+    else if (aType == TDynamicDirCachePage::EUnlocked)
+        {
+        iUnlockedQ.AddFirst(*aPage);
+        aPage->SetPageType(TDynamicDirCachePage::EUnlocked);
+        ++iUnlockedQCount;
+        }
+    else
+        {
+        ASSERT(0);
+        return KErrArgument;
+        }
+
+    return KErrNone;
+    }
+
+/**
+Remove a page from the lookup table, indexed by the starting media address of the page content.
+@param  aPagePos    the starting media position of the page to be removed.
+*/
+TInt CDynamicDirCache::LookupTblRemove(TInt64 aPagePos)
+    {
+    if (aPagePos == 0)
+        {
+        return KErrNone;
+        }
+
+    TInt r = iLookupTable.Remove(TLookupEntry(aPagePos, 0, NULL));
+    return r;
+    }
+
+/**
+Insert a page to the lookup table, indexed by the starting media address of the page content.
+@param  aPagePos    the starting media position of the page to be inserted.
+*/
+TInt CDynamicDirCache::LookupTblAdd(TDynamicDirCachePage* aPage)
+    {
+    ASSERT(aPage);
+    if (!aPage)
+        return KErrArgument;
+
+    if (aPage->StartPos() == 0)
+        {
+        return KErrNone;
+        }
+
+    TInt r = iLookupTable.Insert(TLookupEntry(aPage->StartPos(), iPageSizeInBytes, aPage));
+    return r;
+    }
+
+/**
+Reset the media address of the page to 0, also invalidate the page.
+@param  aPage   the pointer of the page to be reset.
+*/
+TInt CDynamicDirCache::ResetPagePos(TDynamicDirCachePage* aPage)
+    {
+    ASSERT(aPage);
+    if (!aPage)
+        return KErrArgument;
+
+    aPage->ResetPos();
+    return KErrNone;
+    }
+
+/**
+Search the lookup table to find the page start with a specific media address.
+@param  aPos    the starting media address to be searched.
+*/
+TDynamicDirCachePage* CDynamicDirCache::LookupTblFind(TInt64 aPos)
+    {
+    if (aPos == 0)
+        {
+        ASSERT(0);
+        return NULL;
+        }
+
+    TLookupEntry* entry = iLookupTable.Find(TLookupEntry(aPos, 0, NULL));
+    if(entry)
+        {
+        ASSERT(entry->iPage->IsValid());
+        return entry->iPage;
+        }
+
+    return NULL;
+    }