/*

* 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:    Garbage collector

*

*/

#include "glxgarbagecollector.h"

#include <glxassert.h>

#include <glxtracer.h>

#include <glxlog.h>

#include "glxcache.h"

#include "glxerrormanager.h"

#include "glxmedia.h"

#include "glxmedialist.h"

#include "mglxmediauser.h"

#include "glxthumbnailutility.h"

/**

 * Interval for the periodic timer, in microseconds

 */

const TInt KPeriodicInterval = 500000;

/**

 * Start Delay for the periodic timer, in microseconds

 */

const TInt KPeriodicStartDelay = 300000;   // It is Changed to 300Micro Second ; To be able to give Others a Chance to Run before it starts

/** 

 * Max number of items to scan per periodic callback

 * @todo Find optimal value for this

 */

const TInt KMaxScannedMediaCountPerPeriodicCallback = 15;  // Changed from 30; Still there is Scope for Nominal Value Or Dynamic Value

/**

 * Max number of attributes that an item may have in use

 */

const TInt KMaxAttributesInUse = 50;

// -----------------------------------------------------------------------------

// NewL

// -----------------------------------------------------------------------------

//

CGlxGarbageCollector* CGlxGarbageCollector::NewL( 

        const RPointerArray<CGlxCache>& aCaches )

    {

    TRACER( "CGlxGarbageCollector::NewL" );

    CGlxGarbageCollector* self = new( ELeave ) CGlxGarbageCollector( aCaches );

    CleanupStack::PushL( self );

    self->ConstructL();

    CleanupStack::Pop(self);

    return self;

    }

// -----------------------------------------------------------------------------

// Constructor

// -----------------------------------------------------------------------------

//

CGlxGarbageCollector::CGlxGarbageCollector( 

    const RPointerArray<CGlxCache>& aCaches )

        : iCaches( aCaches )

    {

    TRACER("CGlxGarbageCollector::Default Constructor");

    }

// -----------------------------------------------------------------------------

// ConstructL

// -----------------------------------------------------------------------------

//

void CGlxGarbageCollector::ConstructL()

    {

    TRACER("CGlxGarbageCollector::ConstructL");

    // Create callback loop in the lowest priority, so that the garbage

    // collection does not slow down the application

    iPeriodic = CPeriodic::NewL( CActive::EPriorityIdle );

    iAttributesInUse.ReserveL(KMaxAttributesInUse);

    }

// -----------------------------------------------------------------------------

// Destructor

// -----------------------------------------------------------------------------

//

CGlxGarbageCollector::~CGlxGarbageCollector()

    {

    TRACER("CGlxGarbageCollector::Destructor");

    delete iPeriodic;

    iAttributesInUse.Close();

    }

// -----------------------------------------------------------------------------

// CleanupL

// -----------------------------------------------------------------------------

//

void CGlxGarbageCollector::CleanupL()

    {

    TRACER("CGlxGarbageCollector::CleanupL");

    if ( !iPeriodic->IsActive() )

        {

        iPeriodic->Start( KPeriodicStartDelay, KPeriodicInterval, TCallBack( &PeriodicCallbackL, static_cast<TAny*>( this ) ) );

        }

    else

        {

        // a full cleanup round is required to make the cache fully clean,

        // if cleanup is currently ongoing. we don't know whether the cache

        // was modified before or after the current (cache or media) index being

        // cleaned up.

        iRequiresFullCleanupRound = ETrue;

        }

    }

// -----------------------------------------------------------------------------

// CancelCleanup

// -----------------------------------------------------------------------------

//

void CGlxGarbageCollector::CancelCleanup()

    {

    TRACER("CGlxGarbageCollector::CancelCleanup");

    if (iPeriodic->IsActive())

        {

        iPeriodic->Cancel();

        // Consideration of Restarting the timer is there; 

        }

    }

// -----------------------------------------------------------------------------

// Callback from periodic timer

// -----------------------------------------------------------------------------

//

TInt CGlxGarbageCollector::PeriodicCallbackL( TAny* aPtr )

    {

    TRACER("CGlxGarbageCollector::PeriodicCallback");

    GLX_ASSERT_DEBUG( aPtr != NULL, Panic( EGlxPanicLogicError ), 

        "Received null pointer for garbage collector" );

    // get "this" pointer

    static_cast< CGlxGarbageCollector* >( aPtr )->PeriodicCallbackL();

    // return value ignored for periodic timers

    return 0;

    }

// -----------------------------------------------------------------------------

// Flush Count Pages

// -----------------------------------------------------------------------------

//

void CGlxGarbageCollector::FlushPagesL(TInt aCount)

    {

    TBool reachedEnd = CleanupCaches(aCount);

    if ( reachedEnd )

        {

        // reset to the start of the caches

        iScanningPosition.iCurrentCacheIndex = 0;

        iScanningPosition.iNextMediaIndexToCleanup = 0;

        // next time the full round reaches end, the caches will be fully clean

        // (unless client calls Cleanup() )

        iRequiresFullCleanupRound = EFalse;

        }

    }

// -----------------------------------------------------------------------------

// Callback from periodic timer

// inlined in cpp only => inlines for arm

// -----------------------------------------------------------------------------

//

inline void CGlxGarbageCollector::PeriodicCallbackL()

    {

    TRACER("CGlxGarbageCollector::PeriodicCallbackL");

    TBool reachedEnd = CleanupCaches();

    // determine whether idle callback should be cancelled (note that check 

    // needs to be done before resetting iRequiresFullCleanupRound below)

    // do not cancel if reached the end, but cache is dirty

    if ( reachedEnd && !iRequiresFullCleanupRound )

        {

        iPeriodic->Cancel();

        }

    // if scanned to the end of caches, set up for the next cleanup round

    if ( reachedEnd )

        {

        // reset to the start of the caches

        iScanningPosition.iCurrentCacheIndex = 0;

        iScanningPosition.iNextMediaIndexToCleanup = 0;

        // next time the full round reaches end, the caches will be fully clean

        // (unless client calls Cleanup() )

        iRequiresFullCleanupRound = EFalse;

        }

    }

// -----------------------------------------------------------------------------

// Clean up all caches

// -----------------------------------------------------------------------------

//

TBool CGlxGarbageCollector::CleanupCaches(TInt aCount)

    {

    TRACER( "CGlxGarbageCollector::CleanupCaches" );

    TInt remainingScanCount = 0;

    // set the maximum number of items to scan during this call

    // Count is Needed for Flushing Direct

    remainingScanCount = aCount*KMaxScannedMediaCountPerPeriodicCallback;

    // Iterate through all cache until scanned enough items (remainingScanCount)

    // (unlikely to have many caches, so ok to call RPointerArray::Count() on 

    // each iteration)

    while ( iScanningPosition.iCurrentCacheIndex < iCaches.Count() )

        {

        // clean up current cache

        remainingScanCount = CleanupCache( 

            *iCaches[iScanningPosition.iCurrentCacheIndex], remainingScanCount );

        // exit the loop if reached full scan count, since the above loop might

        // have reached the end of the cache. (so don't increment the current

        // cache index)

        if ( 0 == remainingScanCount )

            {

            break;

            }

        // set indexes to the beginning of the next cache

        iScanningPosition.iCurrentCacheIndex++;

        iScanningPosition.iNextMediaIndexToCleanup = 0; 

        }

    // determine if there is anything more to clean up

    TBool reachedEndOfAllCaches = 

        ( iScanningPosition.iCurrentCacheIndex == iCaches.Count() );

    return reachedEndOfAllCaches;

    }

// -----------------------------------------------------------------------------

// Clean up cache that is currently under cleanup

// return number of items yet to scan during this idle callback

// -----------------------------------------------------------------------------

//

TInt CGlxGarbageCollector::CleanupCache( CGlxCache& aCache,     

        TInt aRemainingScanCount )

    {

    TRACER( "CGlxGarbageCollector::CleanupCache" );

    // set the maximum number of items to scan during this call

    TInt remainingScanCount = aRemainingScanCount;

    // don't store cache.Count() locally, as the count changes during the loop

    while ( iScanningPosition.iNextMediaIndexToCleanup < aCache.Count() &&

            remainingScanCount > 0 && ( aCache.IdSpaceId() != KGlxIdSpaceIdRoot ) )

        {

        CGlxMedia& media = aCache.Media( iScanningPosition.iNextMediaIndexToCleanup );

        if ( media.UserCount() > 0 )

            {

            // the media object still has users. Check if any attributes

            // it has can be deleted.

            TRAPD( err, CleanupMediaL( aCache, media ) );

            // skip the media object if cleanup failed. This allows cleanup to 

            // continue also when has no free memory. Skip also if there

            // are still attributes in use.

            if ( ( media.Count() == 0 && !err ) || ( err > 0 ) )

                {

                // the media object has no more attributes. It can be deleted.

                // don't increment iNextMediaIndexToCleanup since the index

                // of the next item will be decreased by one due to removal

                aCache.Delete( iScanningPosition.iNextMediaIndexToCleanup );

                GLX_LOG_INFO1( "CGlxGarbageCollector - Deleted Media Id=%d since no attributes left", media.Id().Value());

                }

            else if( err < 0 )

                {

                // scan next item

                iScanningPosition.iNextMediaIndexToCleanup++;                

                }

            else 

                {

                // scan next item

                iScanningPosition.iNextMediaIndexToCleanup++;                

                }

            }

        else

            {

            // the media object has no more users in present cache. It may be deleted

            if( !MediaInUse( media ) )

	            {

	            // Bug Fix @ EDDG-7V3CJA:: Recheck other caches for UserCount 

	            aCache.Delete( iScanningPosition.iNextMediaIndexToCleanup );

	            GLX_LOG_INFO1( "CGlxGarbageCollector - Deleted Media Id=%d since no users left", media.Id().Value());

	            }            

            }            

        remainingScanCount--;

        }

    return remainingScanCount;

    }

// -----------------------------------------------------------------------------

// Perform cleanup on provided media object

// -----------------------------------------------------------------------------

//

void CGlxGarbageCollector::CleanupMediaL( CGlxCache& aCache, CGlxMedia& aMedia )

    {

    TRACER("CGlxGarbageCollector::CleanupMediaL");

    // check which attributes can be deleted.

    iAttributesInUse.Reset();

    GetAttributesInUseL( aMedia, iAttributesInUse );

    if ( iAttributesInUse.Count() == 0 )

        {

        User::Leave(1);

        }

    GlxErrorManager::ClearExpiredAndUnusedErrorsL( aMedia, iAttributesInUse );

    // add the error attribute to the list of attributes that are in use, so

    // that it won't be deleted by the loop below.

    // (if there are no errors left, GlxErrorManager::ClearExpiredAndNotInUseErrorsL 

    // would have deleted the error attribute from aMedia, so checking for it

    // does no harm)

    iAttributesInUse.AppendL( GlxErrorManager::ErrorAttribute() );

    // delete all attributes that are not being used

    DeleteOtherAttributes( aCache, aMedia, iAttributesInUse );

    }

// -----------------------------------------------------------------------------

// GetAttributesInUseL

// -----------------------------------------------------------------------------

//

void CGlxGarbageCollector::GetAttributesInUseL( const CGlxMedia& aMedia, 

        RArray<TMPXAttribute>& aAttributes ) const

    {

    TRACER("CGlxGarbageCollector::GetAttributesInUseL");

    // get needed attributes from each user of the media object

    // ( unlikely to have many users, so calling CGlxMedia::UserCount and 

    // CGlxMedia::Id within the loop )

    for ( TInt userIndex = 0; userIndex < aMedia.UserCount(); userIndex++ )

        {

        aMedia.User( userIndex ).GetRequiredAttributesL( aMedia.IndexInUser( userIndex ), 

            aAttributes );

        }

    }

// -----------------------------------------------------------------------------

// Delete all attributes from a media object except those specified

// -----------------------------------------------------------------------------

//

void CGlxGarbageCollector::DeleteOtherAttributes( CGlxCache& /*aCache*/, CGlxMedia& aMedia, 

        const RArray<TMPXAttribute>& aAttributesToKeep ) const

    {

    TRACER("CGlxGarbageCollector::DeleteOtherAttributes");

    // loop backwards so can delete attributes during the loop

    for ( TInt attrIndex = aMedia.Count() - 1; attrIndex >= 0; attrIndex-- )

        {

        // delete the attribute if it is not in use

        if ( KErrNotFound == aAttributesToKeep.Find( aMedia.Attribute( attrIndex ), TMPXAttribute::Match ) )

            {

            GLX_LOG_INFO( "CGlxGarbageCollector::CleanupMediaL - Deleted attribute" );

            aMedia.DeleteAttribute( attrIndex );

            }

        }

    }

// -----------------------------------------------------------------------------

// Check for User Count for media to be deleted in the remaining caches

// -----------------------------------------------------------------------------

//    

TBool CGlxGarbageCollector::MediaInUse(const CGlxMedia&  aMedia) const

	{

	// Bug Fix @ EDDG-7V3CJA :: If media has non zero user count in any of the caches

	// then deletion of texture is to be avoided.	

	for(TInt cacheCount = 0; cacheCount < iCaches.Count(); cacheCount++ )

		{		

		if ( ( iCaches[cacheCount]->Media( aMedia.Id() ) ) 

				&& ( iCaches[cacheCount]->IdSpaceId() != KGlxIdSpaceIdRoot ) )

			{

			if ( ( iCaches[cacheCount]->Media(aMedia.Id() ) )->UserCount() > 0 )

				{

				return ETrue;		

				}

			}

		}

	return EFalse;	

    }