--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/photosgallery/viewframework/medialists/inc/glxgarbagecollector.h	Thu Dec 17 08:45:44 2009 +0200
@@ -0,0 +1,182 @@
+/*
+* 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
+*
+*/
+
+
+
+
+
+#ifndef C_GLXGARBAGECOLLECTOR_H
+#define C_GLXGARBAGECOLLECTOR_H
+
+#include <e32base.h>
+
+
+class CGlxMedia;
+class CGlxCache;
+class T_CGlxGarbageCollector;
+class TMPXAttribute;
+/**
+ * CGlxGarbageCollector
+ *
+ * Garbage collector for the media item cache
+ *
+ * @lib glxmedialists.lib
+ */
+class CGlxGarbageCollector : public CBase
+    {
+public:
+    /**
+     * Two-phase constructor
+     * @return new garbage collector instance
+     */
+    static CGlxGarbageCollector* NewL( const RPointerArray<CGlxCache>& aCaches );
+	
+    /**
+     * Destructor
+     */
+    ~CGlxGarbageCollector();
+
+    /**
+     * Start background garbage collection
+     */
+    void CleanupL();
+    
+    /**
+     * Cancel background garbage collection
+     */
+    void CancelCleanup();
+    
+    /**
+     * Flush Some Pages As System Reach Low Memory Limit
+     * pointer to be used
+     */
+    void FlushPagesL(TInt aCount);
+    
+private:
+    /**
+     * Constructor
+     */
+    CGlxGarbageCollector( const RPointerArray<CGlxCache>& aCaches );
+	
+    /**
+     * Second-phase constructor
+     */
+    void ConstructL();
+    
+    /**
+     * Callback for periodic timer
+     * @see TCallBack
+     */
+    static TInt PeriodicCallbackL( TAny* aPtr );
+    
+    /**
+     * Callback for periodic timer, non-static, and hence allows this
+     * pointer to be used
+     */
+    void PeriodicCallbackL();
+
+    /**
+     * Perform garbage collection on all caches
+     * Only cleans up only a certain number of items each call, to avoid
+     * this call taking a very long time, as this will be called
+     * from the periodic timer callback
+     * @param aCount 
+     * @return ETrue if reached the end of caches; EFalse if not
+     */
+    TBool CleanupCaches(TInt aCount = 1);
+
+    /**
+     * Perform garbage collection on specified cache
+     * Only cleans up only aRemainingScanCount amount of items.
+     * @param aRemainingScanCount maximum number of items to scan
+     * @return the remaining scan count
+     */
+    TInt CleanupCache( CGlxCache& aCache, TInt aRemainingScanCount );
+        
+    /**
+     * Clean a particular media object: remove attributes that no fetch contexts want
+     */
+    void CleanupMediaL( CGlxCache& aCache, CGlxMedia& aMedia );
+    
+    /**
+     * Get a list of all attributes that should not  be deleted form a given 
+     * media object
+     * @param aMedia Media object for which attributes are required
+     * @return aNeededAttributes list of attributes that should not be 
+     *                           deleted 
+     */
+    void GetAttributesInUseL( const CGlxMedia& aMedia, 
+        RArray<TMPXAttribute>& aNeededAttributes ) const;
+
+    /**
+     * Delete attributes from a media object other than those specified
+	 * Removes the fullscreen texture if the fullscreen thumbnail att is deleted
+     * @param aMedia Media object from which to delete attributes
+     * @return aAttributesToKeep List of attributes that will not be deleted
+     */
+    void DeleteOtherAttributes( CGlxCache& aCache, CGlxMedia& aMedia, 
+        const RArray<TMPXAttribute>& aAttributesToKeep ) const;
+        
+    /**
+     * Check user count in remaining caches for media item to be deleted
+     * @param aMedia Media id which is to be checked
+     * @return EFalse if user count is zero in all caches
+     *	       ETrue if user count is non zero in any of the caches  
+     */
+    TBool MediaInUse(const CGlxMedia& aMedia) const;
+private:
+    /**
+     * Abstraction of indexes that control the scanning of the cache across idle 
+     * callbacks
+     */
+    struct TScanIndexes 
+        {
+        /// Index of the cache index that is currently being cleaned up
+    	TInt iCurrentCacheIndex;
+        /// Index of the media index in the current cache that should next be cleaned up
+        TInt iNextMediaIndexToCleanup;
+        };
+
+private: // Data
+    /// Single instance of the garbage collector
+    static CGlxGarbageCollector* iGarbageCollector;
+
+    /// A list of caches that should be kept clean
+    /// not own (pointed cache objects)
+    const RPointerArray<CGlxCache>& iCaches;
+
+    // A list of attributes that are still in use by an item
+    RArray<TMPXAttribute> iAttributesInUse;
+
+    /// Periodic timer active object to use for callbacks
+    /// own
+    CPeriodic* iPeriodic; 
+    
+    /// Scan indexes of the current scanning position in the caches
+    TScanIndexes iScanningPosition;
+    
+    /// Info of whether a full cleanup round should be performed to have all
+    /// garbage freed from all caches.
+    /// ETrue if cleanup should be run from the start before fully cleaned
+    /// EFalse if the caches are clean currently or after the current cleanup
+    /// round completes.
+    TBool iRequiresFullCleanupRound;
+
+    friend class T_CGlxGarbageCollector;
+    };
+
+#endif // C_GLXGARBAGECOLLECTOR_H
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