/*

* Copyright (c) 2005-2009 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:  Object locking features*

*/

#ifndef __MDSOBJECTLOCKLIST_H__

#define __MDSOBJECTLOCKLIST_H__

#include <e32base.h>

#include "mdscommoninternal.h"

class TMdSLockEntry;

class CMdSServerSession;

class CMdsNamespaceDef;

/**

* Metadata object locking.

* When opening objects for modifications, objects

* is locked so that no other session can modify the

* same object at same time.

*/

class CMdSObjectLockList : public CBase

    {

    public: // Constructors and destructor

        virtual ~CMdSObjectLockList();

        static CMdSObjectLockList* NewL();

        static CMdSObjectLockList* NewLC();

    private: // Private constructors

        void ConstructL();

    public: // Public functions

        /**

        * Locks object for modifying.

        * @param aSession   Session where object is being modified.

        * @param aNamespace Object's owner namespace

        * @param aObjId     Object id that is being modified.

        * @return           Returns whether object could be locked or not.

        */

        void LockObjectL( const CMdSServerSession& aSession, 

        		const CMdsNamespaceDef& aNamespace, const TItemId aObjectId );

        /**

        * Unlocks all locked objects of particular session.

        * @param aSession   Session which locked objects are to be released.

        */

        void UnlockBySession( const CMdSServerSession& aSession );

        /**

        * Unlocks locked object by Id.

        * @param aNamespace Object's owner namespace

        * @param aObjId     Object id that is being modified.

        */

        void UnlockById( const CMdsNamespaceDef& aNamespace, 

        		const TItemId aObjectId );

        /**

        * Checks if object is locked for modifying.

        * @param aNamespace Object's owner namespace

        * @param aObjId     An objects id which is going to be checked.

        * @return           <code>ETrue</code> if locked.

        *                   <code>EFalse</code> if not.

        */

        TBool IsLocked( const CMdsNamespaceDef& aNamespace, 

        		const TItemId aObjectId ) const;

    	/**

    	 * Empties the object lock list.

    	 */

        void Reset();

	protected:

		TInt Find( const CMdsNamespaceDef& aNamespace, 

				const TItemId aObjectId ) const;

    private:

        /**

         * Array which have the locked objects.

         */

        RArray<TMdSLockEntry> iLockListArray;

    };

/**

 * Internal data structure for storing information about locked objects.

 */

class TMdSLockEntry

    {

    public:

        /**

    	* Constructs a new lock list object.

        *

    	* @param aSession   session to which object id belongs

        * @param aNamespace Object's owner namespace

    	* @param aId        object id being modified

    	*/

    	TMdSLockEntry( const CMdSServerSession* aSession, 

    			const CMdsNamespaceDef& aNamespace, const TItemId aId )

    	: iSession( aSession ) , iNamespace( aNamespace ), iId( aId )

    	    {}

		static TInt Compare( const TMdSLockEntry& aFirst, 

				const TMdSLockEntry& aSecond );

    public:

        /* Session where object is being modified */

        const CMdSServerSession* iSession;

        /* Object's owner namespace */

        const CMdsNamespaceDef& iNamespace;

        /* Object's id which is being modified */

        TItemId iId;

    };

#endif  // __MDSOBJECTLOCKLIST_H__