/**

* Copyright (c) 2007-2009 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:

* RMBufPoolChain decleration

* 

*

*/

/**

 @file

 @internalTechnology

*/

#ifndef MBUF_POOL_CHAIN_H

#define MBUF_POOL_CHAIN_H

#include <e32def.h>     // for std types

// forward decleration(s) to avoid circular dependency by including this file

// - this is a symptom of multiple class declerations within the same header file

//   eg. es_mbman.h required for CMBufPool, but also contains CMBufManager which inturn requires RMBufPoolChain defined in this file!

class RMBufPoolChain;

#include <es_mbman.h>       // for CMBufPool

// this class is internal to MBM, but alas this can't be enforced by C++ (except by not exporting its header file)

class RMBufPoolChain

	{

	friend class CMBufPoolManager;	// to allow access to private members

	RMBufPoolChain(TInt aMBufSize, CMBufPoolManager& aMBufPoolManager); // to be used only in searching for existing poolchain

	RMBufPoolChain(TInt aMBufSize, TInt aInitialAllocation, TInt aMinGrowth, TInt aHighGrowthThresholdPercentage, CMBufPoolManager& aMBufPoolManager);

	void OpenL();

	void Close();

public:	

	TInt GrowthSize(TInt aSize);

	void ExtendFreeList(CMBufPool* aPool);  // assumed that the caller has already acquired the lock, refer comments within the definition

	TInt Alloc(RMBufQ& aList, TInt aSize, TBool aIsAllocPool);

	static TInt Compare(const TInt* aMBufSize, const RMBufPoolChain& aRHSPoolChain);

	static TInt Compare(const RMBufPoolChain& aLHSPoolChain, const RMBufPoolChain& aRHSPoolChain);

	CMBufPoolManager& MBufPoolManager();

private:

	RWorkerLock iLockFreeList;				// lock for free list

    TInt iLenFree;					// number of bytes free within the pool chain

    TInt iLenTotal;				// number of bytes allocated (free + used) within the pool chain

    RMBufQ iFreeMBufs;				// free list of mbufs ready to be consumed, use of plural naming implies the queue (hence the name isn't appended)

    TDblQue<CMBufPool> iPools;

   	const TInt iMBufSize;          // size (in bytes) of contained mbufs, also stored within mbuf but kept here for encapsulation & ease of reference

    const TInt iInitialAllocation; // initial allocation size in num of MBufs (not bytes)

    TInt iMinGrowth;  				// minimum (automatic) incremental allocation in num of MBufs (not bytes) - actual allocate may be larger (refer )

    TInt iGrowthThreshold; 		// if the num of free mbufs is <= this value, then a a new pool is automatically allocated

	TBool iSignalled;				// background growth in progress

	TInt iNumMBufsToAdd;			// background growth

	TBool iNoMoreSpace;				// last background growth failed

	TInt iLastGrowth;				// last attempted growth

	TInt iMaxGrowthAttempt;			// largest growth attempt

	TInt iDbgPoolLimit;				// limit size of pool chain

	CMBufPoolManager& iMBufPoolManager;

	};

#endif  // MBUF_POOL_CHAIN_H