sl@0: // Copyright (c) 2005-2009 Nokia Corporation and/or its subsidiary(-ies).
sl@0: // All rights reserved.
sl@0: // This component and the accompanying materials are made available
sl@0: // under the terms of "Eclipse Public License v1.0"
sl@0: // which accompanies this distribution, and is available
sl@0: // at the URL "http://www.eclipse.org/legal/epl-v10.html".
sl@0: //
sl@0: // Initial Contributors:
sl@0: // Nokia Corporation - initial contribution.
sl@0: //
sl@0: // Contributors:
sl@0: //
sl@0: // Description:
sl@0: //
sl@0: 
sl@0: #ifndef __IPCBUF_H__
sl@0: #define __IPCBUF_H__
sl@0: 
sl@0: #include <s32buf.h>
sl@0: #include "IpcDefs.h"
sl@0: 
sl@0: //Forward declarations
sl@0: class TIpcArgs;
sl@0: class RSqlDbSession;
sl@0: 
sl@0: /**
sl@0: HIpcBuf class manages the "client to server" transfer of large data blocks.
sl@0: 
sl@0: It caches the data to be sent/retrieved on the client side and sychronises the content of the client-side cache
sl@0: with the content of a similar server-side cache, sending appropriate read/write/sync commands to the server.
sl@0: 
sl@0: An instance of TIpcStreamBuf class is uased as a client-side cache.
sl@0: 
sl@0: The following code fragment shows how the class can be used to send to the server large blocks of data:
sl@0: 
sl@0: @code
sl@0: //Step 1: Create the HIpcBuf instance.
sl@0: HIpcBuf* ipcBuf = HIpcBuf::NewLC(params, function, args);
sl@0: 
sl@0: //Step 2: Create a stream instance. It will be used for sending the data to the server. All details about
sl@0: //		  the data transfer will be performed by the ipcBuf object.
sl@0: RWriteStream out(ipcBuf);
sl@0: 
sl@0: //Step 3: "TheObject" is some large data object which has to be sent to the server. Let's assume 
sl@0: //		  "TheObject" has ExternalizeL() function which can be used to externalize the object into an output stream.
sl@0: TheObject.ExternalizeL(out);
sl@0: 
sl@0: //Step 4: Commit the output stream. After the commit command the server will have all the data transferred.
sl@0: out.CommitL();		
sl@0: 
sl@0: //Step 5: Cleanup.
sl@0: CleanupStack::PopAndDestroy(ipcBuf);
sl@0: @endcode
sl@0: 
sl@0: @see RSqlDbSession;
sl@0: @see TIpcStreamBuf
sl@0: @see RSessionBase
sl@0: 
sl@0: @internalComponent
sl@0: */
sl@0: NONSHARABLE_CLASS(HIpcBuf) : public TStreamBuf
sl@0: 	{
sl@0: public:
sl@0: 	static HIpcBuf* NewL(RSqlDbSession& aSession, TInt aFunction, TIpcArgs& aArgs);
sl@0: 	static HIpcBuf* NewLC(RSqlDbSession& aSession, TInt aFunction, TIpcArgs& aArgs);
sl@0: 	virtual ~HIpcBuf();
sl@0: 	
sl@0: private:
sl@0: 	HIpcBuf(RSqlDbSession& aSession);
sl@0: 	void ConstructL(TInt aFunction, TIpcArgs& aArgs);
sl@0: 	
sl@0: 	// from TStreamBuf
sl@0: 	TInt UnderflowL(TInt aMaxLength);
sl@0: 	void OverflowL();
sl@0: 	void DoRelease();
sl@0: 	void DoSynchL();
sl@0: 	TInt DoReadL(TAny* aPtr, TInt aMaxLength);
sl@0: 	void DoWriteL(const TAny* aPtr, TInt aLength);
sl@0: 	TStreamPos DoSeekL(TMark aMark, TStreamLocation aLocation, TInt anOffset);
sl@0: 	
sl@0: private:
sl@0: 	inline void SetPos(TRead, TInt aPos);
sl@0: 	inline void SetPos(TWrite, TInt aPos);
sl@0: 	inline TInt Pos(TRead) const;
sl@0: 	inline TInt Pos(TWrite) const;
sl@0: 	inline TInt MovePos(TRead, TInt aOffset);
sl@0: 	TInt IpcReadL(TAny* aPtr, TInt aMaxLength);
sl@0: 	void IpcWriteL(const TAny* aPtr, TInt aLength);
sl@0: 	TInt EndL();
sl@0: 
sl@0: 	inline TInt Lag(TRead) const;
sl@0: 	inline TInt Lag(TWrite) const;
sl@0: 	inline TInt Mark(TRead) const;
sl@0: 	inline TInt Mark(TWrite) const;
sl@0: 	
sl@0: private:
sl@0: 	RSqlDbSession& 	iSession;
sl@0: 	TInt			iHandle;
sl@0: 	TInt 			iRPos;
sl@0: 	TInt 			iWPos;
sl@0: 	TIpcStreamBuf	iBuf;
sl@0: 	};
sl@0: 
sl@0: #include "IPCBuf.inl"
sl@0: 
sl@0: #endif//__IPCBUF_H__