/** @file

* Copyright (c) 2005-2006 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:  CUpnpTcpSessionWriter is a class responsible for 

*                   asynchronous writing to a socket owned by CUpnpTcpSession.

*

*/

#ifndef C_UPNPTCPSESSIONWRITER_H

#define C_UPNPTCPSESSIONWRITER_H

#include <e32base.h>

#include <in_sock.h>

#include "upnpretrywrite.h"

class CUpnpTcpSession;

class CUpnpTcpWriteRequest;

/**

 *  CUpnpTcpSessionWriter is responsible for asynchronous writing.

 *  Writer class is owned by CUpnpTcpSession which request asynchronous 

 *  writing from it and is notified by writer when the write request 

 *  is completed or an error occured.

 *  When writer receives data to send it checks if it can be sent to the socket

 *  right away and if session is not yet connected or writer already sends data

 *  then it queues incoming data. When writing to the socket ends, writer checks 

 *  if there is data in queue waiting for sending. If thereis then it issues writing it 

 *  until the queue is empty. After writing all data, the writer notifies session about

 *  completion of the writing taska and switches to waiting state until it receives 

 *  another write request.

 *  @lib DLNAWebServer.lib

 *  @since Series60 2.6

 */

NONSHARABLE_CLASS (CUpnpTcpSessionWriter) : public CActive, MUpnpRetryWriteObserver

    {

public:

    /**

    * CUpnpTcpSessionWriter factory method.

    * @since Series60 2.6

    * @param aSession session that runs and supervises reader.

    * @param aSocket socket from which data will be read.

    * @param aPriority priority with which the reader will be working.

    * @return ?description

    */

    static CUpnpTcpSessionWriter* NewL( CUpnpTcpSession& aSession,

                                        RSocket& aSocket, 

                                        TThreadPriority aPriority );

    /**

    * Virtual destructor.

    * @since Series60 2.6

    */   

    virtual ~CUpnpTcpSessionWriter();

public: // New functions

    /**

    * Issues writing in asynchronous mode.

    * @since Series60 2.6

    * @param aData buffer with data to write.

    */

    void IssueWriteL( const TDesC8& aData );

    /**

    * Function used by CUpnpTcpSession that owns the writer

    * to notify if socket is connected and if writer can write data.

    * @since Series60 2.6

    * @param aConnected

    */

    void SessionConnected( TBool aConnected );

    /**

    * Returnes true if there are some write request queued and

    *   false if all data has been sent already.

    * @since Series60 2.6

    * @return true if there are some write request queued and

    *   false if all data has been sent already.

    */

    TBool HasWriteRequestsToSend();

    /**

    * Returns if retrying of writng occurs

    * @since series60 3.2

    * @return ETrue/EFalse

    */  

    TBool IsRetrying();

    /**

    * Returns if writer is writing some data at the moment.

    * @since series60 2.6

    * @return true if writer writes data at the moment.

    */  

    TBool IsWriting();

protected: // Functions from base CActive

    /**

    * Cancels issued writing request.

    * Standard active object function

    * @since Series60 2.6

    */

    void DoCancel();

    /**

    * Function called when the write request is finished.

    * Standard active object function

    * @since Series60 2.6

    */

    void RunL();

    /**

    * Trap RunL leaves

    * Standard active object function

    * @since Series60 2.0

    */

    TInt RunError( TInt aError );

private: // Constructors and destructors

    /**

    * CUpnpTcpSessionWriter constructor.

    * @since Series60 2.6

    * @param aSession session that runs and supervises reader.

    * @param aSocket socket from which data will be read.

    * @param aPriority priority with which the reader will be working.

    */

    CUpnpTcpSessionWriter( CUpnpTcpSession& aSession,

                           RSocket& aSocket,

                           TThreadPriority aPriority );

    /**

    * By default Symbian 2nd phase constructor is private.

    * @since Series60 2.6

    */

    void ConstructL();

private: // New functions

    /**

    * Sends next queued write request if such exists.

    * @since Series60 2.6

    */

    void SendNextWriteRequestL();

private: // from MUpnpRetryWriteObserver

    /**

    * Called when retrying of writing was succesed.

    * @since Series60 3.2

    */

	void RetryWriteSucceed();

    /**

    * Called when retrying of writing fail.

    * @since Series60 3.2

    */

	void RetryWriteFailL( TInt aError );

private: // Enumerations

    /**

    * TWriteState, records whether a write request is pending.

    *   - EnotConnected Socket is not yet connected so writer cannot write.

    *   - EWriting  A write request is pending with the socket server.

    *   - EWaiting  The idle state for this object. Socket is connected

    *               and the writer waits for write requests form session.

    *   - EDisconnected Session is already disconnected so don't write and don't 

    *               queue requests.

    */

    enum TWriterState

        {

        ENotConnected,

        EWriting,

        EWaiting,

        EDisconnected

        };

private: 

    /**

    * Socket used for writing data, not owned.

    */

    RSocket& iSocket;

    /**

    * Reference to session that owns the writer.

    * Session is request writing and is notified when it's finished or

    * errors occure, not owned.

    */

    CUpnpTcpSession& iSession;

    /**

    * State of the writer.

    */

    TWriterState iState;

    /**

    * Buffer that is used to send data to session.

    * Own.

    */

    RBuf8 iSendBuffer;

    /**

    * List of write requests. If session is unable to send data to session,

    * it is put into write request list.

    * Own.

    */

    RPointerArray<CUpnpTcpWriteRequest> iWriteRequestList;

    /**

    * Initial priority of the active object.

    */

    TThreadPriority iInitialPriority;

    /**

    * Implementation of retrying write to the socket

    */

    CUpnpRetryWrite* iRetryWrite;

    };

#endif // C_UPNPTCPSESSIONWRITER_H

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