DoubleBufferExecStream.h

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/*
// $Id: //open/dev/fennel/exec/DoubleBufferExecStream.h#5 $
// Fennel is a library of data storage and processing components.
// Copyright (C) 2005-2009 The Eigenbase Project
// Copyright (C) 2005-2009 SQLstream, Inc.
// Copyright (C) 2005-2009 LucidEra, Inc.
// Portions Copyright (C) 2004-2009 John V. Sichi
//
// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 2 of the License, or (at your option)
// any later version approved by The Eigenbase Project.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#ifndef Fennel_DoubleBufferExecStream_Included
#define Fennel_DoubleBufferExecStream_Included

#include "fennel/exec/ConduitExecStream.h"
#include "fennel/segment/SegPageLock.h"

FENNEL_BEGIN_NAMESPACE

struct FENNEL_EXEC_EXPORT DoubleBufferExecStreamParams
    : public ConduitExecStreamParams
{
};

class FENNEL_EXEC_EXPORT DoubleBufferExecStream
    : public ConduitExecStream
{
    SegmentAccessor scratchAccessor;
    SegPageLock bufferLock1;
    SegPageLock bufferLock2;
    PBuffer pFrontBuffer, pBackBuffer;

public:
    // implement ExecStream
    virtual void prepare(DoubleBufferExecStreamParams const &params);
    virtual void getResourceRequirements(
        ExecStreamResourceQuantity &minQuantity,
        ExecStreamResourceQuantity &optQuantity);
    virtual void open(bool restart);
    virtual ExecStreamResult execute(ExecStreamQuantum const &quantum);
    virtual void closeImpl();
    virtual ExecStreamBufProvision getOutputBufProvision() const;
    virtual ExecStreamBufProvision getInputBufProvision() const;
};

FENNEL_END_NAMESPACE

#endif

// End DoubleBufferExecStream.h

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