LhxHashGenerator.h

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/*
// $Id: //open/dev/fennel/hashexe/LhxHashGenerator.h#3 $
// Fennel is a library of data storage and processing components.
// Copyright (C) 2006-2009 The Eigenbase Project
// Copyright (C) 2009-2009 SQLstream, Inc.
// Copyright (C) 2006-2009 LucidEra, Inc.
//
// 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_LhxHashGenerator_Included
#define Fennel_LhxHashGenerator_Included

#include "fennel/tuple/TupleData.h"
#include "fennel/tuple/TupleDescriptor.h"

#include "fennel/hashexe/LhxHashBase.h"

using namespace std;

FENNEL_BEGIN_NAMESPACE

class FENNEL_HASHEXE_EXPORT LhxHashGenerator
{
private:
    /*
     * Level at which the hash value seed is generated.
     */
    uint level;

    /*
     * The seed value.
     */
    uint hashValueSeed;

    // REVIEW jvs 25-Aug-2006: Let's unify the magic tables.  Result can
    // probably go to common/HashUtil.h since there's nothing LucidDB-specific
    // about it.
    /*
     * The magic table(same as the one used in LcsHash.cpp).
     */
    uint8_t *magicTable;

    // REVIEW jvs 25-Aug-2006: hashValues below are actually inout, right?

    void hashOneBuffer(uint &hashValue, PConstBuffer pBuf, uint bufSize);

    void hashOneColumn(
        uint &hashValue,
        TupleDatum const &inputCol,
        LhxHashTrim isVarChar);

public:
    void init(uint levelInit);

    uint getLevel();

    uint hash(
        TupleData const &inputTuple,
        TupleProjection const &keyProjection,
        vector<LhxHashTrim> const &isKeyColVarChar);

    uint hash(TupleDatum const &inputCol, LhxHashTrim isVarChar);

    uint hash(PConstBuffer pBuf, uint bufSize);
};

inline uint LhxHashGenerator::getLevel()
{
    return level;
}

inline uint LhxHashGenerator::hash(
    TupleDatum const &inputCol, LhxHashTrim isVarChar)
{
    uint hashValue = hashValueSeed;
    hashOneColumn(hashValue, inputCol, isVarChar);
    return hashValue;
}

inline uint LhxHashGenerator::hash(PConstBuffer pBuf, uint bufSize)
{
    uint hashValue = hashValueSeed;
    hashOneBuffer(hashValue, pBuf, bufSize);
    return hashValue;
}

FENNEL_END_NAMESPACE

#endif

// End LhxHashGenerator.h

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