BTreeNodeAccessor.h

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/*
// $Id: //open/dev/fennel/btree/BTreeNodeAccessor.h#16 $
// 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) 1999-2009 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_BTreeNodeAccessor_Included
#define Fennel_BTreeNodeAccessor_Included

#include "fennel/tuple/TupleDescriptor.h"
#include "fennel/tuple/TupleAccessor.h"
#include "fennel/tuple/TupleData.h"
#include "fennel/btree/BTreeNode.h"

FENNEL_BEGIN_NAMESPACE

class FENNEL_BTREE_EXPORT BTreeNodeAccessor
{
public:
    TupleDescriptor tupleDescriptor;

    TupleAccessor tupleAccessor;

    TupleData tupleData;

    virtual ~BTreeNodeAccessor();

    inline uint getKeyCount(BTreeNode const &node) const;

    virtual void clearNode(BTreeNode &node,uint cbPage);

    virtual PBuffer allocateEntry(
        BTreeNode &node,uint iEntry,uint cbEntry) = 0;

    virtual void deallocateEntry(
        BTreeNode &node,uint iEntry) = 0;

    virtual PConstBuffer getEntryForRead(
        BTreeNode const &node,uint iEntry) = 0;

    // NOTE jvs 10-Feb-2006:  This is commented out to indicate that subclasses
    // need to implement a corresponding inline to be usable with
    // BTreeKeyedNodeAccessor; avoid declaring it virtual to make sure the
    // compiler doesn't get confused about whether it should be inlined.
    /*
    virtual PConstBuffer getEntryForReadInline(
        BTreeNode const &node,uint iEntry) = 0;
    */

    virtual void onInit();

    void dumpNode(std::ostream &os,BTreeNode const &node,PageId pageId);

    virtual bool hasFixedWidthEntries() const = 0;

    virtual void accessTuple(BTreeNode const &node,uint iEntry) = 0;

    virtual uint binarySearch(
        BTreeNode const &node,
        TupleDescriptor const &keyDescriptor,
        TupleData const &searchKey,
        DuplicateSeek dupSeek,
        bool leastUpper,
        TupleData &scratchKey,
        bool &found) = 0;

    virtual int compareFirstKey(
        BTreeNode const &node,
        TupleDescriptor const &keyDescriptor,
        TupleData const &searchKey,
        TupleData &scratchKey) = 0;

    virtual void accessTupleInline(BTreeNode const &node, uint iEntry) = 0;

    enum Capacity {
        CAN_FIT,
        CAN_FIT_WITH_COMPACTION,

        CAN_NOT_FIT
    };

    virtual Capacity calculateCapacity(
        BTreeNode const &node,uint cbEntry) = 0;

    virtual uint getEntryByteCount(uint cbTuple) = 0;

    virtual void unmarshalKey(TupleData &keyData) = 0;

    virtual void compactNode(BTreeNode &node,BTreeNode &scratchNode);

    virtual void splitNode(
        BTreeNode &node,BTreeNode &newNode,uint cbNewTuple,bool monotonic);
};

inline uint BTreeNodeAccessor::getKeyCount(BTreeNode const &node) const
{
    if (node.height && (node.rightSibling == NULL_PAGE_ID)) {
        // For non-leaf nodes on the rightmost fringe, we pretend the last
        // key is +infinity, and ignore whatever's actually stored
        // there (except for its child PageId).
        assert(node.nEntries);
        return node.nEntries - 1;
    }
    return node.nEntries;
}

FENNEL_END_NAMESPACE

#endif

// End BTreeNodeAccessor.h

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