tabindnode.cpp

linux下一款GIS程序源码

// tabindnode.cpp: implementation of the TABINDNode class.
//
//////////////////////////////////////////////////////////////////////

#include "tabindnode.h"

#include "ugk_errhandle.h"

/**********************************************************************
 *                   TABINDNode::TABINDNode()
 *
 * Constructor.
 **********************************************************************/
TABINDNode::TABINDNode(TABAccess eAccessMode /*=TABRead*/)
{
    m_fp = NULL;
    m_poCurChildNode = NULL;
    m_nSubTreeDepth = 0;
    m_nKeyLength = 0;
    m_eFieldType = TABFUnknown;
    m_poDataBlock = NULL;
    m_numEntriesInNode = 0;
    m_nCurIndexEntry = 0;
    m_nPrevNodePtr = 0;
    m_nNextNodePtr = 0;
    m_poBlockManagerRef = NULL;
    m_poParentNodeRef = NULL;
    m_bUnique = FALSE;

    m_eAccessMode = eAccessMode;
}

/**********************************************************************
 *                   TABINDNode::~TABINDNode()
 *
 * Destructor.
 **********************************************************************/
TABINDNode::~TABINDNode()
{
    if (m_poCurChildNode)
        delete m_poCurChildNode;

    if (m_poDataBlock)
        delete m_poDataBlock;
}



/**********************************************************************
 *                   TABINDNode::InitNode()
 *
 * Init a node... this function can be used either to initialize a new
 * node, or to make it point to a new data block in the file.
 *
 * By default, this call will read the data from the file at the
 * specified location if necessary, and leave the object ready to be searched.
 *
 * In write access, if the block does not exist (i.e. nBlockPtr=0) then a
 * new one is created and initialized.
 *
 * poParentNode is used in write access in order to update the parent node
 * when this node becomes full and has to be split.
 *
 * Returns 0 on success, -1 on error.
 **********************************************************************/
int TABINDNode::InitNode(FILE *fp, int nBlockPtr, 
                         int nKeyLength, int nSubTreeDepth, 
                         UGKBool bUnique,
                         TABBinBlockManager *poBlockMgr /*=NULL*/,
                         TABINDNode *poParentNode /*=NULL*/,
                         int nPrevNodePtr /*=0*/, int nNextNodePtr /*=0*/)
{
    /*-----------------------------------------------------------------
     * If the block already points to the right block, then don't do 
     * anything here.
     *----------------------------------------------------------------*/
    if (m_fp == fp && nBlockPtr> 0 && m_nCurDataBlockPtr == nBlockPtr)
        return 0;

    // Keep track of some info
    m_fp = fp;
    m_nKeyLength = nKeyLength;
    m_nSubTreeDepth = nSubTreeDepth;
    m_nCurDataBlockPtr = nBlockPtr;
    m_bUnique = bUnique;

    // Do not overwrite the following values if we receive NULL (the defaults)
    if (poBlockMgr)
        m_poBlockManagerRef = poBlockMgr;
    if (poParentNode)
        m_poParentNodeRef = poParentNode;

    // Set some defaults
    m_numEntriesInNode = 0;
    m_nPrevNodePtr = nPrevNodePtr;
    m_nNextNodePtr = nNextNodePtr;

    m_nCurIndexEntry = 0;

    /*-----------------------------------------------------------------
     * Init RawBinBlock
     * The node's buffer has to be created with read/write access since
     * the index is a very dynamic structure!
     *----------------------------------------------------------------*/
    if (m_poDataBlock == NULL)
        m_poDataBlock = new TABRawBinBlock(TABReadWrite, TRUE);

    if ((m_eAccessMode == TABWrite || m_eAccessMode == TABReadWrite) && 
        nBlockPtr == 0 && m_poBlockManagerRef)
    {
        /*-------------------------------------------------------------
         * Write access: Create and init a new block
         *------------------------------------------------------------*/
        m_nCurDataBlockPtr = m_poBlockManagerRef->AllocNewBlock();
        m_poDataBlock->InitNewBlock(m_fp, 512, m_nCurDataBlockPtr);

        m_poDataBlock->WriteInt32( m_numEntriesInNode );
        m_poDataBlock->WriteInt32( m_nPrevNodePtr );
        m_poDataBlock->WriteInt32( m_nNextNodePtr );
    }
    else
    {
        assert(m_nCurDataBlockPtr > 0);
        /*-------------------------------------------------------------
         * Read the data block from the file, applies to read access, or
         * to write access (to modify an existing block)
         *------------------------------------------------------------*/
        if (m_poDataBlock->ReadFromFile(m_fp, m_nCurDataBlockPtr, 512) != 0)
        {
            // CPLError() has already been called.
            return -1;
        }

        m_poDataBlock->GotoByteInBlock(0);
        m_numEntriesInNode = m_poDataBlock->ReadInt32();
        m_nPrevNodePtr = m_poDataBlock->ReadInt32();
        m_nNextNodePtr = m_poDataBlock->ReadInt32();
    }

    // m_poDataBlock is now positioned at the beginning of the key entries

    return 0;
}



/**********************************************************************
 *                   TABINDNode::GotoNodePtr()
 *
 * Move to the specified node ptr, and read the new node data from the file.
 *
 * This is just a cover funtion on top of InitNode()
 **********************************************************************/
int TABINDNode::GotoNodePtr(UGKInt32 nNewNodePtr)
{
    // First flush current changes if any.
    if ((m_eAccessMode == TABWrite || m_eAccessMode == TABReadWrite) && 
        m_poDataBlock && m_poDataBlock->CommitToFile() != 0)
        return -1;

    assert(nNewNodePtr % 512 == 0);

    // Then move to the requested location.
    return InitNode(m_fp, nNewNodePtr, m_nKeyLength, m_nSubTreeDepth, 
                    m_bUnique);
}



/**********************************************************************
 *                   TABINDNode::ReadIndexEntry()
 *
 * Read the key value and record/node ptr for the specified index entry
 * inside the current node data.
 *
 * nEntryNo is the 0-based index of the index entry that we are interested
 * in inside the current node.
 *
 * Returns the record/node ptr, and copies the key value inside the
 * buffer pointed to by *pKeyValue... this assumes that *pKeyValue points
 * to a buffer big enough to hold the key value (m_nKeyLength bytes).
 * If pKeyValue == NULL, then this parameter is ignored and the key value
 * is not copied.
 **********************************************************************/
UGKInt32 TABINDNode::ReadIndexEntry(int nEntryNo, UGKByte *pKeyValue)
{
    UGKInt32 nRecordPtr = 0;
    if (nEntryNo >= 0 && nEntryNo < m_numEntriesInNode)
    {
        if (pKeyValue)
        {
            m_poDataBlock->GotoByteInBlock(12 + nEntryNo*(m_nKeyLength+4));
            m_poDataBlock->ReadBytes(m_nKeyLength, pKeyValue);
        }
        else
        {
            m_poDataBlock->GotoByteInBlock(12 + nEntryNo*(m_nKeyLength+4)+
                                                                 m_nKeyLength);
        }

        nRecordPtr = m_poDataBlock->ReadInt32();
    }

    return nRecordPtr;
}


/**********************************************************************
 *                   TABINDNode::IndexKeyCmp()
 *
 * Compare the specified index entry with the key value, and 
 * return 0 if equal, an integer less than 0 if key is smaller than 
 * index entry, and an integer greater than 0 if key is bigger than 
 * index entry.
 *
 * nEntryNo is the 0-based index of the index entry that we are interested
 * in inside the current node.
 **********************************************************************/
int   TABINDNode::IndexKeyCmp(UGKByte *pKeyValue, int nEntryNo)
{
    assert(pKeyValue);
    assert(nEntryNo >= 0 && nEntryNo < m_numEntriesInNode);

    m_poDataBlock->GotoByteInBlock(12 + nEntryNo*(m_nKeyLength+4));

    return memcmp(pKeyValue, m_poDataBlock->GetCurDataPtr(), m_nKeyLength);
}



/**********************************************************************
 *                   TABINDNode::SetFieldType()
 *
 * Sets the field type for the current index and recursively set all 
 * children as well.
 * This information will then be used in building the key values, etc.
 *
 * Returns 0 on success, -1 on error.
 **********************************************************************/
int TABINDNode::SetFieldType(TABFieldType eType)
{
    if (m_fp == NULL)
    {
        UGKError(ET_Failure, UGKErr_AssertionFailed,
                 "TABINDNode::SetFieldType(): File has not been opened yet!");
        return -1;
    }

    /*-----------------------------------------------------------------
     * Validate field type with key length
     *----------------------------------------------------------------*/
    if ((eType == TABFInteger && m_nKeyLength != 4) ||
        (eType == TABFSmallInt && m_nKeyLength != 2) ||
        (eType == TABFFloat && m_nKeyLength != 8) ||
        (eType == TABFDecimal && m_nKeyLength != 8) ||
        (eType == TABFDate && m_nKeyLength != 4) ||
        (eType == TABFLogical && m_nKeyLength != 4) )
    {
        UGKError(ET_Failure, UGKErr_IllegalArg,
                  "Index key length (%d) does not match field type (%s).",
                  m_nKeyLength, TABFIELDTYPE_2_STRING(eType) );
        return -1;
    }           
    
    m_eFieldType = eType;

    /*-----------------------------------------------------------------
     * Pass the field type info to child nodes
     *----------------------------------------------------------------*/
    if (m_poCurChildNode)
        return m_poCurChildNode->SetFieldType(eType);

    return 0;
}



/**********************************************************************
 *                   TABINDNode::FindFirst()
 *
 * Start a new search in this node and its children for a key value.
 * If the index is not unique, then FindNext() can be used to return
 * the other values that correspond to the key.
 *
 * Return value:
 *  - the key's corresponding record number in the .DAT file (greater than 0)
 *  - 0 if the key was not found
 *  - or -1 if an error happened
 **********************************************************************/
UGKInt32 TABINDNode::FindFirst(UGKByte *pKeyValue)
{
    if (m_poDataBlock == NULL)
    {
        UGKError(ET_Failure, UGKErr_AssertionFailed,
                  "TABINDNode::Search(): Node has not been initialized yet!");
        return -1;
    }

    /*-----------------------------------------------------------------
     * Unless something has been broken, this method will be called by our
     * parent node after it has established that we are the best candidate
     * to contain the first instance of the key value.  So there is no
     * need to look in the previous or next nodes in the chain... if the
     * value is not found in the current node block then it is not present
     * in the index at all.
     *
     * m_nCurIndexEntry will be used to keep track of the search pointer
     * when FindNext() will be used.
     *----------------------------------------------------------------*/
    m_nCurIndexEntry = 0;

    if (m_nSubTreeDepth == 1)
    {
        /*-------------------------------------------------------------
         * Leaf node level... we look for an exact match
         *------------------------------------------------------------*/
        while(m_nCurIndexEntry < m_numEntriesInNode)
        {
            int nCmpStatus = IndexKeyCmp(pKeyValue, m_nCurIndexEntry);
            if (nCmpStatus > 0)
            {
                /* Not there yet... (pKey > IndexEntry) */
                m_nCurIndexEntry++;