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CdbRooRoBtreeR.cc

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// File and Version Information:
//      $Id: CdbRooRoBtreeR.cc,v 1.1 2004/11/09 20:33:04 gapon Exp $

/// Implementation file for the CdbRooRoBtreeR class
/**
  * @see CdbRooRoBtreeR
  */

#include "BaBar/BaBar.hh"

#include "CdbRooReadonly/CdbRooRoBtreeR.hh"

template< class  K,
          class  FCP,
          UInt_t ORDER >
CdbRooRoBtreeR<K,FCP,ORDER>::CdbRooRoBtreeR( ) :
    CdbRooRoAbsBtreeR<K,FCP,ORDER>( )
{
    _nodes.resize( 2 );

  // Initialize the root node.

    _root = 1;

    init_node( _root, 0 );

  // Initialize a list of free elements as the empty one.
  // The elements will be added as required.

    _free = 0;
}

template< class  K,
          class  FCP,
          UInt_t ORDER >
UInt_t
CdbRooRoBtreeR<K,FCP,ORDER>::allocate( UInt_t parent )
{
    if( _free == 0 ) extend_free_list( );

    UInt_t result = _free;
    {
        _free = readNode( result ).child[0];

        init_node( result, parent );
    }
    return result;
}

template< class  K,
          class  FCP,
          UInt_t ORDER >
void
CdbRooRoBtreeR<K,FCP,ORDER>::release( UInt_t node )
{
    if( node ) {

        CdbRooRoBtreeNodeR<K,ORDER> nodeValue = readNode( node );
        { nodeValue.child[0] = _free; }
        updateNode( node, nodeValue );

        _free = node;
    }
}

template< class  K,
          class  FCP,
          UInt_t ORDER >
void
CdbRooRoBtreeR<K,FCP,ORDER>::init_node( UInt_t node,
                                        UInt_t parent )
{
    CdbRooRoBtreeNodeR<K,ORDER> nodeValue = readNode( node );
    {
        nodeValue.isLeaf = true;
        nodeValue.n      = 0;
        nodeValue.parent = parent;
    }
    updateNode( node, nodeValue );
}

template< class  K,
          class  FCP,
          UInt_t ORDER >
void
CdbRooRoBtreeR<K,FCP,ORDER>::extend_free_list( )
{
    if( _free == 0 ) {
        _free = _nodes.size( );

      // Double the number of elements before the number of elements reaches 1000. Then plainly
      // add a fixed number of elements.
      //
      // NOTES: (1) This policy may change in the future
      //        (2) The policy allows to avoid inefficient use of the persistent space for small B-trees.

        UInt_t sizeIncrement = 1000;
        if(( 0 < _free ) && ( _free < sizeIncrement )) sizeIncrement = _free;

        _nodes.resize( _free + sizeIncrement );

        for( UInt_t node = _free + 1; node < _free + sizeIncrement; ++node ) {

          // End Of the List

            CdbRooRoBtreeNodeR<K,ORDER> nodeValue = readNode( node );
            { nodeValue.child[0] = 0; }
            updateNode( node, nodeValue );

          // Previous node points to the current one

            CdbRooRoBtreeNodeR<K,ORDER> previousNodeValue = readNode( node-1 );
            { previousNodeValue.child[0] = node; }
            updateNode( node-1, previousNodeValue );
        }
    }
}

/////////////////
// End Of File //
/////////////////

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