001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *  
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *  
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License. 
018 *  
019 */
020package org.apache.directory.server.xdbm.search.impl;
021
022
023import org.apache.directory.api.ldap.model.exception.LdapException;
024import org.apache.directory.api.ldap.model.filter.BranchNode;
025import org.apache.directory.api.ldap.model.filter.ExprNode;
026import org.apache.directory.server.core.api.partition.PartitionTxn;
027import org.apache.directory.server.xdbm.search.Optimizer;
028
029
030/**
031 * A do nothing optimizer which labels all nodes with <code>
032 * BigInteger.valueOf( Integer.MAX_VALUE ) </code>, instead of actually 
033 * taking scan counts.
034 * 
035 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
036 */
037public class NoOpOptimizer implements Optimizer
038{
039    /** the maximum size for a count Integer.MAX_VALUE as a BigInteger */
040    private static final Long MAX = Long.MAX_VALUE;
041
042
043    public Long annotate( PartitionTxn partitionTxn, ExprNode node ) throws LdapException
044    {
045        if ( node.isLeaf() )
046        {
047            node.set( DefaultOptimizer.COUNT_ANNOTATION, MAX );
048            return MAX;
049        }
050
051        BranchNode bnode = ( BranchNode ) node;
052        
053        if ( bnode.getChildren().isEmpty() )
054        {
055            bnode.set( DefaultOptimizer.COUNT_ANNOTATION, MAX );
056            return MAX;
057        }
058
059        final int limit = bnode.getChildren().size();
060        for ( int ii = 0; ii < limit; ii++ )
061        {
062            ExprNode child = bnode.getChildren().get( ii );
063            if ( child.isLeaf() )
064            {
065                child.set( DefaultOptimizer.COUNT_ANNOTATION, MAX );
066            }
067            else
068            {
069                annotate( partitionTxn, child );
070            }
071        }
072
073        bnode.set( DefaultOptimizer.COUNT_ANNOTATION, MAX );
074        return MAX;
075    }
076}