/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.exoplatform.services.jcr.impl.core.query.lucene;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.TopFieldDocCollector;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
/**
* Wraps a lucene query result and adds a close method that allows to release
* resources after a query has been executed and the results have been read
* completely.
*/
public final class SortedLuceneQueryHits extends AbstractQueryHits
{
/**
* The Logger instance for this class.
*/
private static final Logger log = LoggerFactory.getLogger("exo.jcr.component.core.SortedLuceneQueryHits");
/**
* The upper limit for the initial fetch size.
*/
private static final int MAX_FETCH_SIZE = 32 * 1024;
/**
* The lower limit for the initial fetch size.
*/
private static final int MIN_FETCH_SIZE = 32;
/**
* The IndexReader in use by the lucene hits.
*/
private final IndexReader reader;
/**
* The index searcher.
*/
private final JcrIndexSearcher searcher;
/**
* The query to execute.
*/
private final Query query;
/**
* The sort criteria.
*/
private final Sort sort;
/**
* The index of the current hit. Initially invalid.
*/
private int hitIndex = -1;
/**
* The score nodes.
*/
private final List scoreNodes = new ArrayList();
/**
* The total number of hits.
*/
private int size;
/**
* Number of hits to retrieve.
*/
private int numHits;
/**
* Creates a new <code>QueryHits</code> instance wrapping <code>hits</code>.
*
* @param reader the IndexReader in use.
* @param searcher the index searcher.
* @param query the query to execute.
* @param sort the sort criteria.
* @param resultFetchHint a hint on how many results should be fetched.
* @throws IOException if an error occurs while reading from the index.
*/
public SortedLuceneQueryHits(IndexReader reader, JcrIndexSearcher searcher, Query query, Sort sort,
long resultFetchHint) throws IOException
{
this.reader = reader;
this.searcher = searcher;
this.query = query;
this.sort = sort;
this.numHits = (int)Math.min(Math.max(resultFetchHint, MIN_FETCH_SIZE), MAX_FETCH_SIZE);
getHits();
}
/**
* {@inheritDoc}
*/
public int getSize()
{
return size;
}
/**
* {@inheritDoc}
*/
public ScoreNode nextScoreNode() throws IOException
{
if (++hitIndex >= size)
{
// no more score nodes
return null;
}
else if (hitIndex >= scoreNodes.size())
{
// refill at least numHits or twice hitIndex
this.numHits = Math.max(this.numHits, hitIndex * 2);
getHits();
}
return (ScoreNode)scoreNodes.get(hitIndex);
}
/**
* Skips <code>n</code> hits.
*
* @param n the number of hits to skip.
* @throws IOException if an error occurs while skipping.
*/
public void skip(int n) throws IOException
{
hitIndex += n;
}
//-------------------------------< internal >-------------------------------
private void getHits() throws IOException
{
TopFieldDocCollector collector = new TopFieldDocCollector(reader, sort, numHits);
searcher.search(query, collector);
this.size = collector.getTotalHits();
ScoreDoc[] docs = collector.topDocs().scoreDocs;
for (int i = scoreNodes.size(); i < docs.length; i++)
{
String uuid = reader.document(docs[i].doc).get(FieldNames.UUID);
//NodeId id = new NodeId(UUID.fromString(uuid));
scoreNodes.add(new ScoreNode(uuid, docs[i].score, docs[i].doc));
}
log.debug("getHits() {}/{}", new Integer(scoreNodes.size()), new Integer(numHits));
// double hits for next round
numHits *= 2;
}
}