/*
* 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.apache.jackrabbit.core.query.lucene;
import java.io.IOException;
import org.apache.jackrabbit.core.id.NodeId;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.TopFieldCollector;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* 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(SortedLuceneQueryHits.class);
/**
* 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 index searcher.
*/
private final IndexSearcher 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 docs.
*/
private ScoreDoc[] scoreDocs = new ScoreDoc[0];
/**
* The total number of hits.
*/
private int size;
/**
* Number of hits to be pre-fetched from the lucene index (will be around 2x
* resultFetchHint).
*/
private int numHits;
private int offset = 0;
/**
* Creates a new <code>QueryHits</code> instance wrapping <code>hits</code>.
*
* @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 pre-fetched from the
* lucene index.
* @throws IOException
* if an error occurs while reading from the index.
*/
public SortedLuceneQueryHits(IndexSearcher searcher, Query query,
Sort sort, long resultFetchHint) throws IOException {
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 - offset >= scoreDocs.length) {
// refill at least numHits or twice hitIndex
this.numHits = Math.max(this.numHits, hitIndex * 2);
getHits();
}
ScoreDoc doc = scoreDocs[hitIndex - offset];
String uuid = searcher.doc(doc.doc,
FieldSelectors.UUID).get(FieldNames.UUID);
NodeId id = new NodeId(uuid);
return new ScoreNode(id, doc.score, doc.doc);
}
/**
* 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 {
TopFieldCollector collector = TopFieldCollector.create(sort, numHits, false, true, false, false);
searcher.search(query, collector);
size = collector.getTotalHits();
offset += scoreDocs.length;
scoreDocs = collector.topDocs(offset, numHits).scoreDocs;
log.debug("getHits() {}/{}", scoreDocs.length, numHits);
// double hits for next round
numHits *= 2;
}
}