/*
* 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.hits;
import java.io.IOException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This is an implementation of Hits which starts with marking hits in an
* ArrayHits instance and switches to a BitSetHits instance if at least the
* threshold of 8kb for the ArrayHits is reached and a BitSetHits instance
* would consume less memory.
*/
public class AdaptingHits implements Hits {
/**
* Logger instance for this class.
*/
private static final Logger log = LoggerFactory.getLogger(AdaptingHits.class);
/**
* The lower threshold before a conversion is tried
*/
private static final int DEFAULT_THRESHOLD = 2048;
/**
* Internal hits instance
*/
private Hits hits;
/**
* The maximum doc number in hits. Used to calculate the expected
* BitSetHits memory footprint.
*/
private int maxDoc;
/**
* The total number of hits. Used to calculate the memory footprint of the
* initial ArrayHits instance.
*/
private int docCount;
private int threshold;
public AdaptingHits() {
this(DEFAULT_THRESHOLD);
}
public AdaptingHits(int threshold) {
this.threshold = threshold;
hits = new ArrayHits();
maxDoc = 0;
}
/**
* {@inheritDoc}
*/
public int next() throws IOException {
// delegate to the internal Hits instance
return hits.next();
}
/**
* {@inheritDoc}
*/
public void set(int doc) {
hits.set(doc);
docCount++;
if (doc > maxDoc) {
maxDoc = doc;
}
if (docCount > threshold && (hits instanceof ArrayHits)) {
int intArraySize = docCount * 4;
int bitSetSize = maxDoc / 8;
if (bitSetSize < intArraySize) {
log.debug("BitSet is smaller than int[]: "
+ bitSetSize + " vs " + intArraySize);
BitSetHits bitSetHits = new BitSetHits();
int i = 0;
while (i > -1) {
try {
i = hits.next();
if (i > -1) {
bitSetHits.set(i);
}
} catch (IOException e) {
throw new RuntimeException(e);
}
}
hits = bitSetHits;
}
}
}
/**
* {@inheritDoc}
*/
public int skipTo(int target) throws IOException {
// delegate to the internal Hits instance
return hits.skipTo(target);
}
Hits getInternalHits() {
return hits;
}
}