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* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.common.lucene.index;
import org.apache.lucene.index.DocsEnum;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.Filter;
import org.apache.lucene.util.BytesRef;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.common.lease.Releasable;
import org.elasticsearch.common.lease.Releasables;
import org.elasticsearch.common.util.BigArrays;
import org.elasticsearch.common.util.BytesRefHash;
import org.elasticsearch.common.util.IntArray;
import org.elasticsearch.common.util.LongArray;
import java.io.IOException;
/**
* A frequency terms enum that maintains a cache of docFreq, totalTermFreq, or both for repeated term lookup.
*/
public class FreqTermsEnum extends FilterableTermsEnum implements Releasable {
private static final int INITIAL_NUM_TERM_FREQS_CACHED = 512;
private final BigArrays bigArrays;
private IntArray termDocFreqs;
private LongArray termsTotalFreqs;
private BytesRefHash cachedTermOrds;
private final boolean needDocFreqs;
private final boolean needTotalTermFreqs;
public FreqTermsEnum(IndexReader reader, String field, boolean needDocFreq, boolean needTotalTermFreq, @Nullable Filter filter, BigArrays bigArrays) throws IOException {
super(reader, field, needTotalTermFreq ? DocsEnum.FLAG_FREQS : DocsEnum.FLAG_NONE, filter);
this.bigArrays = bigArrays;
this.needDocFreqs = needDocFreq;
this.needTotalTermFreqs = needTotalTermFreq;
if (needDocFreq) {
termDocFreqs = bigArrays.newIntArray(INITIAL_NUM_TERM_FREQS_CACHED, false);
} else {
termDocFreqs = null;
}
if (needTotalTermFreq) {
termsTotalFreqs = bigArrays.newLongArray(INITIAL_NUM_TERM_FREQS_CACHED, false);
} else {
termsTotalFreqs = null;
}
cachedTermOrds = new BytesRefHash(INITIAL_NUM_TERM_FREQS_CACHED, bigArrays);
}
@Override
public boolean seekExact(BytesRef text) throws IOException {
//Check cache
long currentTermOrd = cachedTermOrds.add(text);
if (currentTermOrd < 0) { // already seen, initialize instance data with the cached frequencies
currentTermOrd = -1 - currentTermOrd;
boolean found = true;
if (needDocFreqs) {
currentDocFreq = termDocFreqs.get(currentTermOrd);
found = currentDocFreq != NOT_FOUND;
}
if (needTotalTermFreqs) {
currentTotalTermFreq = termsTotalFreqs.get(currentTermOrd);
found = currentTotalTermFreq != NOT_FOUND;
}
current = found ? text : null;
return found;
}
//Cache miss - gather stats
final boolean found = super.seekExact(text);
//Cache the result - found or not.
if (needDocFreqs) {
termDocFreqs = bigArrays.grow(termDocFreqs, currentTermOrd + 1);
termDocFreqs.set(currentTermOrd, currentDocFreq);
}
if (needTotalTermFreqs) {
termsTotalFreqs = bigArrays.grow(termsTotalFreqs, currentTermOrd + 1);
termsTotalFreqs.set(currentTermOrd, currentTotalTermFreq);
}
return found;
}
@Override
public void close() throws ElasticsearchException {
try {
Releasables.close(cachedTermOrds, termDocFreqs, termsTotalFreqs);
} finally {
cachedTermOrds = null;
termDocFreqs = null;
termsTotalFreqs = null;
}
}
}