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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;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Weight;
import java.io.IOException;
import java.util.Objects;
/**
* Base implementation for a query which is cacheable at the index level but
* not the segment level as usually expected.
*/
public abstract class IndexCacheableQuery extends Query {
private Object readerCacheKey;
@Override
public Query rewrite(IndexReader reader) throws IOException {
if (reader.getCoreCacheKey() != this.readerCacheKey) {
IndexCacheableQuery rewritten = (IndexCacheableQuery) clone();
rewritten.readerCacheKey = reader.getCoreCacheKey();
return rewritten;
}
return super.rewrite(reader);
}
@Override
public boolean equals(Object obj) {
return super.equals(obj)
&& readerCacheKey == ((IndexCacheableQuery) obj).readerCacheKey;
}
@Override
public int hashCode() {
return 31 * super.hashCode() + Objects.hashCode(readerCacheKey);
}
@Override
public final Weight createWeight(IndexSearcher searcher, boolean needsScores) throws IOException {
if (readerCacheKey == null) {
throw new IllegalStateException("Rewrite first");
}
if (readerCacheKey != searcher.getIndexReader().getCoreCacheKey()) {
throw new IllegalStateException("Must create weight on the same reader which has been used for rewriting");
}
return doCreateWeight(searcher, needsScores);
}
/** Create a {@link Weight} for this query.
* @see Query#createWeight(IndexSearcher, boolean)
*/
public abstract Weight doCreateWeight(IndexSearcher searcher, boolean needsScores) throws IOException;
}