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/*
* SPDX-License-Identifier: Apache-2.0
*
* The OpenSearch Contributors require contributions made to
* this file be licensed under the Apache-2.0 license or a
* compatible open source license.
*/
/*
* 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.
*/
/*
* Modifications Copyright OpenSearch Contributors. See
* GitHub history for details.
*/
package org.opensearch.search.aggregations.metrics;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.Collector;
import org.apache.lucene.search.FieldDoc;
import org.apache.lucene.search.LeafCollector;
import org.apache.lucene.search.MultiCollector;
import org.apache.lucene.search.Scorable;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.ScoreMode;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.search.TopDocsCollector;
import org.apache.lucene.search.TopFieldCollector;
import org.apache.lucene.search.TopFieldDocs;
import org.apache.lucene.search.TopScoreDocCollector;
import org.apache.lucene.search.TotalHits;
import org.opensearch.OpenSearchException;
import org.opensearch.action.search.MaxScoreCollector;
import org.opensearch.common.lease.Releasables;
import org.opensearch.common.lucene.Lucene;
import org.opensearch.common.lucene.search.TopDocsAndMaxScore;
import org.opensearch.common.util.LongObjectPagedHashMap;
import org.opensearch.search.SearchHit;
import org.opensearch.search.SearchHits;
import org.opensearch.search.aggregations.Aggregator;
import org.opensearch.search.aggregations.InternalAggregation;
import org.opensearch.search.aggregations.LeafBucketCollector;
import org.opensearch.search.aggregations.LeafBucketCollectorBase;
import org.opensearch.search.fetch.FetchPhase;
import org.opensearch.search.fetch.FetchSearchResult;
import org.opensearch.search.internal.SearchContext;
import org.opensearch.search.internal.SubSearchContext;
import org.opensearch.search.rescore.RescoreContext;
import org.opensearch.search.sort.SortAndFormats;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
/**
* Aggregate all docs into the top hits
*
* @opensearch.internal
*/
class TopHitsAggregator extends MetricsAggregator {
/**
* Collectors for top hits
*
* @opensearch.internal
*/
private static class Collectors {
public final TopDocsCollector topDocsCollector;
public final MaxScoreCollector maxScoreCollector;
public final Collector collector;
Collectors(TopDocsCollector topDocsCollector, MaxScoreCollector maxScoreCollector) {
this.topDocsCollector = topDocsCollector;
this.maxScoreCollector = maxScoreCollector;
collector = MultiCollector.wrap(topDocsCollector, maxScoreCollector);
}
}
private final FetchPhase fetchPhase;
private final SubSearchContext subSearchContext;
private final LongObjectPagedHashMap topDocsCollectors;
TopHitsAggregator(
FetchPhase fetchPhase,
SubSearchContext subSearchContext,
String name,
SearchContext context,
Aggregator parent,
Map metadata
) throws IOException {
super(name, context, parent, metadata);
this.fetchPhase = fetchPhase;
topDocsCollectors = new LongObjectPagedHashMap<>(1, context.bigArrays());
this.subSearchContext = subSearchContext;
}
@Override
public ScoreMode scoreMode() {
SortAndFormats sort = subSearchContext.sort();
if (sort != null) {
return sort.sort.needsScores() || subSearchContext.trackScores() ? ScoreMode.COMPLETE : ScoreMode.COMPLETE_NO_SCORES;
} else {
// sort by score
return ScoreMode.COMPLETE;
}
}
@Override
public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, LeafBucketCollector sub) throws IOException {
// Create leaf collectors here instead of at the aggregator level. Otherwise in case this collector get invoked
// when post collecting then we have already replaced the leaf readers on the aggregator level have already been
// replaced with the next leaf readers and then post collection pushes docids of the previous segment, which
// then causes assertions to trip or incorrect top docs to be computed.
final Map leafCollectors = new HashMap<>(1);
return new LeafBucketCollectorBase(sub, null) {
Scorable scorer;
@Override
public void setScorer(Scorable scorer) throws IOException {
this.scorer = scorer;
super.setScorer(scorer);
for (var collector : leafCollectors.values()) {
collector.setScorer(scorer);
}
}
@Override
public void collect(int docId, long bucket) throws IOException {
Collectors collectors = topDocsCollectors.get(bucket);
if (collectors == null) {
SortAndFormats sort = subSearchContext.sort();
int topN = subSearchContext.from() + subSearchContext.size();
if (sort == null) {
for (RescoreContext rescoreContext : context.rescore()) {
topN = Math.max(rescoreContext.getWindowSize(), topN);
}
}
// In the QueryPhase we don't need this protection, because it is build into the IndexSearcher,
// but here we create collectors ourselves and we need prevent OOM because of crazy an offset and size.
topN = Math.min(topN, subSearchContext.searcher().getIndexReader().maxDoc());
if (sort == null) {
collectors = new Collectors(TopScoreDocCollector.create(topN, Integer.MAX_VALUE), null);
} else {
// TODO: can we pass trackTotalHits=subSearchContext.trackTotalHits(){
// Note that this would require to catch CollectionTerminatedException
collectors = new Collectors(
TopFieldCollector.create(sort.sort, topN, Integer.MAX_VALUE),
subSearchContext.trackScores() ? new MaxScoreCollector() : null
);
}
topDocsCollectors.put(bucket, collectors);
}
LeafCollector leafCollector = leafCollectors.get(bucket);
if (leafCollector == null) {
leafCollector = collectors.collector.getLeafCollector(ctx);
if (scorer != null) {
leafCollector.setScorer(scorer);
}
leafCollectors.put(bucket, leafCollector);
}
leafCollector.collect(docId);
}
};
}
@Override
public InternalAggregation buildAggregation(long owningBucketOrdinal) throws IOException {
Collectors collectors = topDocsCollectors.get(owningBucketOrdinal);
if (collectors == null) {
return buildEmptyAggregation();
}
TopDocsCollector topDocsCollector = collectors.topDocsCollector;
TopDocs topDocs = topDocsCollector.topDocs();
float maxScore = Float.NaN;
if (subSearchContext.sort() == null) {
for (RescoreContext ctx : context().rescore()) {
try {
topDocs = ctx.rescorer().rescore(topDocs, context.searcher(), ctx);
} catch (IOException e) {
throw new OpenSearchException("Rescore TopHits Failed", e);
}
}
if (topDocs.scoreDocs.length > 0) {
maxScore = topDocs.scoreDocs[0].score;
}
} else if (subSearchContext.trackScores()) {
TopFieldCollector.populateScores(topDocs.scoreDocs, subSearchContext.searcher(), subSearchContext.query());
maxScore = collectors.maxScoreCollector.getMaxScore();
}
final TopDocsAndMaxScore topDocsAndMaxScore = new TopDocsAndMaxScore(topDocs, maxScore);
subSearchContext.queryResult()
.topDocs(topDocsAndMaxScore, subSearchContext.sort() == null ? null : subSearchContext.sort().formats);
int[] docIdsToLoad = new int[topDocs.scoreDocs.length];
for (int i = 0; i < topDocs.scoreDocs.length; i++) {
docIdsToLoad[i] = topDocs.scoreDocs[i].doc;
}
subSearchContext.docIdsToLoad(docIdsToLoad, 0, docIdsToLoad.length);
fetchPhase.execute(subSearchContext);
FetchSearchResult fetchResult = subSearchContext.fetchResult();
SearchHit[] internalHits = fetchResult.fetchResult().hits().getHits();
for (int i = 0; i < internalHits.length; i++) {
ScoreDoc scoreDoc = topDocs.scoreDocs[i];
SearchHit searchHitFields = internalHits[i];
searchHitFields.shard(subSearchContext.shardTarget());
searchHitFields.score(scoreDoc.score);
if (scoreDoc instanceof FieldDoc) {
FieldDoc fieldDoc = (FieldDoc) scoreDoc;
searchHitFields.sortValues(fieldDoc.fields, subSearchContext.sort().formats);
}
}
return new InternalTopHits(
name,
subSearchContext.from(),
subSearchContext.size(),
topDocsAndMaxScore,
fetchResult.hits(),
metadata()
);
}
@Override
public InternalTopHits buildEmptyAggregation() {
TopDocs topDocs;
if (subSearchContext.sort() != null) {
topDocs = new TopFieldDocs(
new TotalHits(0, TotalHits.Relation.EQUAL_TO),
new FieldDoc[0],
subSearchContext.sort().sort.getSort()
);
} else {
topDocs = Lucene.EMPTY_TOP_DOCS;
}
return new InternalTopHits(
name,
subSearchContext.from(),
subSearchContext.size(),
new TopDocsAndMaxScore(topDocs, Float.NaN),
SearchHits.empty(),
metadata()
);
}
@Override
protected void doClose() {
Releasables.close(topDocsCollectors);
}
}