gaobinlong commented on code in PR #15936: URL: https://github.com/apache/lucene/pull/15936#discussion_r3296267539
########## lucene/grouping/src/java/org/apache/lucene/search/grouping/BlockGroupingCollectorManager.java: ########## @@ -0,0 +1,112 @@ +/* + * 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.lucene.search.grouping; + +import java.io.IOException; +import java.util.ArrayList; +import java.util.Collection; +import java.util.List; +import org.apache.lucene.search.CollectorManager; +import org.apache.lucene.search.Sort; +import org.apache.lucene.search.Weight; + +/** + * A {@link CollectorManager} for {@link BlockGroupingCollector} that merges results from multiple + * collectors into a single {@link TopGroups}. This is intended for use with concurrent search, + * where each segment is searched by a separate {@link BlockGroupingCollector}. + * + * <p>Documents must be indexed as blocks using {@link + * org.apache.lucene.index.IndexWriter#addDocuments IndexWriter.addDocuments()} or {@link + * org.apache.lucene.index.IndexWriter#updateDocuments IndexWriter.updateDocuments()}. + * + * <p>See {@link BlockGroupingCollector} for more details. + * + * @lucene.experimental + */ +public class BlockGroupingCollectorManager + implements CollectorManager<BlockGroupingCollector, TopGroups<?>> { + + private final Sort groupSort; + private final int topNGroups; + private final boolean needsScores; + private final Weight lastDocPerGroup; + + private final Sort withinGroupSort; + private final int groupOffset; + private final int withinGroupOffset; + private final int maxDocsPerGroup; + + private final List<BlockGroupingCollector> collectors; + + public BlockGroupingCollectorManager( + Sort groupSort, + int topNGroups, + boolean needsScores, + Weight lastDocPerGroup, + Sort withinGroupSort, + int groupOffset, + int withinGroupOffset, + int maxDocsPerGroup) { + this.groupSort = groupSort; + this.topNGroups = topNGroups; + this.needsScores = needsScores; + this.lastDocPerGroup = lastDocPerGroup; + this.collectors = new ArrayList<>(); + this.withinGroupSort = withinGroupSort; + this.groupOffset = groupOffset; + this.withinGroupOffset = withinGroupOffset; + this.maxDocsPerGroup = maxDocsPerGroup; + } + + @Override + public BlockGroupingCollector newCollector() throws IOException { + BlockGroupingCollector collector = + new BlockGroupingCollector(groupSort, topNGroups, needsScores, lastDocPerGroup); + collectors.add(collector); + return collector; + } + + @Override + public TopGroups<?> reduce(Collection<BlockGroupingCollector> collectors) throws IOException { + if (collectors.isEmpty()) { + return null; + } + + if (collectors.size() == 1) { + return collectors + .iterator() + .next() + .getTopGroups(withinGroupSort, groupOffset, withinGroupOffset, maxDocsPerGroup); + } + + // Merge results from multiple collectors + List<TopGroups<?>> shardGroupsList = new ArrayList<>(); + for (BlockGroupingCollector collector : collectors) { + TopGroups<?> topGroups = + collector.getTopGroups(withinGroupSort, 0, withinGroupOffset, maxDocsPerGroup); + if (topGroups != null) { Review Comment: collector.getTopGroups can return null; For empty groups array case, we need to filter here, and also add a protection in the merge method, please help to review. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
