zacharymorn commented on code in PR #972: URL: https://github.com/apache/lucene/pull/972#discussion_r911590359
########## lucene/core/src/java/org/apache/lucene/search/BlockMaxMaxscoreScorer.java: ########## @@ -0,0 +1,322 @@ +/* + * 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; + +import java.io.IOException; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Collection; +import java.util.Comparator; +import java.util.LinkedList; +import java.util.List; + +/** Scorer implementing Block-Max Maxscore algorithm */ +public class BlockMaxMaxscoreScorer extends Scorer { + // current doc ID of the leads + private int doc; + + // doc id boundary that all scorers maxScore are valid + private int upTo = -1; + + // heap of scorers ordered by doc ID + private final DisiPriorityQueue essentialsScorers; + // list of scorers ordered by maxScore + private final LinkedList<DisiWrapper> maxScoreSortedEssentialScorers; + + private final DisiWrapper[] allScorers; + + // sum of max scores of scorers in nonEssentialScorers list + private float nonEssentialMaxScoreSum; + + private long cost; + + private final MaxScoreSumPropagator maxScoreSumPropagator; + + // scaled min competitive score + private float minCompetitiveScore = 0; + + private int cachedScoredDoc = -1; + private float cachedScore = 0; + + /** + * Constructs a Scorer that scores doc based on Block-Max-Maxscore (BMM) algorithm + * http://engineering.nyu.edu/~suel/papers/bmm.pdf . This algorithm has lower overhead compared to + * WANDScorer, and could be used for simple disjunction queries. + * + * @param weight The weight to be used. + * @param scorers The sub scorers this Scorer should iterate on for optional clauses + */ + public BlockMaxMaxscoreScorer(Weight weight, List<Scorer> scorers) throws IOException { + super(weight); + + this.doc = -1; + this.allScorers = new DisiWrapper[scorers.size()]; + this.essentialsScorers = new DisiPriorityQueue(scorers.size()); + this.maxScoreSortedEssentialScorers = new LinkedList<>(); + + long cost = 0; + for (int i = 0; i < scorers.size(); i++) { + DisiWrapper w = new DisiWrapper(scorers.get(i)); + cost += w.cost; + allScorers[i] = w; + } + + this.cost = cost; + maxScoreSumPropagator = new MaxScoreSumPropagator(scorers); + } + + @Override + public DocIdSetIterator iterator() { + // twoPhaseIterator needed to honor scorer.setMinCompetitiveScore guarantee + return TwoPhaseIterator.asDocIdSetIterator(twoPhaseIterator()); + } + + @Override + public TwoPhaseIterator twoPhaseIterator() { + DocIdSetIterator approximation = + new DocIdSetIterator() { + + @Override + public int docID() { + return doc; + } + + @Override + public int nextDoc() throws IOException { + return advance(doc + 1); + } + + @Override + public int advance(int target) throws IOException { + while (true) { + + if (target > upTo) { + updateMaxScoresAndLists(target); + } else { + // minCompetitiveScore might have increased, + // move potentially no-longer-competitive scorers from essential to non-essential + // list + movePotentiallyNonCompetitiveScorers(); + } + + assert target <= upTo; + + DisiWrapper top = essentialsScorers.top(); + + if (top == null) { + // all scorers in non-essential list, skip to next boundary or return no_more_docs + if (upTo == NO_MORE_DOCS) { + return doc = NO_MORE_DOCS; + } else { + target = upTo + 1; + } + } else { + // position all scorers in essential list to on or after target + while (top.doc < target) { + top.doc = top.iterator.advance(target); + top = essentialsScorers.updateTop(); + } + + if (top.doc == NO_MORE_DOCS) { + return doc = NO_MORE_DOCS; + } else if (top.doc > upTo) { + target = upTo + 1; + } else { + double docScoreUpperBound = nonEssentialMaxScoreSum; + + for (DisiWrapper w = essentialsScorers.topList(); w != null; w = w.next) { + docScoreUpperBound += w.scorer.score(); + } Review Comment: I've created a follow-up issue for this https://issues.apache.org/jira/browse/LUCENE-10636. -- This is an automated message from the Apache Git Service. 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