| /* |
| * 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.Arrays; |
| import java.util.List; |
| |
| import org.apache.lucene.index.Impact; |
| import org.apache.lucene.index.Impacts; |
| import org.apache.lucene.index.ImpactsSource; |
| import org.apache.lucene.search.similarities.Similarity.SimScorer; |
| import org.apache.lucene.util.ArrayUtil; |
| |
| /** |
| * Compute maximum scores based on {@link Impacts} and keep them in a cache in |
| * order not to run expensive similarity score computations multiple times on |
| * the same data. |
| * @lucene.internal |
| */ |
| final class MaxScoreCache { |
| |
| private final ImpactsSource impactsSource; |
| private final SimScorer scorer; |
| private float[] maxScoreCache; |
| private int[] maxScoreCacheUpTo; |
| |
| /** |
| * Sole constructor. |
| */ |
| public MaxScoreCache(ImpactsSource impactsSource, SimScorer scorer) { |
| this.impactsSource = impactsSource; |
| this.scorer = scorer; |
| maxScoreCache = new float[0]; |
| maxScoreCacheUpTo = new int[0]; |
| } |
| |
| private void ensureCacheSize(int size) { |
| if (maxScoreCache.length < size) { |
| int oldLength = maxScoreCache.length; |
| maxScoreCache = ArrayUtil.grow(maxScoreCache, size); |
| maxScoreCacheUpTo = ArrayUtil.growExact(maxScoreCacheUpTo, maxScoreCache.length); |
| Arrays.fill(maxScoreCacheUpTo, oldLength, maxScoreCacheUpTo.length, -1); |
| } |
| } |
| |
| private float computeMaxScore(List<Impact> impacts) { |
| float maxScore = 0; |
| for (Impact impact : impacts) { |
| maxScore = Math.max(scorer.score(impact.freq, impact.norm), maxScore); |
| } |
| return maxScore; |
| } |
| |
| /** |
| * Return the first level that includes all doc IDs up to {@code upTo}, |
| * or -1 if there is no such level. |
| */ |
| int getLevel(int upTo) throws IOException { |
| final Impacts impacts = impactsSource.getImpacts(); |
| for (int level = 0, numLevels = impacts.numLevels(); level < numLevels; ++level) { |
| final int impactsUpTo = impacts.getDocIdUpTo(level); |
| if (upTo <= impactsUpTo) { |
| return level; |
| } |
| } |
| return -1; |
| } |
| |
| /** |
| * Return the maximum score for the given {@code level}. |
| */ |
| float getMaxScoreForLevel(int level) throws IOException { |
| final Impacts impacts = impactsSource.getImpacts(); |
| ensureCacheSize(level + 1); |
| final int levelUpTo = impacts.getDocIdUpTo(level); |
| if (maxScoreCacheUpTo[level] < levelUpTo) { |
| maxScoreCache[level] = computeMaxScore(impacts.getImpacts(level)); |
| maxScoreCacheUpTo[level] = levelUpTo; |
| } |
| return maxScoreCache[level]; |
| } |
| |
| /** |
| * Return the maximum level at which scores are all less than {@code minScore}, |
| * or -1 if none. |
| */ |
| private int getSkipLevel(Impacts impacts, float minScore) throws IOException { |
| final int numLevels = impacts.numLevels(); |
| for (int level = 0; level < numLevels; ++level) { |
| if (getMaxScoreForLevel(level) >= minScore) { |
| return level - 1; |
| } |
| } |
| return numLevels - 1; |
| } |
| |
| /** |
| * Return the an inclusive upper bound of documents that all have a score that |
| * is less than {@code minScore}, or {@code -1} if the current document may |
| * be competitive. |
| */ |
| int getSkipUpTo(float minScore) throws IOException { |
| final Impacts impacts = impactsSource.getImpacts(); |
| final int level = getSkipLevel(impacts, minScore); |
| if (level == -1) { |
| return -1; |
| } |
| return impacts.getDocIdUpTo(level); |
| } |
| |
| } |