jpountz commented on code in PR #14204: URL: https://github.com/apache/lucene/pull/14204#discussion_r1947961440
########## lucene/facet/src/java/org/apache/lucene/facet/histogram/HistogramCollector.java: ########## @@ -0,0 +1,274 @@ +/* + * 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.facet.histogram; + +import java.io.IOException; +import org.apache.lucene.index.DocValues; +import org.apache.lucene.index.DocValuesSkipper; +import org.apache.lucene.index.DocValuesType; +import org.apache.lucene.index.FieldInfo; +import org.apache.lucene.index.LeafReaderContext; +import org.apache.lucene.index.NumericDocValues; +import org.apache.lucene.index.SortedNumericDocValues; +import org.apache.lucene.internal.hppc.LongIntHashMap; +import org.apache.lucene.search.CollectionTerminatedException; +import org.apache.lucene.search.Collector; +import org.apache.lucene.search.LeafCollector; +import org.apache.lucene.search.Scorable; +import org.apache.lucene.search.ScoreMode; + +final class HistogramCollector implements Collector { + + private final String field; + private final long interval; + private final int maxBuckets; + private final LongIntHashMap counts; + + HistogramCollector(String field, long interval, int maxBuckets) { + this.field = field; + this.interval = interval; + this.maxBuckets = maxBuckets; + this.counts = new LongIntHashMap(); + } + + @Override + public LeafCollector getLeafCollector(LeafReaderContext context) throws IOException { + FieldInfo fi = context.reader().getFieldInfos().fieldInfo(field); + if (fi == null) { + // The segment has no values, nothing to do. + throw new CollectionTerminatedException(); + } + if (fi.getDocValuesType() != DocValuesType.NUMERIC + && fi.getDocValuesType() != DocValuesType.SORTED_NUMERIC) { + throw new IllegalStateException( + "Expected numeric field, but got doc-value type: " + fi.getDocValuesType()); + } + SortedNumericDocValues values = DocValues.getSortedNumeric(context.reader(), field); + NumericDocValues singleton = DocValues.unwrapSingleton(values); + if (singleton == null) { + return new HistogramNaiveLeafCollector(values, interval, maxBuckets, counts); + } else { + DocValuesSkipper skipper = context.reader().getDocValuesSkipper(field); + if (skipper != null) { + long leafMinQuotient = Math.floorDiv(skipper.minValue(), interval); + long leafMaxQuotient = Math.floorDiv(skipper.maxValue(), interval); + if (leafMaxQuotient - leafMinQuotient <= 1024) { + // Only use the optimized implementation if there is a small number of unique quotients, + // so that we can count them using a dense array instead of a hash table. + return new HistogramLeafCollector(singleton, skipper, interval, maxBuckets, counts); + } + } + return new HistogramNaiveSingleValuedLeafCollector(singleton, interval, maxBuckets, counts); + } + } + + @Override + public ScoreMode scoreMode() { + return ScoreMode.COMPLETE_NO_SCORES; + } + + LongIntHashMap getCounts() { + return counts; + } + + /** + * Naive implementation of a histogram {@link LeafCollector}, which iterates all maches and looks + * up the value to determine the corresponding bucket. + */ + private static class HistogramNaiveLeafCollector implements LeafCollector { + + private final SortedNumericDocValues values; + private final long interval; + private final int maxBuckets; + private final LongIntHashMap counts; + + HistogramNaiveLeafCollector( + SortedNumericDocValues values, long interval, int maxBuckets, LongIntHashMap counts) { + this.values = values; + this.interval = interval; + this.maxBuckets = maxBuckets; + this.counts = counts; + } + + @Override + public void setScorer(Scorable scorer) throws IOException {} + + @Override + public void collect(int doc) throws IOException { + if (values.advanceExact(doc)) { + int valueCount = values.docValueCount(); + long prevQuotient = Long.MIN_VALUE; + for (int i = 0; i < valueCount; ++i) { + final long value = values.nextValue(); + final long quotient = Math.floorDiv(value, interval); + // We must not double-count values that divide to the same quotient since this returns doc + // counts as opposed to value counts. + if (quotient != prevQuotient) { + counts.addTo(quotient, 1); Review Comment: Thanks for the feedback, I tried to reuse terms from mathematical [division](https://en.wikipedia.org/wiki/Division_(mathematics)) but having it mixed up with "bucket" certainly doesn't help. You got it right, though I'm not sure if "quantile" would be a good fit. I can try to use "bucket" more consistently, wdyt? -- 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: issues-unsubscr...@lucene.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org
