jtuglu1 commented on code in PR #18813: URL: https://github.com/apache/druid/pull/18813#discussion_r2601403891
########## extensions-contrib/spectator-histogram/src/main/java/org/apache/druid/spectator/histogram/SpectatorHistogramAggregateHelper.java: ########## @@ -0,0 +1,132 @@ +/* + * 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.druid.spectator.histogram; + +import it.unimi.dsi.fastutil.ints.Int2ObjectMap; +import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap; +import org.apache.druid.java.util.common.IAE; + +import java.nio.ByteBuffer; +import java.util.IdentityHashMap; + +/** + * Helper class for Spectator histogram implementations of {@link org.apache.druid.query.aggregation.BufferAggregator} and {@link org.apache.druid.query.aggregation.VectorAggregator}. + */ +public class SpectatorHistogramAggregateHelper +{ + private final IdentityHashMap<ByteBuffer, Int2ObjectMap<SpectatorHistogram>> histogramCache = new IdentityHashMap<>(); + + public void init(ByteBuffer buffer, int position) + { + SpectatorHistogram emptyCounts = new SpectatorHistogram(); + addToCache(buffer, position, emptyCounts); + } + + /** + * Merge obj ({@link SpectatorHistogram} or {@link Object}) into {@param current}. + */ + public void merge(SpectatorHistogram current, Object obj) + { + if (obj instanceof SpectatorHistogram) { + SpectatorHistogram other = (SpectatorHistogram) obj; + current.merge(other); + } else if (obj instanceof Number) { + current.insert((Number) obj); + } else { + throw new IAE( + "Expected a Number, but received [%s] of type [%s]", + obj, + obj.getClass() + ); + } + } + + /** + * Merge {@param value} into {@param current}. + */ + public void merge(SpectatorHistogram current, long value) + { + current.insert(value); + } + + /** + * Fetches the SpectatorHistogram at the given buffer/position pair in the cache + */ + public SpectatorHistogram get(final ByteBuffer buffer, final int position) + { + // histogramCache is an IdentityHashMap where the reference of buffer is used for equality checks. + // So the returned object isn't impacted by the changes in the buffer object made by concurrent threads. Review Comment: Also worth noting this pattern is repeated in `TDigestSketchBufferAggregator` and `DDSketchBufferAggregator`, which are required to be thread-safe. -- 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]
