| /* |
| * 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.datasketches.tuple; |
| |
| import static java.lang.Math.min; |
| import static org.apache.datasketches.Util.DEFAULT_NOMINAL_ENTRIES; |
| |
| import java.lang.reflect.Array; |
| |
| import org.apache.datasketches.QuickSelect; |
| import org.apache.datasketches.SketchesArgumentException; |
| |
| /** |
| * Compute a union of two or more tuple sketches. |
| * A new instance represents an empty set. |
| * Every update() computes a union with the internal set |
| * and can only grow the internal set. |
| * @param <S> Type of Summary |
| */ |
| public class Union<S extends Summary> { |
| private final SummarySetOperations<S> summarySetOps_; |
| private QuickSelectSketch<S> qsk_; |
| private long thetaLong_; // need to maintain outside of the sketch |
| private boolean empty_; |
| |
| /** |
| * Creates new instance with default nominal entries |
| * @param summarySetOps instance of SummarySetOperations |
| */ |
| public Union(final SummarySetOperations<S> summarySetOps) { |
| this(DEFAULT_NOMINAL_ENTRIES, summarySetOps); |
| } |
| |
| /** |
| * Creates new instance |
| * @param nomEntries nominal number of entries. Forced to the nearest power of 2 greater than |
| * given value. |
| * @param summarySetOps instance of SummarySetOperations |
| */ |
| public Union(final int nomEntries, final SummarySetOperations<S> summarySetOps) { |
| summarySetOps_ = summarySetOps; |
| qsk_ = new QuickSelectSketch<>(nomEntries, null); |
| thetaLong_ = qsk_.getThetaLong(); |
| empty_ = true; |
| } |
| |
| /** |
| * Updates the internal set by adding entries from the given sketch |
| * @param sketchIn input sketch to add to the internal set. |
| * If null or empty, it is ignored. |
| */ |
| public void update(final Sketch<S> sketchIn) { |
| if ((sketchIn == null) || sketchIn.isEmpty()) { return; } |
| empty_ = false; |
| if (sketchIn.thetaLong_ < thetaLong_) { thetaLong_ = sketchIn.thetaLong_; } |
| final SketchIterator<S> it = sketchIn.iterator(); |
| while (it.next()) { |
| qsk_.merge(it.getHash(), it.getSummary(), summarySetOps_); |
| } |
| if (qsk_.thetaLong_ < thetaLong_) { |
| thetaLong_ = qsk_.thetaLong_; |
| } |
| } |
| |
| /** |
| * Updates the internal set by combining entries using the hashes from the Theta Sketch and |
| * summary values from the given summary and rules from the summarySetOps defined by the |
| * Union constructor. |
| * @param sketchIn the given Theta Sketch input. If null or empty, it is ignored. |
| * @param summary the given proxy summary for the Theta Sketch, which doesn't have one. This may |
| * not be null. |
| */ |
| @SuppressWarnings("unchecked") |
| public void update(final org.apache.datasketches.theta.Sketch sketchIn, final S summary) { |
| if (summary == null) { |
| throw new SketchesArgumentException("Summary cannot be null."); } |
| if ((sketchIn == null) || sketchIn.isEmpty()) { return; } |
| empty_ = false; |
| final long thetaIn = sketchIn.getThetaLong(); |
| if (thetaIn < thetaLong_) { thetaLong_ = thetaIn; } |
| final org.apache.datasketches.theta.HashIterator it = sketchIn.iterator(); |
| while (it.next()) { |
| qsk_.merge(it.get(), (S)summary.copy(), summarySetOps_); |
| } |
| if (qsk_.thetaLong_ < thetaLong_) { |
| thetaLong_ = qsk_.thetaLong_; |
| } |
| } |
| |
| /** |
| * Gets the internal set as a CompactSketch |
| * @return result of the unions so far |
| */ |
| @SuppressWarnings("unchecked") |
| public CompactSketch<S> getResult() { |
| if (empty_) { |
| return qsk_.compact(); |
| } |
| if ((thetaLong_ >= qsk_.thetaLong_) && (qsk_.getRetainedEntries() <= qsk_.getNominalEntries())) { |
| return qsk_.compact(); |
| } |
| long theta = min(thetaLong_, qsk_.thetaLong_); |
| |
| int numHashes = 0; |
| { |
| final SketchIterator<S> it = qsk_.iterator(); |
| while (it.next()) { |
| if (it.getHash() < theta) { numHashes++; } |
| } |
| } |
| if (numHashes == 0) { |
| return new CompactSketch<>(null, null, theta, empty_); |
| } |
| if (numHashes > qsk_.getNominalEntries()) { |
| final long[] hashArr = new long[numHashes]; // temporary, order will be destroyed by quick select |
| final SketchIterator<S> it = qsk_.iterator(); |
| int i = 0; |
| while (it.next()) { |
| final long hash = it.getHash(); |
| if (hash < theta) { hashArr[i++] = hash; } |
| } |
| theta = QuickSelect.select(hashArr, 0, numHashes - 1, qsk_.getNominalEntries()); |
| numHashes = qsk_.getNominalEntries(); |
| } |
| final Class<S> summaryType = (Class<S>) qsk_.getSummaryTable().getClass().getComponentType(); |
| final long[] hashArr = new long[numHashes]; |
| final S[] summaries = (S[]) Array.newInstance(summaryType, numHashes); |
| final SketchIterator<S> it = qsk_.iterator(); |
| int i = 0; |
| while (it.next()) { |
| final long hash = it.getHash(); |
| if (hash < theta) { |
| hashArr[i] = hash; |
| summaries[i] = (S) it.getSummary().copy(); |
| i++; |
| } |
| } |
| return new CompactSketch<>(hashArr, summaries, theta, empty_); |
| } |
| |
| /** |
| * Resets the internal set to the initial state, which represents an empty set |
| */ |
| public void reset() { |
| qsk_.reset(); |
| thetaLong_ = qsk_.getThetaLong(); |
| empty_ = true; |
| } |
| } |