| /* |
| * 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.wayang.basic.operators; |
| |
| import java.util.Optional; |
| import java.util.function.IntUnaryOperator; |
| import java.util.function.LongUnaryOperator; |
| import org.apache.commons.lang3.Validate; |
| import org.apache.logging.log4j.LogManager; |
| import org.apache.logging.log4j.Logger; |
| import org.apache.wayang.core.api.Configuration; |
| import org.apache.wayang.core.optimizer.OptimizationContext; |
| import org.apache.wayang.core.optimizer.cardinality.CardinalityEstimator; |
| import org.apache.wayang.core.optimizer.cardinality.FixedSizeCardinalityEstimator; |
| import org.apache.wayang.core.plan.wayangplan.UnaryToUnaryOperator; |
| import org.apache.wayang.core.types.DataSetType; |
| |
| /** |
| * A random sample operator randomly selects its inputs from the input slot and pushes that element to the output slot. |
| */ |
| public class SampleOperator<Type> extends UnaryToUnaryOperator<Type, Type> { |
| |
| protected final Logger logger = LogManager.getLogger(this.getClass()); |
| |
| public enum Methods { |
| /** |
| * Represents an arbitrary sampling method. |
| */ |
| ANY, |
| /** |
| * Bernoulli sampling. |
| */ |
| BERNOULLI, |
| /** |
| * Randomly pick a sample. |
| */ |
| RANDOM, |
| /** |
| * Shuffle a data partition first, then sequentially take the sample from this partition. |
| */ |
| SHUFFLE_PARTITION_FIRST, |
| /** |
| * Reservoir sampling. |
| */ |
| RESERVOIR; |
| } |
| |
| /** |
| * Special dataset size that represents "unknown". |
| */ |
| // TODO: With 0 being a legal dataset size, it would be nice to use a different "null" value, e.g., -1. |
| public static final long UNKNOWN_DATASET_SIZE = 0L; |
| |
| /** |
| * Generate a random seed. |
| */ |
| public static long randomSeed() { |
| return System.nanoTime(); |
| } |
| |
| /** |
| * This function determines the sample size by the number of iterations. |
| */ |
| protected IntUnaryOperator sampleSizeFunction; |
| |
| /** |
| * This function optionally determines the seed by the number of iterations. |
| */ |
| protected LongUnaryOperator seedFunction; |
| |
| /** |
| * Size of the dataset to be sampled or {@value #UNKNOWN_DATASET_SIZE} if a dataset size is not known. |
| */ |
| protected Long datasetSize = UNKNOWN_DATASET_SIZE; |
| |
| private Methods sampleMethod; |
| |
| /** |
| * Creates a new instance with any sampling method. |
| * |
| * @param sampleSize size of the sample |
| * @param type {@link DataSetType} of the sampled dataset |
| */ |
| public SampleOperator(Integer sampleSize, DataSetType<Type> type) { |
| this(iterationNumber -> sampleSize, type); |
| } |
| |
| /** |
| * Creates a new instance with any sampling method. |
| * |
| * @param sampleSizeFunction user-specified size of the sample in dependence of the current iteration number |
| * @param type {@link DataSetType} of the sampled dataset |
| */ |
| public SampleOperator(IntUnaryOperator sampleSizeFunction, DataSetType<Type> type) { |
| this(sampleSizeFunction, type, Methods.ANY, iterationNumber -> randomSeed()); |
| } |
| |
| /** |
| * Creates a new instance given the sample size and the seed. |
| */ |
| public SampleOperator(Integer sampleSize, DataSetType<Type> type, Methods sampleMethod, long seed) { |
| this(iterationNumber -> sampleSize, type, sampleMethod, iterationNumber -> seed); |
| } |
| |
| /** |
| * Creates a new instance given the sample size and the method. |
| */ |
| public SampleOperator(IntUnaryOperator sampleSizeFunction, DataSetType<Type> type, Methods sampleMethod) { |
| this(sampleSizeFunction, type, sampleMethod, iterationNumber -> randomSeed()); |
| } |
| |
| /** |
| * Creates a new instance given a user-defined sample size. |
| */ |
| public SampleOperator(IntUnaryOperator sampleSizeFunction, DataSetType<Type> type, Methods sampleMethod, long seed) { |
| this(sampleSizeFunction, type, sampleMethod, iterationNumber -> seed); |
| } |
| |
| /** |
| * Creates a new instance given user-defined sample size and seed methods. |
| */ |
| public SampleOperator(IntUnaryOperator sampleSizeFunction, DataSetType<Type> type, Methods sampleMethod, LongUnaryOperator seedFunction) { |
| super(type, type, true); |
| this.sampleSizeFunction = sampleSizeFunction; |
| this.sampleMethod = sampleMethod; |
| this.seedFunction = seedFunction; |
| } |
| |
| /** |
| * Copies an instance (exclusive of broadcasts). |
| * |
| * @param that that should be copied |
| */ |
| public SampleOperator(SampleOperator<Type> that) { |
| super(that); |
| this.sampleSizeFunction = that.sampleSizeFunction; |
| this.seedFunction = that.seedFunction; |
| this.sampleMethod = that.getSampleMethod(); |
| this.datasetSize = that.getDatasetSize(); |
| } |
| |
| |
| public DataSetType<Type> getType() { |
| return this.getInputType(); |
| } |
| |
| public long getDatasetSize() { |
| return this.datasetSize; |
| } |
| |
| public void setDatasetSize(long datasetSize) { |
| this.datasetSize = datasetSize; |
| } |
| |
| /** |
| * Find out whether this instance knows about the size of the incoming dataset. |
| * |
| * @return whether it knows the dataset size |
| */ |
| protected boolean isDataSetSizeKnown() { |
| return this.datasetSize > 0; |
| } |
| |
| public Methods getSampleMethod() { |
| return this.sampleMethod; |
| } |
| |
| public void setSampleMethod(Methods sampleMethod) { |
| this.sampleMethod = sampleMethod; |
| } |
| |
| public void setSeedFunction(LongUnaryOperator seedFunction) { |
| this.seedFunction = seedFunction; |
| } |
| |
| /** |
| * Retrieve the sample size for this instance w.r.t. the current iteration. |
| * |
| * @param operatorContext provides the current iteration number |
| * @return the sample size |
| */ |
| protected int getSampleSize(OptimizationContext.OperatorContext operatorContext) { |
| assert operatorContext.getOperator() == this; |
| final int iterationNumber = operatorContext.getOptimizationContext().getIterationNumber(); |
| return this.sampleSizeFunction.applyAsInt(iterationNumber); |
| } |
| |
| /** |
| * Retrieve the seed for this instance w.r.t. the current iteration. |
| * |
| * @param operatorContext provides the current iteration number |
| * @return the seed |
| */ |
| protected long getSeed(OptimizationContext.OperatorContext operatorContext) { |
| assert operatorContext.getOperator() == this; |
| final int iterationNumber = operatorContext.getOptimizationContext().getIterationNumber(); |
| return this.seedFunction.applyAsLong(iterationNumber); |
| } |
| |
| @Override |
| public Optional<CardinalityEstimator> createCardinalityEstimator( |
| final int outputIndex, |
| final Configuration configuration) { |
| Validate.inclusiveBetween(0, this.getNumOutputs() - 1, outputIndex); |
| // TODO: Incorporate OperatoContext would allow for precise estimation. |
| return Optional.of(new FixedSizeCardinalityEstimator(this.sampleSizeFunction.applyAsInt(0))); |
| } |
| } |
| |