| /** |
| * 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.apex.malhar.lib.window.accumulation; |
| |
| import java.util.List; |
| |
| import org.apache.apex.malhar.lib.window.Accumulation; |
| import org.apache.hadoop.classification.InterfaceStability.Evolving; |
| |
| import com.google.common.collect.Lists; |
| |
| /** |
| * The CompositeAccumulation is an Accumulation which delegate task to sub accumulations. |
| * |
| * |
| * @since 3.7.0 |
| */ |
| @SuppressWarnings("rawtypes") |
| @Evolving |
| public class CompositeAccumulation<InputT> implements Accumulation<InputT, List, List> |
| { |
| /** |
| * The AccumulationTag hide the implementation and prevent invalid input parameters |
| * |
| */ |
| public static class AccumulationTag |
| { |
| private int index; |
| private AccumulationTag(int index) |
| { |
| this.index = index; |
| } |
| } |
| |
| private List<Accumulation<InputT, Object, ?>> accumulations = Lists.newArrayList(); |
| |
| /** |
| * @param accumulation The sub accumulation add to the composite. |
| * @return The AccumulationTag. The client can get the value of sub accumulation by returned AccumulationTag. |
| */ |
| public AccumulationTag addAccumulation(Accumulation<InputT, Object, ?> accumulation) |
| { |
| accumulations.add(accumulation); |
| return new AccumulationTag(accumulations.size() - 1); |
| } |
| |
| /** |
| * |
| * @param tag The tag represents the sub accumulation, which can be got from method addAccumulation() |
| * @param output The output of the composite accumulation |
| * @return The output of sub accumulation. |
| */ |
| public Object getSubOutput(AccumulationTag tag, List output) |
| { |
| int index = tag.index; |
| return accumulations.get(index).getOutput(output.get(index)); |
| } |
| |
| @Override |
| public List defaultAccumulatedValue() |
| { |
| List defaultValues = Lists.newArrayList(); |
| for (Accumulation accumulation : accumulations) { |
| defaultValues.add(accumulation.defaultAccumulatedValue()); |
| } |
| return defaultValues; |
| } |
| |
| @SuppressWarnings({ "rawtypes", "unchecked" }) |
| @Override |
| public List accumulate(List accumulatedValues, InputT input) |
| { |
| for (int index = 0; index < accumulations.size(); ++index) { |
| Accumulation accumulation = accumulations.get(index); |
| Object oldValue = accumulatedValues.get(index); |
| Object newValue = accumulation.accumulate(oldValue, input); |
| if (newValue != oldValue) { |
| accumulatedValues.set(index, newValue); |
| } |
| } |
| return accumulatedValues; |
| } |
| |
| @Override |
| public List merge(List accumulatedValues1, List accumulatedValues2) |
| { |
| for (int index = 0; index < accumulations.size(); ++index) { |
| accumulatedValues1.set(index, |
| accumulations.get(index).merge(accumulatedValues1.get(index), accumulatedValues2.get(index))); |
| } |
| return accumulatedValues1; |
| } |
| |
| @Override |
| public List getOutput(List accumulatedValues) |
| { |
| return accumulatedValues; |
| } |
| |
| @Override |
| public List getRetraction(List values) |
| { |
| return values; |
| } |
| } |