| /** |
| * 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.storm.trident.partition; |
| |
| import java.util.Arrays; |
| import java.util.List; |
| import org.apache.storm.generated.GlobalStreamId; |
| import org.apache.storm.grouping.CustomStreamGrouping; |
| import org.apache.storm.task.WorkerTopologyContext; |
| import org.apache.storm.utils.Utils; |
| |
| public class IndexHashGrouping implements CustomStreamGrouping { |
| int _index; |
| List<Integer> _targets; |
| |
| public IndexHashGrouping(int index) { |
| _index = index; |
| } |
| |
| public static int objectToIndex(Object val, int numPartitions) { |
| if (val == null) { |
| return 0; |
| } |
| return Utils.toPositive(val.hashCode()) % numPartitions; |
| } |
| |
| @Override |
| public void prepare(WorkerTopologyContext context, GlobalStreamId stream, List<Integer> targetTasks) { |
| _targets = targetTasks; |
| } |
| |
| @Override |
| public List<Integer> chooseTasks(int fromTask, List<Object> values) { |
| int i = objectToIndex(values.get(_index), _targets.size()); |
| return Arrays.asList(_targets.get(i)); |
| } |
| |
| } |