| /** |
| * 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 backtype.storm.grouping; |
| |
| import java.io.Serializable; |
| import java.util.List; |
| |
| import backtype.storm.generated.GlobalStreamId; |
| import backtype.storm.task.WorkerTopologyContext; |
| |
| public interface CustomStreamGrouping extends Serializable { |
| |
| /** |
| * Tells the stream grouping at runtime the tasks in the target bolt. |
| * This information should be used in chooseTasks to determine the target tasks. |
| * <p> |
| * It also tells the grouping the metadata on the stream this grouping will be used on. |
| */ |
| void prepare(WorkerTopologyContext context, GlobalStreamId stream, List<Integer> targetTasks); |
| |
| /** |
| * This function implements a custom stream grouping. It takes in as input |
| * the number of tasks in the target bolt in prepare and returns the |
| * tasks to send the tuples to. |
| * |
| * @param values the values to group on |
| */ |
| List<Integer> chooseTasks(int taskId, List<Object> values); |
| } |