content: /**
   * 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 backtype.storm.generated.GlobalStreamId;
  import backtype.storm.task.WorkerTopologyContext;
  import java.io.Serializable;
  import java.util.List;
  
  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.
       * 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);
  }
  