storm-core/src/jvm/storm/trident/partition/GlobalGrouping.java

/**
 * 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 storm.trident.partition;

import backtype.storm.generated.GlobalStreamId;
import backtype.storm.grouping.CustomStreamGrouping;
import backtype.storm.task.WorkerTopologyContext;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class GlobalGrouping implements CustomStreamGrouping {
    List<Integer> target;
    
    @Override
    public void prepare(WorkerTopologyContext context, GlobalStreamId stream, List<Integer> targets) {
        List<Integer> sorted = new ArrayList<>(targets);
        Collections.sort(sorted);
        target = Arrays.asList(sorted.get(0));
    }

    @Override
    public List<Integer> chooseTasks(int i, List<Object> list) {
        return target;
    }
}