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 storm.trident.state.map;
  
  import backtype.storm.tuple.Fields;
  import backtype.storm.tuple.Values;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import storm.trident.operation.ReducerAggregator;
  import storm.trident.operation.TridentCollector;
  import storm.trident.operation.TridentOperationContext;
  import storm.trident.state.ReducerValueUpdater;
  import storm.trident.state.StateUpdater;
  import storm.trident.state.ValueUpdater;
  import storm.trident.tuple.ComboList;
  import storm.trident.tuple.TridentTuple;
  import storm.trident.tuple.TridentTupleView.ProjectionFactory;
  
  public class MapReducerAggStateUpdater implements StateUpdater<MapState> {
      private static final long serialVersionUID = 8667174018978959987L;
      ReducerAggregator _agg;
      Fields _groupFields;
      Fields _inputFields;
      transient ProjectionFactory _groupFactory;
      transient ProjectionFactory _inputFactory;
      ComboList.Factory _factory;
  
      public MapReducerAggStateUpdater(ReducerAggregator agg, Fields groupFields, Fields inputFields) {
          _agg = agg;
          _groupFields = groupFields;
          _inputFields = inputFields;
          _factory = new ComboList.Factory(groupFields.size(), 1);
      }
  
      @Override
      public void updateState(MapState map, List<TridentTuple> tuples, TridentCollector collector) {
          Map<List<Object>, List<TridentTuple>> grouped = new HashMap<>();
          
          for(TridentTuple t: tuples) {
              List<Object> group = _groupFactory.create(t);
              List<TridentTuple> groupTuples = grouped.get(group);
              if(groupTuples==null) {
                  groupTuples = new ArrayList<>();
                  grouped.put(group, groupTuples);
              }
              groupTuples.add(_inputFactory.create(t));
          }
          List<List<Object>> uniqueGroups = new ArrayList<>(grouped.keySet());
          List<ValueUpdater> updaters = new ArrayList<>(uniqueGroups.size());
          for(List<Object> group: uniqueGroups) {
              updaters.add(new ReducerValueUpdater(_agg, grouped.get(group)));
          }
          List<Object> results = map.multiUpdate(uniqueGroups, updaters);
  
          for (int i = 0; i < uniqueGroups.size(); i++) {
              List<Object> group = uniqueGroups.get(i);
              Object result = results.get(i);
              collector.emit(_factory.create(new List[] { group, new Values(result) }));
          }
      }
  
      @Override
      public void prepare(Map conf, TridentOperationContext context) {
          _groupFactory = context.makeProjectionFactory(_groupFields);
          _inputFactory = context.makeProjectionFactory(_inputFields);
      }
  
      @Override
      public void cleanup() {
      }
  
  }
  