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.operation.impl;
  
  import backtype.storm.tuple.Fields;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import storm.trident.JoinType;
  import storm.trident.operation.GroupedMultiReducer;
  import storm.trident.operation.TridentCollector;
  import storm.trident.operation.TridentMultiReducerContext;
  import storm.trident.operation.impl.JoinerMultiReducer.JoinState;
  import storm.trident.tuple.ComboList;
  import storm.trident.tuple.TridentTuple;
  
  public class JoinerMultiReducer implements GroupedMultiReducer<JoinState> {
  
      List<JoinType> _types;
      List<Fields> _sideFields;
      int _numGroupFields;
      ComboList.Factory _factory;
  
      public JoinerMultiReducer(List<JoinType> types, int numGroupFields, List<Fields> sides) {
          _types = types;
          _sideFields = sides;
          _numGroupFields = numGroupFields;
      }
  
      @Override
      public void prepare(Map conf, TridentMultiReducerContext context) {
          int[] sizes = new int[_sideFields.size() + 1];
          sizes[0] = _numGroupFields;
          for (int i = 0; i < _sideFields.size(); i++) {
              sizes[i + 1] = _sideFields.get(i).size();
          }
          _factory = new ComboList.Factory(sizes);
      }
  
      @Override
      public JoinState init(TridentCollector collector, TridentTuple group) {
          return new JoinState(_types.size(), group);
      }
  
      @Override
      public void execute(JoinState state, int streamIndex, TridentTuple group, TridentTuple input, TridentCollector collector) {
          // TODO: do the inner join incrementally, emitting the cross join with this tuple, against all other sides
          // TODO: only do cross join if at least one tuple in each side
          List<List> side = state.sides[streamIndex];
          if (side.isEmpty()) {
              state.numSidesReceived++;
          }
  
          side.add(input);
          if (state.numSidesReceived == state.sides.length) {
              emitCrossJoin(state, collector, streamIndex, input);
          }
      }
  
      @Override
      public void complete(JoinState state, TridentTuple group, TridentCollector collector) {
          List<List>[] sides = state.sides;
          boolean wasEmpty = state.numSidesReceived < sides.length;
          for (int i = 0; i < sides.length; i++) {
              if (sides[i].isEmpty() && _types.get(i) == JoinType.OUTER) {
                  state.numSidesReceived++;
                  sides[i].add(makeNullList(_sideFields.get(i).size()));
              }
          }
          if (wasEmpty && state.numSidesReceived == sides.length) {
              emitCrossJoin(state, collector, -1, null);
          }
      }
  
      @Override
      public void cleanup() {
      }
  
      private List<Object> makeNullList(int size) {
          List<Object> ret = new ArrayList(size);
          for (int i = 0; i < size; i++) {
              ret.add(null);
          }
          return ret;
      }
  
      private void emitCrossJoin(JoinState state, TridentCollector collector, int overrideIndex, TridentTuple overrideTuple) {
          List<List>[] sides = state.sides;
          int[] indices = state.indices;
          for (int i = 0; i < indices.length; i++) {
              indices[i] = 0;
          }
  
          boolean keepGoing = true;
          // emit cross-join of all emitted tuples
          while (keepGoing) {
              List[] combined = new List[sides.length + 1];
              combined[0] = state.group;
              for (int i = 0; i < sides.length; i++) {
                  if (i == overrideIndex) {
                      combined[i + 1] = overrideTuple;
                  } else {
                      combined[i + 1] = sides[i].get(indices[i]);
                  }
              }
              collector.emit(_factory.create(combined));
              keepGoing = increment(sides, indices, indices.length - 1, overrideIndex);
          }
      }
  
      // return false if can't increment anymore
      // TODO: DRY this code up with what's in ChainedAggregatorImpl
      private boolean increment(List[] lengths, int[] indices, int j, int overrideIndex) {
          if (j == -1)
              return false;
          if (j == overrideIndex) {
              return increment(lengths, indices, j - 1, overrideIndex);
          }
          indices[j]++;
          if (indices[j] >= lengths[j].size()) {
              indices[j] = 0;
              return increment(lengths, indices, j - 1, overrideIndex);
          }
          return true;
      }
  
      public static class JoinState {
          List<List>[] sides;
          int numSidesReceived = 0;
          int[] indices;
          TridentTuple group;
  
          public JoinState(int numSides, TridentTuple group) {
              sides = new List[numSides];
              indices = new int[numSides];
              this.group = group;
              for (int i = 0; i < numSides; i++) {
                  sides[i] = new ArrayList<List>();
              }
          }
      }
  
  }
  