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 com.jstorm.example.unittests.window;
  
  import backtype.storm.task.OutputCollector;
  import backtype.storm.task.TopologyContext;
  import backtype.storm.topology.OutputFieldsDeclarer;
  import backtype.storm.topology.base.BaseWindowedBolt;
  import backtype.storm.tuple.Fields;
  import backtype.storm.tuple.Tuple;
  import backtype.storm.tuple.Values;
  import backtype.storm.windowing.TupleWindow;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.List;
  import java.util.Map;
  
  /**
   * @author binyang.dby on 2016/7/21.
   */
  public class SlidingWindowTestSumBolt extends BaseWindowedBolt {
      private OutputCollector collector;
      private static Logger LOG = LoggerFactory.getLogger(SlidingWindowTestSumBolt.class);
      private int sum = 0;
  
      @Override
      public void prepare(Map stormConf, TopologyContext context, OutputCollector collector) {
          this.collector = collector;
      }
  
      @Override
      public void execute(TupleWindow inputWindow) {
          /*
           * The inputWindow gives a view of (a) all the events in the window (b)
           * events that expired since last activation of the window (c) events
           * that newly arrived since last activation of the window
           */
          List<Tuple> tuplesInWindow = inputWindow.get();
          List<Tuple> newTuples = inputWindow.getNew();
          List<Tuple> expiredTuples = inputWindow.getExpired();
  
          LOG.debug("Events in current window: " + tuplesInWindow.size());
          /*
           * Instead of iterating over all the tuples in the window to compute the
           * sum, the values for the new events are added and old events are
           * subtracted. Similar optimizations might be possible in other
           * windowing computations.
           */
          for (Tuple tuple : newTuples) {
              sum += (int) tuple.getValue(0);
          }
          for (Tuple tuple : expiredTuples) {
              sum -= (int) tuple.getValue(0);
          }
          collector.emit(new Values(sum));
          LOG.info("#sum = " + sum);
      }
  
      @Override
      public void declareOutputFields(OutputFieldsDeclarer declarer) {
          declarer.declare(new Fields("sum"));
      }
  }
  