content: package backtype.storm.testing;
  
  import backtype.storm.task.TopologyContext;
  import backtype.storm.topology.OutputFieldsDeclarer;
  import backtype.storm.coordination.BatchOutputCollector;
  import backtype.storm.topology.base.BaseTransactionalBolt;
  import backtype.storm.transactional.ICommitter;
  import backtype.storm.transactional.TransactionAttempt;
  import backtype.storm.tuple.Fields;
  import backtype.storm.tuple.Tuple;
  import backtype.storm.tuple.Values;
  import java.util.Map;
  
  public class CountingCommitBolt extends BaseTransactionalBolt implements ICommitter {
      BatchOutputCollector _collector;
      TransactionAttempt _id;
      int _count = 0;
      
      @Override
      public void prepare(Map conf, TopologyContext context, BatchOutputCollector collector, TransactionAttempt id) {
          _id = id;
          _collector = collector;
      }
  
      @Override
      public void execute(Tuple tuple) {
          _count++;
      }
  
      @Override
      public void finishBatch() {
          _collector.emit(new Values(_id, _count));        
      }   
  
      @Override
      public void declareOutputFields(OutputFieldsDeclarer declarer) {
          declarer.declare(new Fields("tx", "count"));
      }
  
  }
  