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Azure EventHubs Spout for Apache Storm

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 * 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,
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package com.microsoft.eventhubs.samples.bolt;

import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import backtype.storm.task.TopologyContext;
import backtype.storm.topology.BasicOutputCollector;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.topology.base.BaseBasicBolt;
import backtype.storm.tuple.Fields;
import backtype.storm.tuple.Tuple;
import backtype.storm.tuple.Values;

/**
 * Partially count number of messages from EventHubs
 */
public class PartialCountBolt extends BaseBasicBolt {
  private static final long serialVersionUID = 1L;
  private static final Logger logger = LoggerFactory
      .getLogger(PartialCountBolt.class);
  private static final int PartialCountBatchSize = 1000; 
  
  private int partialCount;
  
  @Override
  public void prepare(Map stormConf, TopologyContext context) {
    partialCount = 0;
  }
  
  @Override
  public void execute(Tuple tuple, BasicOutputCollector collector) {
    partialCount++;
    if(partialCount == PartialCountBatchSize) {
      collector.emit(new Values(PartialCountBatchSize));
      partialCount = 0;
    }
  }

  @Override
  public void declareOutputFields(OutputFieldsDeclarer declarer) {
    declarer.declare(new Fields("partial_count"));
  }

}