src/examples/pipes/impl/wordcount-simple.cc

/**
 * 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.
 */

#include "hadoop/Pipes.hh"
#include "hadoop/TemplateFactory.hh"
#include "hadoop/StringUtils.hh"

const std::string WORDCOUNT = "WORDCOUNT";
const std::string INPUT_WORDS = "INPUT_WORDS";
const std::string OUTPUT_WORDS = "OUTPUT_WORDS";

class WordCountMap: public HadoopPipes::Mapper {
public:
  HadoopPipes::TaskContext::Counter* inputWords;
  
  WordCountMap(HadoopPipes::TaskContext& context) {
    inputWords = context.getCounter(WORDCOUNT, INPUT_WORDS);
  }
  
  void map(HadoopPipes::MapContext& context) {
    std::vector<std::string> words = 
      HadoopUtils::splitString(context.getInputValue(), " ");
    for(unsigned int i=0; i < words.size(); ++i) {
      context.emit(words[i], "1");
    }
    context.incrementCounter(inputWords, words.size());
  }
};

class WordCountReduce: public HadoopPipes::Reducer {
public:
  HadoopPipes::TaskContext::Counter* outputWords;

  WordCountReduce(HadoopPipes::TaskContext& context) {
    outputWords = context.getCounter(WORDCOUNT, OUTPUT_WORDS);
  }

  void reduce(HadoopPipes::ReduceContext& context) {
    int sum = 0;
    while (context.nextValue()) {
      sum += HadoopUtils::toInt(context.getInputValue());
    }
    context.emit(context.getInputKey(), HadoopUtils::toString(sum));
    context.incrementCounter(outputWords, 1); 
  }
};

int main(int argc, char *argv[]) {
  return HadoopPipes::runTask(HadoopPipes::TemplateFactory<WordCountMap, 
                              WordCountReduce>());
}