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
   *
   *     https://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 example;
  
  import java.io.IOException;
  import java.util.*;
  
  import org.apache.avro.Schema;
  import org.apache.avro.Schema.Type;
  import org.apache.avro.mapred.AvroWrapper;
  import org.apache.avro.mapred.Pair;
  import org.apache.avro.mapreduce.AvroJob;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.conf.Configured;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.io.IntWritable;
  import org.apache.hadoop.io.LongWritable;
  import org.apache.hadoop.io.NullWritable;
  import org.apache.hadoop.io.Text;
  import org.apache.hadoop.mapreduce.Job;
  import org.apache.hadoop.mapreduce.Mapper;
  import org.apache.hadoop.mapreduce.Reducer;
  import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
  import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
  import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
  import org.apache.hadoop.util.Tool;
  import org.apache.hadoop.util.ToolRunner;
  
  /**
   * The classic WordCount example modified to output Avro Pair<CharSequence,
   * Integer> records instead of text.
   */
  public class MapReduceAvroWordCount extends Configured implements Tool {
  
    public static class Map
      extends Mapper<LongWritable, Text, Text, IntWritable> {
  
      private final static IntWritable one = new IntWritable(1);
      private Text word = new Text();
  
      public void map(LongWritable key, Text value, Context context)
        throws IOException, InterruptedException {
        String line = value.toString();
        StringTokenizer tokenizer = new StringTokenizer(line);
        while (tokenizer.hasMoreTokens()) {
          word.set(tokenizer.nextToken());
          context.write(word, one);
        }
      }
    }
  
    public static class Reduce
      extends Reducer<Text, IntWritable,
              AvroWrapper<Pair<CharSequence, Integer>>, NullWritable> {
  
      public void reduce(Text key, Iterable<IntWritable> values,
                         Context context)
        throws IOException, InterruptedException {
        int sum = 0;
        for (IntWritable value : values) {
          sum += value.get();
        }
        context.write(new AvroWrapper<Pair<CharSequence, Integer>>
                      (new Pair<CharSequence, Integer>(key.toString(), sum)),
                      NullWritable.get());
      }
    }
  
    public int run(String[] args) throws Exception {
      if (args.length != 2) {
        System.err.println("Usage: AvroWordCount <input path> <output path>");
        return -1;
      }
  
      Job job = new Job(getConf());
      job.setJarByClass(MapReduceAvroWordCount.class);
      job.setJobName("wordcount");
  
      // We call setOutputSchema first so we can override the configuration
      // parameters it sets
      AvroJob.setOutputKeySchema(job,
                                 Pair.getPairSchema(Schema.create(Type.STRING),
                                                    Schema.create(Type.INT)));
      job.setOutputValueClass(NullWritable.class);
  
      job.setMapperClass(Map.class);
      job.setReducerClass(Reduce.class);
  
      job.setInputFormatClass(TextInputFormat.class);
  
      job.setMapOutputKeyClass(Text.class);
      job.setMapOutputValueClass(IntWritable.class);
      job.setSortComparatorClass(Text.Comparator.class);
  
      FileInputFormat.setInputPaths(job, new Path(args[0]));
      FileOutputFormat.setOutputPath(job, new Path(args[1]));
  
      job.waitForCompletion(true);
  
      return 0;
    }
  
    public static void main(String[] args) throws Exception {
      int res =
        ToolRunner.run(new Configuration(), new MapReduceAvroWordCount(), args);
      System.exit(res);
    }
  }
  