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 org.apache.avro.*;
  import org.apache.avro.Schema.Type;
  import org.apache.avro.mapred.*;
  import org.apache.hadoop.conf.*;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.mapred.*;
  import org.apache.hadoop.util.*;
  
  import example.avro.User;
  
  public class MapredColorCount extends Configured implements Tool {
  
    public static class ColorCountMapper extends AvroMapper<User, Pair<CharSequence, Integer>> {
      @Override
      public void map(User user, AvroCollector<Pair<CharSequence, Integer>> collector, Reporter reporter)
          throws IOException {
        CharSequence color = user.getFavoriteColor();
        // We need this check because the User.favorite_color field has type ["string", "null"]
        if (color == null) {
          color = "none";
        }
        collector.collect(new Pair<CharSequence, Integer>(color, 1));
      }
    }
  
    public static class ColorCountReducer extends AvroReducer<CharSequence, Integer,
                                                              Pair<CharSequence, Integer>> {
      @Override
      public void reduce(CharSequence key, Iterable<Integer> values,
                         AvroCollector<Pair<CharSequence, Integer>> collector,
                         Reporter reporter)
          throws IOException {
        int sum = 0;
        for (Integer value : values) {
          sum += value;
        }
        collector.collect(new Pair<CharSequence, Integer>(key, sum));
      }
    }
  
    public int run(String[] args) throws Exception {
      if (args.length != 2) {
        System.err.println("Usage: MapredColorCount <input path> <output path>");
        return -1;
      }
  
      JobConf conf = new JobConf(getConf(), MapredColorCount.class);
      conf.setJobName("colorcount");
  
      FileInputFormat.setInputPaths(conf, new Path(args[0]));
      FileOutputFormat.setOutputPath(conf, new Path(args[1]));
  
      AvroJob.setMapperClass(conf, ColorCountMapper.class);
      AvroJob.setReducerClass(conf, ColorCountReducer.class);
  
      // Note that AvroJob.setInputSchema and AvroJob.setOutputSchema set
      // relevant config options such as input/output format, map output
      // classes, and output key class.
      AvroJob.setInputSchema(conf, User.getClassSchema());
      AvroJob.setOutputSchema(conf, Pair.getPairSchema(Schema.create(Type.STRING),
          Schema.create(Type.INT)));
  
      JobClient.runJob(conf);
      return 0;
    }
  
    public static void main(String[] args) throws Exception {
      int res = ToolRunner.run(new Configuration(), new MapredColorCount(), args);
      System.exit(res);
    }
  }
  