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.Schema;
  import org.apache.avro.mapred.AvroKey;
  import org.apache.avro.mapred.AvroValue;
  import org.apache.avro.mapreduce.AvroJob;
  import org.apache.avro.mapreduce.AvroKeyInputFormat;
  import org.apache.avro.mapreduce.AvroKeyValueOutputFormat;
  import org.apache.hadoop.conf.Configured;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.io.IntWritable;
  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.output.FileOutputFormat;
  import org.apache.hadoop.util.Tool;
  import org.apache.hadoop.util.ToolRunner;
  
  import example.avro.User;
  
  public class MapReduceColorCount extends Configured implements Tool {
  
    public static class ColorCountMapper extends
        Mapper<AvroKey<User>, NullWritable, Text, IntWritable> {
  
      @Override
      public void map(AvroKey<User> key, NullWritable value, Context context)
          throws IOException, InterruptedException {
  
        CharSequence color = key.datum().getFavoriteColor();
        if (color == null) {
          color = "none";
        }
        context.write(new Text(color.toString()), new IntWritable(1));
      }
    }
  
    public static class ColorCountReducer extends
        Reducer<Text, IntWritable, AvroKey<CharSequence>, AvroValue<Integer>> {
  
      @Override
      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 AvroKey<CharSequence>(key.toString()), new AvroValue<Integer>(sum));
      }
    }
  
    public int run(String[] args) throws Exception {
      if (args.length != 2) {
        System.err.println("Usage: MapReduceColorCount <input path> <output path>");
        return -1;
      }
  
      Job job = new Job(getConf());
      job.setJarByClass(MapReduceColorCount.class);
      job.setJobName("Color Count");
  
      FileInputFormat.setInputPaths(job, new Path(args[0]));
      FileOutputFormat.setOutputPath(job, new Path(args[1]));
  
      job.setInputFormatClass(AvroKeyInputFormat.class);
      job.setMapperClass(ColorCountMapper.class);
      AvroJob.setInputKeySchema(job, User.getClassSchema());
      job.setMapOutputKeyClass(Text.class);
      job.setMapOutputValueClass(IntWritable.class);
  
      job.setOutputFormatClass(AvroKeyValueOutputFormat.class);
      job.setReducerClass(ColorCountReducer.class);
      AvroJob.setOutputKeySchema(job, Schema.create(Schema.Type.STRING));
      AvroJob.setOutputValueSchema(job, Schema.create(Schema.Type.INT));
  
      return (job.waitForCompletion(true) ? 0 : 1);
    }
  
    public static void main(String[] args) throws Exception {
      int res = ToolRunner.run(new MapReduceColorCount(), args);
      System.exit(res);
    }
  }
  