avro.mr.MapReduceColorCountSeqFile.java Source code

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Here is the source code for avro.mr.MapReduceColorCountSeqFile.java

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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,
 * 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 avro.mr;

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.AvroSequenceFileInputFormat;
import org.apache.avro.mapreduce.AvroSequenceFileOutputFormat;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
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;

/**
 * ColorCount reads in data files containing User records, defined in
 * examples/user.avsc, and counts the number of instances of each favorite
 * color. (This example draws inspiration from the canonical WordCount MapReduce
 * application.)
 * 
 * @link http://avro.apache.org/docs/current/mr.html
 */
public class MapReduceColorCountSeqFile extends Configured implements Tool {

    public static class ColorCountMapper extends Mapper<AvroKey<Long>, AvroValue<User>, Text, IntWritable> {

        @Override
        public void map(AvroKey<Long> key, AvroValue<User> value, Context context)
                throws IOException, InterruptedException {

            CharSequence color = value.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 = Job.getInstance(getConf());
        job.setJarByClass(MapReduceColorCountSeqFile.class);
        job.setJobName("Color Count 2");

        FileInputFormat.setInputPaths(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        job.setInputFormatClass(AvroSequenceFileInputFormat.class);
        AvroJob.setInputKeySchema(job, Schema.create(Schema.Type.LONG));
        AvroJob.setInputValueSchema(job, User.getClassSchema());

        job.setMapperClass(ColorCountMapper.class);
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(IntWritable.class);

        job.setOutputFormatClass(AvroSequenceFileOutputFormat.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 MapReduceColorCountSeqFile(), args);
        System.exit(res);
    }

}