AvroKeyValueMapReduce.java

package hip.ch3.avro;

import hip.ch3.avro.gen.Stock;
import hip.ch3.avro.gen.StockAvg;
import hip.util.Cli;
import hip.util.CliCommonOpts;
import org.apache.avro.Schema;
import org.apache.avro.mapred.AvroKey;
import org.apache.avro.mapred.AvroValue;
import org.apache.avro.mapreduce.*;
import org.apache.commons.math.stat.descriptive.moment.Mean;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.DoubleWritable;
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.*;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

import java.io.IOException;

public class AvroKeyValueMapReduce extends Configured implements Tool {

  /**
   * Main entry point for the example.
   *
   * @param args arguments
   * @throws Exception when something goes wrong
   */
  public static void main(final String[] args) throws Exception {
    int res = ToolRunner.run(new Configuration(), new AvroKeyValueMapReduce(), args);
    System.exit(res);
  }

  /**
   * The MapReduce driver - setup and launch the job.
   *
   * @param args the command-line arguments
   * @return the process exit code
   * @throws Exception if something goes wrong
   */
  public int run(final String[] args) throws Exception {

    Cli cli = Cli.builder().setArgs(args).addOptions(CliCommonOpts.MrIoOpts.values()).build();
    int result = cli.runCmd();

    if (result != 0) {
      return result;
    }

    Path inputPath = new Path(cli.getArgValueAsString(CliCommonOpts.MrIoOpts.INPUT));
    Path outputPath = new Path(cli.getArgValueAsString(CliCommonOpts.MrIoOpts.OUTPUT));

    Configuration conf = super.getConf();

    Job job = new Job(conf);
    job.setJarByClass(AvroKeyValueMapReduce.class);

    FileInputFormat.setInputPaths(job, inputPath);
    job.setInputFormatClass(AvroKeyValueInputFormat.class);
    AvroJob.setInputKeySchema(job, Schema.create(Schema.Type.STRING));
    AvroJob.setInputValueSchema(job, Stock.SCHEMA$);

    job.setMapperClass(Map.class);
    job.setReducerClass(Reduce.class);

    job.setMapOutputKeyClass(Text.class);
    job.setMapOutputValueClass(DoubleWritable.class);

    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(AvroValue.class);
    job.setOutputFormatClass(AvroKeyValueOutputFormat.class);
    AvroJob.setOutputValueSchema(job, StockAvg.SCHEMA$);

    FileOutputFormat.setOutputPath(job, outputPath);

    return job.waitForCompletion(true) ? 0 : 1;
  }

  public static class Map extends Mapper<AvroKey<CharSequence>, AvroValue<Stock>, Text, DoubleWritable> {

    @Override
    public void map(AvroKey<CharSequence> key,
                    AvroValue<Stock> value,
                    Context context) throws IOException, InterruptedException {
      context.write(new Text(key.toString()),
          new DoubleWritable(value.datum().getOpen()));
    }
  }

  public static class Reduce extends Reducer<Text, DoubleWritable, Text, AvroValue<StockAvg>> {

    @Override
    protected void reduce(Text key, Iterable<DoubleWritable> values, Context context) throws IOException, InterruptedException {
      Mean mean = new Mean();
      for (DoubleWritable val: values) {
        mean.increment(val.get());
      }
      StockAvg avg = new StockAvg();
      avg.setSymbol(key.toString());
      avg.setAvg(mean.getResult());
      context.write(key, new AvroValue<StockAvg>(avg));
    }
  }
}