content: package com.manning.hip.ch13;
  
  
  import org.apache.commons.io.IOUtils;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  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.KeyValueTextInputFormat;
  import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  
  public final class SideEffectJob {
    private static final Logger log = LoggerFactory.getLogger(
        SideEffectJob.class);
  
    public static void main(String... args) throws Exception {
      runJob(args[0], args[1]);
    }
  
    public static void runJob(String input, String output)
        throws Exception {
      Configuration conf = new Configuration();
  
      Job job = new Job(conf);
      job.setJarByClass(SideEffectJob.class);
      job.setMapperClass(Map.class);
      //job.setReducerClass(Reduce.class);
      job.setNumReduceTasks(0);
  
      job.setInputFormatClass(KeyValueTextInputFormat.class);
      job.setMapOutputKeyClass(Text.class);
      job.setMapOutputValueClass(Text.class);
  
      Path outputPath = new Path(output);
  
      FileInputFormat.setInputPaths(job, input);
      FileOutputFormat.setOutputPath(job, outputPath);
  
      outputPath.getFileSystem(conf).delete(outputPath, true);
  
      job.waitForCompletion(true);
    }
  
    public static class Map
        extends Mapper<Text, Text, Text, Text> {
  
      OutputStream sideEffectStream;
  
      @Override
      protected void setup(Context context)
          throws IOException, InterruptedException {
        Path attemptDir = FileOutputFormat.getWorkOutputPath(context);
        String filename = context.getTaskAttemptID()
            .getTaskID().toString();
  
        Path sideEffectFile = new Path(attemptDir, filename);
  
        sideEffectStream = FileSystem.get(context.getConfiguration())
            .create(sideEffectFile);
  
        log.info("Opened file = {}", sideEffectFile);
      }
  
      @Override
      protected void map(Text key, Text value, Context context)
          throws IOException, InterruptedException {
  
        IOUtils.write(key.toString(), sideEffectStream);
  
        context.write(key, value);
      }
  
      @Override
      protected void cleanup(Context context)
          throws IOException, InterruptedException {
        sideEffectStream.close();
      }
    }
  
    public static class Reduce
        extends Reducer<Text, Text, Text, Text> {
  
      public void reduce(Text key, Iterable<Text> values,
                         Context context)
          throws IOException, InterruptedException {
        if(log.isDebugEnabled()) {
          log.debug("Input K[{}]", key);
        }
        for (Text val : values) {
          if(log.isDebugEnabled()) {
            log.debug("Input V[{}]", val);
            log.debug("Output K[{}],V[{}]", key, val);
          }
          context.write(key, val);
        }
      }
    }
  }
  