MapperCleaner.java

package com.sequenceiq.lastfm.etl;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
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.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.kitesdk.morphline.api.Command;
import org.kitesdk.morphline.api.MorphlineContext;
import org.kitesdk.morphline.api.Record;
import org.kitesdk.morphline.base.Fields;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class MapperCleaner {

    private static final String MORPHLINE_FILE = "morphlineFile";
    private static final String MORPHLINE_ID = "morphlineId";

    private static class Cleaner extends Mapper<Object, Text, Text, NullWritable> {
        private static final Logger LOGGER = LoggerFactory.getLogger(Cleaner.class);
        private final Record record = new Record();
        private Command morphline;

        @Override
        protected void setup(Context context) throws IOException, InterruptedException {
            File morphLineFile = new File(context.getConfiguration().get(MORPHLINE_FILE));
            String morphLineId = context.getConfiguration().get(MORPHLINE_ID);
            RecordEmitter recordEmitter = new RecordEmitter(context);
            MorphlineContext morphlineContext = new MorphlineContext.Builder().build();
            morphline = new org.kitesdk.morphline.base.Compiler()
                    .compile(morphLineFile, morphLineId, morphlineContext, recordEmitter);
        }

        public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
            record.put(Fields.ATTACHMENT_BODY, new ByteArrayInputStream(value.toString().getBytes()));
            if (!morphline.process(record)) {
                LOGGER.info("Morphline failed to process record: {}", record);
            }
            record.removeAll(Fields.ATTACHMENT_BODY);
        }

    }

    private static final class RecordEmitter implements Command {
        private static final Logger LOGGER = LoggerFactory.getLogger(RecordEmitter.class);
        private final Text line = new Text();
        private final Mapper.Context context;

        private RecordEmitter(Mapper.Context context) {
            this.context = context;
        }

        @Override
        public void notify(Record notification) {
        }

        @Override
        public Command getParent() {
            return null;
        }

        @Override
        public boolean process(Record record) {
            line.set(record.get("_attachment_body").get(0).toString());
            try {
                context.write(line, null);
            } catch (Exception e) {
                LOGGER.warn("Cannot write record to context", e);
            }
            return true;
        }
    }

    public static void main(final String[] args) throws Exception {
        Configuration conf = new Configuration();
        conf.set(MORPHLINE_FILE, args[2]);
        conf.set(MORPHLINE_ID, args[3]);
        Job job = Job.getInstance(conf, "data cleaning");
        job.setJarByClass(MapperCleaner.class);
        job.setMapperClass(Cleaner.class);
        job.setNumReduceTasks(0);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(NullWritable.class);
        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));
        System.exit(job.waitForCompletion(true) ? 0 : 1);
    }
}