HadoopWordCount2.java

/*
 * 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 org.apache.ignite.internal.processors.hadoop.impl.examples;

import java.io.IOException;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.compress.SnappyCodec;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;

/**
 * Example job for testing hadoop task execution.
 */
public class HadoopWordCount2 {
    /**
     * Entry point to start job.
     *
     * @param args Command line parameters.
     * @throws Exception If fails.
     */
    public static void main(String[] args) throws Exception {
        if (args.length != 2) {
            System.out.println("usage: [input] [output]");
            System.exit(-1);
        }

        Job job = getJob(args[0], args[1]);

        job.submit();
    }

    /**
     * Gets fully configured Job instance.
     *
     * @param input Input file name.
     * @param output Output directory name.
     * @return Job instance.
     * @throws IOException If fails.
     */
    public static Job getJob(String input, String output) throws IOException {
        Job job = Job.getInstance();

        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);

        setTasksClasses(job, true, true, true, false);

        FileInputFormat.setInputPaths(job, new Path(input));
        FileOutputFormat.setOutputPath(job, new Path(output));

        job.setJarByClass(HadoopWordCount2.class);

        return job;
    }

    /**
     * Sets task classes with related info if needed into configuration object.
     *
     * @param job Configuration to change.
     * @param setMapper Option to set mapper and input format classes.
     * @param setCombiner Option to set combiner class.
     * @param setReducer Option to set reducer and output format classes.
     */
    public static void setTasksClasses(Job job, boolean setMapper, boolean setCombiner, boolean setReducer,
            boolean outputCompression) {
        if (setMapper) {
            job.setMapperClass(HadoopWordCount2Mapper.class);
            job.setInputFormatClass(TextInputFormat.class);
        }

        if (setCombiner)
            job.setCombinerClass(HadoopWordCount2Combiner.class);

        if (setReducer) {
            job.setReducerClass(HadoopWordCount2Reducer.class);
            job.setOutputFormatClass(TextOutputFormat.class);
        }

        if (outputCompression) {
            job.setOutputFormatClass(SequenceFileOutputFormat.class);

            SequenceFileOutputFormat.setOutputCompressionType(job, SequenceFile.CompressionType.BLOCK);

            SequenceFileOutputFormat.setCompressOutput(job, true);

            job.getConfiguration().set(FileOutputFormat.COMPRESS_CODEC, SnappyCodec.class.getName());
        }
    }
}