src/java/org/apache/hcatalog/rcfile/RCFileMapReduceOutputFormat.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.hcatalog.rcfile;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hive.ql.io.RCFile;
import org.apache.hadoop.hive.serde2.columnar.BytesRefArrayWritable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.DefaultCodec;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.output.FileOutputCommitter;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.ReflectionUtils;

/**
 * The RC file input format using new Hadoop mapreduce APIs.
 */
public class RCFileMapReduceOutputFormat extends
    FileOutputFormat<WritableComparable<?>, BytesRefArrayWritable> {

    /**
     * Set number of columns into the given configuration.
     * @param conf
     *          configuration instance which need to set the column number
     * @param columnNum
     *          column number for RCFile's Writer
     *
     */
    public static void setColumnNumber(Configuration conf, int columnNum) {
        assert columnNum > 0;
        conf.setInt(RCFile.COLUMN_NUMBER_CONF_STR, columnNum);
    }

    /* (non-Javadoc)
    * @see org.apache.hadoop.mapreduce.lib.output.FileOutputFormat#getRecordWriter(org.apache.hadoop.mapreduce.TaskAttemptContext)
    */
    @Override
    public org.apache.hadoop.mapreduce.RecordWriter<WritableComparable<?>, BytesRefArrayWritable> getRecordWriter(
        TaskAttemptContext task) throws IOException, InterruptedException {

        //FileOutputFormat.getWorkOutputPath takes TaskInputOutputContext instead of
        //TaskAttemptContext, so can't use that here
        FileOutputCommitter committer = (FileOutputCommitter) getOutputCommitter(task);
        Path outputPath = committer.getWorkPath();

        FileSystem fs = outputPath.getFileSystem(task.getConfiguration());

        if (!fs.exists(outputPath)) {
            fs.mkdirs(outputPath);
        }

        Path file = getDefaultWorkFile(task, "");

        CompressionCodec codec = null;
        if (getCompressOutput(task)) {
            Class<?> codecClass = getOutputCompressorClass(task, DefaultCodec.class);
            codec = (CompressionCodec) ReflectionUtils.newInstance(codecClass, task.getConfiguration());
        }

        final RCFile.Writer out = new RCFile.Writer(fs, task.getConfiguration(), file, task, codec);

        return new RecordWriter<WritableComparable<?>, BytesRefArrayWritable>() {

            /* (non-Javadoc)
            * @see org.apache.hadoop.mapreduce.RecordWriter#write(java.lang.Object, java.lang.Object)
            */
            @Override
            public void write(WritableComparable<?> key, BytesRefArrayWritable value)
                throws IOException {
                out.append(value);
            }

            /* (non-Javadoc)
            * @see org.apache.hadoop.mapreduce.RecordWriter#close(org.apache.hadoop.mapreduce.TaskAttemptContext)
            */
            @Override
            public void close(TaskAttemptContext task) throws IOException, InterruptedException {
                out.close();
            }
        };
    }

}