org.apache.avro.mapreduce.AvroSequenceFileOutputFormat.java Source code

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Here is the source code for org.apache.avro.mapreduce.AvroSequenceFileOutputFormat.java

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/**
 * 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.avro.mapreduce;

import java.io.IOException;

import org.apache.avro.Schema;
import org.apache.avro.hadoop.io.AvroSequenceFile;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.SequenceFile.CompressionType;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.DefaultCodec;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.ReflectionUtils;

/**
 * A sequence file output format that knows how to write AvroKeys and AvroValues in
 * addition to Writables.
 *
 * @param <K> The job output key type (may be a Writable, AvroKey).
 * @param <V> The job output value type (may be a Writable, AvroValue).
 */
public class AvroSequenceFileOutputFormat<K, V> extends FileOutputFormat<K, V> {
    /** Configuration key for storing the type of compression for the target sequence file. */
    private static final String CONF_COMPRESSION_TYPE = "mapred.output.compression.type";

    /** The default compression type for the target sequence file. */
    private static final CompressionType DEFAULT_COMPRESSION_TYPE = CompressionType.RECORD;

    /** {@inheritDoc} */
    @Override
    public RecordWriter<K, V> getRecordWriter(TaskAttemptContext context) throws IOException, InterruptedException {
        Configuration conf = context.getConfiguration();

        // Configure compression if requested.
        CompressionCodec codec = null;
        CompressionType compressionType = CompressionType.NONE;
        if (getCompressOutput(context)) {
            // Find the kind of compression to do.
            compressionType = getOutputCompressionType(conf);

            // Find the right codec.
            Class<?> codecClass = getOutputCompressorClass(context, DefaultCodec.class);
            codec = (CompressionCodec) ReflectionUtils.newInstance(codecClass, conf);
        }

        // Get the path of the output file.
        Path outputFile = getDefaultWorkFile(context, "");
        FileSystem fs = outputFile.getFileSystem(conf);

        // Configure the writer.
        AvroSequenceFile.Writer.Options options = new AvroSequenceFile.Writer.Options().withFileSystem(fs)
                .withConfiguration(conf).withOutputPath(outputFile).withKeyClass(context.getOutputKeyClass())
                .withValueClass(context.getOutputValueClass()).withProgressable(context)
                .withCompressionType(compressionType).withCompressionCodec(codec);
        Schema keySchema = AvroJob.getOutputKeySchema(conf);
        if (null != keySchema) {
            options.withKeySchema(keySchema);
        }
        Schema valueSchema = AvroJob.getOutputValueSchema(conf);
        if (null != valueSchema) {
            options.withValueSchema(valueSchema);
        }
        final SequenceFile.Writer out = AvroSequenceFile.createWriter(options);

        return new RecordWriter<K, V>() {
            @Override
            public void write(K key, V value) throws IOException {
                out.append(key, value);
            }

            @Override
            public void close(TaskAttemptContext context) throws IOException {
                out.close();
            }
        };
    }

    /**
     * Sets the type of compression for the output sequence file.
     *
     * @param job The job configuration.
     * @param compressionType The compression type for the target sequence file.
     */
    public static void setOutputCompressionType(Job job, CompressionType compressionType) {
        setCompressOutput(job, true);
        job.getConfiguration().set(CONF_COMPRESSION_TYPE, compressionType.name());
    }

    /**
     * Gets type of compression for the output sequence file.
     *
     * @param conf The job configuration.
     * @return The compression type.
     */
    public static CompressionType getOutputCompressionType(Configuration conf) {
        String typeName = conf.get(CONF_COMPRESSION_TYPE, DEFAULT_COMPRESSION_TYPE.name());
        return CompressionType.valueOf(typeName);
    }
}