com.bigfishgames.biginsights.upsight.mapreduce.MyAvroKeyOutputFormat.java Source code

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Here is the source code for com.bigfishgames.biginsights.upsight.mapreduce.MyAvroKeyOutputFormat.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 com.bigfishgames.biginsights.upsight.mapreduce;

import java.io.IOException;
import java.io.OutputStream;

import org.apache.avro.Schema;
import org.apache.avro.file.CodecFactory;
import org.apache.avro.generic.GenericData;
import org.apache.avro.hadoop.io.AvroSerialization;
import org.apache.avro.mapred.AvroKey;
import org.apache.avro.mapreduce.AvroJob;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;

/**
 * FileOutputFormat for writing Avro container files.
 *
 * <p>Since Avro container files only contain records (not key/value pairs), this output
 * format ignores the value.</p>
 *
 * @param <T> The (java) type of the Avro data to write.
 */
public class MyAvroKeyOutputFormat<T> extends MyAvroOutputFormatBase<AvroKey<T>, NullWritable> {
    /** A factory for creating record writers. */
    private final RecordWriterFactory mRecordWriterFactory;

    /**
     * Constructor.
     */
    public MyAvroKeyOutputFormat() {
        this(new RecordWriterFactory());
    }

    /**
     * Constructor.
     *
     * @param recordWriterFactory A factory for creating record writers.
     */
    protected MyAvroKeyOutputFormat(RecordWriterFactory recordWriterFactory) {
        mRecordWriterFactory = recordWriterFactory;
    }

    /**
     * A factory for creating record writers.
     *
     * @param <T> The java type of the avro record to write.
     */
    protected static class RecordWriterFactory<T> {
        /**
         * Creates a new record writer instance.
         *
         * @param writerSchema The writer schema for the records to write.
         * @param compressionCodec The compression type for the writer file.
         * @param outputStream The target output stream for the records.
         * @param syncInterval The sync interval for the writer file.
         */
        protected RecordWriter<AvroKey<T>, NullWritable> create(Schema writerSchema, GenericData dataModel,
                CodecFactory compressionCodec, OutputStream outputStream, int syncInterval) throws IOException {
            return new MyAvroKeyRecordWriter<T>(writerSchema, dataModel, compressionCodec, outputStream,
                    syncInterval);
        }
    }

    /** {@inheritDoc} */
    @Override
    @SuppressWarnings("unchecked")
    public RecordWriter<AvroKey<T>, NullWritable> getRecordWriter(TaskAttemptContext context) throws IOException {
        Configuration conf = context.getConfiguration();
        // Get the writer schema.
        Schema writerSchema = AvroJob.getOutputKeySchema(conf);
        boolean isMapOnly = context.getNumReduceTasks() == 0;
        if (isMapOnly) {
            Schema mapOutputSchema = AvroJob.getMapOutputKeySchema(conf);
            if (mapOutputSchema != null) {
                writerSchema = mapOutputSchema;
            }
        }
        if (null == writerSchema) {
            throw new IOException(
                    "AvroKeyOutputFormat requires an output schema. Use AvroJob.setOutputKeySchema().");
        }

        GenericData dataModel = AvroSerialization.createDataModel(conf);

        return mRecordWriterFactory.create(writerSchema, dataModel, getCompressionCodec(context),
                getAvroFileOutputStream(context), getSyncInterval(context));
    }
}