content: /*
   * 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
   *
   *     https://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 java.io.OutputStream;
  
  import org.apache.avro.Schema;
  import org.apache.avro.file.CodecFactory;
  import org.apache.avro.file.DataFileConstants;
  import org.apache.avro.file.DataFileWriter;
  import org.apache.avro.generic.GenericData;
  import org.apache.avro.generic.GenericRecord;
  import org.apache.avro.hadoop.io.AvroDatumConverter;
  import org.apache.avro.hadoop.io.AvroKeyValue;
  import org.apache.hadoop.mapreduce.RecordWriter;
  import org.apache.hadoop.mapreduce.TaskAttemptContext;
  
  /**
   * Writes key/value pairs to an Avro container file.
   *
   * <p>
   * Each entry in the Avro container file will be a generic record with two
   * fields, named 'key' and 'value'. The input types may be basic Writable
   * objects like Text or IntWritable, or they may be AvroWrapper subclasses
   * (AvroKey or AvroValue). Writable objects will be converted to their
   * corresponding Avro types when written to the generic record key/value pair.
   * </p>
   *
   * @param <K> The type of key to write.
   * @param <V> The type of value to write.
   */
  public class AvroKeyValueRecordWriter<K, V> extends RecordWriter<K, V> implements Syncable {
    /** A writer for the Avro container file. */
    private final DataFileWriter<GenericRecord> mAvroFileWriter;
  
    /**
     * The writer schema for the generic record entries of the Avro container file.
     */
    private final Schema mKeyValuePairSchema;
  
    /** A reusable Avro generic record for writing key/value pairs to the file. */
    private final AvroKeyValue<Object, Object> mOutputRecord;
  
    /** A helper object that converts the input key to an Avro datum. */
    private final AvroDatumConverter<K, ?> mKeyConverter;
  
    /** A helper object that converts the input value to an Avro datum. */
    private final AvroDatumConverter<V, ?> mValueConverter;
  
    /**
     * Constructor.
     *
     * @param keyConverter     A key to Avro datum converter.
     * @param valueConverter   A value to Avro datum converter.
     * @param dataModel        The data model for key and value.
     * @param compressionCodec A compression codec factory for the Avro container
     *                         file.
     * @param outputStream     The output stream to write the Avro container file
     *                         to.
     * @param syncInterval     The sync interval for the Avro container file.
     * @throws IOException If the record writer cannot be opened.
     */
    public AvroKeyValueRecordWriter(AvroDatumConverter<K, ?> keyConverter, AvroDatumConverter<V, ?> valueConverter,
        GenericData dataModel, CodecFactory compressionCodec, OutputStream outputStream, int syncInterval)
        throws IOException {
      // Create the generic record schema for the key/value pair.
      mKeyValuePairSchema = AvroKeyValue.getSchema(keyConverter.getWriterSchema(), valueConverter.getWriterSchema());
  
      // Create an Avro container file and a writer to it.
      mAvroFileWriter = new DataFileWriter<GenericRecord>(dataModel.createDatumWriter(mKeyValuePairSchema));
      mAvroFileWriter.setCodec(compressionCodec);
      mAvroFileWriter.setSyncInterval(syncInterval);
      mAvroFileWriter.create(mKeyValuePairSchema, outputStream);
  
      // Keep a reference to the converters.
      mKeyConverter = keyConverter;
      mValueConverter = valueConverter;
  
      // Create a reusable output record.
      mOutputRecord = new AvroKeyValue<>(new GenericData.Record(mKeyValuePairSchema));
    }
  
    /**
     * Constructor.
     *
     * @param keyConverter     A key to Avro datum converter.
     * @param valueConverter   A value to Avro datum converter.
     * @param dataModel        The data model for key and value.
     * @param compressionCodec A compression codec factory for the Avro container
     *                         file.
     * @param outputStream     The output stream to write the Avro container file
     *                         to.
     * @throws IOException If the record writer cannot be opened.
     */
    public AvroKeyValueRecordWriter(AvroDatumConverter<K, ?> keyConverter, AvroDatumConverter<V, ?> valueConverter,
        GenericData dataModel, CodecFactory compressionCodec, OutputStream outputStream) throws IOException {
      this(keyConverter, valueConverter, dataModel, compressionCodec, outputStream,
          DataFileConstants.DEFAULT_SYNC_INTERVAL);
    }
  
    /**
     * Gets the writer schema for the key/value pair generic record.
     *
     * @return The writer schema used for entries of the Avro container file.
     */
    public Schema getWriterSchema() {
      return mKeyValuePairSchema;
    }
  
    /** {@inheritDoc} */
    @Override
    public void write(K key, V value) throws IOException {
      mOutputRecord.setKey(mKeyConverter.convert(key));
      mOutputRecord.setValue(mValueConverter.convert(value));
      mAvroFileWriter.append(mOutputRecord.get());
    }
  
    /** {@inheritDoc} */
    @Override
    public void close(TaskAttemptContext context) throws IOException {
      mAvroFileWriter.close();
    }
  
    /** {@inheritDoc} */
    @Override
    public long sync() throws IOException {
      return mAvroFileWriter.sync();
    }
  }
  