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.trevni.avro.mapreduce;
  
  import java.io.IOException;
  
  import org.apache.avro.Schema;
  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.AvroDatumConverterFactory;
  import org.apache.avro.hadoop.io.AvroKeyValue;
  import org.apache.avro.mapred.AvroKey;
  import org.apache.avro.mapred.AvroValue;
  import org.apache.hadoop.mapreduce.TaskAttemptContext;
  
  /**
   * Writes key/value pairs to an Trevni container file.
   *
   * <p>
   * Each entry in the Trevni 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 AvroTrevniKeyValueRecordWriter<K, V>
      extends AvroTrevniRecordWriterBase<AvroKey<K>, AvroValue<V>, GenericRecord> {
  
    /**
     * The writer schema for the generic record entries of the Trevni container
     * file.
     */
    Schema mKeyValuePairSchema;
  
    /** A reusable Avro generic record for writing key/value pairs to the file. */
    AvroKeyValue<Object, Object> keyValueRecord;
  
    /** A helper object that converts the input key to an Avro datum. */
    AvroDatumConverter<K, ?> keyConverter;
  
    /** A helper object that converts the input value to an Avro datum. */
    AvroDatumConverter<V, ?> valueConverter;
  
    /**
     * Constructor.
     * 
     * @param context The TaskAttempContext to supply the writer with information
     *                form the job configuration
     */
    public AvroTrevniKeyValueRecordWriter(TaskAttemptContext context) throws IOException {
      super(context);
  
      mKeyValuePairSchema = initSchema(context);
      keyValueRecord = new AvroKeyValue<>(new GenericData.Record(mKeyValuePairSchema));
    }
  
    /** {@inheritDoc} */
    @Override
    public void write(AvroKey<K> key, AvroValue<V> value) throws IOException, InterruptedException {
  
      keyValueRecord.setKey(key.datum());
      keyValueRecord.setValue(value.datum());
      writer.write(keyValueRecord.get());
      if (writer.sizeEstimate() >= blockSize) // block full
        flush();
    }
  
    /** {@inheritDoc} */
    @SuppressWarnings("unchecked")
    @Override
    protected Schema initSchema(TaskAttemptContext context) {
      AvroDatumConverterFactory converterFactory = new AvroDatumConverterFactory(context.getConfiguration());
  
      keyConverter = converterFactory.create((Class<K>) context.getOutputKeyClass());
      valueConverter = converterFactory.create((Class<V>) context.getOutputValueClass());
  
      // Create the generic record schema for the key/value pair.
      return AvroKeyValue.getSchema(keyConverter.getWriterSchema(), valueConverter.getWriterSchema());
  
    }
  
  }
  