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.mapred;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  
  import org.apache.hadoop.io.serializer.Serialization;
  import org.apache.hadoop.io.serializer.Deserializer;
  import org.apache.hadoop.io.serializer.Serializer;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.conf.Configured;
  
  import org.apache.avro.Schema;
  import org.apache.avro.generic.GenericData;
  import org.apache.avro.io.BinaryEncoder;
  import org.apache.avro.io.BinaryDecoder;
  import org.apache.avro.io.DecoderFactory;
  import org.apache.avro.io.DatumReader;
  import org.apache.avro.io.DatumWriter;
  import org.apache.avro.io.EncoderFactory;
  
  /** The {@link Serialization} used by jobs configured with {@link AvroJob}. */
  public class AvroSerialization<T> extends Configured implements Serialization<AvroWrapper<T>> {
  
    @Override
    public boolean accept(Class<?> c) {
      return AvroWrapper.class.isAssignableFrom(c);
    }
  
    /**
     * Returns the specified map output deserializer. Defaults to the final output
     * deserializer if no map output schema was specified.
     */
    @Override
    public Deserializer<AvroWrapper<T>> getDeserializer(Class<AvroWrapper<T>> c) {
      Configuration conf = getConf();
      boolean isKey = AvroKey.class.isAssignableFrom(c);
      Schema schema = isKey ? Pair.getKeySchema(AvroJob.getMapOutputSchema(conf))
          : Pair.getValueSchema(AvroJob.getMapOutputSchema(conf));
      GenericData dataModel = AvroJob.createMapOutputDataModel(conf);
      DatumReader<T> datumReader = dataModel.createDatumReader(schema);
      return new AvroWrapperDeserializer(datumReader, isKey);
    }
  
    private static final DecoderFactory FACTORY = DecoderFactory.get();
  
    private class AvroWrapperDeserializer implements Deserializer<AvroWrapper<T>> {
  
      private DatumReader<T> reader;
      private BinaryDecoder decoder;
      private boolean isKey;
  
      public AvroWrapperDeserializer(DatumReader<T> reader, boolean isKey) {
        this.reader = reader;
        this.isKey = isKey;
      }
  
      @Override
      public void open(InputStream in) {
        this.decoder = FACTORY.directBinaryDecoder(in, decoder);
      }
  
      @Override
      public AvroWrapper<T> deserialize(AvroWrapper<T> wrapper) throws IOException {
        T datum = reader.read(wrapper == null ? null : wrapper.datum(), decoder);
        if (wrapper == null) {
          wrapper = isKey ? new AvroKey<>(datum) : new AvroValue<>(datum);
        } else {
          wrapper.datum(datum);
        }
        return wrapper;
      }
  
      @Override
      public void close() throws IOException {
        decoder.inputStream().close();
      }
  
    }
  
    /** Returns the specified output serializer. */
    @Override
    public Serializer<AvroWrapper<T>> getSerializer(Class<AvroWrapper<T>> c) {
      // AvroWrapper used for final output, AvroKey or AvroValue for map output
      boolean isFinalOutput = c.equals(AvroWrapper.class);
      Configuration conf = getConf();
      Schema schema = isFinalOutput ? AvroJob.getOutputSchema(conf)
          : (AvroKey.class.isAssignableFrom(c) ? Pair.getKeySchema(AvroJob.getMapOutputSchema(conf))
              : Pair.getValueSchema(AvroJob.getMapOutputSchema(conf)));
      GenericData dataModel = AvroJob.createDataModel(conf);
      return new AvroWrapperSerializer(dataModel.createDatumWriter(schema));
    }
  
    private class AvroWrapperSerializer implements Serializer<AvroWrapper<T>> {
  
      private DatumWriter<T> writer;
      private OutputStream out;
      private BinaryEncoder encoder;
  
      public AvroWrapperSerializer(DatumWriter<T> writer) {
        this.writer = writer;
      }
  
      @Override
      public void open(OutputStream out) {
        this.out = out;
        this.encoder = new EncoderFactory().binaryEncoder(out, null);
      }
  
      @Override
      public void serialize(AvroWrapper<T> wrapper) throws IOException {
        writer.write(wrapper.datum(), encoder);
        // would be a lot faster if the Serializer interface had a flush()
        // method and the Hadoop framework called it when needed rather
        // than for every record.
        encoder.flush();
      }
  
      @Override
      public void close() throws IOException {
        out.close();
      }
  
    }
  
  }
  