[MRUNIT-193] Serialization.copy throws NPE instead of ISE (missing serilization impl) for Hadoop 2.x

• Type: Bug
• Status: Resolved
• Priority: Trivial
• Resolution: Fixed
• Affects Version/s: 1.0.0
• Fix Version/s: 1.1.0
• Assignee: Cosmin Lehene
• Reporter: Cosmin Lehene
• Created: 07/Oct/13 16:07
• Updated: 06/May/14 21:56
• Resolved: 04/Mar/14 18:54

Description

This may be the result of a refactoring.
The current code attempts to catch a NPE with the intent to detect a missing serialization implementation.

However this behavior differs between Hadoop 1.x and 2.x
Hadoop 1.x will NPE in the first try/catch block, while 2.x will in the second.

    try {
      serializer = (Serializer<Object>) serializationFactory
          .getSerializer(clazz);
      deserializer = (Deserializer<Object>) serializationFactory
          .getDeserializer(clazz);
    } catch (NullPointerException e) {
      throw new IllegalStateException(
          "No applicable class implementing Serialization in conf at io.serializations for "
              + orig.getClass(), e);
    }
    try {
      final DataOutputBuffer outputBuffer = new DataOutputBuffer();
      serializer.open(outputBuffer);
      serializer.serialize(orig);
      final DataInputBuffer inputBuffer = new DataInputBuffer();
      inputBuffer.reset(outputBuffer.getData(), outputBuffer.getLength());
      deserializer.open(inputBuffer);
      return (T) deserializer.deserialize(copy);
    } catch (final IOException e) {
      throw new RuntimeException(e);
    }

Hadoop 1.x

  public <T> Serializer<T> getSerializer(Class<T> c) {
    return getSerialization(c).getSerializer(c);
  }

Hadoop 2.x

  public <T> Serializer<T> getSerializer(Class<T> c) {
    Serialization<T> serializer = getSerialization(c);
    if (serializer != null) {
      return serializer.getSerializer(c);
    }
    return null;
  }