[KAFKA-8911] Implicit TimeWindowedSerde creates Serde with null inner serializer

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.3.0
• Fix Version/s: 2.4.0
• Component/s: streams
• Assignee: Michał
• Reporter: Michał
• Created: 16/Sep/19 12:27
• Updated: 30/Sep/19 22:54
• Resolved: 30/Sep/19 22:54

Description

Serdes.scala contains an implicit def timeWindowedSerde as below:

 

implicit def timeWindowedSerde[T]: WindowedSerdes.TimeWindowedSerde[T] = new WindowedSerdes.TimeWindowedSerde[T]()

It creates a new TimeWindowedSerde without inner serializer, which is a bug. Even in WindowedSerdes.java it says that empty constructor is for reflection.

// Default constructor needed for reflection object creation
public TimeWindowedSerde() {
    super(new TimeWindowedSerializer<>(), new TimeWindowedDeserializer<>());
}

public TimeWindowedSerde(final Serde<T> inner) {
     super(new TimeWindowedSerializer<>(inner.serializer()), new TimeWindowedDeserializer<>(inner.deserializer()));
}

All above failes for me when I try to implicitly access the right Serde:

private val twSerde = implicitly[TimeWindowedSerde[String]]

and I have to create the object properly on my own

  private val twSerde = new WindowedSerdes.TimeWindowedSerde[String](implicitly[Serde[String]])

it could be fixed with a proper call in Serdes.scala

  implicit def timeWindowedSerde[T](implicit tSerde: Serde[T]): WindowedSerdes.TimeWindowedSerde[T] =
    new WindowedSerdes.TimeWindowedSerde[T](tSerde)

But maybe also the scope of the default constructor for TimeWindowedSerde should be changed?

BR, Michał

Issue Links

• links to: GitHub Pull Request #7352