Errors using Jackson serialization with durable state store

Akka
,
1

I am working on switching my application from Java serialization to Jackson. I am running up against an error in my custom durable state store plugin that I am having trouble tracking down.

Here is the relevant portion of the stack trace:

Caused by: java.lang.IllegalStateException: Can't access current ActorSystem, Serialization.currentTransportInformation was not set.
        at akka.serialization.jackson.ActorSystemAccess.currentSystem(ActorSystemAccess.scala:19)
        at akka.serialization.jackson.ActorSystemAccess.currentSystem$(ActorSystemAccess.scala:15)
        at akka.serialization.jackson.TypedActorRefSerializer.currentSystem(TypedActorRefModule.scala:37)
        at akka.serialization.jackson.TypedActorRefSerializer.serialize(TypedActorRefModule.scala:41)
        at akka.serialization.jackson.TypedActorRefSerializer.serialize(TypedActorRefModule.scala:37)
        at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:732)
        at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:772)
        ... 27 common frames omitted

And this is how I’m performing the state serialization:

Serialization serialization = SerializationExtension.get(system);
Serializer serializer = serialization.findSerializerFor(value);
int serializerId = serializer.identifier();
String manifest = Serializers.manifestFor(serializer, value);
byte[] state = serializer.toBinary(value);

I am not sure how else I should be passing the system into the serializer, or why if I provide it there Jackson wouldn’t have access to it. I’ve looked at a few other durable state store implementations floating around online and their serialization code all look pretty similar to this.

2

The reason why it is needed eludes me right now, but you should be able to use akka.serialization.Serialization.withTransportInformation(system) { ... serialization call ... } to pass the system to the serializer and make it work.

3

Thanks for the suggestion. Unfortunately it looks like withTransportInformation is a private method which my code is unable to access. Changing the serialization code to this:

return akka.serialization.Serialization.withTransportInformation(() -> {
	Serialization serialization = new Serialization(system);
	Serializer serializer = serialization.findSerializerFor(value);
	int serializerId = serializer.identifier();
	String manifest = Serializers.manifestFor(serializer, value);
	byte[] state = serializer.toBinary(value);
	return new SerializationResult(serializerId, manifest, state);
});

Results in the following compiler error.

MariaDBDurableStateStoreJavaImpl.java:171: error: <T>withTransportInformation(Function0<T>) has private access in Serialization
                return akka.serialization.Serialization.withTransportInformation(() -> {
                                                       ^
  where T is a type-variable:
    T extends Object declared in method <T>withTransportInformation(Function0<T>)
4

I should also clarify that I’m using Akka 2.9.3 if that makes a difference.

5

There’s two withTransportInformations, one that takes an ActorSystem and a function (which is public) and one that’s private which just takes a function.

So it would be something in Java like:

return akka.serialization.Serialization$.MODULE$.withTransportInformation(
    actorSystem,
    () -> {
        // build a SerializationResult
    }
)

Note that using serialization.serialize and inspecting the returned Try will do the withTransportInformation for you (the R2DBC plugin among others takes advantage of this).

2 Likes
6

I still wasn’t able to access that method, I think it is probably some quirk of how Java and Scala interact. However, calling serialization.serialize(value).get() appears to work as expected so I will go that route. Thanks for the assistance.

7

Ah, yes, the public static method ends up on akka.serialization.Serialization$.

# On 2.9.0's jar, but should be the same in 2.9.3
$ javap -p Serialization.class | grep with
  private <T> T withTransportInformation(scala.Function0<T>);

$ javap -p Serialization$.class | grep with
  public <T> T withTransportInformation(akka.actor.ExtendedActorSystem, scala.Function0<T>);

So it would be

return akka.serialization.Serialization$.MODULE$.withTransportInformation(
  actorSystem,
  () -> {
    // build a SerializationResult
  });

I’ll edit my earlier post.