HDDS-15205. Cut WritableRPCEngine

[adoroszlai]

What changes were proposed in this pull request?

Port from Hadoop: HADOOP-19864. Cut WritableRPCEngine.

Ozone uses ProtobufRpcEngine, never used WritableRPCEngine.

https://issues.apache.org/jira/browse/HDDS-15205

How was this patch tested?

https://github.com/adoroszlai/ozone/actions/runs/25539302248

[ivandika3]

LGTM +1. Same as HADOOP-19764 but without additional comments.

[adoroszlai]

Thanks @ivandika3 for the review. I have noticed a follow-up PR (apache/hadoop#8470), included in another commit here.

[ivandika3]

@adoroszlai The implementation looks good and there is already a +1 so I think it's ok to include in this patch. I'm still +1.

[ivandika3]

@adoroszlai I think we should include the test testUnregisteredRpcKindRejectedWithoutDeserialization.

In the future Ozone might decide to change the Hadoop RPC logic to suite Ozone's need so we need test to catch regressions.

[adoroszlai]

I think we should include the test testUnregisteredRpcKindRejectedWithoutDeserialization.

Unit tests for Hadoop RPC are not included in Ozone, because RPC was copied from Hadoop 3.2, the last version without ProtobufRpcEngine2, and tests in that version use JUnit4, which we no longer support.

We can attempt to copy and migrate tests in a follow-up.

[ivandika3]

@adoroszlai Got it, thanks for the info.