GameServerSets: DeleteFunc could receive a DeletedFinalStateUnknown

[markmandel]

This should have a check on it anyway, but I went hunting as I was wondering if this might be the cause for #414

[markmandel]

/cc @Oleksii-Terekhov @aLekSer - don't know if this is the problem, but it might be.

Was thinking about instances where things could go into perpetual eventual backoff, and thought of DeleteFunc's - and there was one instance where the type check was not in place.

Not 100% convinced this is the leak, because if this part of code failed, it would have panicked, which I would have thought we should have seen in the logs, or we should have seen the controller restart. But worth a shot - I could be wrong.

[agones-bot]

Build Succeeded 👏

Build Id: dda4e391-2a72-4e76-a050-2e1160b70c3e

The following development artifacts have been built, and will exist for the next 30 days:

• image: gcr.io/agones-images/agones-controller:0.7.0-507fb98
• image: gcr.io/agones-images/agones-sdk:0.7.0-507fb98
• image: gcr.io/agones-images/agones-ping:0.7.0-507fb98
• Linux C++ SDK (build: dev): agonessdk-0.7.0-507fb98-dev-linux-arch_64.tar.gz
• Linux C++ SDK (build: runtime): agonessdk-0.7.0-507fb98-runtime-linux-arch_64.tar.gz
• Linux C++ SDK (source): agonessdk-0.7.0-507fb98-src.zip
• SDK Server: agonessdk-server-0.7.0-507fb98.zip

To install this version:

• git fetch https://github.com/GoogleCloudPlatform/agones.git pull/442/head:pr_442 && git checkout pr_442
• helm install install/helm/agones --namespace agones-system --name agones --set agones.image.tag=0.7.0-507fb98