[jira] [Commented] (KAFKA-10575) StateRestoreListener#onRestoreEnd should always be triggered

["Nicholas Telford (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-10575?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17605878#comment-17605878 ] 

Nicholas Telford commented on KAFKA-10575:
------------------------------------------

Hi [~guozhang], I ran in to this issue today and have some thoughts on it.

I agree that {{onRestoreEnd}} currently implies that the restoration _completed_, since that's what the documentation says. I suggest we add a new method, {{StateRestoreListener#onRestoreAbort}} (or {{onRestoreSuspend}} or {{onRestorePaused}}, etc.), which handles the case that restoration was stopped before it could complete (i.e. because the {{Task}} was closed.

It should be enough to simply call this new method in {{StoreChangelogReader#unregister}}, which is called when {{Task}}s are closed/migrated.

For backwards compatibility, this new method should have a {{default}} implementation in the {{StateRestoreListener}} interface that is a no-op.

What do you think? And since this involves adding a new method, do we need a KIP for this?

> StateRestoreListener#onRestoreEnd should always be triggered
> ------------------------------------------------------------
>
>                 Key: KAFKA-10575
>                 URL: https://issues.apache.org/jira/browse/KAFKA-10575
>             Project: Kafka
>          Issue Type: Improvement
>          Components: streams
>            Reporter: Guozhang Wang
>            Assignee: highluck
>            Priority: Major
>
> Today we only trigger `StateRestoreListener#onRestoreEnd` when we complete the restoration of an active task and transit it to the running state. However the restoration can also be stopped when the restoring task gets closed (because it gets migrated to another client, for example). We should also trigger the callback indicating its progress when the restoration stopped in any scenarios.



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