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https://issues.apache.org/jira/browse/FLINK-20480?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17244929#comment-17244929
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Yun Tang commented on FLINK-20480:
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I think setting {{CheckpointedFunction}} interfaces as final in
{{FlinkKafkaConsumerBase}} is to ensure the snapshot & restore logic is not
open for users within Kafka connector. Maybe kafka connector guys could help
answer more.
You could implement a {{DataStreamSource}} wrapping {{FlinkKafkaConsumerBase}}
which extends {{AbstractUdfStreamOperator}} and you could add some logic in
{{AbstractUdfStreamOperator#snapshotState}} which is still open for users.
> Methods from CheckpointedFunction interface in FlinkKafkaConsumerBase are set
> to final
> --------------------------------------------------------------------------------------
>
> Key: FLINK-20480
> URL: https://issues.apache.org/jira/browse/FLINK-20480
> Project: Flink
> Issue Type: Wish
> Components: Connectors / Kafka
> Environment: Flink 1.11
> Reporter: lidesheng
> Priority: Major
>
> I created a subclass from FlinkKafkaConsumerBase and wanna add some logic in
> checkpoint snapshot. I failed to do it because methods from
> CheckpointedFunction interface in FlinkKafkaConsumerBase are set to final.
> understand that these methods are set to final because offsets are required
> to hold and commit, so they do not want to be overridden by subclasses. Can
> we provide an additional abstract method to provide subclasses for their own
> state related operations? Call it in then end of final method default logic
> is emtpy.
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