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https://issues.apache.org/jira/browse/FLINK-6849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16040295#comment-16040295
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mingleizhang commented on FLINK-6849:
-------------------------------------
I think we can do this refactor by the below three steps.
1. Refactor {{OperatorStateBackend}} to having a more functionality, add the
function of create and cache already registered state, such as add
{{getOrCreateOperatorState}} and {{getPartitionedState}} methods to
{{OperatorStateBackend}} interface.
2. Add abstract class implements for {{OperatorStateBackend}}. For example, we
can have a class called {{AbstractOperatorStateBackend}}.
3. Remove the concrete cache operation for {{DefaultOperatorStateBackend}} and
then implement that in {{AbstractOperatorStateBackend}}.
[~tzulitai], What do you think ? It would be helpful if you can take a look at
those steps.
> Refactor operator state backend and internal operator state hierarchy
> ---------------------------------------------------------------------
>
> Key: FLINK-6849
> URL: https://issues.apache.org/jira/browse/FLINK-6849
> Project: Flink
> Issue Type: Improvement
> Components: State Backends, Checkpointing
> Reporter: Tzu-Li (Gordon) Tai
>
> Currently, compared to the keyed state backends, the operator state backends,
> as well as operator state interfaces, lacks proper hierarchy.
> One issue with this lack of hierarchy is that the general concerns of
> implementing state registration is different between the keyed and operator
> backends (aside from what is naturally different, such as namespace and key
> which is not relevant for the operator backend). For example, in the keyed
> backend hierarchy, {{AbstractKeyedStateBackend}} has caches that shortcuts
> re-accessing already registered state. This behaviour is missing in the
> operator backend hierarchy, and for example needs to be explicitly handled by
> the concrete {{DefaultOperatorStateBackend}} subclass implementation.
> As of now, the need of a proper hierarchy also on the operator backend side
> might not be that prominent, but will mostly likely become more prominent as
> we wish to introduce more state structures for operator state (e.g. a
> {{MapState}} for operator state has already been discussed a few times
> already) as well as more options besides memory-backed operator state.
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