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https://issues.apache.org/jira/browse/KAFKA-7917?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16765620#comment-16765620
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Guozhang Wang commented on KAFKA-7917:
--------------------------------------
Another related issue is https://issues.apache.org/jira/browse/KAFKA-3229: when
we call `init` on wrapper we'd need to remember the "outer-most wrapper" store
so that it can be returned in the `ProcessorContext#getStateStore`. So suppose
we've done 7917 to collapse all the layers, we can remove the second `root`
parameter and implement `init` as (i.e. we call context register in the outer
store):
```
super.init();
context.register(batchingStateRestoreCallback);
```
Then there will be two cases:
1. the inner store is streams built-in, whose `init` not call
context.register().
2. the inner store is user customized, which may already call
context.register(); in this case we just need allow `ProcessorStateManager` to
overwrite the inner store with the outer ones with the call on outer store.
> Streams store cleanup: collapse layers
> --------------------------------------
>
> Key: KAFKA-7917
> URL: https://issues.apache.org/jira/browse/KAFKA-7917
> Project: Kafka
> Issue Type: Improvement
> Components: streams
> Reporter: John Roesler
> Priority: Major
>
> Following on KAFKA-7916, we can consider collapsing the "streams management
> layers" into one.
> Right now, we have:
> * metering (also handles moving from pojo world to bytes world)
> * change-logging
> * caching
> This is good compositional style, but we also have some runtime overhead of
> calling through all these layers, as well as some mental overhead of
> understanding how many and which layers we are going through.
> Also, there are dependencies between the caching and change-logging layers.
> I _think_ it would simplify the code if we collapsed these into one layer
> with boolean switches to turn on or off the different aspects. (rather than
> wrapping the store with the different layers or not depending on the same
> boolean conditions)
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