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https://issues.apache.org/jira/browse/SLING-3279?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13845595#comment-13845595
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Jukka Zitting commented on SLING-3279:
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Instead of using Oak's {{Observer}} interface directly, I think it would make
more sense for Sling to use a some more generic interface (for example in
Jackrabbit API) that can be implemented by both Oak and Jackrabbit 2.x (and any
other backend repository that supports observation). This should avoid the
direct Oak dependency in Sling and also make it possible to tailor the
observation interface more specifically based on the needs of the client code.
bq. thread pool ... OakExecutor
I'd rather avoid such a custom interface and the related coupling between Sling
and Oak. How about if Sling just provides a generic {{java.lang.Executor}}
service based on the configured thread pool?
> Leverage improved observation support from Oak
> ----------------------------------------------
>
> Key: SLING-3279
> URL: https://issues.apache.org/jira/browse/SLING-3279
> Project: Sling
> Issue Type: Improvement
> Components: JCR
> Reporter: Michael Dürig
>
> OAK-1120 introduces better support for observation, which could be used by
> Sling. For example JcrResourceListener could be rewritten leveraging Oak's
> Observer. Since Oak observers already run on background threads further
> decoupling (like it is currently done) is not necessary. This makes it
> unnecessary to queue potentially a lot of events in Sling. Since neither Oak
> there does queue events (they are generated by need) this will probably
> greatly improve scalability in the face of many events.
> Furthermore OSGi filters could be passed down and translated to Oak such that
> filtering is done much closer to the source of the events.
> Finally instead of using a centralised event dispatcher (like
> JcrResourceListener currently is) it would be better to install a dedicated
> Observer for each OSGi event listener since dispatching is already handled by
> Oak and thread pooling (i.e. assigning threads for dispatching call backs to
> observers) can be controlled through Sling's thread pool support (*). This
> has the further advantage of making individual stats available for the
> listeners through JMX.
> (*) Register an OakExecutor backed by e.g. a Sling thread pool and it will be
> picked up by Oak.
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