[jira] [Updated] (SLING-3279) Leverage improved observation support from Oak

["Michael Dürig (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SLING-3279?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Michael Dürig updated SLING-3279:
---------------------------------

    Attachment: SLING-3279.patch

First implementation based on the Oak Observer interface. All unit tests pass. Note: this needs the changes from http://svn.apache.org/r1574896 in Oak.

[~cziegeler], as discussed, could you see how to best get this into Sling? Probably best as an separate bundle which could be used as an alternative when running on Oak.

> 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
>         Attachments: SLING-3279.patch
>
>
> 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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