[jira] [Commented] (CURATOR-476) PathChildrenCache never gets initialized if a child dies even before a data watch is registered for it

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CURATOR-476?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16576291#comment-16576291 ] 

ASF GitHub Bot commented on CURATOR-476:
----------------------------------------

GitHub user rsouhrain opened a pull request:

    https://github.com/apache/curator/pull/275

    CURATOR-476 PathChildrenCache should check resultCode=-101 for getData(...) done on non-existent child and remove it from it's initialSet

    

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/rsouhrain/curator CURATOR-476

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/curator/pull/275.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #275
    
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commit 895015165dca24fb58aa23a1949bed0476761910
Author: rsouhrain <rs...@...>
Date:   2018-08-10T13:10:18Z

    CURATOR-476 PathChildrenCache should check resultCode=-101 for getData(...) done on non-existent child and remove it from it's initialSet

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> PathChildrenCache never gets initialized if a child dies even before a data watch is registered for it
> ------------------------------------------------------------------------------------------------------
>
>                 Key: CURATOR-476
>                 URL: https://issues.apache.org/jira/browse/CURATOR-476
>             Project: Apache Curator
>          Issue Type: Bug
>          Components: Recipes
>            Reporter: Rohan Suri
>            Priority: Major
>
> h5. What's happening:
> When PathChildrenCache is started with PathChildrenCache.StartMode.POST_INITIALIZED_EVENT there could be the following scenario:
>  1. PCC calls getChildren("../parent") and gets the list of it's children
>  2. PCC calls processChildren(...) where it puts them into it's \{initialSet} – set of children whose data it will fetch and cache
>  3. Later in the same method it calls getDataAndStat(..."/parent/somechild") where it calls getData(...) on this child and registers a dataWatcher for this child
> Midst of step 2&3, child node could get deleted – but since step 3 hasn't completed yet, the dataWatcher isn't triggered (since it is not even registered) and we miss the NodeDeleted event.
> Since our \{initialSet} still contains the child path, the initialized event is never fired.
> h5. The fix:
> As of now there's only one codepath to removing a path from the \{initialSet} (done from the data watcher)
> The remove should also be called in the callback of our getData(..."/parent/somechild") being done in Step 3 if the resultCode=-101(KeeperException.NoNode)



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