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From "Rohan Suri (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CURATOR-476) PathChildrenCache never gets initialized if a child dies even before a data watch is registered for it
Date Fri, 10 Aug 2018 12:47:00 GMT

     [ https://issues.apache.org/jira/browse/CURATOR-476?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Rohan Suri updated CURATOR-476:
-------------------------------
    Summary: PathChildrenCache never gets initialized if a child dies even before a data watch
is registered for it  (was: PathChildrenCache never get initialized if a child dies before
a data watch is registered for it)

> 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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