[jira] [Commented] (SLING-10011) Use javax.jcr.Item.getParent() when resolving parent JCR node in JcrResourceProvider#getParent

["Angela Schreiber (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SLING-10011?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17389845#comment-17389845 ] 

Angela Schreiber commented on SLING-10011:
------------------------------------------

[~joerghoh], i am a bit confused about the status of this ticket. you state the modification by [~miroslav] has been merged but the ticket is in status reopened. 

here my take on this:
- the reason why {{Session.getItemOrNull}} has been used before instead of {{Item.getParent()}} was the fact that getParent might throw an exception (see also [~cziegeler]'s comment on the patch)
- if we were to use {{Item.getParent()}} instead now, there is no need to check for the parent being a Node.... {{Item.getParent()}} will automatically return a {{Node}} and it will never be null. so the proposed changes from [~miroslav] could be further simplified.
- if {{Item.getParent()}}  cannot be used because of the exceptions, we should consider adding {{JackrabbitSession.getParentOrNull(Item item)}} or alternatively introduce {{JackrabbitItem}}, which would have this method.

wdyt?



> Use javax.jcr.Item.getParent() when resolving parent JCR node in JcrResourceProvider#getParent
> ----------------------------------------------------------------------------------------------
>
>                 Key: SLING-10011
>                 URL: https://issues.apache.org/jira/browse/SLING-10011
>             Project: Sling
>          Issue Type: Improvement
>          Components: JCR
>    Affects Versions: JCR Resource 3.0.22
>            Reporter: Miroslav Smiljanic
>            Assignee: Joerg Hoh
>            Priority: Minor
>             Fix For: JCR Resource 3.0.24
>
>          Time Spent: 3h 20m
>  Remaining Estimate: 0h
>
> Currently [JcrResourceProvider.getParent|https://github.com/apache/sling-org-apache-sling-jcr-resource/blob/org.apache.sling.jcr.resource-3.0.22/src/main/java/org/apache/sling/jcr/resource/internal/helper/jcr/JcrResourceProvider.java#L361] is using JcrItemResourceFactory.getItemOrNull(String path), which eventually is using JCR session to retrieve parent node using absolute path.
> I propose using javax.jcr.Item.getParent() instead.
> Reasoning wold be to utilise potential improvements in JCR implementation that would for a given node retrieve the whole subtree. That can be configured for example by using particular node type or node path.
> {noformat}
>     root
>      |
>      a 
>    /   \
>   b     c    
> {noformat}
> If node 'a' in picture above, is matching desired configuration, then code below would return the whole subtree.
> {code:java}
> Node a = jcrSession.getNode("a");
> {code}
> That further means retrieved subtree can be traversed in memory, without the need to communicate with the JCR repository storage.
> (!)That is particularly important when remote (cloud) storage is used for repository in JCR implementation, and tree traversal can be done without doing additional network roundtrips.
> {code:java}
> //JCR tree traversal happens in memory
> Node b = a.getNode("b");
> Node c = a.getNode("c");
> {code}
> Also going from child to parent, is resolved in memory as well (proposal relates to this fact)
> {code:java}
> //JCR tree traversal happens in memory
> assert b.getParent() == c.getParent();
> {code}
> Jackrabbit Oak, for document node store is supporting node bundling for configured node type
>  [http://jackrabbit.apache.org/oak/docs/nodestore/document/node-bundling.html]
> Currently I am also doing some experiments to support node bundling/aggregation for arbitrary node store ([NodeDelegateFullyLoaded|https://github.com/smiroslav/jackrabbit-oak/blob/ppnextgen_newstore/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/delegate/NodeDelegateFullyLoaded.java], [FullyLoadedTree|https://github.com/smiroslav/jackrabbit-oak/blob/ppnextgen_newstore/oak-core/src/main/java/org/apache/jackrabbit/oak/core/FullyLoadedTree.java]).



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