[jira] [Created] (SLING-3301) Add internal component for hierarchy queries

["Carsten Ziegeler (JIRA)" <ji...@apache.org>]

Carsten Ziegeler created SLING-3301:
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             Summary: Add internal component for hierarchy queries
                 Key: SLING-3301
                 URL: https://issues.apache.org/jira/browse/SLING-3301
             Project: Sling
          Issue Type: Bug
          Components: ResourceResolver
    Affects Versions: Resource Resolver 1.0.6
            Reporter: Alexander Klimetschek
            Assignee: Carsten Ziegeler
            Priority: Critical
             Fix For: Resource Resolver 1.1.0


SLING-2457 fixed the ACL issue with super type lookups, but at the cost of creating a new admin resource resolver for every super type lookup. If an inheritance chain contains multiple super types (N), a single call can trigger the creation of N admin sessions. Often this also happens for a number of resources per request, depending on the application, so you might end up creating many Jackrabbit JCR sessions per request. While creating a resource resolver / session is cheap, having too many at the same time has a big performance impact on the read performance due to increased concurrency in the JCR repository layer.

This affects:
* ResourceUtil.isA()
* Resource.isResourceType()
* ResourceResolver.isResourceType()
* implementation in ResourceResolverImpl.isResourceType() and getParentResourceType() [1]

A simple fix could be to cache a single admin resolver for the duration of the resource resolver containing it and reusing it for subsequent isResourceType() calls.

Another improvement could also be to cache the isResourceType() lookups - if this is a typical short-lived request resource resolver. Within a request resource type hierarchies are unlikely to change and should probably be stable (and with Jackrabbit Oak the session won't refresh anyway). The cache would simply be a map of "resource type" => "is also this resource type", so that the super lookups don't have to be done again and again. Often an application might iterate over a tree of data and looking for the same resource type again and again, so the hit rate for the cache will be high.

[1] https://svn.apache.org/viewvc/sling/trunk/bundles/resourceresolver/src/main/java/org/apache/sling/resourceresolver/impl/ResourceResolverImpl.java?revision=1537136&view=markup



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