[SLING-11780] Cache non-existing resources

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: Resource Resolver 1.10.0
• Component/s: ResourceResolver
• Assignee: Joerg Hoh
• Reporter: Joerg Hoh
• Created: 20/Feb/23 08:53
• Updated: 20/Feb/23 12:56

Description

I found that in many situations various Sling features probe for the existence of resources, for example the Sling Servlet Resolution and also Sling Context-Aware Configuration. If these functions are called multiple times during the lifetime of a ResourceResolver, the ResourceResolver always checks for the presence of these resources and will consistently return "null" (non-existing resource).
Due to the MVCC pattern we can cache the information that a resource does not exist at the ResourceResolver.

To support changes performed to the Repository by this specific ResourceResolver, this cache should be purged by a modifying operations (move, copy, create, delete), but also on refresh.

(Background: I found that for the rendering on a mildly complex AEM page (WKND sample content) I have 18 paths, for which the existence of a resource is tested more than 50 times and consistently returned "null". I expect that a caching of this information will save a good number of CPU cycles in Oak.