[jira] [Commented] (SLING-2780) Make ResourceMetadata read-only when delivered to client code

["Alexander Klimetschek (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SLING-2780?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13674491#comment-13674491 ] 

Alexander Klimetschek commented on SLING-2780:
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With this change and a custom, wrapping ResourceProvider I now get an exception "ResourceMetadata is locked" when requesting that resource (/overlay/foo) in a GET request (see below). The exception happens during sling's request initialization phase. My custom provider does wrap resources from another location/provider, which are accessed through the ResourceResolver.  The safe and right solution seems to wrap the metadata object:

    ResourceMetadata metadata = new ResourceMetadata();
    metadata.putAll(getResource().getResourceMetadata());

But I just want to point out that this might break some existing resource providers. And the question is if resource decorators are safe.


GET /overlay/foo HTTP/1.1] org.apache.sling.engine.impl.SlingRequestProcessorImpl service: Uncaught Throwable java.lang.UnsupportedOperationException: ResourceMetadata is locked
	at org.apache.sling.api.resource.ResourceMetadata.checkReadOnly(ResourceMetadata.java:310)
	at org.apache.sling.api.resource.ResourceMetadata.put(ResourceMetadata.java:322)
	at org.apache.sling.api.resource.ResourceMetadata.setResolutionPath(ResourceMetadata.java:254)
	at org.apache.sling.resourceresolver.impl.ResourceResolverImpl.getResourceInternal(ResourceResolverImpl.java:916)
	at org.apache.sling.resourceresolver.impl.ResourceResolverImpl.getChildInternal(ResourceResolverImpl.java:872)
	at org.apache.sling.resourceresolver.impl.ResourceResolverImpl.resolveInternal(ResourceResolverImpl.java:819)
	at org.apache.sling.resourceresolver.impl.ResourceResolverImpl.resolve(ResourceResolverImpl.java:319)
	at org.apache.sling.engine.impl.request.RequestData.initResource(RequestData.java:208)
	at org.apache.sling.engine.impl.SlingRequestProcessorImpl.processRequest(SlingRequestProcessorImpl.java:140)
	at org.apache.sling.engine.impl.SlingMainServlet.service(SlingMainServlet.java:206)

                
> Make ResourceMetadata read-only when delivered to client code
> -------------------------------------------------------------
>
>                 Key: SLING-2780
>                 URL: https://issues.apache.org/jira/browse/SLING-2780
>             Project: Sling
>          Issue Type: New Feature
>          Components: API, ResourceResolver
>    Affects Versions: API 2.3.0, Resource Resolver 1.0.4
>            Reporter: Carsten Ziegeler
>            Assignee: Carsten Ziegeler
>             Fix For: API 2.4.0, Resource Resolver 1.0.6
>
>
> As recently discussed in the mailing list, ResourceMetadata is an object which provides additional metadata information about a resource but is not intended to be changed by client code.
> As ResourceMetadata extends from (Hash)Map it is read/write by default and might potentially be changed by client code.
> We should update the API docs that this object is read-only and also enforce it in our implementation.
> It seems so far no one is changing the ResourceMetadata after it has left the resource resolver, therefore we can make it read-only after it is returned by the resource resolver.

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