I struggle to understand how the built-in caching mechanism of Sling works when using AdapterFactory.
Here is my first AdapterFactory:
@component(
property = {
AdapterFactory.ADAPTABLE_CLASSES + "=org.apache.sling.api.SlingHttpServletRequest",
AdapterFactory.ADAPTER_CLASSES + "=com.example.Foo"
}
)
public final class FooAdapterFactory implements AdapterFactory {
@Override
public <AdapterType> AdapterType getAdapter(Object adaptable, Class<AdapterType> adapterTypeClass) {
SlingHttpServletRequest request = (SlingHttpServletRequest) adaptable;
return Optional.ofNullable(request.getResourceResolver().adaptTo(PageManager.class))
.map(pageManager -> pageManager.getContainingPage(request.getResource()))
.map(page -> page.getContentResource())
// the following line is not cached:
.map(contentResource -> contentResource.adaptTo(Bar.class))
// continue the chain with the Bar instance
.map(...)
.orElse(null);
}
}
And the my second AdapterFactory:
@component(service = AdapterFactory.class,
property = {
AdapterFactory.ADAPTABLE_CLASSES + "=org.apache.sling.api.resource.Resource",
AdapterFactory.ADAPTER_CLASSES + "=com.example.Bar"
}
)
public final class BarAdapterFactory implements AdapterFactory {
@Override
public <AdapterType> AdapterType getAdapter(Object adaptable, Class<AdapterType> adapterTypeClass) {
Resource resource = (Resource) adaptable;
// perform costly operation using the resource
// ...
}
}
From the sightly template, I call the FooAdapterFactory from various locations (multiple components on the same page use Foo) with:
<sly data-sly-use.foo="com.example.Foo" />
For a single HTTP request to /content/example/mypage.html, I would expect the second call (and the following ones) to contentResource.adaptTo(Bar.class) to be cached as contentResource is a JcrNodeResource, which extends SlingAdaptable. and therefore should be cached by Sling from what I understand.
However, this is not the case and my costly operation done in BarAdapterFactory.getAdapter() is called for each call to <sly data-sly-use.foo="com.example.Foo" />.
Can someone point out what I am missing here please? Or is there a better to achieve what I am trying to do?
Thanks in advance
