while there is a getIfUpToDate() method in MCRCache there is no way to give this information when the index is filled. This is important in this use case:
- query cache with method above end retrieve null value
- construct new cache entry with a complex algorithm
- store cache entry
As the timestamp differs in 1. and 3. we could use stalled information in 2. and store it with an uptodate "flag" in step 3.