The TBranch BranchCallback needs a built-in BasketCache.

[jpivarski]

What's the right interface to caches in Java? In Python, we accept any dict-like object as a cache, and that dict-like object is allowed to delete key-value pairs whenever it wants (so we try to extract, and failing that, go to the file). Java, being strongly typed, probably has some interface for "caches" that we can just use. Certainly there are LRU libraries that we can just use (it might even be in the standard library). If we have to create our own cache Interface to wrap up caches from libraries, so be it, but we should not be writing an LRU algorithm.