notes/plan for hpss performance work

[Andrew Bennetts]

John Arbash Meinel wrote:
> Aaron Bentley wrote:
[...]
> I would recommend to merge something like this anyway:
[...]
> === modified file 'bzrlib/remote.py'
[...]
> @@ -794,6 +795,8 @@
> ~         ancestry = self._parents_map
> ~         if ancestry is None:
> ~             # Repository is not locked, so there's no cache.
> +            trace.mutter_callsite(3, 'RemoteRepository.get_parent_map() called'
> +                    ' on an unlocked repository')
> ~             missing_revisions = set(keys)
> ~             ancestry = {}
> ~         else:
>
> We could put it under "-Devil" or "-Dhpss" if we want, but I think calling
> get_parent_map() on an unlocked repository is a BadThing (tm) anyway.

I think that's a great idea.

-Andrew.