[PATCH] localrepo: introduce persistent caching of revset revision's branch names

[Matt Mackall]

On Wed, 2014-10-15 at 02:33 +0200, Mads Kiilerich wrote:
> # HG changeset patch
> # User Mads Kiilerich <madski at unity3d.com>
> # Date 1413333190 -7200
> #      Wed Oct 15 02:33:10 2014 +0200
> # Node ID 85189122b49b31dddbcddb7c0925afa019dc4403
> # Parent  48c0b101a9de1fdbd638daa858da845cd05a6be7
> localrepo: introduce persistent caching of revset revision's branch names
> 
> It is expensive to create a changectx and extract the branch name. That shows
> up when filtering on branches in revsets.
> 
> To speed things up, cache the results on disk. To avoid using too much space,
> all branch names are only stored once and each revision references one of these
> names. To verify that the cache is valid, we also store the tip hash in the
> cache file.

If we're going to add such a cache, I think it needs to not need
rebuilding across a strip.

-- 
Mathematics is the supreme nostalgia of our time.