tags: cache `repo.changelog` access when checking tags nodes
The tags reading process checks if the nodes referenced in tags exist. Caching
the access to `repo.changelog` provides a large speedup for repositories with
many tags.
running `hg perftags` in a large private repository
before: ! wall 0.393464 comb 0.390000 user 0.330000 sys 0.060000 (median of 25)
after: ! wall 0.267711 comb 0.270000 user 0.210000 sys 0.060000 (median of 38)
--- a/mercurial/localrepo.py Tue Nov 20 10:46:20 2018 +0000
+++ b/mercurial/localrepo.py Tue Nov 20 10:38:15 2018 +0000
@@ -1417,10 +1417,11 @@
tags, tt = self._findtags()
else:
tags = self._tagscache.tags
+ rev = self.changelog.rev
for k, v in tags.iteritems():
try:
# ignore tags to unknown nodes
- self.changelog.rev(v)
+ rev(v)
t[k] = v
except (error.LookupError, ValueError):
pass