[PATCH 3 of 5] tags: cache `repo.changelog` access when checking tags nodes

Boris Feld boris.feld at octobus.net
Tue Nov 20 14:18:07 EST 2018


# HG changeset patch
# User Boris Feld <boris.feld at octobus.net>
# Date 1542710295 0
#      Tue Nov 20 10:38:15 2018 +0000
# Node ID 1ad7353bec2584a53f2bb4fbca44310fa827f2d0
# Parent  7760b12bd4fb467f4fb7e4d0d5094fc324f30f49
# EXP-Topic perf-tags
# Available At https://bitbucket.org/octobus/mercurial-devel/
#              hg pull https://bitbucket.org/octobus/mercurial-devel/ -r 1ad7353bec25
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.

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)

diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -1416,13 +1416,11 @@ class localrepository(object):
             tags, tt = self._findtags()
         else:
             tags = self._tagscache.tags
+        rev = self.changelog.nodemap.get
         for k, v in tags.iteritems():
-            try:
-                # ignore tags to unknown nodes
-                self.changelog.rev(v)
+            # ignore tags to unknown nodes
+            if rev(v) is not None:
                 t[k] = v
-            except (error.LookupError, ValueError):
-                pass
         return t
 
     def _findtags(self):


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