diff mercurial/scmutil.py @ 39254:7a759ad2d06d

shortest: use nodetree for finding shortest node within revset

This speeds up `hg log -T '{shortest(node,1)}\n'` in my repo from 12s
to 4.5s. That's very close to the 4.1s it takes without the
disambiguation revset configured. My repo has 69.5k revisions, of
which 550 were in the configured revset ("not public()").

Differential Revision: https://phab.mercurial-scm.org/D4120

--- a/mercurial/scmutil.py	Mon Aug 20 15:57:03 2018 -0700
+++ b/mercurial/scmutil.py	Sun Aug 05 00:42:07 2018 -0700
@@ -34,6 +34,7 @@
     obsutil,
     pathutil,
     phases,
+    policy,
     pycompat,
     revsetlang,
     similar,
@@ -52,6 +53,8 @@
 else:
     from . import scmposix as scmplatform
 
+parsers = policy.importmod(r'parsers')
+
 termsize = scmplatform.termsize
 
 class status(tuple):
@@ -514,6 +517,24 @@
                 cache['disambiguationrevset'] = revs
         if cl.rev(node) in revs:
             hexnode = hex(node)
+            nodetree = None
+            if cache is not None:
+                nodetree = cache.get('disambiguationnodetree')
+            if not nodetree:
+                try:
+                    nodetree = parsers.nodetree(cl.index, len(revs))
+                except AttributeError:
+                    # no native nodetree
+                    pass
+                else:
+                    for r in revs:
+                        nodetree.insert(r)
+                    if cache is not None:
+                        cache['disambiguationnodetree'] = nodetree
+            if nodetree is not None:
+                length = max(nodetree.shortest(node), minlength)
+                prefix = hexnode[:length]
+                return disambiguate(prefix)
             for length in range(minlength, len(hexnode) + 1):
                 matches = []
                 prefix = hexnode[:length]