diff mercurial/localrepo.py @ 40424:7caf632e30c3

filecache: unimplement __set__() and __delete__() (API)

Implementing __set__() implies that the descriptor can't be overridden by
obj.__dict__, which means any property access involves slow function call.

  "Data descriptors with __set__() and __get__() defined always override
  a redefinition in an instance dictionary. In contrast, non-data descriptors
  can be overridden by instances."

  https://docs.python.org/2.7/reference/datamodel.html#invoking-descriptors

This patch basically backs out 236bb604dc39, "scmutil: update cached copy
when filecached attribute is assigned (issue3263)." The problem described
in issue3263 (which is #3264 in Bugzilla) should no longer happen since
repo._bookmarkcurrent has been moved to repo._bookmarks.active. We still
have a risk of introducing similar bugs, but I think that's the cost we
have to pay.

  $ hg perfrevset 'branch(tip)' -R mercurial
  (orig) wall 0.139511 comb 0.140000 user 0.140000 sys 0.000000 (best of 66)
  (prev) wall 0.114195 comb 0.110000 user 0.110000 sys 0.000000 (best of 81)
  (this) wall 0.099038 comb 0.110000 user 0.100000 sys 0.010000 (best of 93)

--- a/mercurial/localrepo.py	Sat Oct 20 19:13:05 2018 +0900
+++ b/mercurial/localrepo.py	Sat Oct 20 17:56:00 2018 +0900
@@ -91,17 +91,16 @@
     def __get__(self, repo, type=None):
         if repo is None:
             return self
-        # inlined the fast path as the cost of function call matters
+        # proxy to unfiltered __dict__ since filtered repo has no entry
         unfi = repo.unfiltered()
         try:
             return unfi.__dict__[self.sname]
         except KeyError:
             pass
         return super(_basefilecache, self).__get__(unfi, type)
-    def __set__(self, repo, value):
-        return super(_basefilecache, self).__set__(repo.unfiltered(), value)
-    def __delete__(self, repo):
-        return super(_basefilecache, self).__delete__(repo.unfiltered())
+
+    def set(self, repo, value):
+        return super(_basefilecache, self).set(repo.unfiltered(), value)
 
 class repofilecache(_basefilecache):
     """filecache for files in .hg but outside of .hg/store"""