branchmap: pre-filter topological heads before ancestors based filtering
authorPierre-Yves David <pierre-yves.david@fb.com>
Sat, 30 Aug 2014 12:33:12 +0200
changeset 22357 9c3c3dc14a65
parent 22356 3c8fb24334e9
child 22358 198e2da3ee20
branchmap: pre-filter topological heads before ancestors based filtering We know that topological heads will not be ancestors of anything, so we filter them out to potentially reduce the range of the ancestors computation. On a strongly headed repo this gives humble speedup: from 0.1984 to 0.1629
mercurial/branchmap.py
--- a/mercurial/branchmap.py	Sat Aug 30 12:20:50 2014 +0200
+++ b/mercurial/branchmap.py	Sat Aug 30 12:33:12 2014 +0200
@@ -239,6 +239,10 @@
             newbranches.setdefault(branch, []).append(r)
             if closesbranch:
                 self._closednodes.add(cl.node(r))
+
+        # fetch current topological heads to speed up filtering
+        topoheads = set(cl.headrevs())
+
         # if older branchheads are reachable from new ones, they aren't
         # really branchheads. Note checking parents is insufficient:
         # 1 (branch a) -> 2 (branch b) -> 3 (branch a)
@@ -255,8 +259,11 @@
             # This prunes out two kinds of heads - heads that are superseded by
             # a head in newheadrevs, and newheadrevs that are not heads because
             # an existing head is their descendant.
-            ancestors = set(cl.ancestors(newheadrevs, min(bheadset)))
-            bheadset -= ancestors
+            uncertain = bheadset - topoheads
+            if uncertain:
+                floorrev = min(uncertain)
+                ancestors = set(cl.ancestors(newheadrevs, floorrev))
+                bheadset -= ancestors
             bheadrevs = sorted(bheadset)
             self[branch] = [cl.node(rev) for rev in bheadrevs]
             tiprev = bheadrevs[-1]