revlog: introduce isancestor method for efficiently determining node lineage
Hide the not so obvious use of commonancestorsheads.
--- a/mercurial/commands.py Tue Sep 09 17:16:24 2014 -0400
+++ b/mercurial/commands.py Tue Aug 19 01:13:10 2014 +0200
@@ -454,7 +454,7 @@
node = scmutil.revsingle(repo, rev).node()
op1, op2 = repo.dirstate.parents()
- if node not in repo.changelog.commonancestorsheads(op1, node):
+ if not repo.changelog.isancestor(node, op1):
raise util.Abort(_('cannot backout change that is not an ancestor'))
p1, p2 = repo.changelog.parents(node)
--- a/mercurial/revlog.py Tue Sep 09 17:16:24 2014 -0400
+++ b/mercurial/revlog.py Tue Aug 19 01:13:10 2014 +0200
@@ -745,6 +745,13 @@
ancs = ancestor.commonancestorsheads(self.parentrevs, a, b)
return map(self.node, ancs)
+ def isancestor(self, a, b):
+ """return True if node a is an ancestor of node b
+
+ The implementation of this is trivial but the use of
+ commonancestorsheads is not."""
+ return a in self.commonancestorsheads(a, b)
+
def ancestor(self, a, b):
"""calculate the least common ancestor of nodes a and b"""