[PATCH 1 of 2] graft: find ancestors of destination lazily

[Siddharth Agarwal]

# HG changeset patch
# User Siddharth Agarwal <sid0 at fb.com>
# Date 1365303917 25200
#      Sat Apr 06 20:05:17 2013 -0700
# Node ID aff777b0929f7c26ffe97f226389271dd3d353d4
# Parent  85707a2ede81f521041ae7c089e1cadc745a072d
graft: find ancestors of destination lazily

When the revisions to graft are numerically close to the destination, this
avoids one walk up the DAG, which for a repository with over 470,000
changesets translates to around 1.1 seconds.

diff -r 85707a2ede81 -r aff777b0929f mercurial/commands.py
--- a/mercurial/commands.py	Thu Mar 28 00:30:40 2013 -0700
+++ b/mercurial/commands.py	Sat Apr 06 20:05:17 2013 -0700
@@ -2917,9 +2917,13 @@ def graft(ui, repo, *revs, **opts):
         return -1
 
     # check for ancestors of dest branch
-    for rev in repo.revs('::. and %ld', revs):
-        ui.warn(_('skipping ancestor revision %s\n') % rev)
-        revs.remove(rev)
+    crev = repo['.'].rev()
+    ancestors = repo.changelog.ancestors([crev], inclusive=True)
+    # don't mutate while iterating, create a copy
+    for rev in list(revs):
+        if rev in ancestors:
+            ui.warn(_('skipping ancestor revision %s\n') % rev)
+            revs.remove(rev)
     if not revs:
         return -1