# HG changeset patch
# User Tony Tung <tonytung@merly.org>
# Date 2016-05-02 22:22:16
# Node ID e2178f7d17c01fcd5a60b7c2a3f016f1d464c8cf
# Parent  4a65c9c6cd3fdd8e56a366dd16a8bc138f2e0ad6

manifest: improve filesnotin performance by using lazymanifest diff

lazymanifests can compute diffs significantly faster than taking the set
of two manifests and calculating the delta.

when running hg diff --git -c . on Facebook's big repo, this reduces the
run time from 2.1s to 1.5s.

diff --git a/mercurial/manifest.py b/mercurial/manifest.py
--- a/mercurial/manifest.py
+++ b/mercurial/manifest.py
@@ -211,8 +211,10 @@ class manifestdict(object):
 
     def filesnotin(self, m2):
         '''Set of files in this manifest that are not in the other'''
-        files = set(self)
-        files.difference_update(m2)
+        diff = self.diff(m2)
+        files = set(filepath
+                    for filepath, hashflags in diff.iteritems()
+                    if hashflags[1][0] is None)
         return files
 
     @propertycache