scmutil: introduce filecache The idea is being able to associate a file with a property, and watch that file stat info for modifications when we decide it's important for it to be up-to-date. Once it changes, we recreate the object. On filesystems that can't uniquely identify a file, we always recreate. As a consequence, localrepo.invalidate() will become much less expensive in the case where nothing changed on-disk.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-filecache.py.out	Sat Jul 09 19:06:59 2011 +0300
@@ -0,0 +1,15 @@
+basic:
+
+creating
+creating
+creating
+creating
+
+fakeuncacheable:
+
+creating
+creating
+creating
+creating
+creating
+creating