[meld] Short-circuit file time comparison when we don't need Decimal precision

[Kai Willadsen <kaiw src gnome org>]

commit b42db6f6348b27f7361eab632e5a069076f8061b
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Feb 10 07:44:12 2013 +1000

    Short-circuit file time comparison when we don't need Decimal precision

 meld/dirdiff.py |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/meld/dirdiff.py b/meld/dirdiff.py
index 7bcfbb3..08e29fb 100644
--- a/meld/dirdiff.py
+++ b/meld/dirdiff.py
@@ -64,6 +64,11 @@ class StatItem(namedtuple('StatItem', 'mode size time')):
         if self.size != other.size:
             return False
 
+        # Shortcut to avoid expensive Decimal calculations. 2 seconds is our
+        # current accuracy threshold (for VFAT), so should be safe for now.
+        if abs(self.time - other.time) > 2:
+            return False
+
         dectime1 = Decimal(str(self.time)).scaleb(Decimal(9)).quantize(1)
         dectime2 = Decimal(str(other.time)).scaleb(Decimal(9)).quantize(1)
         mtime1 = dectime1 // prefs.dirdiff_time_resolution_ns