diff mercurial/windows.py @ 14927:2aa3e07b2f07

posix, windows: introduce cachestat

This class contains a stat result, and possibly other file info to reliably
determine between two points in time whether a file has changed.

Uniquely identifying a file gives us that reliability because we either
atomic rename or append. So one of two will happen: the file 'id' will change,
or the size of the file will change.

posix implements it simply by calling os.stat() and checking if the result
has st_ino.

For now on Windows we always assume the path is uncacheable. This can be
improved on NTFS due to file IDs: http://msdn.microsoft.com/en-us/library/aa363788(v=vs.85).aspx

So we need to find out if a file path is on an NTFS drive, for that we have:

- GetVolumeInformation, which unfortunately only works with a root path (but is available on XP)
- GetVolumeInformationByHandleW, works on a full file path but requires Vista or higher

--- a/mercurial/windows.py	Sat Jul 23 12:29:52 2011 +0200
+++ b/mercurial/windows.py	Mon Jul 25 15:03:02 2011 +0300
@@ -286,4 +286,11 @@
 
 from win32 import *
 
+class cachestat(object):
+    def __init__(self, path):
+        pass
+
+    def cacheable(self):
+        return False
+
 expandglobs = True