From e384237be04dcedb72177edae5c6b44b8872318f Mon Sep 17 00:00:00 2001
From: David Stainton <dstainton415@gmail.com>
Date: Mon, 18 Jan 2016 17:06:47 +0100
Subject: [PATCH] Add comment about FUDGE_SECONDS and refer to our design doc

---
 src/allmydata/frontends/magic_folder.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/allmydata/frontends/magic_folder.py b/src/allmydata/frontends/magic_folder.py
index 353b8fac..ab9b729e 100644
--- a/src/allmydata/frontends/magic_folder.py
+++ b/src/allmydata/frontends/magic_folder.py
@@ -492,6 +492,10 @@ class WriteFileMixin(object):
         finally:
             os.umask(old_mask)
 
+        # FUDGE_SECONDS is used to determine if another process
+        # has written to the same file concurrently. This is described
+        # in the Earth Dragon section of our design document:
+        # docs/proposed/magic-folder/remote-to-local-sync.rst
         os.utime(replacement_path_u, (now, now - self.FUDGE_SECONDS))
         if is_conflict:
             print "0x00 ------------ <><> is conflict; calling _rename_conflicted_file... %r %r" % (abspath_u, replacement_path_u)
-- 
2.45.2