From fdb697cef945f0ba9c3e1fd668669422348dbc7d Mon Sep 17 00:00:00 2001 From: "http://joeyh.name/" Date: Wed, 11 Jun 2014 19:51:15 +0000 Subject: Added a comment --- ...ent_2_a6a3871747306913b69abcd73d13305e._comment | 26 ++++++++++++++++++++++ 1 file changed, 26 insertions(+) create mode 100644 doc/bugs/Windows_file_timestamp_timezone_madness/comment_2_a6a3871747306913b69abcd73d13305e._comment diff --git a/doc/bugs/Windows_file_timestamp_timezone_madness/comment_2_a6a3871747306913b69abcd73d13305e._comment b/doc/bugs/Windows_file_timestamp_timezone_madness/comment_2_a6a3871747306913b69abcd73d13305e._comment new file mode 100644 index 000000000..c213aa0a9 --- /dev/null +++ b/doc/bugs/Windows_file_timestamp_timezone_madness/comment_2_a6a3871747306913b69abcd73d13305e._comment @@ -0,0 +1,26 @@ +[[!comment format=mdwn + username="http://joeyh.name/" + ip="108.236.230.124" + subject="comment 2" + date="2014-06-11T19:51:15Z" + content=""" +Note that multiple time zone changes complicate this. I think that means that the delta can't be simply applied when comparing inode caches. Instead, probably it needs to be applied when generating inode caches. + +A scenario: + +1. Time zone is at +1h when the inode sential is written. +2. Time zone changes to +2h +3. File F is added (with a current timestamp of T) +4. Time zone changes to +5h + +I am a little confused by which way windows moves the timestamps when the time zone changes. Let's assume I might get the sign wrong. + +Let F's timestamp after step 4, F4 = T+-3h. + +Let the delta after step 4, D4 = +-4h +And, let the delta after step 2, D2 = +-1h + +If step 3 writes the current timestamp to the inode cache, then the cache still has T in it after step 4. F4+D4 /= T (T +-3h +-4h /= T). So comparison doesn't work. + +If instead the current delta is applied when generating inode caches (both for storing on disk, and for immediate comparison), then the inode cache will have T+D2 in it. Then after step 4, generating a new inode cache for F will yield F4+D4. So, does F4+D4 == T+D2? T +-3h +-4h == T +-1h YES! +"""]] -- cgit v1.2.3