mirrors/git-annex
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages 1 Wiki Activity Actions

this just went from horrible to insanely weird

Browse source
This commit is contained in:
Joey Hess 2014-06-12 15:17:32 -04:00
parent 5c5c5cda85
commit 9dd380cf3b
1 changed files with 20 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

30
doc/bugs/Windows_file_timestamp_timezone_madness.mdwn
View file

@ -5,14 +5,24 @@ appear to change.
This means that after such a change, git-annex will see new mtimes, and This means that after such a change, git-annex will see new mtimes, and
want to re-checksum every file in the repo. want to re-checksum every file in the repo.
The best way to fix this seems to be to normalize the timestamp returned by
getFileStatus, which is relative to the current time zone, to be relative
to UTC. (As is always the case on Unix, of course).
However, to do that, I need to know the current timezone.
Unfortunately, Data.Time.LocalTime.getCurrentTimeZone doesn't seem to really
work on windows. It always returns a time zone 60 minutes from UTS in my tests,
no matter what the zone really is. I need to test this more widely and file
a GHC bug if appropriate.
[[!tag confirmed]] [[!tag confirmed]]
> Update: Actually, I seem to have been getting confused by behavior of
> cygwin terminal setting TZ. That indeed led to timestamp changes when the
> time zone changed. I have made git-annex unset TZ to avoid this.
>
> Without TZ set, time stamps are actually stable across time zone changes.
> Ie, a simple program to read the time stamp of a file and print it
> always shows the same thing, before and after a timezone change.
>
> However, and here's where it gets truely ghastly: A program that stats a
> file in a loop will see its timestamp change when the timezone changes.
> I suspect this might be a bug in the Haskell RTS caching something it
> should not. Stopping and re-running the program gets back to the
> original timestamp.
>
> I have not tested DST changes, but it's hard to imagine it being any
> worse than the above behavior.
>
> So, that's insane then. We can't trust timestamps to be stable on windows
> when git-annex is running for a long period of time. --[[Joey]]