git-annex/Logs/UUID.hs
Joey Hess 2cecc8d2a3
Added GIT_ANNEX_VECTOR_CLOCK environment variable
Can be used to override the default timestamps used in log files in the
git-annex branch. This is a dangerous environment variable; use with
caution.

Note that this only affects writing to the logs on the git-annex branch.
It is not used for metadata in git commits (other env vars can be set for
that).

There are many other places where timestamps are still used, that don't
get committed to git, but do touch disk. Including regular timestamps
of files, and timestamps embedded in some files in .git/annex/, including
the last fsck timestamp and timestamps in transfer log files.

A good way to find such things in git-annex is to get for getPOSIXTime and
getCurrentTime, although some of the results are of course false positives
that never hit disk (unless git-annex gets swapped out..)

So this commit does NOT necessarily make git-annex comply with some HIPPA
privacy regulations; it's up to the user to determine if they can use it in
a way compliant with such regulations.

Benchmarking: It takes 0.00114 milliseconds to call getEnv
"GIT_ANNEX_VECTOR_CLOCK" when that env var is not set. So, 100 thousand log
files can be written with an added overhead of only 0.114 seconds. That
should be by far swamped by the actual overhead of writing the log files
and making the commit containing them.

This commit was supported by the NSF-funded DataLad project.
2017-08-14 14:19:58 -04:00

96 lines
2.9 KiB
Haskell

{- git-annex uuids
-
- Each git repository used by git-annex has an annex.uuid setting that
- uniquely identifies that repository.
-
- UUIDs of remotes are cached in git config, using keys named
- remote.<name>.annex-uuid
-
- uuid.log stores a list of known uuids, and their descriptions.
-
- Copyright 2010-2012 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Logs.UUID (
uuidLog,
describeUUID,
recordUUID,
uuidMap,
uuidMapLoad
) where
import Types.UUID
import Annex.Common
import Annex.VectorClock
import qualified Annex
import qualified Annex.Branch
import Logs
import Logs.UUIDBased
import qualified Annex.UUID
import qualified Data.Map as M
{- Records a description for a uuid in the log. -}
describeUUID :: UUID -> String -> Annex ()
describeUUID uuid desc = do
c <- liftIO currentVectorClock
Annex.Branch.change uuidLog $
showLog id . changeLog c uuid desc . fixBadUUID . parseLog Just
{- Temporarily here to fix badly formatted uuid logs generated by
- versions 3.20111105 and 3.20111025.
-
- Those logs contain entries with the UUID and description flipped.
- Due to parsing, if the description is multiword, only the first
- will be taken to be the UUID. So, if the UUID of an entry does
- not look like a UUID, and the last word of the description does,
- flip them back.
-}
fixBadUUID :: Log String -> Log String
fixBadUUID = M.fromList . map fixup . M.toList
where
fixup (k, v)
| isbad = (fixeduuid, LogEntry (newertime v) fixedvalue)
| otherwise = (k, v)
where
kuuid = fromUUID k
isbad = not (isuuid kuuid) && not (null ws) && isuuid lastword
ws = words $ value v
lastword = Prelude.last ws
fixeduuid = toUUID lastword
fixedvalue = unwords $ kuuid: Prelude.init ws
-- For the fixed line to take precidence, it should be
-- slightly newer, but only slightly.
newertime (LogEntry (VectorClock c) _) = VectorClock (c + minimumPOSIXTimeSlice)
newertime (LogEntry Unknown _) = VectorClock minimumPOSIXTimeSlice
minimumPOSIXTimeSlice = 0.000001
isuuid s = length s == 36 && length (splitc '-' s) == 5
{- Records the uuid in the log, if it's not already there. -}
recordUUID :: UUID -> Annex ()
recordUUID u = go . M.lookup u =<< uuidMap
where
go (Just "") = set
go Nothing = set
go _ = noop
set = describeUUID u ""
{- The map is cached for speed. -}
uuidMap :: Annex UUIDMap
uuidMap = maybe uuidMapLoad return =<< Annex.getState Annex.uuidmap
{- Read the uuidLog into a simple Map.
-
- The UUID of the current repository is included explicitly, since
- it may not have been described and so otherwise would not appear. -}
uuidMapLoad :: Annex UUIDMap
uuidMapLoad = do
m <- (simpleMap . parseLog Just) <$> Annex.Branch.get uuidLog
u <- Annex.UUID.getUUID
let m' = M.insertWith' preferold u "" m
Annex.changeState $ \s -> s { Annex.uuidmap = Just m' }
return m'
where
preferold = flip const