git-annex/Logs/UUID.hs
Joey Hess c7c2015435 add ConfigMonitor thread
Monitors git-annex branch for changes, which are noticed by the Merger
thread whenever the branch ref is changed (either due to an incoming push,
or a local change), and refreshes cached config values for modified config
files.

Rate limited to run no more often than once per minute. This is important
because frequent git-annex branch changes happen when files are being
added, or transferred, etc.

A primary use case is that, when preferred content changes are made,
and get pushed to remotes, the remotes start honoring those settings.
Other use cases include propigating repository description and trust
changes to remotes, and learning when a remote has added a new special
remote, so the webapp can present the GUI to enable that special remote
locally.

Also added a uuid.log cache. All other config files already had caches.
2012-10-20 16:43:35 -04:00

99 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 <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Logs.UUID (
uuidLog,
describeUUID,
recordUUID,
uuidMap,
uuidMapLoad
) where
import qualified Data.Map as M
import Data.Time.Clock.POSIX
import Types.UUID
import Common.Annex
import qualified Annex
import qualified Annex.Branch
import Logs.UUIDBased
import qualified Annex.UUID
{- Filename of uuid.log. -}
uuidLog :: FilePath
uuidLog = "uuid.log"
{- Records a description for a uuid in the log. -}
describeUUID :: UUID -> String -> Annex ()
describeUUID uuid desc = do
ts <- liftIO getPOSIXTime
Annex.Branch.change uuidLog $
showLog id . changeLog ts 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 (Date $ newertime v) fixedvalue)
| otherwise = (k, v)
where
kuuid = fromUUID k
isbad = not (isuuid kuuid) && 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 (Date d) _) = d + minimumPOSIXTimeSlice
newertime (LogEntry Unknown _) = minimumPOSIXTimeSlice
minimumPOSIXTimeSlice = 0.000001
isuuid s = length s == 36 && length (split "-" 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