git-annex/UUID.hs
2011-08-20 16:11:42 -04:00

106 lines
2.5 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
-
- Copyright 2010 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module UUID (
UUID,
getUUID,
getUncachedUUID,
prepUUID,
genUUID,
describeUUID,
uuidMap,
uuidLog
) where
import Control.Monad.State
import System.Cmd.Utils
import System.IO
import qualified Data.Map as M
import Data.Maybe
import qualified Git
import qualified Branch
import Types
import Types.UUID
import qualified Annex
import qualified Build.SysConfig as SysConfig
import Config
configkey :: String
configkey = "annex.uuid"
{- Filename of uuid.log. -}
uuidLog :: FilePath
uuidLog = "uuid.log"
{- Generates a UUID. There is a library for this, but it's not packaged,
- so use the command line tool. -}
genUUID :: IO UUID
genUUID = liftIO $ pOpen ReadFromPipe command params $ \h -> hGetLine h
where
command = SysConfig.uuid
params = if command == "uuid"
-- request a random uuid be generated
then ["-m"]
-- uuidgen generates random uuid by default
else []
{- Looks up a repo's UUID. May return "" if none is known.
-}
getUUID :: Git.Repo -> Annex UUID
getUUID r = do
g <- Annex.gitRepo
let c = cached g
let u = getUncachedUUID r
if c /= u && u /= ""
then do
updatecache g u
return u
else return c
where
cached g = Git.configGet g cachekey ""
updatecache g u = when (g /= r) $ setConfig cachekey u
cachekey = "remote." ++ fromMaybe "" (Git.repoRemoteName r) ++ ".annex-uuid"
getUncachedUUID :: Git.Repo -> UUID
getUncachedUUID r = Git.configGet r configkey ""
{- Make sure that the repo has an annex.uuid setting. -}
prepUUID :: Annex ()
prepUUID = do
u <- getUUID =<< Annex.gitRepo
when ("" == u) $ do
uuid <- liftIO genUUID
setConfig configkey uuid
{- Records a description for a uuid in the uuidLog. -}
describeUUID :: UUID -> String -> Annex ()
describeUUID uuid desc = do
m <- uuidMap
let m' = M.insert uuid desc m
Branch.change uuidLog (serialize m')
where
serialize m = unlines $ map (\(u, d) -> u++" "++d) $ M.toList m
{- Read and parse the uuidLog into a Map -}
uuidMap :: Annex (M.Map UUID String)
uuidMap = do
s <- Branch.get uuidLog
return $ M.fromList $ map pair $ lines s
where
pair l =
if 1 < length (words l)
then (head $ words l, unwords $ drop 1 $ words l)
else ("", "")