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|
{- git-annex key/value backends
-
- Copyright 2010-2017 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Backend (
list,
orderedList,
genKey,
getBackend,
chooseBackend,
lookupBackendVariety,
maybeLookupBackendVariety,
isStableKey,
) where
import Annex.Common
import qualified Annex
import Annex.CheckAttr
import Types.Key
import Types.KeySource
import qualified Types.Backend as B
-- When adding a new backend, import it here and add it to the list.
import qualified Backend.Hash
import qualified Backend.WORM
import qualified Backend.URL
import qualified Data.Map as M
list :: [Backend]
list = Backend.Hash.backends ++ Backend.WORM.backends ++ Backend.URL.backends
{- List of backends in the order to try them when storing a new key. -}
orderedList :: Annex [Backend]
orderedList = do
l <- Annex.getState Annex.backends -- list is cached here
if not $ null l
then return l
else do
f <- Annex.getState Annex.forcebackend
case f of
Just name | not (null name) ->
return [lookupname name]
_ -> do
l' <- gen . annexBackends <$> Annex.getGitConfig
Annex.changeState $ \s -> s { Annex.backends = l' }
return l'
where
gen [] = list
gen ns = map lookupname ns
lookupname = lookupBackendVariety . parseKeyVariety
{- Generates a key for a file, trying each backend in turn until one
- accepts it. -}
genKey :: KeySource -> Maybe Backend -> Annex (Maybe (Key, Backend))
genKey source trybackend = do
bs <- orderedList
let bs' = maybe bs (: bs) trybackend
genKey' bs' source
genKey' :: [Backend] -> KeySource -> Annex (Maybe (Key, Backend))
genKey' [] _ = return Nothing
genKey' (b:bs) source = do
r <- B.getKey b source
case r of
Nothing -> genKey' bs source
Just k -> return $ Just (makesane k, b)
where
-- keyNames should not contain newline characters.
makesane k = k { keyName = map fixbadchar (keyName k) }
fixbadchar c
| c == '\n' = '_'
| otherwise = c
getBackend :: FilePath -> Key -> Annex (Maybe Backend)
getBackend file k = case maybeLookupBackendVariety (keyVariety k) of
Just backend -> return $ Just backend
Nothing -> do
warning $ "skipping " ++ file ++ " (unknown backend " ++ formatKeyVariety (keyVariety k) ++ ")"
return Nothing
{- Looks up the backend that should be used for a file.
- That can be configured on a per-file basis in the gitattributes file. -}
chooseBackend :: FilePath -> Annex (Maybe Backend)
chooseBackend f = Annex.getState Annex.forcebackend >>= go
where
go Nothing = maybeLookupBackendVariety . parseKeyVariety
<$> checkAttr "annex.backend" f
go (Just _) = Just . Prelude.head <$> orderedList
{- Looks up a backend by variety. May fail if unsupported or disabled. -}
lookupBackendVariety :: KeyVariety -> Backend
lookupBackendVariety v = fromMaybe unknown $ maybeLookupBackendVariety v
where
unknown = giveup $ "unknown backend " ++ formatKeyVariety v
maybeLookupBackendVariety :: KeyVariety -> Maybe Backend
maybeLookupBackendVariety v = M.lookup v varietyMap
varietyMap :: M.Map KeyVariety Backend
varietyMap = M.fromList $ zip (map B.backendVariety list) list
isStableKey :: Key -> Bool
isStableKey k = maybe False (`B.isStableKey` k)
(maybeLookupBackendVariety (keyVariety k))
|
