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