3334d3831b
retrieveExport is part of ongoing transition to make remote methods throw exceptions, rather than silently hide them. getKey very rarely fails, and when it does it's always for the same reason (user configured annex.backend to url for some reason). So, this will avoid dealing with Nothing everywhere it's used. This commit was sponsored by Ilya Shlyakhter on Patreon.
103 lines
3.2 KiB
Haskell
103 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 AGPL version 3 or higher.
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-}
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module Backend (
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list,
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defaultBackend,
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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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import Utility.Metered
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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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import qualified Data.ByteString.Char8 as S8
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list :: [Backend]
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list = Backend.Hash.backends ++ Backend.WORM.backends ++ Backend.URL.backends
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{- Backend to use by default when generating a new key. -}
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defaultBackend :: Annex Backend
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defaultBackend = maybe cache return =<< Annex.getState Annex.backend
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where
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cache = do
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n <- maybe (annexBackend <$> Annex.getGitConfig) (return . Just)
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=<< Annex.getState Annex.forcebackend
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let b = case n of
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Just name | valid name -> lookupname name
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_ -> Prelude.head list
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Annex.changeState $ \s -> s { Annex.backend = Just b }
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return b
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valid name = not (null name)
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lookupname = lookupBackendVariety . parseKeyVariety . encodeBS
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{- Generates a key for a file. -}
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genKey :: KeySource -> MeterUpdate -> Maybe Backend -> Annex (Key, Backend)
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genKey source meterupdate preferredbackend = do
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b <- maybe defaultBackend return preferredbackend
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case B.getKey b of
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Just a -> do
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k <- a source meterupdate
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return (makesane k, b)
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Nothing -> giveup $ "Cannot generate a key for backend " ++
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decodeBS (formatKeyVariety (B.backendVariety b))
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where
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-- keyNames should not contain newline characters.
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makesane k = alterKey k $ \d -> d
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{ keyName = S8.map fixbadchar (fromKey keyName k)
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}
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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 (fromKey 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 " ++ decodeBS (formatKeyVariety (fromKey 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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- or forced with --backend. -}
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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 . encodeBS
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<$> checkAttr "annex.backend" f
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go (Just _) = Just <$> defaultBackend
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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 " ++ decodeBS (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 (fromKey keyVariety k))
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