96aba8eff7
This reverts commit 4536c93bb2.
That broke Read/Show of a Key, and unfortunately Key is read in at least
one place; the GitAnnexDistribution data type.
It would be worth bringing this optimisation back, but it would need
either a custom Read/Show instance that preserves back-compat, or
wrapping Key in a data type that contains the serialization, or changing
how GitAnnexDistribution is serialized.
Also, the Eq instance would need to compare keys with and without a
cached seralization the same.
97 lines
3 KiB
Haskell
97 lines
3 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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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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-- 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 -> Maybe Backend -> Annex (Maybe (Key, Backend))
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genKey source preferredbackend = do
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b <- maybe defaultBackend return preferredbackend
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B.getKey b source >>= return . \case
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Nothing -> Nothing
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Just k -> 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 = S8.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 " ++ decodeBS (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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- 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 (keyVariety k))
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