4536c93bb2
This will speed up the common case where a Key is deserialized from disk, but is then serialized to build eg, the path to the annex object. It means that every place a Key has any of its fields changed, the cache has to be dropped. I've grepped and found them all. But, it would be better to avoid that gotcha somehow..
100 lines
3.1 KiB
Haskell
100 lines
3.1 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
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{ keyName = S8.map fixbadchar (keyName k)
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, keySerialization = Nothing
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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 (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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