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-rw-r--r--src/Storage/Internal.hs273
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diff --git a/src/Storage/Internal.hs b/src/Storage/Internal.hs
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--- a/src/Storage/Internal.hs
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-module Storage.Internal where
-
-import Codec.Compression.Zlib
-
-import Control.Arrow
-import Control.Concurrent
-import Control.DeepSeq
-import Control.Exception
-import Control.Monad
-import Control.Monad.Identity
-
-import Crypto.Hash
-
-import Data.Bits
-import Data.ByteArray (ByteArray, ByteArrayAccess, ScrubbedBytes)
-import qualified Data.ByteArray as BA
-import Data.ByteString (ByteString)
-import qualified Data.ByteString as B
-import qualified Data.ByteString.Char8 as BC
-import qualified Data.ByteString.Lazy as BL
-import Data.Char
-import Data.Function
-import Data.Hashable
-import qualified Data.HashTable.IO as HT
-import Data.Kind
-import Data.List
-import Data.Map (Map)
-import qualified Data.Map as M
-import Data.UUID (UUID)
-
-import Foreign.Storable (peek)
-
-import System.Directory
-import System.FilePath
-import System.INotify (INotify)
-import System.IO
-import System.IO.Error
-import System.IO.Unsafe (unsafePerformIO)
-import System.Posix.Files
-import System.Posix.IO
-
-
-data Storage' c = Storage
- { stBacking :: StorageBacking c
- , stParent :: Maybe (Storage' Identity)
- , stRefGeneration :: MVar (HT.BasicHashTable RefDigest Generation)
- , stRefRoots :: MVar (HT.BasicHashTable RefDigest [RefDigest])
- }
-
-instance Eq (Storage' c) where
- (==) = (==) `on` (stBacking &&& stParent)
-
-instance Show (Storage' c) where
- show st@(Storage { stBacking = StorageDir { dirPath = path }}) = "dir" ++ showParentStorage st ++ ":" ++ path
- show st@(Storage { stBacking = StorageMemory {} }) = "mem" ++ showParentStorage st
-
-showParentStorage :: Storage' c -> String
-showParentStorage Storage { stParent = Nothing } = ""
-showParentStorage Storage { stParent = Just st } = "@" ++ show st
-
-data StorageBacking c
- = StorageDir { dirPath :: FilePath
- , dirWatchers :: MVar ([(HeadTypeID, INotify)], WatchList c)
- }
- | StorageMemory { memHeads :: MVar [((HeadTypeID, HeadID), Ref' c)]
- , memObjs :: MVar (Map RefDigest BL.ByteString)
- , memKeys :: MVar (Map RefDigest ScrubbedBytes)
- , memWatchers :: MVar (WatchList c)
- }
- deriving (Eq)
-
-newtype WatchID = WatchID Int
- deriving (Eq, Ord, Num)
-
-data WatchList c = WatchList
- { wlNext :: WatchID
- , wlList :: [WatchListItem c]
- }
-
-data WatchListItem c = WatchListItem
- { wlID :: WatchID
- , wlHead :: (HeadTypeID, HeadID)
- , wlFun :: Ref' c -> IO ()
- }
-
-
-newtype RefDigest = RefDigest (Digest Blake2b_256)
- deriving (Eq, Ord, NFData, ByteArrayAccess)
-
-instance Show RefDigest where
- show = BC.unpack . showRefDigest
-
-data Ref' c = Ref (Storage' c) RefDigest
-
-instance Eq (Ref' c) where
- Ref _ d1 == Ref _ d2 = d1 == d2
-
-instance Show (Ref' c) where
- show ref@(Ref st _) = show st ++ ":" ++ BC.unpack (showRef ref)
-
-instance ByteArrayAccess (Ref' c) where
- length (Ref _ dgst) = BA.length dgst
- withByteArray (Ref _ dgst) = BA.withByteArray dgst
-
-instance Hashable RefDigest where
- hashWithSalt salt ref = salt `xor` unsafePerformIO (BA.withByteArray ref peek)
-
-instance Hashable (Ref' c) where
- hashWithSalt salt ref = salt `xor` unsafePerformIO (BA.withByteArray ref peek)
-
-refStorage :: Ref' c -> Storage' c
-refStorage (Ref st _) = st
-
-refDigest :: Ref' c -> RefDigest
-refDigest (Ref _ dgst) = dgst
-
-showRef :: Ref' c -> ByteString
-showRef = showRefDigest . refDigest
-
-showRefDigestParts :: RefDigest -> (ByteString, ByteString)
-showRefDigestParts x = (BC.pack "blake2", showHex x)
-
-showRefDigest :: RefDigest -> ByteString
-showRefDigest = showRefDigestParts >>> \(alg, hex) -> alg <> BC.pack "#" <> hex
-
-readRefDigest :: ByteString -> Maybe RefDigest
-readRefDigest x = case BC.split '#' x of
- [alg, dgst] | BA.convert alg == BC.pack "blake2" ->
- refDigestFromByteString =<< readHex @ByteString dgst
- _ -> Nothing
-
-refDigestFromByteString :: ByteArrayAccess ba => ba -> Maybe RefDigest
-refDigestFromByteString = fmap RefDigest . digestFromByteString
-
-hashToRefDigest :: BL.ByteString -> RefDigest
-hashToRefDigest = RefDigest . hashFinalize . hashUpdates hashInit . BL.toChunks
-
-showHex :: ByteArrayAccess ba => ba -> ByteString
-showHex = B.concat . map showHexByte . BA.unpack
- where showHexChar x | x < 10 = x + o '0'
- | otherwise = x + o 'a' - 10
- showHexByte x = B.pack [ showHexChar (x `div` 16), showHexChar (x `mod` 16) ]
- o = fromIntegral . ord
-
-readHex :: ByteArray ba => ByteString -> Maybe ba
-readHex = return . BA.concat <=< readHex'
- where readHex' bs | B.null bs = Just []
- readHex' bs = do (bx, bs') <- B.uncons bs
- (by, bs'') <- B.uncons bs'
- x <- hexDigit bx
- y <- hexDigit by
- (B.singleton (x * 16 + y) :) <$> readHex' bs''
- hexDigit x | x >= o '0' && x <= o '9' = Just $ x - o '0'
- | x >= o 'a' && x <= o 'z' = Just $ x - o 'a' + 10
- | otherwise = Nothing
- o = fromIntegral . ord
-
-
-newtype Generation = Generation Int
- deriving (Eq, Show)
-
-data Head' c a = Head HeadID (Stored' c a)
- deriving (Eq, Show)
-
-newtype HeadID = HeadID UUID
- deriving (Eq, Ord, Show)
-
-newtype HeadTypeID = HeadTypeID UUID
- deriving (Eq, Ord)
-
-data Stored' c a = Stored (Ref' c) a
- deriving (Show)
-
-instance Eq (Stored' c a) where
- Stored r1 _ == Stored r2 _ = refDigest r1 == refDigest r2
-
-instance Ord (Stored' c a) where
- compare (Stored r1 _) (Stored r2 _) = compare (refDigest r1) (refDigest r2)
-
-storedStorage :: Stored' c a -> Storage' c
-storedStorage (Stored (Ref st _) _) = st
-
-
-type Complete = Identity
-type Partial = Either RefDigest
-
-class (Traversable compl, Monad compl) => StorageCompleteness compl where
- type LoadResult compl a :: Type
- returnLoadResult :: compl a -> LoadResult compl a
- ioLoadBytes :: Ref' compl -> IO (compl BL.ByteString)
-
-instance StorageCompleteness Complete where
- type LoadResult Complete a = a
- returnLoadResult = runIdentity
- ioLoadBytes ref@(Ref st dgst) = maybe (error $ "Ref not found in complete storage: "++show ref) Identity
- <$> ioLoadBytesFromStorage st dgst
-
-instance StorageCompleteness Partial where
- type LoadResult Partial a = Either RefDigest a
- returnLoadResult = id
- ioLoadBytes (Ref st dgst) = maybe (Left dgst) Right <$> ioLoadBytesFromStorage st dgst
-
-unsafeStoreRawBytes :: Storage' c -> BL.ByteString -> IO (Ref' c)
-unsafeStoreRawBytes st raw = do
- let dgst = hashToRefDigest raw
- case stBacking st of
- StorageDir { dirPath = sdir } -> writeFileOnce (refPath sdir dgst) $ compress raw
- StorageMemory { memObjs = tobjs } ->
- dgst `deepseq` -- the TVar may be accessed when evaluating the data to be written
- modifyMVar_ tobjs (return . M.insert dgst raw)
- return $ Ref st dgst
-
-ioLoadBytesFromStorage :: Storage' c -> RefDigest -> IO (Maybe BL.ByteString)
-ioLoadBytesFromStorage st dgst = loadCurrent st >>=
- \case Just bytes -> return $ Just bytes
- Nothing | Just parent <- stParent st -> ioLoadBytesFromStorage parent dgst
- | otherwise -> return Nothing
- where loadCurrent Storage { stBacking = StorageDir { dirPath = spath } } = handleJust (guard . isDoesNotExistError) (const $ return Nothing) $
- Just . decompress . BL.fromChunks . (:[]) <$> (B.readFile $ refPath spath dgst)
- loadCurrent Storage { stBacking = StorageMemory { memObjs = tobjs } } = M.lookup dgst <$> readMVar tobjs
-
-refPath :: FilePath -> RefDigest -> FilePath
-refPath spath rdgst = intercalate "/" [spath, "objects", BC.unpack alg, pref, rest]
- where (alg, dgst) = showRefDigestParts rdgst
- (pref, rest) = splitAt 2 $ BC.unpack dgst
-
-
-openLockFile :: FilePath -> IO Handle
-openLockFile path = do
- createDirectoryIfMissing True (takeDirectory path)
- fd <- retry 10 $
- openFd path WriteOnly (Just $ unionFileModes ownerReadMode ownerWriteMode) (defaultFileFlags { exclusive = True })
- fdToHandle fd
- where
- retry :: Int -> IO a -> IO a
- retry 0 act = act
- retry n act = catchJust (\e -> if isAlreadyExistsError e then Just () else Nothing)
- act (\_ -> threadDelay (100 * 1000) >> retry (n - 1) act)
-
-writeFileOnce :: FilePath -> BL.ByteString -> IO ()
-writeFileOnce file content = bracket (openLockFile locked)
- hClose $ \h -> do
- fileExist file >>= \case
- True -> removeLink locked
- False -> do BL.hPut h content
- hFlush h
- rename locked file
- where locked = file ++ ".lock"
-
-writeFileChecked :: FilePath -> Maybe ByteString -> ByteString -> IO (Either (Maybe ByteString) ())
-writeFileChecked file prev content = bracket (openLockFile locked)
- hClose $ \h -> do
- (prev,) <$> fileExist file >>= \case
- (Nothing, True) -> do
- current <- B.readFile file
- removeLink locked
- return $ Left $ Just current
- (Nothing, False) -> do B.hPut h content
- hFlush h
- rename locked file
- return $ Right ()
- (Just expected, True) -> do
- current <- B.readFile file
- if current == expected then do B.hPut h content
- hFlush h
- rename locked file
- return $ return ()
- else do removeLink locked
- return $ Left $ Just current
- (Just _, False) -> do
- removeLink locked
- return $ Left Nothing
- where locked = file ++ ".lock"
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-07 22:52:17 +0000