Commit 66c9cf9d845865092c2117834226014fca8bf30a - tansu

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Database/Tansu/Backend/Ephemeral.hs less more

43	43	createEphemeralDb ls = EDB (M.fromList [ (encode k, encode v) \| (k, v) <- ls ])
44	44
45	45	-- \| Run a 'Tansu' operation with an empty in-memory table.
46		withNewEphemeralDb :: (TansuDb -> IO a) -> IO a
	46	withNewEphemeralDb :: (TansuDb k v -> IO a) -> IO a
47	47	withNewEphemeralDb = withEphemeralDb $ EDB M.empty
48	48
49	49	-- \| Run a 'Tansu' operation with an existing in-memory table.
50		withEphemeralDb :: EphemeralDb -> (TansuDb -> IO a) -> IO a
	50	withEphemeralDb :: EphemeralDb -> (TansuDb k v -> IO a) -> IO a
51	51	withEphemeralDb init comp = do
52	52	lock <- newMVar ()
53	53	table <- newIORef (fromEDB init)

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Database/Tansu/Backend/Filesystem.hs less more

46	46	-- @.lock@ file in the specified directory, but note that
47	47	-- file locking is not a guaranteed way of ensuring exclusion,
48	48	-- and that the files themselves are not locked in any way.
49		withFilesystemDb :: FilePath -> (TansuDb -> IO a) -> IO a
	49	withFilesystemDb :: FilePath -> (TansuDb k v -> IO a) -> IO a
50	50	withFilesystemDb path comp = do
51	51	createDirectoryIfMissing True path
52	52	comp $ TansuDb { dbSet = filePathSet path

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Database/Tansu/Internal.hs less more

23	23	-- should treat this as an abstract type, but the full definition
24	24	-- is exposed by the "Database.Tansu.Internal" module so that
25	25	-- other libraries can implement new storage backends.
26		data TansuDb = TansuDb
	26	--
	27	-- A given instantiation of the database will have
	28	data TansuDb k v = TansuDb
27	29	{ dbSet :: ByteString -> ByteString -> IO (Either TansuError ())
28	30	, dbGet :: ByteString -> IO (Either TansuError ByteString)
29	31	, dbDel :: ByteString -> IO (Either TansuError ())

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Database/Tansu.hs less more

	1	{-# LANGUAGE RankNTypes #-}
	2
1	3	module Database.Tansu ( -- * The 'Tansu' monad
2	4	Tansu
3	5	, TansuDb

24	26	)
25	27	import Database.Tansu.Internal
26	28
27		type TansuM ~~a = ReaderT TansuDb~~ (ExceptionT TansuError IO) a
	29	type TansuM k v a = ReaderT (TansuDb k v) (ExceptionT TansuError IO) a
28	30
29	31	-- \| The 'Tansu' type is a monad which represents some sequence
30	32	-- of 'get' and 'set' operations. Ideally, backends should
31	33	-- make some guarantee about the atomicity of a given
32	34	-- 'Tansu' computation, but you should consult the documentation
33	35	-- about a given backend to make sure that holds.
34		newtype Tansu k v a = Tansu { runTansu :: TansuM a }
	36	newtype Tansu k v a = Tansu { runTansu :: TansuM k v a }
35	37
36	38	instance Functor (Tansu k v) where
37	39	fmap f (Tansu t) = Tansu (fmap f t)

94	96	-- \| Given a storage backend and a 'Tansu' computation, execute the
95	97	-- sequence of 'get' and 'set' commands and produce either the value
96	98	-- or the error encountered while running the computation.
97		run :: TansuDb -> Tansu k v a -> IO (Either TansuError a)
	99	run :: TansuDb k v -> Tansu k v a -> IO (Either TansuError a)
98	100	run db (Tansu comp) =
99	101	dbRunTransaction db (runExceptionT (runReaderT db comp))

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README.md less more

68	68	del :: (Serialize k) => k -> Tansu k v ()
69	69
70	70	-- run a Tansu computation
71		run :: TansuDb -> Tansu k v a -> IO (Either TansuError a)
	71	run :: TansuDb k v -> Tansu k v a -> IO (Either TansuError a)
72	72	~~~
73	73
74	74	A value of type `TansuDb` should be supplied by a _backend_, which can

80	80	backends can be simply implemented separately from the core `tansu`
81	81	library, and backends can be easily swapped out as desired.
82	82
	83	## Tansu Backends
	84
	85	[...]
	86
83	87	## About the Name
84	88
85	89	A _tansu_ is a kind of

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sample/Main.hs less more

13	13	putStrLn "Testing ephemeral db"
14	14	withNewEphemeralDb sample
15	15
16		sample :: TansuDb -> IO ()
	16	sample :: TansuDb String String -> IO ()
17	17	sample db = do
18	18	putStrLn "Populating test database"
19	19	run db $ do