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Clean up
This commit is contained in:
Nikita Volkov
parent
5fb0fe331f
commit
d7fb2ce0b9
@ -39,13 +39,8 @@ library
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library
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other-modules:
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HighSQL.Prelude
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HighSQL.CompositionT
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HighSQL.QQ
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HighSQL.QQ.Parser
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HighSQL.API
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HighSQL.Conversion
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exposed-modules:
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HighSQL
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HighSQL.Backend
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build-depends:
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-- template-haskell:
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@ -1,26 +0,0 @@
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module HighSQL
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(
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-- * Pool
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Pool,
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Settings(..),
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withPool,
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-- * Error
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Error(..),
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-- * Transaction
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T,
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-- ** Execution
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-- |
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-- Functions for execution of transactions.
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-- They determine the transactional locking strategy of the database.
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read,
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write,
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admin,
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-- ** Statement Quasi-Quote
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q,
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-- * Results Stream
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ResultsStream,
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)
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where
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import HighSQL.API as API
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import HighSQL.QQ as QQ
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@ -1,279 +0,0 @@
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module HighSQL.API where
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import HighSQL.Prelude hiding (read, Read, write, Write, Error)
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import qualified Data.Pool as Pool
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import qualified HighSQL.CompositionT as CompositionT
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import qualified HighSQL.Backend as Backend
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import qualified HighSQL.Conversion as Conversion
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import qualified ListT
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-- * Pool
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-------------------------
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-- |
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-- A pool of connections to the database.
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newtype Pool =
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Pool (Pool.Pool Backend.Connection)
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-- |
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-- Pool initization settings.
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data Settings =
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Settings {
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-- |
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-- The number of stripes (distinct sub-pools) to maintain.
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-- The smallest acceptable value is 1.
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striping1 :: Word32,
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-- |
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-- The maximum number of connections to keep open per a pool stripe.
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-- The smallest acceptable value is 1.
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-- Requests for connections will block if this limit is reached
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-- on a single stripe,
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-- even if other stripes have idle connections available.
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striping2 :: Word32,
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-- |
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-- The amount of time for which an unused connection is kept open.
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-- The smallest acceptable value is 0.5 seconds.
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connectionTimeout :: NominalDiffTime
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}
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-- |
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-- Initialize a pool given a backend and settings
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-- and run an IO computation with it,
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-- while automating the resource management.
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withPool :: Backend.Backend -> Settings -> (Pool -> IO a) -> IO a
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withPool b s =
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bracket acquire release
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where
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acquire =
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do
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pool <-
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Pool.createPool
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(Backend.connect b) (Backend.disconnect) (striping1 s)
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(connectionTimeout s) (striping2 s)
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return (Pool pool)
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release (Pool pool) =
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Pool.purgePool pool
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-- * Error
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-------------------------
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-- |
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-- The only exception type that this API can raise.
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data Error =
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-- |
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-- Cannot connect to a server
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-- or the connection got interrupted.
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ConnectionError Text |
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-- |
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-- Attempt to parse a statement execution result into an incompatible type.
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-- Indicates either a mismatching schema or an incorrect query.
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ResultParsingError [Backend.Value] TypeRep |
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-- |
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-- A free-form backend-specific exception.
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BackendError SomeException
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deriving (Show, Typeable)
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instance Exception Error
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-- * Transaction
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-------------------------
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-- |
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-- A transaction with a level @l@,
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-- running on an anonymous state-thread @s@
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-- and gaining a result @r@.
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newtype T l s r =
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T (CompositionT.T (ReaderT Backend.Connection IO) r)
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deriving (Functor, Applicative, Monad)
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-- |
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-- Execute a transaction in a write mode (if 'True') using a connections pool.
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--
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-- * Automatically determines,
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-- whether it's actually a transaction or just a single action
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-- and executes accordingly.
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--
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-- * Automatically retries the transaction in case of a
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-- 'Backend.TransactionError' exception.
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--
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-- * Rethrows all the other exceptions after wrapping them in 'Error'.
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transaction :: Bool -> Pool -> (forall s. T l s r) -> IO r
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transaction w (Pool p) (T t) =
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do
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e <-
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try $ Pool.withResource p $
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\c ->
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case CompositionT.run t of
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(False, r) ->
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runReaderT r c
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(True, r) ->
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retry
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where
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retry =
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do
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Backend.beginTransaction c w
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e <- try $ runReaderT r c
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case e of
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Left (Backend.TransactionError) ->
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do
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Backend.finishTransaction c False
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retry
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Left e ->
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do
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Backend.finishTransaction c False
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throwIO e
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Right r ->
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do
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Backend.finishTransaction c True
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return r
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case e of
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Left (Backend.ConnectionError t) ->
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throwIO (ConnectionError t)
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Left (Backend.BackendError e) ->
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throwIO (BackendError e)
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Left (Backend.TransactionError) ->
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$bug "Unexpected TransactionError"
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Right r ->
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return r
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-- ** Levels
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-------------------------
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data Read
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-- |
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-- Execute a transaction on a connections pool.
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--
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-- Requires minimal locking from the database,
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-- however you can only execute the \"SELECT\" statements in it.
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-- The API ensures of that on the type-level.
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read :: Pool -> (forall s. T Read s r) -> IO r
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read = transaction False
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data Write
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-- |
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-- Execute a transaction on a connections pool.
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--
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-- Allows to execute the \"SELECT\", \"UPDATE\", \"INSERT\"
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-- and \"DELETE\" statements.
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-- However, compared to 'read', this transaction requires the database to choose
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-- a more resource-demanding locking strategy.
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write :: Pool -> (forall s. T Write s r) -> IO r
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write = transaction True
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data Admin
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-- |
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-- Execute a transaction on a connections pool.
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--
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-- Same as 'write', but allows you to perform any kind of statements,
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-- including \"CREATE\", \"DROP\" and \"ALTER\".
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admin :: Pool -> (forall s. T Admin s r) -> IO r
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admin = transaction True
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-- ** Privileges
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-------------------------
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-- |
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-- \"SELECT\"
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class SelectPrivilege l where
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-- |
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-- Produce a results stream from a statement.
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select ::
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forall s r.
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(Conversion.Row r, Typeable r) => Statement -> ResultsStream s (T l s) r
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select (Statement bs vl) =
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do
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(w, s) <-
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lift $ T $ lift $ do
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Backend.Connection {..} <- ask
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liftIO $ do
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ps <- prepare bs
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executeStreaming ps vl Nothing
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l <- ResultsStream $ hoist (T . liftIO) $ replicateM w s
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maybe (throwParsingError l (typeOf (undefined :: r))) return $ Conversion.fromRow l
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where
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throwParsingError vl t =
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ResultsStream $ lift $ T $ liftIO $ throwIO $ ResultParsingError vl t
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instance SelectPrivilege Read
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instance SelectPrivilege Write
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instance SelectPrivilege Admin
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-- |
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-- \"UPDATE\", \"INSERT\", \"DELETE\"
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class UpdatePrivilege l where
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-- |
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-- Execute and count the amount of affected rows.
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update :: Statement -> T l s Integer
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update (Statement bs vl) =
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T $ do
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Backend.Connection {..} <- lift $ ask
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liftIO $ do
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ps <- prepare bs
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executeCountingEffects ps vl
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-- |
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-- Execute and return the possibly auto-incremented number.
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insert :: Statement -> T l s (Maybe Integer)
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insert (Statement bs vl) =
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T $ do
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Backend.Connection {..} <- lift $ ask
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liftIO $ do
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ps <- prepare bs
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executeIncrementing ps vl
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instance UpdatePrivilege Write
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instance UpdatePrivilege Admin
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-- |
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-- \"CREATE\", \"ALTER\", \"DROP\", \"TRUNCATE\"
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class CreatePrivilege l where
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create :: Statement -> T l s ()
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create (Statement bs vl) =
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T $ do
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Backend.Connection {..} <- lift $ ask
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liftIO $ do
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ps <- prepare bs
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execute ps vl
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instance CreatePrivilege Admin
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-- * Statement
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-------------------------
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data Statement =
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Statement !ByteString ![Backend.Value]
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deriving (Show)
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-- * Results Stream
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-------------------------
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-- |
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-- A stream of results,
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-- which fetches only those that you reach.
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--
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-- It is implemented as a wrapper around 'ListT.ListT',
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-- hence all the utility functions of the list transformer API
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-- are applicable to this type.
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--
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-- It uses the same trick as 'ST' to become impossible to be run outside of
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-- its transaction.
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-- Hence you can only access it while remaining in a transaction,
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-- and when the transaction finishes it safely gets automatically released.
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newtype ResultsStream s m r =
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ResultsStream (ListT.ListT m r)
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deriving (Functor, Applicative, Alternative, Monad, MonadTrans, MonadPlus,
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Monoid, ListT.ListMonad, ListT.ListTrans)
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@ -1,40 +0,0 @@
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module HighSQL.CompositionT where
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import HighSQL.Prelude
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-- |
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-- A monad transformer,
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-- which serves a purpose of detecting composition of the inner monad.
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data T m r =
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T Bool (m r)
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-- |
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-- Unwrap into a boolean signifying whether the base monad is a composition and
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-- the base monad itself.
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run :: T m r -> (Bool, m r)
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run (T c m) = (c, m)
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instance Monad m => Monad (T m) where
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return a =
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T False (return a)
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(>>=) (T _ m) k =
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T True (m >>= \a -> case k a of T _ m' -> m')
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instance Functor f => Functor (T f) where
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fmap f (T c m) = T c (fmap f m)
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instance Applicative f => Applicative (T f) where
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pure a =
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T False (pure a)
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(<*>) (T _ a) (T _ b) =
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T True (a <*> b)
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instance MonadTrans T where
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lift m =
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T False m
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instance MonadIO m => MonadIO (T m) where
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liftIO io =
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T False (liftIO io)
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@ -1,139 +0,0 @@
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-- |
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-- An open API for implementation of specific backend drivers.
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module HighSQL.Conversion where
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import HighSQL.Prelude
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import Language.Haskell.TH
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import qualified Data.Text as Text
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import qualified HighSQL.Backend as Backend
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-- * Value
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-------------------------
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class Value a where
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toValue :: a -> Backend.Value
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fromValue :: Backend.Value -> Maybe a
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-- Generate standard instances using Template Haskell:
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let
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inst :: Name -> Dec
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inst t =
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InstanceD [] (AppT (ConT ''Value) (ConT t)) [d1, d2]
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where
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c =
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mkName $ "Backend." ++ nameBase t
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d1 =
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FunD 'toValue [Clause [] (NormalB (ConE c)) []]
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d2 =
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FunD 'fromValue [c1, c2]
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where
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c1 =
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Clause [p] (NormalB e) []
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where
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p = ConP c [VarP v]
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v = mkName "a"
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e = AppE (ConE 'Just) (VarE v)
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c2 =
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Clause [WildP] (NormalB (ConE 'Nothing)) []
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in
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mapM (return . inst)
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[''NominalDiffTime, ''UTCTime, ''ZonedTime, ''TimeOfDay, ''LocalTime,
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''Day, ''Rational, ''Double, ''Bool, ''Char, ''Integer, ''Int64, ''Int32,
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''Word64, ''Word32, ''ByteString, ''Text]
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instance Value String where
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toValue = Backend.Text . Text.pack
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fromValue = \case Backend.Text a -> Just (Text.unpack a); _ -> Nothing
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instance Value Word where
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toValue = Backend.Word64 . fromIntegral
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fromValue = \case Backend.Word64 a -> Just (fromIntegral a); _ -> Nothing
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instance Value Int where
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toValue = Backend.Int64 . fromIntegral
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fromValue = \case Backend.Int64 a -> Just (fromIntegral a); _ -> Nothing
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instance Value a => Value (Maybe a) where
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toValue = Backend.Maybe . fmap toValue
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fromValue = \case Backend.Maybe a -> traverse fromValue a; _ -> Nothing
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-- * Row
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-------------------------
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class Row r where
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fromRow :: [Backend.Value] -> Maybe r
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-- Generate tuple instaces using Template Haskell:
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let
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inst :: Int -> Dec
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inst arity =
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InstanceD constraints head [fromRowDec]
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where
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varNames =
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[1 .. arity] >>= \i -> return (mkName ('_' : show i))
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varTypes =
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map VarT varNames
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constraints =
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map (ClassP ''Value . pure) varTypes
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head =
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AppT (ConT ''Row) (foldl AppT (TupleT arity) varTypes)
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fromRowDec =
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FunD 'fromRow [c1, c2]
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where
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c1 =
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Clause [ListP (map VarP varNames)] (NormalB e) []
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where
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e =
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foldQueue queue
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where
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con = ConE (tupleDataName arity)
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queue =
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(con :) $
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(VarE '(<$>) :) $
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intersperse (VarE '(<*>)) $
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map (AppE (VarE 'fromValue) . VarE) varNames
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foldQueue =
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\case
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e : o : t -> UInfixE e o (foldQueue t)
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e : [] -> e
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_ -> $bug "Unexpected queue size"
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c2 =
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Clause [WildP] (NormalB (ConE 'Nothing)) []
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in
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mapM (return . inst) [2 .. 24]
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|
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-- Generate single-type instaces using Template Haskell:
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let
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inst :: Name -> Dec
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inst n =
|
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InstanceD [] (AppT (ConT ''Row) (ConT n)) [fromRowDec]
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where
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fromRowDec =
|
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FunD 'fromRow [c1, c2]
|
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where
|
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c1 =
|
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Clause [ListP [VarP v]] (NormalB e) []
|
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where
|
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v = mkName "a"
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e = AppE (VarE 'fromValue) (VarE v)
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c2 =
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Clause [WildP] (NormalB (ConE 'Nothing)) []
|
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in
|
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mapM (return . inst)
|
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[''NominalDiffTime, ''UTCTime, ''ZonedTime, ''TimeOfDay, ''LocalTime,
|
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''Day, ''Rational, ''Double, ''Bool, ''Char, ''Integer, ''Int64,
|
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''Int32, ''Word64, ''Word32, ''ByteString, ''Text]
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instance Row () where
|
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fromRow = \case [] -> Just (); _ -> Nothing
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|
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instance Row String where
|
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fromRow = fmap Text.unpack . fromRow
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|
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instance Row Word where
|
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fromRow = fmap (fromIntegral :: Word64 -> Word) . fromRow
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|
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instance Row Int where
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fromRow = fmap (fromIntegral :: Int64 -> Int) . fromRow
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@ -1,104 +0,0 @@
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module HighSQL.QQ where
|
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|
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import HighSQL.Prelude
|
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import Language.Haskell.TH
|
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import Language.Haskell.TH.Quote
|
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import qualified HighSQL.QQ.Parser as Parser
|
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import qualified HighSQL.API as API
|
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import qualified HighSQL.Backend as Backend
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import qualified HighSQL.Conversion as Conversion
|
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|
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|
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-- |
|
||||
-- Produces a lambda-expression,
|
||||
-- which takes as many parameters as there are placeholders in the statement
|
||||
-- and, depending on the statement kind, results in one of the following types:
|
||||
--
|
||||
-- [@SELECT@]
|
||||
--
|
||||
-- A stream of results, with 'API.T' as the inner monad:
|
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--
|
||||
-- @'API.ResultsStream' s ('API.T' l s) r@
|
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--
|
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-- [@INSERT@]
|
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--
|
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-- A transaction,
|
||||
-- which returns the possibly auto-incremented value
|
||||
-- (of the @id@ column typically):
|
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--
|
||||
-- @'API.T' l s (Maybe Integer)@
|
||||
--
|
||||
-- [@UPDATE, DELETE@]
|
||||
--
|
||||
-- A transaction,
|
||||
-- which returns the amount of affected rows:
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||||
--
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||||
-- @'API.T' l s Integer@
|
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--
|
||||
-- [@CREATE, ALTER, DROP, TRUNCATE@]
|
||||
--
|
||||
-- A unit transaction:
|
||||
--
|
||||
-- @'API.T' l s ()@
|
||||
--
|
||||
-- Example:
|
||||
--
|
||||
-- >write session $ do
|
||||
-- > artistIDMaybe <- ListT.head $ [q| SELECT id FROM artists WHERE name = ? |] "Metallica"
|
||||
-- > userIDMaybe <- ListT.head $ [q| SELECT id FROM users WHERE name = ? |] "Nikita Volkov"
|
||||
-- > forM_ ((,) <$> artistIDMaybe <*> userIDMaybe) $ \(artistID, userID) ->
|
||||
-- > [q| INSERT INTO artists_fans (artist_id, user_id) VALUES (?, ?) |] artistID userID
|
||||
--
|
||||
-- Of course, the same thing can be implemented a bit smarter:
|
||||
--
|
||||
-- >write session $ sequence_ $ ListT.head $ do
|
||||
-- > artistID <- [q| SELECT id FROM artists WHERE name = ? |] "Metallica"
|
||||
-- > userID <- [q| SELECT id FROM users WHERE name = ? |] "Nikita Volkov"
|
||||
-- > return $ [q| INSERT INTO artists_fans (artist_id, user_id) VALUES (?, ?) |] artistID userID
|
||||
--
|
||||
-- In both examples above we execute a 'write' transaction,
|
||||
-- in which we query two tables and insert a row into a third one.
|
||||
q :: QuasiQuoter
|
||||
q =
|
||||
QuasiQuoter
|
||||
parseExp
|
||||
(const $ fail "Pattern context is not supported")
|
||||
(const $ fail "Type context is not supported")
|
||||
(const $ fail "Declaration context is not supported")
|
||||
|
||||
|
||||
parseExp :: String -> Q Exp
|
||||
parseExp s =
|
||||
do
|
||||
(k, n) <-
|
||||
either (fail . (showString "Parsing failure: ")) return (Parser.parse (fromString s))
|
||||
return $ fmapLamE (AppE (VarE (conName k))) (statementF s n)
|
||||
where
|
||||
conName =
|
||||
\case
|
||||
Parser.Select -> 'API.select
|
||||
Parser.Update -> 'API.update
|
||||
Parser.Insert -> 'API.insert
|
||||
Parser.Delete -> 'API.update
|
||||
Parser.Create -> 'API.create
|
||||
Parser.Alter -> 'API.create
|
||||
Parser.Drop -> 'API.create
|
||||
Parser.Truncate -> 'API.create
|
||||
|
||||
-- |
|
||||
-- An expression of an arbitrary arg-length function,
|
||||
-- which produces a "API.Statement".
|
||||
statementF :: String -> Int -> Exp
|
||||
statementF s n =
|
||||
LamE pats exp
|
||||
where
|
||||
vars = map (mkName . ('_' :) . show) [1 .. n]
|
||||
pats = map VarP vars
|
||||
exp = AppE (AppE (ConE 'API.Statement) (LitE (StringL s))) (ListE exps)
|
||||
where
|
||||
exps = map (AppE (VarE 'Conversion.toValue) . VarE) vars
|
||||
|
||||
fmapLamE :: (Exp -> Exp) -> Exp -> Exp
|
||||
fmapLamE f =
|
||||
\case
|
||||
LamE pats exp -> LamE pats (f exp)
|
||||
Loading…
Reference in New Issue
Block a user