mirror of
https://github.com/alexwl/haskell-code-explorer.git
synced 2024-11-25 23:56:17 +03:00
131 lines
4.3 KiB
Haskell
131 lines
4.3 KiB
Haskell
{-# LANGUAGE CPP #-}
|
|
{-# LANGUAGE OverloadedStrings #-}
|
|
{-# LANGUAGE TypeApplications #-}
|
|
{-# LANGUAGE TypeFamilyDependencies #-}
|
|
{-# LANGUAGE TypeFamilies #-}
|
|
{-# LANGUAGE FlexibleContexts #-}
|
|
{-# LANGUAGE FlexibleInstances #-}
|
|
{-# LANGUAGE TypeSynonymInstances #-}
|
|
{-# LANGUAGE ScopedTypeVariables #-}
|
|
{-# LANGUAGE DeriveGeneric #-}
|
|
{-# LANGUAGE DeriveAnyClass #-}
|
|
{-# LANGUAGE StrictData #-}
|
|
{-# OPTIONS_GHC -Wno-orphans #-}
|
|
|
|
-- | Read-only on-disk key-value store
|
|
|
|
module Store where
|
|
|
|
import Control.DeepSeq (NFData)
|
|
import Control.Monad.IO.Class (liftIO)
|
|
import qualified Control.Monad.State.Strict as S
|
|
import qualified Data.ByteString as BS
|
|
import qualified Data.ByteString.Short as BSS
|
|
import Data.Either (Either)
|
|
import qualified Data.Map.Strict as M
|
|
import Data.Serialize (Serialize, decode, encode, get, put)
|
|
import GHC.Generics (Generic)
|
|
import Prelude hiding (lookup)
|
|
import System.Directory (doesFileExist)
|
|
import System.FilePath ((</>))
|
|
import System.IO (Handle, IOMode(..), hTell, withFile)
|
|
import System.IO.MMap (mmapFileByteString)
|
|
|
|
data Store = Store
|
|
{ index :: M.Map BSS.ShortByteString Location
|
|
, values :: BS.ByteString
|
|
}
|
|
|
|
data Location = Location
|
|
{ offset :: Int
|
|
, length :: Int
|
|
} deriving (Show, Eq, Ord, Generic, NFData)
|
|
|
|
instance Serialize Location
|
|
|
|
#if MIN_VERSION_cereal(0,5,8)
|
|
#else
|
|
instance Serialize BSS.ShortByteString where
|
|
put = put . BSS.fromShort
|
|
get = BSS.toShort <$> get
|
|
#endif
|
|
|
|
class StoreItem item where
|
|
toByteString :: item -> BS.ByteString
|
|
fromByteString :: BS.ByteString -> Either String item
|
|
type KeyArgs item = arg | arg -> item
|
|
itemKey :: KeyArgs item -> BSS.ShortByteString
|
|
|
|
indexFileName :: FilePath
|
|
indexFileName = "index"
|
|
|
|
valuesFileName :: FilePath
|
|
valuesFileName = "values"
|
|
|
|
data ReadMode
|
|
= ReadEntireFile
|
|
| MemoryMapFile
|
|
deriving (Show, Eq)
|
|
|
|
load :: FilePath -> ReadMode -> IO (Either String Store)
|
|
load directoryPath readMode = do
|
|
let valuesFilePath = directoryPath </> valuesFileName
|
|
indexFilePath = directoryPath </> indexFileName
|
|
(valuesFileExists, indexFileExists) <-
|
|
(,) <$> doesFileExist indexFilePath <*> doesFileExist valuesFilePath
|
|
case (valuesFileExists, indexFileExists) of
|
|
(True, True) -> do
|
|
indexFile <- BS.readFile indexFilePath
|
|
valuesFile <-
|
|
case readMode of
|
|
ReadEntireFile -> BS.readFile valuesFilePath
|
|
MemoryMapFile -> mmapFileByteString valuesFilePath Nothing
|
|
let eitherIndex = decode @(M.Map BSS.ShortByteString Location) indexFile
|
|
case eitherIndex of
|
|
Right locMap -> return . Right $ Store {index = locMap, values = valuesFile}
|
|
Left err -> return . Left $ "Error while decoding index : " ++ err
|
|
(False, False) ->
|
|
return . Left $ "Cannot find index and values in " ++ directoryPath
|
|
(True, False) -> return . Left $ "Cannot find index in " ++ directoryPath
|
|
(False, True) -> return . Left $ "Cannot find values in " ++ directoryPath
|
|
|
|
lookup :: (StoreItem item) => KeyArgs item -> Store -> Either String item
|
|
lookup keyArgs = lookupByteString (itemKey keyArgs)
|
|
|
|
lookupByteString ::
|
|
(StoreItem item) => BSS.ShortByteString -> Store -> Either String item
|
|
lookupByteString key store =
|
|
case M.lookup key (index store) of
|
|
Just (Location off len) ->
|
|
fromByteString . BS.take len . BS.drop off $ values store
|
|
Nothing -> Left $ "Cannot find item with key " ++ show key
|
|
|
|
data State =
|
|
State (M.Map BSS.ShortByteString Location)
|
|
Handle
|
|
|
|
add :: (StoreItem item) => item -> KeyArgs item -> S.StateT State IO ()
|
|
add item keyArgs = do
|
|
let bs = toByteString item
|
|
len = BS.length bs
|
|
State locMap handle <- S.get
|
|
off <- liftIO $ fromIntegral <$> hTell handle
|
|
_ <- liftIO $ BS.hPut handle bs
|
|
S.put $ State (M.insert (itemKey keyArgs) (Location off len) locMap) handle
|
|
|
|
createStore ::
|
|
FilePath -> (Handle -> IO (M.Map BSS.ShortByteString Location)) -> IO ()
|
|
createStore directoryPath action =
|
|
withFile (directoryPath </> valuesFileName) WriteMode $ \valuesHandle -> do
|
|
locMap <- action valuesHandle
|
|
BS.writeFile (directoryPath </> indexFileName) (encode locMap)
|
|
|
|
writeValues ::
|
|
Handle
|
|
-> M.Map BSS.ShortByteString Location
|
|
-> S.StateT State IO ()
|
|
-> IO (M.Map BSS.ShortByteString Location)
|
|
writeValues handle locMap action = do
|
|
State locMap' _ <- S.execStateT action (State locMap handle)
|
|
return locMap'
|