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- {-# LANGUAGE OverloadedStrings #-}
- module Walrus.Backend (
- Backend(..),
- BackendHandler,
- module Walrus.Backend.Metadata,
- parseBackend,
- callBackend,
- runBackendOnce
- ) where
- import qualified Data.Attoparsec.ByteString.Char8 as A
- import qualified Data.Attoparsec.ByteString.Lazy as LA
- import Data.Attoparsec.ByteString.Char8.Extras
- import qualified Data.ByteString.Lazy as LBS
- import qualified Data.Char as C
- import Data.Textual.Class
- import Control.Monad.IO.Class
- import Control.Lens
- import Walrus.Backend.Metadata
- import Network
- import System.IO
- import System.IO.Uniform
- import System.IO.Uniform.Streamline
- --import System.IO.Uniform.HandlePair as HP
- --import System.IO.Uniform.Network as Net
- import qualified System.Process as P
- data Backend = TCPBackend String Int |
- ExecBackend String [String] deriving (Show, Read, Ord, Eq)
- type BackendHandler = Metadata -> LBS.ByteString -> IO (Either String (Metadata, LBS.ByteString))
- parseBackend :: A.Parser Backend
- parseBackend = A.choice [
- do
- tp "tcp"
- h <- tillSpace
- p <- A.decimal
- return $ TCPBackend h p,
- do
- tp "exec"
- f <- qStr
- skipHorizontalSpace
- pp <- parseParameters
- return $ ExecBackend f pp
- ]
- where
- tp t = do
- skipHorizontalSpace
- A.stringCI t
- skipHorizontalSpace
- tillSpace :: A.Parser String
- tillSpace = fromTextual <$> A.takeTill C.isSpace
- parseParameters :: A.Parser [String]
- parseParameters = do
- p <- qStr
- skipHorizontalSpace
- if null p then return [] else do
- pp <- parseParameters
- return $ p : pp
- qStr :: A.Parser String
- qStr = fromTextual <$> quotedString '\\' " " ""
- callBackend :: Backend -> (Metadata, LBS.ByteString) -> IO (Either String (Metadata, LBS.ByteString))
- callBackend b (m, qdt) = do
- let rm = renderMetadata m
- edt' <- intBk b $ LBS.concat [
- fromTextual rm,
- qdt]
- case LA.parse repParse edt' of
- LA.Fail _ _ e -> return $ Left e
- LA.Done edt m' -> return $ Right (m', edt)
- where
- intBk :: Backend -> LBS.ByteString -> IO LBS.ByteString
- intBk (TCPBackend h p) = runTcp h p
- intBk (ExecBackend f aa) = runExec f aa
- repParse = parseMetadata
- runBackendOnce :: UniformIO u => u -> BackendHandler -> IO (Either String ())
- runBackendOnce u f = withTarget u $ do
- m' <- runAttoparsec parseMetadata
- case m' of
- Left e -> return . Left . show $ e
- Right m -> do
- dt <- recieveN' $ m^.dataSize
- r <- liftIO $ f m dt
- case r of
- Left e -> return . Left $ e
- Right (mo, dto) -> do
- send $ renderMetadata mo
- send' dto
- return . Right $ ()
- runTcp :: String -> Int -> LBS.ByteString -> IO LBS.ByteString
- runTcp host port dt = do
- h <- connectTo host (PortNumber . fromIntegral $ port)
- bkgTrans h dt
- bkgTrans :: Handle -> LBS.ByteString -> IO LBS.ByteString
- bkgTrans h dt = do
- hSetNewlineMode h noNewlineTranslation
- LBS.hPut h dt
- hFlush h
- LBS.hGetContents h
- runExec :: String -> [String] -> LBS.ByteString -> IO LBS.ByteString
- runExec f args dt = do
- (Just i, Just o, _, _) <- P.createProcess (
- (P.proc f args){P.std_in=P.CreatePipe}{
- P.std_out=P.CreatePipe}{P.std_err=P.Inherit}
- )
- mapM_ (`hSetNewlineMode` noNewlineTranslation) [i, o]
- LBS.hPut i dt
- hFlush i
- LBS.hGetContents o
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