diff options
Diffstat (limited to 'Utility')
-rw-r--r-- | Utility/CoProcess.hs | 77 |
1 files changed, 60 insertions, 17 deletions
diff --git a/Utility/CoProcess.hs b/Utility/CoProcess.hs index f72850fc5..534229d51 100644 --- a/Utility/CoProcess.hs +++ b/Utility/CoProcess.hs @@ -1,7 +1,7 @@ {- Interface for running a shell command as a coprocess, - sending it queries and getting back results. - - - Copyright 2012 Joey Hess <joey@kitenet.net> + - Copyright 2012-2013 Joey Hess <joey@kitenet.net> - - Licensed under the GNU GPL version 3 or higher. -} @@ -18,29 +18,72 @@ module Utility.CoProcess ( import Common -type CoProcessHandle = (ProcessHandle, Handle, Handle, CreateProcess) +import Control.Concurrent.MVar -start :: FilePath -> [String] -> Maybe [(String, String)] -> IO CoProcessHandle -start command params env = do - (from, to, _err, pid) <- runInteractiveProcess command params Nothing env - return (pid, to, from, proc command params) +type CoProcessHandle = MVar CoProcessState + +data CoProcessState = CoProcessState + { coProcessPid :: ProcessHandle + , coProcessTo :: Handle + , coProcessFrom :: Handle + , coProcessSpec :: CoProcessSpec + } + +data CoProcessSpec = CoProcessSpec + { coProcessRestartable :: Bool + , coProcessCmd :: FilePath + , coProcessParams :: [String] + , coProcessEnv :: Maybe [(String, String)] + } + +start :: Bool -> FilePath -> [String] -> Maybe [(String, String)] -> IO CoProcessHandle +start restartable cmd params env = do + s <- start' $ CoProcessSpec restartable cmd params env + newMVar s + +start' :: CoProcessSpec -> IO CoProcessState +start' s = do + (to, from, _err, pid) <- runInteractiveProcess (coProcessCmd s) (coProcessParams s) Nothing (coProcessEnv s) + return $ CoProcessState pid to from s stop :: CoProcessHandle -> IO () -stop (pid, from, to, p) = do - hClose to - hClose from - forceSuccessProcess p pid +stop ch = do + s <- readMVar ch + hClose $ coProcessTo s + hClose $ coProcessFrom s + let p = proc (coProcessCmd $ coProcessSpec s) (coProcessParams $ coProcessSpec s) + forceSuccessProcess p (coProcessPid s) +{- To handle a restartable process, any IO exception thrown by the send and + - receive actions are assumed to mean communication with the process + - failed, and the failed action is re-run with a new process. -} query :: CoProcessHandle -> (Handle -> IO a) -> (Handle -> IO b) -> IO b -query (_, from, to, _) send receive = do - _ <- send to - hFlush to - receive from +query ch send receive = do + s <- readMVar ch + restartable s (send $ coProcessTo s) $ const $ + restartable s (hFlush $ coProcessTo s) $ const $ + restartable s (receive $ coProcessFrom s) $ + return + where + restartable s a cont + | coProcessRestartable (coProcessSpec s) = + maybe restart cont =<< catchMaybeIO a + | otherwise = cont =<< a + restart = do + s <- takeMVar ch + void $ catchMaybeIO $ do + hClose $ coProcessTo s + hClose $ coProcessFrom s + void $ waitForProcess $ coProcessPid s + s' <- start' (coProcessSpec s) + putMVar ch s' + query ch send receive rawMode :: CoProcessHandle -> IO CoProcessHandle -rawMode ch@(_, from, to, _) = do - raw from - raw to +rawMode ch = do + s <- readMVar ch + raw $ coProcessFrom s + raw $ coProcessTo s return ch where raw h = do |