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Diffstat (limited to 'src/Plugins/BufferedPipeReader.hs')
-rw-r--r-- | src/Plugins/BufferedPipeReader.hs | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/src/Plugins/BufferedPipeReader.hs b/src/Plugins/BufferedPipeReader.hs new file mode 100644 index 0000000..be6a652 --- /dev/null +++ b/src/Plugins/BufferedPipeReader.hs @@ -0,0 +1,83 @@ +----------------------------------------------------------------------------- +-- | +-- Module : Plugins.BufferedPipeReader +-- Copyright : (c) Jochen Keil +-- License : BSD-style (see LICENSE) +-- +-- Maintainer : Jochen Keil <jochen dot keil at gmail dot com> +-- Stability : unstable +-- Portability : unportable +-- +-- A plugin for reading (temporarily) from named pipes with reset +-- +----------------------------------------------------------------------------- + +module Plugins.BufferedPipeReader where + +import Control.Monad(forM_, when) +import Control.Concurrent +import Control.Concurrent.STM +import System.IO +import System.IO.Unsafe(unsafePerformIO) + +import Plugins +import Signal + +data BufferedPipeReader = BufferedPipeReader String [(Int, Bool, String)] + deriving (Read, Show) + +signal :: MVar SignalType +signal = unsafePerformIO newEmptyMVar + +instance Exec BufferedPipeReader where + alias ( BufferedPipeReader a _ ) = a + + trigger br@( BufferedPipeReader _ _ ) sh = + takeMVar signal >>= sh . Just >> trigger br sh + + start ( BufferedPipeReader _ ps ) cb = do + + (chan, str, rst) <- initV + forM_ ps $ \p -> forkIO $ reader p chan + writer chan str rst + + where + initV :: IO ( TChan (Int, Bool, String), TMVar String, TVar Bool ) + initV = atomically $ do + tc <- newTChan + ts <- newEmptyTMVar + tb <- newTVar False + return (tc, ts, tb) + + reader :: (Int, Bool, FilePath) -> TChan (Int, Bool, String) -> IO () + reader p@(to, tg, fp) tc = do + openFile fp ReadWriteMode >>= hGetLineSafe >>= \dt -> + atomically $ writeTChan tc (to, tg, dt) + reader p tc + + writer :: TChan (Int, Bool, String) -> TMVar String -> TVar Bool -> IO () + writer tc ts otb = do + (to, tg, dt, ntb) <- update + cb dt + when tg $ putMVar signal Reveal + when (to /= 0) $ sfork $ reset to tg ts ntb + writer tc ts ntb + + where + sfork :: IO () -> IO () + sfork f = forkIO f >> return () + + update :: IO (Int, Bool, String, TVar Bool) + update = atomically $ do + (to, tg, dt) <- readTChan tc + when (to == 0) $ tryPutTMVar ts dt >> return () + writeTVar otb False + tb <- newTVar True + return (to, tg, dt, tb) + + reset :: Int -> Bool -> TMVar String -> TVar Bool -> IO () + reset to tg ts tb = do + threadDelay ( to * 100 * 1000 ) + readTVarIO tb >>= \b -> when b $ do + when tg $ putMVar signal Hide + atomically (tryTakeTMVar ts) >>= maybe (return ()) cb |