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|
----------------------------------------------------------------------
-- |
-- Module : GF.System.Signal
-- Maintainer : Bjorn Bringert
-- Stability : (stability)
-- Portability : (portability)
--
-- > CVS $Date: 2005/11/07 20:15:05 $
-- > CVS $Author: bringert $
-- > CVS $Revision: 1.1 $
--
-- Allows SIGINT (Ctrl-C) to interrupt computations.
-----------------------------------------------------------------------------
module GF.System.Signal where
import Control.Concurrent (myThreadId, killThread)
import Control.Exception (Exception,catch)
import Prelude hiding (catch)
import System.IO
import System.Posix.Signals
-- | Run an IO action, and allow it to be interrupted
-- by a SIGINT to the current process. Returns
-- an exception if the process did not complete
-- normally.
-- NOTES:
-- * This will replace any existing SIGINT
-- handlers, and after the computation has completed
-- the default handler will be installed for SIGINT.
-- * If the IO action is lazy (e.g. using readFile,
-- unsafeInterleaveIO etc.) the lazy computation will
-- not be interruptible, as it will be performed
-- after the signal handler has been removed.
runInterruptibly :: IO a -> IO (Either Exception a)
runInterruptibly a = do t <- myThreadId
installHandler sigINT (Catch (killThread t)) Nothing
x <- p `catch` h
installHandler sigINT Default Nothing
return x
where p = a >>= \x -> return $! Right $! x
h e = return $ Left e
-- | Like 'runInterruptibly', but always returns (), whether
-- the computation fails or not.
runInterruptibly_ :: IO () -> IO ()
runInterruptibly_ = fmap (either (const ()) id) . runInterruptibly
|
