-- #hide
module GHC.TopHandler (
- runMainIO, runIO, runNonIO, reportStackOverflow, reportError
+ runMainIO, runIO, runIOFastExit, runNonIO, reportStackOverflow, reportError
) where
import Prelude
import System.IO
import Control.Exception
+import Foreign.C ( CInt )
import GHC.IOBase
import GHC.Exception
import GHC.Prim (unsafeCoerce#)
runIO :: IO a -> IO a
runIO main = catchException main topHandler
+-- | Like 'runIO', but in the event of an exception that causes an exit,
+-- we don't shut down the system cleanly, we just exit. This is
+-- useful in some cases, because the safe exit version will give other
+-- threads a chance to clean up first, which might shut down the
+-- system in a different way. For example, try
+--
+-- main = forkIO (runIO (exitWith (ExitFailure 1))) >> threadDelay 10000
+--
+-- This will sometimes exit with "interrupted" and code 0, because the
+-- main thread is given a chance to shut down when the child thread calls
+-- safeExit. There is a race to shut down between the main and child threads.
+--
+runIOFastExit :: IO a -> IO a
+runIOFastExit main = catchException main topHandlerFastExit
+ -- NB. this is used by the testsuite driver
+
-- | The same as 'runIO', but for non-IO computations. Used for
-- wrapping @foreign export@ and @foreign import \"wrapper\"@ when these
-- are used to export Haskell functions with non-IO types.
runNonIO a = catchException (a `seq` return a) topHandler
topHandler :: Exception -> IO a
-topHandler err = catchException (real_handler err) topHandler
+topHandler err = catchException (real_handler safeExit err) topHandler
+
+topHandlerFastExit :: Exception -> IO a
+topHandlerFastExit err =
+ catchException (real_handler fastExit err) topHandlerFastExit
-- Make sure we handle errors while reporting the error!
-- (e.g. evaluating the string passed to 'error' might generate
-- another error, etc.)
--
-real_handler :: Exception -> IO a
-real_handler ex =
+real_handler :: (Int -> IO a) -> Exception -> IO a
+real_handler exit exn =
cleanUp >>
- case ex of
+ case exn of
AsyncException StackOverflow -> do
reportStackOverflow
- safeExit 2
+ exit 2
-- only the main thread gets ExitException exceptions
- ExitException ExitSuccess -> safeExit 0
- ExitException (ExitFailure n) -> safeExit n
+ ExitException ExitSuccess -> exit 0
+ ExitException (ExitFailure n) -> exit n
other -> do
reportError other
- safeExit 1
+ exit 1
reportStackOverflow :: IO a
-- we have to use unsafeCoerce# to get the 'IO a' result type, since the
-- compiler doesn't let us declare that as the result type of a foreign export.
safeExit :: Int -> IO a
-safeExit r = unsafeCoerce# (shutdownHaskellAndExit r)
+safeExit r = unsafeCoerce# (shutdownHaskellAndExit $ fromIntegral r)
-- NOTE: shutdownHaskellAndExit must be called "safe", because it *can*
-- re-enter Haskell land through finalizers.
-foreign import ccall "shutdownHaskellAndExit"
- shutdownHaskellAndExit :: Int -> IO ()
+foreign import ccall "Rts.h shutdownHaskellAndExit"
+ shutdownHaskellAndExit :: CInt -> IO ()
+
+fastExit :: Int -> IO a
+fastExit r = unsafeCoerce# (stg_exit (fromIntegral r))
+
+foreign import ccall "Rts.h stg_exit"
+ stg_exit :: CInt -> IO ()
\end{code}