X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;ds=sidebyside;f=GHC%2FTopHandler.lhs;h=3c64fc8a0d13b5972cdcc4913599317b2e2d3373;hb=7c0b04fd273621130062418bb764809c79488dd2;hp=5fc32365906dc82230baf6880bffeba0f1cdbebf;hpb=bf49462cfddfa22110a922d0417a5fc887fcf992;p=haskell-directory.git

diff --git a/GHC/TopHandler.lhs b/GHC/TopHandler.lhs
index 5fc3236..3c64fc8 100644
--- a/GHC/TopHandler.lhs
+++ b/GHC/TopHandler.lhs
@@ -14,29 +14,52 @@
 --
 -----------------------------------------------------------------------------
 
+-- #hide
 module GHC.TopHandler (
-   runIO, runNonIO, reportStackOverflow, reportError 
+   runMainIO, runIO, runIOFastExit, runNonIO, reportStackOverflow, reportError
   ) where
 
 import Prelude
 
 import System.IO
+import Control.Exception
 
-import Foreign.C.String
-import Foreign.Ptr
+import Foreign.C	( CInt )
 import GHC.IOBase
 import GHC.Exception
 import GHC.Prim (unsafeCoerce#)
 
--- | 'runIO' is wrapped around @Main.main@ by @TcModule@.  It is also wrapped
--- around every @foreign export@ and @foreign import \"wrapper\"@ to mop up
--- any uncaught exceptions.  Thus, the result of running
--- 'System.Exit.exitWith' in a foreign-exported function is the same as
--- in the main thread: it terminates the program.
+-- | 'runMainIO' is wrapped around 'Main.main' (or whatever main is
+-- called in the program).  It catches otherwise uncaught exceptions,
+-- and also flushes stdout\/stderr before exiting.
+runMainIO :: IO a -> IO a
+runMainIO main = (do a <- main; cleanUp; return a) `catchException` topHandler
+
+-- | 'runIO' is wrapped around every @foreign export@ and @foreign
+-- import \"wrapper\"@ to mop up any uncaught exceptions.  Thus, the
+-- result of running 'System.Exit.exitWith' in a foreign-exported
+-- function is the same as in the main thread: it terminates the
+-- program.
 --
 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.
@@ -45,71 +68,71 @@ runNonIO :: a -> IO a
 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 =
-  case ex of
-	AsyncException StackOverflow -> reportStackOverflow True
+real_handler :: (Int -> IO a) -> Exception -> IO a
+real_handler exit exn =
+  cleanUp >>
+  case exn of
+	AsyncException StackOverflow -> do
+	   reportStackOverflow
+	   exit 2
 
 	-- only the main thread gets ExitException exceptions
-	ExitException ExitSuccess     -> safe_exit 0
-	ExitException (ExitFailure n) -> safe_exit n
-
-	Deadlock    -> reportError True 
-			"no threads to run:  infinite loop or deadlock?"
-  
-	ErrorCall s -> reportError True s
-	other       -> reportError True (showsPrec 0 other "\n")
-
-reportStackOverflow :: Bool -> IO a
-reportStackOverflow bombOut = do
-   (hFlush stdout) `catchException` (\ _ -> return ())
-   callStackOverflowHook
-   if bombOut 
-	then exit 2
-	else return undefined
-
-reportError :: Bool -> String -> IO a
-reportError bombOut str = do
-   (hFlush stdout) `catchException` (\ _ -> return ())
-   withCStringLen str $ \(cstr,len) -> do
-     writeErrString errorHdrHook cstr len
-     if bombOut 
-	then exit 1
-        else return undefined
-
-#ifndef ILX
-foreign import ccall "&ErrorHdrHook" errorHdrHook :: Ptr ()
-#else
-foreign import ccall "ErrorHdrHook" errorHdrHook :: Ptr ()
-#endif
-
-foreign import ccall unsafe "writeErrString__"
-	writeErrString :: Ptr () -> CString -> Int -> IO ()
+	ExitException ExitSuccess     -> exit 0
+	ExitException (ExitFailure n) -> exit n
+
+	other -> do
+	   reportError other
+	   exit 1
+	   
+
+reportStackOverflow :: IO a
+reportStackOverflow = do callStackOverflowHook; return undefined
+
+reportError :: Exception -> IO a
+reportError ex = do
+   handler <- getUncaughtExceptionHandler
+   handler ex
+   return undefined
 
 -- SUP: Are the hooks allowed to re-enter Haskell land?  If so, remove
 -- the unsafe below.
 foreign import ccall unsafe "stackOverflow"
 	callStackOverflowHook :: IO ()
 
-foreign import ccall unsafe "stg_exit"
-	stg_exit :: Int -> IO ()
+-- try to flush stdout/stderr, but don't worry if we fail
+-- (these handles might have errors, and we don't want to go into
+-- an infinite loop).
+cleanUp :: IO ()
+cleanUp = do
+  hFlush stdout `catchException` \_ -> return ()
+  hFlush stderr `catchException` \_ -> return ()
+
+cleanUpAndExit :: Int -> IO a
+cleanUpAndExit r = do cleanUp; safeExit r
 
-exit :: Int -> IO a
-exit r = unsafeCoerce# (stg_exit r)
+-- 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)
 
 -- NOTE: shutdownHaskellAndExit must be called "safe", because it *can*
 -- re-enter Haskell land through finalizers.
-foreign import ccall "shutdownHaskellAndExit" 
+foreign import ccall "Rts.h shutdownHaskellAndExit"
   shutdownHaskellAndExit :: Int -> IO ()
 
--- 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.
-safe_exit :: Int -> IO a
-safe_exit r = unsafeCoerce# (shutdownHaskellAndExit r)
+fastExit :: Int -> IO a
+fastExit r = unsafeCoerce# (stg_exit (fromIntegral r))
+
+foreign import ccall "Rts.h stg_exit"
+  stg_exit :: CInt -> IO ()
 \end{code}