> timeout :: Int -> IO a -> IO (Maybe a)
> timeout time action = do
> someMVar <- newEmptyMVar -- MVar is a Maybe
> timeoutThread <- forkIO $ nothingIzer time someMVar
> forkIO $ actionRunner action someMVar timeoutThread
> takeMVar someMVar >>= return
> where
> nothingIzer time mvar = threadDelay time >> putMVar mvar Nothing
> actionRunner action mvar timeoutThread = do
> res <- action
> killThread timeoutThread
> putMVar mvar $ Just res
> main :: IO ()
> main = do
> res <- timeout (5 * 10 ^ 6) (getLine >>= putStrLn)
> case res of
> Nothing -> putStrLn "Timeout"
> Just x -> putStrLn "Success"
On Tue, Mar 23, 2010 at 11:31 AM, Roel van Dijk
<vandijk.roel@gmail.com> wrote:
I tried a few things. First I added another timeout to main, so the
program kills itself after a few seconds.
doit :: IO (Maybe ())
doit = timeout 12000000 $ {- yield >> -} return ()
main :: IO ()
main = do _ <- timeout 5000000 $ forever doit
return ()
This program failed to terminate. But when I compiled -with threaded
and added a yield to doit, it worked (kinda). If the timeout in doit
is not too long, like 200 milliseconds, the program has constant space
usage. But when I increased the timeout in doit to 12 seconds I got a
stack overflow.
I'll investigate further when I have more time.
Regards,
Roel