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{-# LANGUAGE CPP #-}
{-# LANGUAGE BangPatterns #-}
-- Test that threadDelay actually sleeps for (at least) as long as we
-- ask it
-- On windows the resolution of getCurrentTime is far too low to avoid
-- false positives for this test. So we use the internal method from
-- GHC.Event.Windows.Clock instead.
module Main (main) where
import Control.Concurrent
import Control.Monad
import Data.Time
#if defined(mingw32_HOST_OS)
import GHC.Event.Windows.Clock
#endif
main :: IO ()
main = mapM_ delay (0 : take 7 (iterate (*5) 100))
delay :: Int -> IO ()
delay n = do
#if defined(mingw32_HOST_OS)
!sec_start <- getClock >>= getTime
threadDelay n
!sec_end <- getClock >>= getTime
let diff = sec_end - sec_start
when (diff * 1000000 < fromIntegral n) $ do
putStrLn "threadDelay returned early"
print(sec_start, sec_end, n, diff*1000000)
#else
tS <- getCurrentTime
threadDelay n
tE <- getCurrentTime
let req = fromIntegral n * 10 ^ (6 :: Int)
obs = floor (diffUTCTime tE tS * 10 ^ (12 :: Int))
diff = obs - req
diff' :: Double
diff' = fromIntegral diff / 10 ^ (12 :: Int)
when (obs < req) $ print (tS, tE, req, obs, diff, diff')
#endif
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