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module InterruptibleDelay where
import Control.Concurrent
import Control.Monad
import Control.Exception ({-evaluate,-}handle,ErrorCall(..))
import Data.Time.Clock (NominalDiffTime)
type Microseconds = Int
microseconds :: NominalDiffTime -> Microseconds
microseconds d = round $ 1000000 * d
data InterruptibleDelay = InterruptibleDelay
{ delayThread :: MVar ThreadId
}
interruptibleDelay :: IO InterruptibleDelay
interruptibleDelay = do
fmap InterruptibleDelay newEmptyMVar
startDelay :: InterruptibleDelay -> Microseconds -> IO Bool
startDelay d interval = do
thread <- myThreadId
handle (\(ErrorCall _)-> do
debugNoise $ "delay interrupted"
return False) $ do
putMVar (delayThread d) thread
threadDelay interval
void $ takeMVar (delayThread d)
return True
where debugNoise str = return ()
interruptDelay :: InterruptibleDelay -> IO ()
interruptDelay d = do
mthread <- do
tryTakeMVar (delayThread d)
flip (maybe $ return ()) mthread $ \thread -> do
throwTo thread (ErrorCall "Interrupted delay")
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