36d73b0017
Including support for unbound thread sleeping. Haskell's max thread sleep is 37 minutes, due to maxBound Int!
42 lines
1.2 KiB
Haskell
42 lines
1.2 KiB
Haskell
{- thread scheduling
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-
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- Copyright 2012 Joey Hess <joey@kitenet.net>
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- Copyright 2011 Bas van Dijk & Roel van Dijk
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Utility.ThreadScheduler where
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import Common
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import Control.Concurrent
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newtype Seconds = Seconds { fromSeconds :: Int }
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deriving (Eq, Ord, Show)
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{- Runs an action repeatedly forever, sleeping at least the specified number
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- of seconds in between. -}
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runEvery :: Seconds -> IO a -> IO a
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runEvery n a = forever $ do
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threadDelaySeconds n
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a
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threadDelaySeconds :: Seconds -> IO ()
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threadDelaySeconds (Seconds n) = unboundDelay (fromIntegral n * oneSecond)
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where
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oneSecond = 1000000 -- microseconds
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{- Like threadDelay, but not bounded by an Int.
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-
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- There is no guarantee that the thread will be rescheduled promptly when the
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- delay has expired, but the thread will never continue to run earlier than
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- specified.
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-
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- Taken from the unbounded-delay package to avoid a dependency for 4 lines
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- of code.
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-}
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unboundDelay :: Integer -> IO ()
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unboundDelay time = do
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let maxWait = min time $ toInteger (maxBound :: Int)
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threadDelay $ fromInteger maxWait
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when (maxWait /= time) $ unboundDelay (time - maxWait)
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