mirror of https://github.com/voidlizard/hbs2
63 lines
1.5 KiB
Haskell
63 lines
1.5 KiB
Haskell
module HBS2.Polling where
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import HBS2.Prelude.Plated
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import Data.Heap (Entry(..))
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import Data.Heap qualified as Heap
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import Data.Time.Clock
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import Data.HashMap.Strict qualified as HashMap
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import Lens.Micro.Platform
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import Data.Function
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data Polling =
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Polling
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{ waitBefore :: NominalDiffTime
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, waitOnEmpty :: NominalDiffTime
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}
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polling :: forall a m . (MonadIO m, Hashable a)
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=> Polling
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-> m [(a, NominalDiffTime)]
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-> (a -> m ())
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-> m ()
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polling o listEntries action = do
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let tsMin = toTimeSpec (TimeoutSec 0.01)
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-- FIXME: might-be-concurrent
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pause (TimeoutNDT (waitBefore o))
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now0 <- getTimeCoarse
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refs0 <- listEntries <&> fmap (set _2 now0) <&> HashMap.fromList
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fix (\next mon -> do
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now <- getTimeCoarse
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refs <- listEntries <&> HashMap.fromList
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let mon' = mon `HashMap.union`
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HashMap.fromList [ (e, now + toTimeSpec (TimeoutNDT t))
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| (e, t) <- HashMap.toList refs
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]
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let q = Heap.fromList [ Entry t e
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| (e, t) <- HashMap.toList mon'
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]
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case Heap.uncons q of
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Just (Entry t r, _) | t <= now -> do
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action r
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next (HashMap.delete r mon')
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Just (Entry t _, _) | otherwise -> do
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pause (max (TimeoutTS tsMin) (TimeoutTS (t - now)))
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next mon'
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Nothing -> do
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pause (TimeoutNDT (waitOnEmpty o))
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next mon'
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) refs0
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