urbit/pkg/hs/urbit-king/lib/Urbit/Vere/Behn.hs

49 lines
1.2 KiB
Haskell

{-|
Behn: Timer Driver
-}
module Urbit.Vere.Behn (behn) where
import Urbit.Arvo hiding (Behn)
import Urbit.Prelude
import Urbit.Vere.Pier.Types
import Urbit.Time (Wen)
import Urbit.Timer (Timer)
import qualified Urbit.Time as Time
import qualified Urbit.Timer as Timer
-- Behn Stuff ------------------------------------------------------------------
bornEv :: KingId -> Ev
bornEv king = EvBlip $ BlipEvBehn $ BehnEvBorn (king, ()) ()
wakeEv :: Ev
wakeEv = EvBlip $ BlipEvBehn $ BehnEvWake () ()
sysTime = view Time.systemTime
behn :: KingId -> QueueEv -> ([Ev], Acquire (EffCb e BehnEf))
behn king enqueueEv =
(initialEvents, runBehn)
where
initialEvents = [bornEv king]
runBehn :: Acquire (EffCb e BehnEf)
runBehn = do
tim <- mkAcquire Timer.init Timer.stop
pure (handleEf tim)
handleEf :: Timer -> BehnEf -> RIO e ()
handleEf b = io . \case
BehnEfVoid v -> absurd v
BehnEfDoze (i, ()) mWen -> do
when (i == king) (doze b mWen)
doze :: Timer -> Maybe Wen -> IO ()
doze tim = \case
Nothing -> Timer.stop tim
Just t -> Timer.start tim (sysTime t) $ atomically (enqueueEv wakeEv)