shrub/pkg/hs/urbit-king/lib/Urbit/Vere/Behn.hs
2020-12-10 18:05:10 -08:00

74 lines
2.0 KiB
Haskell

-- This is required due to the use of 'Void' in a constructor slot in
-- combination with 'deriveNoun', which will generate an unreachable pattern.
{-# OPTIONS_GHC -Wno-overlapping-patterns #-}
{-|
Behn: Timer Driver
-}
module Urbit.Vere.Behn (behn, DriverApi(..), behn') where
import Data.Time.Clock.System (SystemTime)
import Urbit.Arvo
import Urbit.Prelude
import Urbit.Vere.Pier.Types
import Urbit.King.App (HasKingId(..), HasPierEnv(..))
import Urbit.Noun.Time (Wen)
import Urbit.Timer (Timer)
import qualified Urbit.Noun.Time as Time
import qualified Urbit.Timer as Timer
-- Behn Stuff ------------------------------------------------------------------
behn' :: HasPierEnv e => RIO e ([Ev], RAcquire e (DriverApi BehnEf))
behn' = do
env <- ask
pure ([bornEv (fromIntegral (env ^. kingIdL))], runDriver env)
where
runDriver env = do
ventQ :: TQueue EvErr <- newTQueueIO
diOnEffect <- liftAcquire (behn env (writeTQueue ventQ))
let diEventSource = fmap RRWork <$> tryReadTQueue ventQ
pure (DriverApi {..})
bornEv :: KingId -> Ev
bornEv king = EvBlip $ BlipEvBehn $ BehnEvBorn (king, ()) ()
wakeEv :: Ev
wakeEv = EvBlip $ BlipEvBehn $ BehnEvWake () ()
sysTime :: Wen -> SystemTime
sysTime = view Time.systemTime
wakeErr :: WorkError -> IO ()
wakeErr _ = pure ()
behn
:: HasKingId e
=> e
-> (EvErr -> STM ())
-> Acquire (BehnEf -> IO ())
behn env enqueueEv = runBehn
where
king = fromIntegral (env ^. kingIdL)
runBehn :: Acquire (BehnEf -> IO ())
runBehn = do
tim <- mkAcquire Timer.init Timer.stop
pure (runRIO env . 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 (EvErr wakeEv wakeErr))