mirror of
https://github.com/urbit/shrub.git
synced 2024-12-20 17:32:11 +03:00
93 lines
2.7 KiB
Haskell
93 lines
2.7 KiB
Haskell
{-|
|
|
This allows multiple (zero or more) terminal clients to connect to
|
|
the *same* logical arvo terminal. Terminals that connect will be
|
|
given full event history since the creation of the demuxer.
|
|
-}
|
|
|
|
module Urbit.Vere.Term.Demux (Demux, mkDemux, addDemux, useDemux) where
|
|
|
|
import Urbit.Prelude
|
|
|
|
import Urbit.Arvo (Belt)
|
|
import Urbit.Vere.Term.API (Client(Client))
|
|
|
|
import qualified Urbit.Vere.Term.API as Term
|
|
import qualified Urbit.Vere.Term.Logic as Logic
|
|
|
|
|
|
-- External --------------------------------------------------------------------
|
|
|
|
data KeyedSet a = KeyedSet
|
|
{ _ksTable :: IntMap a
|
|
, _nextKey :: Int
|
|
}
|
|
|
|
instance Semigroup (KeyedSet a) where
|
|
KeyedSet t1 k1 <> KeyedSet t2 k2 = KeyedSet (t1 <> t2) (max k1 k2)
|
|
|
|
instance Monoid (KeyedSet a) where
|
|
mempty = KeyedSet mempty 0
|
|
|
|
ksInsertKey :: a -> KeyedSet a -> (Int, KeyedSet a)
|
|
ksInsertKey x (KeyedSet tbl nex) =
|
|
(nex, KeyedSet (insertMap nex x tbl) (succ nex))
|
|
|
|
ksInsert :: a -> KeyedSet a -> KeyedSet a
|
|
ksInsert x s = snd $ ksInsertKey x s
|
|
|
|
ksDelete :: Int -> KeyedSet a -> KeyedSet a
|
|
ksDelete k (KeyedSet t n) = KeyedSet (deleteMap k t) n
|
|
|
|
--------------------------------------------------------------------------------
|
|
|
|
data Demux = Demux
|
|
{ dConns :: TVar (KeyedSet Client)
|
|
, dStash :: TVar Logic.St
|
|
}
|
|
|
|
mkDemux :: STM Demux
|
|
mkDemux = Demux <$> newTVar mempty <*> newTVar Logic.init
|
|
|
|
addDemux :: Client -> Demux -> STM ()
|
|
addDemux conn Demux{..} = do
|
|
modifyTVar' dConns (ksInsert conn)
|
|
stash <- readTVar dStash
|
|
Term.give conn (Logic.toTermEv <$> Logic.drawState stash)
|
|
|
|
useDemux :: Demux -> Client
|
|
useDemux d = Client { give = dGive d, take = dTake d }
|
|
|
|
|
|
-- Internal --------------------------------------------------------------------
|
|
|
|
steps :: [Term.Ev] -> Logic.St -> Logic.St
|
|
steps termEvs st = foldl' Logic.step st $ concat $ Logic.fromTermEv <$> termEvs
|
|
|
|
dGive :: Demux -> [Term.Ev] -> STM ()
|
|
dGive Demux{..} evs = do
|
|
modifyTVar' dStash (force $ steps evs)
|
|
conns <- readTVar dConns
|
|
for_ (_ksTable conns) $ \c -> Term.give c evs
|
|
|
|
{-|
|
|
Returns Nothing if any connected client disconnected. A `Demux`
|
|
terminal lives forever, so you can continue to call this after it
|
|
returns `Nothing`.
|
|
|
|
If there are no attached clients, this will not return until one
|
|
is attached.
|
|
-}
|
|
dTake :: Demux -> STM (Maybe Belt)
|
|
dTake Demux{..} = do
|
|
conns <- readTVar dConns
|
|
waitForBelt conns >>= \case
|
|
(_, Just b ) -> pure (Just b)
|
|
(k, Nothing) -> do writeTVar dConns (ksDelete k conns)
|
|
pure Nothing
|
|
where
|
|
waitForBelt :: KeyedSet Client -> STM (Int, Maybe Belt)
|
|
waitForBelt ks = asum
|
|
$ fmap (\(k,c) -> (k,) <$> Term.take c)
|
|
$ mapToList
|
|
$ _ksTable ks
|