diff --git a/sodium.cabal b/sodium.cabal --- a/sodium.cabal +++ b/sodium.cabal @@ -1,5 +1,5 @@ name: sodium -version: 0.7.0.0 +version: 0.8.0.0 synopsis: Sodium Reactive Programming (FRP) System description: A general purpose Reactive Programming (FRP) system. This is part of a project to @@ -41,6 +41,8 @@ * 0.6.0.2 - Fix memory leak - see memory-test-8 & memory-test-8a; . * 0.7.0.0 - Add split primitive. + . + * 0.8.0.0 - Add executeIO primitive. license: BSD3 license-file: LICENSE @@ -145,8 +147,12 @@ library hs-source-dirs: src - exposed-modules: FRP.Sodium, FRP.Sodium.Internal, FRP.Sodium.Context + exposed-modules: FRP.Sodium, + FRP.Sodium.Internal, + FRP.Sodium.Context, + FRP.Sodium.IO other-modules: FRP.Sodium.Plain build-depends: base >= 4.3.0.0 && < 4.8.0.0, containers >= 0.4.0.0 && < 0.6.0.0, mtl >= 2.0.0.0 && < 2.2.0.0 + ghc-options: -O2 diff --git a/src/FRP/Sodium/Context.hs b/src/FRP/Sodium/Context.hs --- a/src/FRP/Sodium/Context.hs +++ b/src/FRP/Sodium/Context.hs @@ -26,8 +26,6 @@ -- -- State changes to 'hold' values occur after processing of the transaction is complete. sync :: Reactive r a -> IO a - -- Lift an arbitrary IO action into a 'Reactive'. - ioReactive :: IO a -> Reactive r a -- | Returns an event, and a push action for pushing a value into the event. newEvent :: Reactive r (Event r a, a -> Reactive r ()) -- | Listen for firings of this event. The returned @IO ()@ is an IO action @@ -88,6 +86,28 @@ -- a block of input data into frames. We obviously want each frame to have -- its own transaction so that state is updated separately each frame. split :: Event r [a] -> Event r a + +class Context r => ContextIO r where + -- | Execute the specified IO operation asynchronously on a separate thread, and + -- signal the output event in a new transaction upon its completion. + -- + -- Caveat: Where 'switch' or 'switchE' is used, when some reactive logic has been + -- switched away, we rely on garbage collection to actually disconnect this logic + -- from any input it may be listening to. With normal Sodium code, everything is + -- pure, so before garbage collection happens, the worst we will get is some wasted + -- CPU cycles. If you are using 'executeAsyncIO'/'executeSyncIO' inside a 'switch' + -- or 'switchE', however, it is possible that logic that has been switched away + -- hasn't been garbage collected yet. This logic /could/ still run, and if it has + -- observable effects, you could see it running after it is supposed to have been + -- switched out. One way to avoid this is to pipe the source event for IO out of the + -- switch, run the 'executeAsyncIO'/'executeSyncIO' outside the switch, and pipe its + -- output back into the switch contents. + executeAsyncIO :: Event r (IO a) -> Event r a + -- | Execute the specified IO operation synchronously and fire the output event + -- in the same transaction. + -- + -- Caveat: See 'executeAsyncIO'. + executeSyncIO :: Event r (IO a) -> Event r a -- | A time-varying value, British spelling. type Behaviour r a = Behavior r a diff --git a/src/FRP/Sodium/IO.hs b/src/FRP/Sodium/IO.hs new file mode 100644 --- /dev/null +++ b/src/FRP/Sodium/IO.hs @@ -0,0 +1,48 @@ +module FRP.Sodium.IO where + +import FRP.Sodium.Context +import FRP.Sodium.Internal + +import Control.Concurrent (forkIO) + + +-- | Execute the specified IO operation asynchronously on a separate thread, and +-- signal the output event in a new transaction upon its completion. +-- +-- Caveat: Where 'switch' or 'switchE' is used, when some reactive logic has been +-- switched away, we rely on garbage collection to actually disconnect this logic +-- from any input it may be listening to. With normal Sodium code, everything is +-- pure, so before garbage collection happens, the worst we will get is some wasted +-- CPU cycles. If you are using 'executeAsyncIO'/'executeSyncIO' inside a 'switch' +-- or 'switchE', however, it is possible that logic that has been switched away +-- hasn't been garbage collected yet. This logic /could/ still run, and if it has +-- observable effects, you could see it running after it is supposed to have been +-- switched out. One way to avoid this is to pipe the source event for IO out of the +-- switch, run the 'executeAsyncIO'/'executeSyncIO' outside the switch, and pipe its +-- output back into the switch contents. +executeAsyncIO :: Event Plain (IO a) -> Event Plain a +executeAsyncIO ev = Event gl cacheRef (dep ev) + where + cacheRef = unsafeNewIORef Nothing ev + gl = do + (l, push, nodeRef) <- ioReactive newEventImpl + unlistener <- later $ linkedListen ev (Just nodeRef) False $ \action -> do + ioReactive $ do + _ <- forkIO $ sync . push =<< action + return () + addCleanup_Listen unlistener l + +-- | Execute the specified IO operation synchronously and fire the output event +-- in the same transaction. +-- +-- Caveat: See 'executeAsyncIO'. +executeSyncIO :: Event Plain (IO a) -> Event Plain a +executeSyncIO ev = Event gl cacheRef (dep ev) + where + cacheRef = unsafeNewIORef Nothing ev + gl = do + (l, push, nodeRef) <- ioReactive newEventImpl + unlistener <- later $ linkedListen ev (Just nodeRef) False $ \action -> do + push =<< ioReactive action + addCleanup_Listen unlistener l + diff --git a/src/FRP/Sodium/Internal.hs b/src/FRP/Sodium/Internal.hs --- a/src/FRP/Sodium/Internal.hs +++ b/src/FRP/Sodium/Internal.hs @@ -19,7 +19,10 @@ addCleanup_Listen, Sample(..), addCleanup_Sample, - later + later, + dep, + unsafeNewIORef, + Plain ) where import qualified FRP.Sodium.Context as C diff --git a/src/FRP/Sodium/Plain.hs b/src/FRP/Sodium/Plain.hs --- a/src/FRP/Sodium/Plain.hs +++ b/src/FRP/Sodium/Plain.hs @@ -110,7 +110,6 @@ } sync = sync - ioReactive = ioReactive newEvent = newEvent listen = listen never = never