{-# LANGUAGE BangPatterns #-} {-# LANGUAGE CPP #-} {-# LANGUAGE ExistentialQuantification #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE NoImplicitPrelude #-} {-# LANGUAGE Trustworthy #-} -- TODO: use the new Windows IO manager module GHC.Event.TimerManager #if defined(javascript_HOST_ARCH) () where #else ( -- * Types TimerManager -- * Creation , new , newWith , newDefaultBackend , emControl -- * Running , finished , loop , step , shutdown , cleanup , wakeManager -- * Registering interest in timeout events , TimeoutCallback , TimeoutKey , registerTimeout , updateTimeout , unregisterTimeout ) where #include "EventConfig.h" ------------------------------------------------------------------------ -- Imports import Control.Exception (finally) import Data.Foldable (sequence_) import Data.IORef (IORef, atomicModifyIORef', mkWeakIORef, newIORef, readIORef, writeIORef) import GHC.Base import GHC.Clock (getMonotonicTimeNSec) import GHC.Conc.Signal (runHandlers) import GHC.Enum (maxBound) import GHC.Num (Num(..)) import GHC.Real (quot, fromIntegral) import GHC.Show (Show(..)) import GHC.Event.Control import GHC.Event.Internal (Backend, Event, evtRead, Timeout(..)) import GHC.Event.Unique (UniqueSource, newSource, newUnique) import GHC.Event.TimeOut import System.Posix.Types (Fd) import qualified GHC.Event.Internal as I import qualified GHC.Event.PSQ as Q #if defined(HAVE_POLL) import qualified GHC.Event.Poll as Poll #else # error not implemented for this operating system #endif ------------------------------------------------------------------------ -- Types data State = Created | Running | Dying | Finished deriving ( Eq -- ^ @since 4.7.0.0 , Show -- ^ @since 4.7.0.0 ) -- | The event manager state. data TimerManager = TimerManager { emBackend :: !Backend , emTimeouts :: {-# UNPACK #-} !(IORef TimeoutQueue) , emState :: {-# UNPACK #-} !(IORef State) , emUniqueSource :: {-# UNPACK #-} !UniqueSource , emControl :: {-# UNPACK #-} !Control } ------------------------------------------------------------------------ -- Creation handleControlEvent :: TimerManager -> Fd -> Event -> IO () handleControlEvent mgr fd _evt = do msg <- readControlMessage (emControl mgr) fd case msg of CMsgWakeup -> return () CMsgDie -> writeIORef (emState mgr) Finished CMsgSignal fp s -> runHandlers fp s newDefaultBackend :: IO Backend #if defined(HAVE_POLL) newDefaultBackend = Poll.new #else newDefaultBackend = errorWithoutStackTrace "no back end for this platform" #endif -- | Create a new event manager. new :: IO TimerManager new = newWith =<< newDefaultBackend newWith :: Backend -> IO TimerManager newWith be = do timeouts <- newIORef Q.empty ctrl <- newControl True state <- newIORef Created us <- newSource _ <- mkWeakIORef state $ do st <- atomicModifyIORef' state $ \s -> (Finished, s) when (st /= Finished) $ do I.delete be closeControl ctrl let mgr = TimerManager { emBackend = be , emTimeouts = timeouts , emState = state , emUniqueSource = us , emControl = ctrl } _ <- I.modifyFd be (controlReadFd ctrl) mempty evtRead _ <- I.modifyFd be (wakeupReadFd ctrl) mempty evtRead return mgr -- | Asynchronously shuts down the event manager, if running. shutdown :: TimerManager -> IO () shutdown mgr = do state <- atomicModifyIORef' (emState mgr) $ \s -> (Dying, s) when (state == Running) $ sendDie (emControl mgr) finished :: TimerManager -> IO Bool finished mgr = (== Finished) `liftM` readIORef (emState mgr) cleanup :: TimerManager -> IO () cleanup mgr = do writeIORef (emState mgr) Finished I.delete (emBackend mgr) closeControl (emControl mgr) ------------------------------------------------------------------------ -- Event loop -- | Start handling events. This function loops until told to stop, -- using 'shutdown'. -- -- /Note/: This loop can only be run once per 'TimerManager', as it -- closes all of its control resources when it finishes. loop :: TimerManager -> IO () loop mgr = do state <- atomicModifyIORef' (emState mgr) $ \s -> case s of Created -> (Running, s) _ -> (s, s) case state of Created -> go `finally` cleanup mgr Dying -> cleanup mgr _ -> do cleanup mgr errorWithoutStackTrace $ "GHC.Event.Manager.loop: state is already " ++ show state where go = do running <- step mgr when running go step :: TimerManager -> IO Bool step mgr = do timeout <- mkTimeout _ <- I.poll (emBackend mgr) (Just timeout) (handleControlEvent mgr) state <- readIORef (emState mgr) state `seq` return (state == Running) where -- | Call all expired timer callbacks and return the time to the -- next timeout. mkTimeout :: IO Timeout mkTimeout = do now <- getMonotonicTimeNSec (expired, timeout) <- atomicModifyIORef' (emTimeouts mgr) $ \tq -> let (expired, tq') = Q.atMost now tq timeout = case Q.minView tq' of Nothing -> Forever Just (Q.E _ t _, _) -> -- This value will always be positive since the call -- to 'atMost' above removed any timeouts <= 'now' let t' = t - now in t' `seq` Timeout t' in (tq', (expired, timeout)) sequence_ $ map Q.value expired return timeout -- | Wake up the event manager. wakeManager :: TimerManager -> IO () wakeManager mgr = sendWakeup (emControl mgr) ------------------------------------------------------------------------ -- Registering interest in timeout events expirationTime :: Int -> IO Q.Prio expirationTime us = do now <- getMonotonicTimeNSec let expTime -- Currently we treat overflows by clamping to maxBound. If humanity -- still exists in 2500 CE we will ned to be a bit more careful here. -- See #15158. | (maxBound - now) `quot` 1000 < fromIntegral us = maxBound | otherwise = now + ns where ns = 1000 * fromIntegral us return expTime -- | Register a timeout in the given number of microseconds. The -- returned 'TimeoutKey' can be used to later unregister or update the -- timeout. The timeout is automatically unregistered after the given -- time has passed. -- -- Be careful not to exceed @maxBound :: Int@, which on 32-bit machines is only -- 2147483647 μs, less than 36 minutes. -- registerTimeout :: TimerManager -> Int -> TimeoutCallback -> IO TimeoutKey registerTimeout mgr us cb = do !key <- newUnique (emUniqueSource mgr) if us <= 0 then cb else do expTime <- expirationTime us -- "unsafeInsertNew" is safe - the key must not exist in the PSQ. It -- doesn't because we just generated it from a unique supply. editTimeouts mgr (Q.unsafeInsertNew key expTime cb) return $ TK key -- | Unregister an active timeout. unregisterTimeout :: TimerManager -> TimeoutKey -> IO () unregisterTimeout mgr (TK key) = editTimeouts mgr (Q.delete key) -- | Update an active timeout to fire in the given number of -- microseconds. -- -- Be careful not to exceed @maxBound :: Int@, which on 32-bit machines is only -- 2147483647 μs, less than 36 minutes. -- updateTimeout :: TimerManager -> TimeoutKey -> Int -> IO () updateTimeout mgr (TK key) us = do expTime <- expirationTime us editTimeouts mgr (Q.adjust (const expTime) key) editTimeouts :: TimerManager -> TimeoutEdit -> IO () editTimeouts mgr g = do wake <- atomicModifyIORef' (emTimeouts mgr) f when wake (wakeManager mgr) where f q = (q', wake) where q' = g q wake = case Q.minView q of Nothing -> True Just (Q.E _ t0 _, _) -> case Q.minView q' of Just (Q.E _ t1 _, _) -> -- don't wake the manager if the -- minimum element didn't change. t0 /= t1 _ -> True #endif