From 38548ef5e6d42df370ea687285193762919b80c3 Mon Sep 17 00:00:00 2001
From: Andreas Voellmy <andreas.voellmy@gmail.com>
Date: Thu, 20 Dec 2012 00:41:00 -0500
Subject: Separated the IO manager into a timer manager and a file IO manager.

This is a preliminary patch; ultimately the single file IO manager will be replaced by per-capability managers.
---
 libraries/base/GHC/Event.hs        |  3 +-
 libraries/base/GHC/Event/Thread.hs | 64 ++++++++++++++++++++++++++++++++++++--
 2 files changed, 63 insertions(+), 4 deletions(-)

(limited to 'libraries/base/GHC')

diff --git a/libraries/base/GHC/Event.hs b/libraries/base/GHC/Event.hs
index 257412fa48..05104097b7 100644
--- a/libraries/base/GHC/Event.hs
+++ b/libraries/base/GHC/Event.hs
@@ -14,6 +14,7 @@ module GHC.Event
 
       -- * Creation
     , getSystemEventManager
+    , getSystemTimerManager
 
       -- * Registering interest in I/O events
     , Event
@@ -36,5 +37,5 @@ module GHC.Event
     ) where
 
 import GHC.Event.Manager
-import GHC.Event.Thread (getSystemEventManager)
+import GHC.Event.Thread (getSystemEventManager, getSystemTimerManager)
 
diff --git a/libraries/base/GHC/Event/Thread.hs b/libraries/base/GHC/Event/Thread.hs
index e6851087b3..3cdbdd3b7d 100644
--- a/libraries/base/GHC/Event/Thread.hs
+++ b/libraries/base/GHC/Event/Thread.hs
@@ -3,6 +3,7 @@
 
 module GHC.Event.Thread
     ( getSystemEventManager
+    , getSystemTimerManager
     , ensureIOManagerIsRunning
     , threadWaitRead
     , threadWaitWrite
@@ -13,6 +14,7 @@ module GHC.Event.Thread
     , registerDelay
     ) where
 
+import Control.Exception (finally)
 import Data.IORef (IORef, newIORef, readIORef, writeIORef)
 import Data.Maybe (Maybe(..))
 import Foreign.C.Error (eBADF, errnoToIOError)
@@ -39,7 +41,7 @@ import System.Posix.Types (Fd)
 -- run /earlier/ than specified.
 threadDelay :: Int -> IO ()
 threadDelay usecs = mask_ $ do
-  mgr <- getSystemEventManager
+  mgr <- getSystemTimerManager
   m <- newEmptyMVar
   reg <- registerTimeout mgr usecs (putMVar m ())
   takeMVar m `onException` M.unregisterTimeout mgr reg
@@ -50,7 +52,7 @@ threadDelay usecs = mask_ $ do
 registerDelay :: Int -> IO (TVar Bool)
 registerDelay usecs = do
   t <- atomically $ newTVar False
-  mgr <- getSystemEventManager
+  mgr <- getSystemTimerManager
   _ <- registerTimeout mgr usecs . atomically $ writeTVar t True
   return t
 
@@ -164,16 +166,40 @@ ioManager = unsafePerformIO $ do
    m <- newMVar Nothing
    sharedCAF m getOrSetSystemEventThreadIOManagerThreadStore
 
+getSystemTimerManager :: IO EventManager
+getSystemTimerManager = do 
+  Just mgr <- readIORef timerManager
+  return mgr
+
+foreign import ccall unsafe "getOrSetSystemTimerThreadEventManagerStore"
+    getOrSetSystemTimerThreadEventManagerStore :: Ptr a -> IO (Ptr a)
+
+timerManager :: IORef (Maybe EventManager)
+timerManager = unsafePerformIO $ do
+    em <- newIORef Nothing
+    sharedCAF em getOrSetSystemTimerThreadEventManagerStore
+{-# NOINLINE timerManager #-}
+
+foreign import ccall unsafe "getOrSetSystemTimerThreadIOManagerThreadStore"
+    getOrSetSystemTimerThreadIOManagerThreadStore :: Ptr a -> IO (Ptr a)
+
+{-# NOINLINE timerManagerThreadVar #-}
+timerManagerThreadVar :: MVar (Maybe ThreadId)
+timerManagerThreadVar = unsafePerformIO $ do
+   m <- newMVar Nothing
+   sharedCAF m getOrSetSystemTimerThreadIOManagerThreadStore
+
 ensureIOManagerIsRunning :: IO ()
 ensureIOManagerIsRunning
   | not threaded = return ()
   | otherwise = do
       startIOManagerThread
+      startTimerManagerThread
 
 startIOManagerThread :: IO ()
 startIOManagerThread = modifyMVar_ ioManager $ \old -> do
   let create = do
-        !mgr <- new True
+        !mgr <- new False
         writeIORef eventManager $ Just mgr
         !t <- forkIO $ loop mgr
         labelThread t "IOManager"
@@ -197,4 +223,36 @@ startIOManagerThread = modifyMVar_ ioManager $ \old -> do
           create
         _other         -> return st
 
+startTimerManagerThread :: IO ()
+startTimerManagerThread = modifyMVar_ timerManagerThreadVar $ \old -> do
+  let shutdownEM = do
+        mem <- readIORef eventManager
+        case mem of
+          Nothing -> return ()
+          Just em -> M.shutdown em
+  let create = do
+        !mgr <- new True
+        writeIORef timerManager $ Just mgr
+        !t <- forkIO $ loop mgr `finally` shutdownEM
+        labelThread t "TimerManager"
+        return $ Just t
+  case old of
+    Nothing            -> create
+    st@(Just t) -> do
+      s <- threadStatus t
+      case s of
+        ThreadFinished -> create
+        ThreadDied     -> do 
+          -- Sanity check: if the thread has died, there is a chance
+          -- that event manager is still alive. This could happend during
+          -- the fork, for example. In this case we should clean up
+          -- open pipes and everything else related to the event manager.
+          -- See #4449
+          mem <- readIORef timerManager
+          _ <- case mem of
+                 Nothing -> return ()
+                 Just em -> M.cleanup em
+          create
+        _other         -> return st
+
 foreign import ccall unsafe "rtsSupportsBoundThreads" threaded :: Bool
-- 
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