[commit: base] : Avoid conditional compilation in GHC.Event.Manager. (1dbc927)

[Johan Tibell]

Repository : ssh://darcs.haskell.org//srv/darcs/packages/base

On branch  : 

http://hackage.haskell.org/trac/ghc/changeset/1dbc9270f771d06b9398637a986f07e72afaac18

>---------------------------------------------------------------

commit 1dbc9270f771d06b9398637a986f07e72afaac18
Author: Andreas Voellmy <andreas.voellmy at gmail.com>
Date:   Fri Jan 4 10:51:00 2013 -0500

    Avoid conditional compilation in GHC.Event.Manager.
    
    Use ordinary Bool value to distinguish between backends supporting oneShot mode and eliminate several uses of conditional compilation in favor of ordinary conditional expressions using this Bool value. The benefit of this change is that more of the code compiles on more of the platforms.

>---------------------------------------------------------------

 GHC/Event/Manager.hs |   38 +++++++++++++++++++-------------------
 1 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/GHC/Event/Manager.hs b/GHC/Event/Manager.hs
index 1f956a1..da0a461 100644
--- a/GHC/Event/Manager.hs
+++ b/GHC/Event/Manager.hs
@@ -130,6 +130,14 @@ hashFd fd = fromIntegral fd `mod` callbackArraySize
 callbackTableVar :: EventManager -> Fd -> MVar (IM.IntMap [FdData])
 callbackTableVar mgr fd = emFds mgr ! hashFd fd
 {-# INLINE callbackTableVar #-}
+
+haveOneShot :: Bool
+{-# INLINE haveOneShot #-}
+#if defined(HAVE_EPOLL) || defined(HAVE_KQUEUE)
+haveOneShot = True
+#else
+haveOneShot = False
+#endif
 ------------------------------------------------------------------------
 -- Creation
 
@@ -265,15 +273,13 @@ registerFd_ mgr@(EventManager{..}) cb fd evs = do
       reg  = FdKey fd u
       !fdd = FdData reg evs cb
   modifyMVar (callbackTableVar mgr fd) $ \oldMap ->
-#if defined(HAVE_EPOLL) || defined(HAVE_KQUEUE)
-    if emOneShot
+    if haveOneShot && emOneShot
     then case IM.insertWith (++) fd' [fdd] oldMap of
       (Nothing,   n) -> do I.modifyFdOnce emBackend fd evs
                            return (n, (reg, False))
       (Just prev, n) -> do I.modifyFdOnce emBackend fd (combineEvents evs prev)
                            return (n, (reg, False))
     else
-#endif
       let (!newMap, (oldEvs, newEvs)) =
             case IM.insertWith (++) fd' [fdd] oldMap of
               (Nothing,   n) -> (n, (mempty, evs))
@@ -330,12 +336,9 @@ unregisterFd_ mgr@(EventManager{..}) (FdKey fd u) =
               (Just prev, newm) -> (newm, pairEvents prev newm fd')
         modify = oldEvs /= newEvs
     when modify $
-#if defined(HAVE_EPOLL) || defined(HAVE_KQUEUE)    
-      if emOneShot && newEvs /= mempty
+      if haveOneShot && emOneShot && newEvs /= mempty
       then I.modifyFdOnce emBackend fd newEvs
-      else
-#endif        
-        I.modifyFd emBackend fd oldEvs newEvs
+      else I.modifyFd emBackend fd oldEvs newEvs
     return (newMap, modify)
 
 -- | Drop a previous file descriptor registration.
@@ -411,21 +414,18 @@ onFdEvent mgr fd evs =
       where
         -- nothing to rearm.
         aux [] _    []          =
-#if defined(HAVE_EPOLL) || defined(HAVE_KQUEUE)
-           return (curmap, cbs)
-#else
-          do I.modifyFd (emBackend mgr) fd (eventsOf cbs) mempty
-             return (curmap, cbs)
-#endif
+          if haveOneShot 
+          then return (curmap, cbs)
+          else do I.modifyFd (emBackend mgr) fd (eventsOf cbs) mempty
+                  return (curmap, cbs)
+
         -- reinsert and rearm; note that we already have the lock on the
         -- callback table for this fd, and we deleted above, so we know there
         -- is no entry in the table for this fd.
         aux [] fdds saved@(_:_) = do
-#if defined(HAVE_EPOLL) || defined(HAVE_KQUEUE)
-          I.modifyFdOnce (emBackend mgr) fd $ eventsOf saved
-#else
-          I.modifyFd (emBackend mgr) fd (eventsOf cbs) $ eventsOf saved
-#endif
+          if haveOneShot 
+            then I.modifyFdOnce (emBackend mgr) fd $ eventsOf saved
+            else I.modifyFd (emBackend mgr) fd (eventsOf cbs) $ eventsOf saved
           return (snd $ IM.insertWith (\_ _ -> saved) fd' saved curmap, fdds)
 
         -- continue, saving those callbacks that don't match the event