[commit: base] : Update closeFd_ to avoid unnecessary backend modifications. (e9d98e5)

[Johan Tibell]

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

On branch  : 

http://hackage.haskell.org/trac/ghc/changeset/e9d98e5c6e0590d239a789868976b64d93675fe9

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

commit e9d98e5c6e0590d239a789868976b64d93675fe9
Author: Andreas Voellmy <andreas.voellmy at gmail.com>
Date:   Fri Jan 4 09:47:37 2013 -0500

    Update closeFd_ to avoid unnecessary backend modifications.
    
    This makes closeFd follow the patten of closeFd_.

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

 GHC/Event/Manager.hs |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/GHC/Event/Manager.hs b/GHC/Event/Manager.hs
index fe6fb39..32dfc6d 100644
--- a/GHC/Event/Manager.hs
+++ b/GHC/Event/Manager.hs
@@ -369,8 +369,9 @@ closeFd_ mgr oldMap fd = do
     (Nothing,  _)       -> return oldMap
     (Just fds, !newMap) -> do
       let oldEvs = eventsOf fds
-      I.modifyFd (emBackend mgr) fd oldEvs mempty
-      when (oldEvs /= mempty) $ wakeManager mgr
+      when (oldEvs /= mempty) $ do
+        I.modifyFd (emBackend mgr) fd oldEvs mempty
+        wakeManager mgr
       forM_ fds $ \(FdData reg ev cb) -> cb reg (ev `mappend` evtClose)
       return newMap
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