removed threading problem with Xlib

The output just stopped at some point until a new XEvent was received

As XLockDisplay is in theory a good idea, with XNextEvent blocking its
not usable.

As it turned out, a window can be shared between display connections.

Now the eventloop has its own display connection (which also removes the
need for the lock introduced before).

Additionally the screeninfo doesn't need to be fetched into a TVar in
the eventerloop anymore.

Also this was needed for the signalHandlers to work correctly again.

2 files changed, 33 insertions, 40 deletions

diff --git a/src/Main.hs b/src/Main.hs
index 34a298d..0d4c113 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -56,9 +56,9 @@ main = do
   fs    <- initFont d (font conf)
   cls   <- mapM (parseTemplate conf) (splitTemplate conf)
   vars  <- mapM (mapM startCommand) cls
-  (r,w, srs) <- createWin d fs conf
+  (r,w) <- createWin d fs conf
   sig   <- setupSignalHandler
-  eventLoop (XConf d r w fs conf) vars sig srs
+  eventLoop (XConf d r w fs conf) vars sig
 
 -- | Splits the template in its parts
 splitTemplate :: Config -> [String]
diff --git a/src/Xmobar.hs b/src/Xmobar.hs
index e41c2b7..abf6ab3 100644
--- a/src/Xmobar.hs
+++ b/src/Xmobar.hs
@@ -79,13 +79,12 @@ instance Exception WakeUp
 data SignalType = Wakeup | Reposition | ChangeScreen
 
 -- | The event loop
-eventLoop :: XConf -> [[(Maybe ThreadId, TVar String)]] -> MVar SignalType -> [Rectangle] -> IO ()
-eventLoop xcfg@(XConf d _ w fs _) vs signal screeninfo = do
+eventLoop :: XConf -> [[(Maybe ThreadId, TVar String)]] -> MVar SignalType -> IO ()
+eventLoop xcfg@(XConf d _ w fs _) vs signal = do
     tv <- atomically $ newTVar []
-    tsrs <- atomically $ newTVar screeninfo
     _ <- forkIO (checker tv [] `catch` \(SomeException _) -> putStrLn "Oh Noez checker" >> return ())
-    _ <- forkOS (eventer tsrs `catch` \(SomeException _) -> putStrLn "Oh Noez eventer" >>return ())
-    go tv xcfg tsrs
+    _ <- forkOS (eventer `catch` \(SomeException _) -> putStrLn "Oh Noez eventer" >>return ())
+    go tv xcfg
   where
     -- interrupt the drawing thread every time a var is updated
     checker tvar ov = do
@@ -99,56 +98,52 @@ eventLoop xcfg@(XConf d _ w fs _) vs signal screeninfo = do
 
     concatV = fmap concat . mapM (readTVar . snd)
 
-    eventer tsrs =
+    eventer =
       alloca $ \ptrEventBase ->
       alloca $ \ptrErrorBase ->
       allocaXEvent $ \e -> do
         _ <- xrrQueryExtension d ptrEventBase ptrErrorBase
         xrrEventBase <- peek ptrEventBase
+
+        dpy <- openDisplay ""
+        --  keyPressMask is the same value as RRScreenChangeNotify
+        xrrSelectInput    dpy (defaultRootWindow dpy) keyPressMask
+        selectInput       dpy w (exposureMask .|. structureNotifyMask)
+
         forever $ do
-          nextEvent d e
+          nextEvent dpy e
           ev <- getEvent e
           case ev of
-            ConfigureEvent {} -> sendRepos
+            ConfigureEvent {} -> putMVar signal Reposition
             ExposeEvent {} -> putMVar signal Wakeup
             _ ->
               --  keyPressMask is the same value as RRScreenChangeNotify
-              when ( (fromIntegral (ev_event_type ev) - xrrEventBase) == fromIntegral keyPressMask) sendRepos
-       where
-         sendRepos = do
-           srs <- getScreenInfo d
-           atomically $ writeTVar tsrs srs
-           putMVar signal Reposition
+              when ( (fromIntegral (ev_event_type ev) - xrrEventBase) == fromIntegral keyPressMask)
+                   $ putMVar signal Reposition
 
 
     -- Continuously wait for a timer interrupt or an expose event
-    go tv xc@(XConf _ _ _ _ cfg) tsrs = do
+    go tv xc@(XConf _ _ _ _ cfg) = do
       typ <- takeMVar signal
       case typ of
         Wakeup -> do
           runX xc (updateWin tv)
-          go tv xc tsrs
-        Reposition -> do
-          ncfg <- reposWindow cfg
-          go tv ncfg tsrs
+          go tv xc
+        Reposition -> reposWindow cfg
         ChangeScreen ->
           case position cfg of
             OnScreen n o -> do
-              srs <- readTVarIO tsrs
+              srs <- getScreenInfo d
               if n == length srs then do
-                  ncfg <- reposWindow (cfg {position = OnScreen 1 o})
-                  go tv ncfg tsrs
-                else do
-                  ncfg <- reposWindow (cfg {position = OnScreen (n+1) o})
-                  go tv ncfg tsrs
-            o -> do
-              ncfg <- reposWindow (cfg {position = OnScreen 1 o})
-              go tv ncfg tsrs
+                  reposWindow (cfg {position = OnScreen 1 o})
+                else
+                  reposWindow (cfg {position = OnScreen (n+1) o})
+            o ->
+              reposWindow (cfg {position = OnScreen 1 o})
       where
         reposWindow rcfg = do
-          srs <- readTVarIO tsrs
-          r' <- repositionWin d w fs rcfg srs
-          return (XConf d r' w fs rcfg)
+          r' <- repositionWin d w fs rcfg
+          go tv (XConf d r' w fs rcfg)
 
 -- | Signal handling
 setupSignalHandler :: IO (MVar SignalType)
@@ -186,7 +181,7 @@ startCommand (com,s,ss)
 -- $window
 
 -- | The function to create the initial window
-createWin :: Display -> XFont -> Config -> IO (Rectangle,Window,[Rectangle])
+createWin :: Display -> XFont -> Config -> IO (Rectangle,Window)
 createWin d fs c = do
   let dflt = defaultScreen d
   srs     <- getScreenInfo d
@@ -195,17 +190,15 @@ createWin d fs c = do
   let ht    = as + ds + 4
       (r,o) = setPosition (position c) srs (fi ht)
   win <- newWindow  d (defaultScreenOfDisplay d) rootw r o
-  --  keyPressMask is the same value as RRScreenChangeNotify
-  xrrSelectInput    d rootw keyPressMask
-  selectInput       d win (exposureMask .|. structureNotifyMask)
   setProperties r c d win srs
   when (lowerOnStart c) (lowerWindow d win)
   mapWindow         d win
-  return (r,win, srs)
+  return (r,win)
 
 -- | Updates the size and position of the window
-repositionWin :: Display -> Window -> XFont -> Config -> [Rectangle] -> IO (Rectangle)
-repositionWin d win fs c srs = do
+repositionWin :: Display -> Window -> XFont -> Config -> IO (Rectangle)
+repositionWin d win fs c = do
+  srs     <- getScreenInfo d
   (as,ds) <- textExtents fs "0"
   let ht    = as + ds + 4
       (r,_) = setPosition (position c) srs (fi ht)