1 files changed, 17 insertions, 4 deletions
diff --git a/src/Xmobar/Plugins/Date.hs b/src/Xmobar/Plugins/Date.hs
index 1cb0596..d7de2e9 100644
--- a/src/Xmobar/Plugins/Date.hs
+++ b/src/Xmobar/Plugins/Date.hs
@@ -17,22 +17,35 @@
 --
 -----------------------------------------------------------------------------
 
-module Xmobar.Plugins.Date (Date(..)) where
+module Xmobar.Plugins.Date (Date(..), date) where
 
 import Xmobar.Run.Exec
 
 #if ! MIN_VERSION_time(1,5,0)
 import System.Locale
 #endif
+import Data.IORef
 import Data.Time
+import Control.Concurrent.Async (concurrently_)
 
 data Date = Date String String Int
     deriving (Read, Show)
 
 instance Exec Date where
     alias (Date _ a _) = a
-    run   (Date f _ _) = date f
     rate  (Date _ _ r) = r
+    start (Date f _ r) cb =
+        -- refresh time zone once a minute to avoid wasting CPU cycles
+        withRefreshingZone 600 $ \zone ->
+            doEveryTenthSeconds r $ date zone f >>= cb
 
-date :: String -> IO String
-date format = fmap (formatTime defaultTimeLocale format) getZonedTime
+date :: IORef TimeZone -> String -> IO String
+date zoneRef format = do
+    zone <- readIORef zoneRef
+    fmap (formatTime defaultTimeLocale format . utcToZonedTime zone) getCurrentTime
+
+withRefreshingZone :: Int -> (IORef TimeZone -> IO ()) -> IO ()
+withRefreshingZone r action = do
+    zone <- newIORef =<< getCurrentTimeZone
+    let refresh = atomicWriteIORef zone =<< getCurrentTimeZone
+    concurrently_ (doEveryTenthSeconds r refresh) (action zone)