display errors when any named thread crashes

Assistant/Threads/DaemonStatus.hs

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+{- git-annex assistant daemon status thread
+ -
+ - Copyright 2012 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Assistant.Threads.DaemonStatus where
+
+import Assistant.Common
+import Assistant.DaemonStatus
+import Assistant.ThreadedMonad
+import Utility.ThreadScheduler
+import Utility.NotificationBroadcaster
+
+thisThread :: ThreadName
+thisThread = "DaemonStatus"
+
+{- This writes the daemon status to disk, when it changes, but no more
+ - frequently than once every ten minutes.
+ -}
+daemonStatusThread :: ThreadState -> DaemonStatusHandle -> NamedThread
+daemonStatusThread st dstatus = thread $ do
+	notifier <- newNotificationHandle
+		=<< changeNotifier <$> getDaemonStatus dstatus
+	checkpoint
+	runEvery (Seconds tenMinutes) $ do
+		waitNotification notifier
+		checkpoint
+	where
+		thread = NamedThread thisThread
+		checkpoint = do
+			status <- getDaemonStatus dstatus
+			file <- runThreadState st $ fromRepo gitAnnexDaemonStatusFile
+			writeDaemonStatusFile file status
+