Implement some kind of announcer shutdown

Probably this crashes the program when the tchan is used.  Fixable.

1 files changed, 10 insertions, 5 deletions

diff --git a/Announcer.hs b/Announcer.hs
index 7d1d605d..e0f8b47e 100644
--- a/Announcer.hs
+++ b/Announcer.hs
@@ -153,7 +153,9 @@ readTChanTimeout timeout pktChannel = do
     toMicroseconds :: POSIXTime -> Int
     toMicroseconds = undefined
 
-listener :: TChan KPS -> IO ()
+data SchedulerCommand = ShutdownScheduler | ScheduledAction KPS
+
+listener :: TChan SchedulerCommand -> IO ()
 listener chan = relisten PSQ.empty
   where
     note :: String -> IO ()
@@ -162,14 +164,17 @@ listener chan = relisten PSQ.empty
       case minView queue of
         Nothing -> do
           note "queue empty - listening indefinitely"
-          (k, p, s) <- atomically $ readTChan chan
-          note "handling new event"
-          relisten $ PSQ.insert' k s p queue
+          atomically (readTChan chan) >>= \case
+            ShutdownScheduler -> return ()
+            ScheduledAction (k, p, s) -> do
+              note "handling new event"
+              relisten $ PSQ.insert' k s p queue
         Just ((k, p, s), queue') -> do
           note "queue full - listening with timeout"
           now <- getPOSIXTime
           readTChanTimeout (p - now) chan >>= \case
-            Just (k, p, s) -> do
+            Just (ShutdownScheduler) -> return ()
+            Just (ScheduledAction (k, p, s)) -> do
               note "handling new event (event occurred before timeout)"
               relisten $ PSQ.insert' k s p queue
             Nothing -> do