On Wed, Jan 21, 2009 at 11:36 PM, Belka
Hi!
Could somebody please share some experience on how to implement daemon start and stop directives. In theory I need something like this: 1. "my_daemon start" - starts my app with an infinite loop of serving inside. 2. "my_daemon stop" - puts in some TVar a value signalizing, that stop is given - infinite loop brakes.
You can abstract this pattern: -- runs its argument in an infinite loop, and returns an action that stops the loop daemon :: IO () -> IO (IO ()) daemon action = do stopvar <- atomically $ newTVar False let run = do stop <- atomically $ readTVar stopvar if stop then return () else (action >> run) forkIO run return (atomically $ writeTVar stopvar True) TVars are overkill here, actually, an IORef would be just fine, I think. Luke