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{- git-annex assistant named threads.
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Assistant.NamedThread where
import Common.Annex
import Assistant.Types.NamedThread
import Assistant.Types.ThreadName
import Assistant.Types.DaemonStatus
import Assistant.Types.UrlRenderer
import Assistant.DaemonStatus
import Assistant.Monad
import Control.Concurrent
import Control.Concurrent.Async
import qualified Data.Map as M
import qualified Control.Exception as E
#ifdef WITH_WEBAPP
import Assistant.WebApp.Types
import Assistant.Types.Alert
import Assistant.Alert
import qualified Data.Text as T
#endif
{- Starts a named thread, if it's not already running.
-
- Named threads are run by a management thread, so if they crash
- an alert is displayed, allowing the thread to be restarted. -}
startNamedThread :: UrlRenderer -> NamedThread -> Assistant ()
startNamedThread urlrenderer namedthread@(NamedThread name a) = do
m <- startedThreads <$> getDaemonStatus
case M.lookup name m of
Nothing -> start
Just (aid, _) -> do
r <- liftIO (E.try (poll aid) :: IO (Either E.SomeException (Maybe (Either E.SomeException ()))))
case r of
Right Nothing -> noop
_ -> start
where
start = do
d <- getAssistant id
aid <- liftIO $ runmanaged $ d { threadName = name }
restart <- asIO $ startNamedThread urlrenderer namedthread
modifyDaemonStatus_ $ \s -> s
{ startedThreads = M.insertWith' const name (aid, restart) (startedThreads s) }
runmanaged d = do
aid <- async $ runAssistant d a
void $ forkIO $ manager d aid
return aid
manager d aid = do
r <- E.try (wait aid) :: IO (Either E.SomeException ())
case r of
Right _ -> noop
Left e -> do
let msg = unwords
[ fromThreadName $ threadName d
, "crashed:", show e
]
hPutStrLn stderr msg
#ifdef WITH_WEBAPP
button <- runAssistant d $ mkAlertButton
(T.pack "Restart Thread")
urlrenderer
(RestartThreadR name)
runAssistant d $ void $ addAlert $
(warningAlert (fromThreadName name) msg)
{ alertButton = Just button }
#endif
namedThreadId :: NamedThread -> Assistant (Maybe ThreadId)
namedThreadId (NamedThread name _) = do
m <- startedThreads <$> getDaemonStatus
return $ asyncThreadId . fst <$> M.lookup name m
{- Waits for all named threads that have been started to finish.
-
- Note that if a named thread crashes, it will probably
- cause this to crash as well. Also, named threads that are started
- after this is called will not be waited on. -}
waitNamedThreads :: Assistant ()
waitNamedThreads = do
m <- startedThreads <$> getDaemonStatus
liftIO $ mapM_ (wait . fst) $ M.elems m
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