reconnect XMPP when NetWatcher notices a change

Assistant/Pushes.hs

@@ -11,6 +11,7 @@ import Common.Annex
 import Utility.TSet
 
 import Control.Concurrent.STM
+import Control.Concurrent.MSampleVar
 import Data.Time.Clock
 import qualified Data.Map as M
 
@@ -18,8 +19,13 @@ import qualified Data.Map as M
 type PushMap = M.Map Remote UTCTime
 type FailedPushMap = TMVar PushMap
 
-{- Used to notify about successful pushes. -}
-newtype PushNotifier = PushNotifier (TSet UUID)
+{- The TSet is recent, successful pushes that other remotes should be
+ - notified about.
+ -
+ - The MSampleVar is written to when the PushNotifier thread should be
+ - restarted for some reason.
+ -}
+data PushNotifier = PushNotifier (TSet UUID) (MSampleVar ())
 
 {- The TMVar starts empty, and is left empty when there are no
  - failed pushes. This way we can block until there are some failed pushes.
@@ -50,10 +56,18 @@ changeFailedPushMap v a = atomically $
 			| otherwise = putTMVar v $! m
 
 newPushNotifier :: IO PushNotifier
-newPushNotifier = PushNotifier <$> newTSet
+newPushNotifier = PushNotifier
+	<$> newTSet
+	<*> newEmptySV
 
 notifyPush :: [UUID] -> PushNotifier -> IO ()
-notifyPush us (PushNotifier s) = putTSet s us
+notifyPush us (PushNotifier s _) = putTSet s us
 
 waitPush :: PushNotifier -> IO [UUID]
-waitPush (PushNotifier s) = getTSet s
+waitPush (PushNotifier s _) = getTSet s
+
+notifyRestart :: PushNotifier -> IO ()
+notifyRestart (PushNotifier _ sv) = writeSV sv ()
+
+waitRestart :: PushNotifier -> IO ()
+waitRestart (PushNotifier _ sv) = readSV sv