allow both one push and one receive-pack to run at the same time

Noticed that when pairing, sometimes both sides start to push, and the other
side sends a PushRequest, and the two deadlock, neither doing anything.
(Timeout eventually breaks this.) So, let both run at the same time.

Assistant/NetMessager.hs

@@ -33,69 +33,68 @@ notifyNetMessagerRestart =
 waitNetMessagerRestart :: Assistant ()
 waitNetMessagerRestart = readSV <<~ (netMessagerRestart . netMessager)
 
-getPushRunning :: Assistant PushRunning
-getPushRunning =
-	(atomically . readTMVar) <<~ (netMessagerPushRunning . netMessager)
-
-{- Runs an action that runs either the send or receive end of a push.
+{- Runs an action that runs either the send or receive side of a push.
  -
  - While the push is running, netMessagesPush will get messages put into it
  - relating to this push, while any messages relating to other pushes
- - go to netMessagesDeferred. Once the push finishes, those deferred
- - messages will be fed to handledeferred for processing.
+ - on the same side go to netMessagesDeferred. Once the push finishes,
+ - those deferred messages will be fed to handledeferred for processing.
  -}
-runPush :: PushRunning -> (NetMessage -> Assistant ()) -> Assistant a -> Assistant a
-runPush v handledeferred a = do
+runPush :: PushSide -> ClientID -> (NetMessage -> Assistant ()) -> Assistant a -> Assistant a
+runPush side clientid handledeferred a = do
 	nm <- getAssistant netMessager
-	let pr = netMessagerPushRunning nm
-	let setup = void $ atomically $ swapTMVar pr v
+	let runningv = getSide side $ netMessagerPushRunning nm
+	let setup = void $ atomically $ swapTMVar runningv $ Just clientid
 	let cleanup = atomically $ do
-		void $ swapTMVar pr NoPushRunning
-		emptytchan (netMessagesPush nm)
+		void $ swapTMVar runningv Nothing
+		emptytchan (getSide side $ netMessagesPush nm)
 	r <- E.bracket_ setup cleanup <~> a
 	(void . forkIO) <~> processdeferred nm
 	return r
   where
 	emptytchan c = maybe noop (const $ emptytchan c) =<< tryReadTChan c
 	processdeferred nm = do
-		s <- liftIO $ atomically $ swapTMVar (netMessagesDeferredPush nm) S.empty
+		s <- liftIO $ atomically $ swapTMVar (getSide side $ netMessagesPushDeferred nm) S.empty
 		mapM_ rundeferred (S.toList s)
 	rundeferred m = (void . (E.try :: (IO () -> IO (Either SomeException ()))))
 		<~> handledeferred m
 
 {- While a push is running, matching push messages are put into
- - netMessagesPush, while others go to netMessagesDeferredPush.
+ - netMessagesPush, while others that involve the same side go to
+ - netMessagesDeferredPush.
+ -
+ - When no push is running involving the same side, returns False.
+ -
  - To avoid bloating memory, only messages that initiate pushes are
  - deferred.
- -
- - When no push is running, returns False.
  -}
 queueNetPushMessage :: NetMessage -> Assistant Bool
-queueNetPushMessage m = do
+queueNetPushMessage m@(Pushing clientid stage) = do
 	nm <- getAssistant netMessager
 	liftIO $ atomically $ do
-		running <- readTMVar (netMessagerPushRunning nm)
-		case running of
-			NoPushRunning -> return False
-			SendPushRunning runningcid -> do
-				go nm m runningcid
-				return True
-			ReceivePushRunning runningcid -> do
-				go nm m runningcid
-				return True
+		v <- readTMVar (getSide side $ netMessagerPushRunning nm)
+		case v of
+			Nothing -> return False
+			(Just runningclientid)
+				| runningclientid == clientid -> queue nm
+				| isPushInitiation stage -> defer nm
+				| otherwise -> discard
   where
-	go nm (Pushing cid stage) runningcid
-		| cid == runningcid = writeTChan (netMessagesPush nm) m
-		| isPushInitiation stage = defer nm
-		| otherwise = noop
-	go _ _ _ = noop
-
+	side = pushDestinationSide stage
+	queue nm = do
+		writeTChan (getSide side $ netMessagesPush nm) m
+		return True
 	defer nm = do
-		s <- takeTMVar (netMessagesDeferredPush nm)
-		putTMVar (netMessagesDeferredPush nm) $ S.insert m s
+		let mv = getSide side $ netMessagesPushDeferred nm
+		s <- takeTMVar mv
+		putTMVar mv $ S.insert m s
+		return True
+	discard = return True
+queueNetPushMessage _ = return False
 
-waitNetPushMessage :: Assistant (NetMessage)
-waitNetPushMessage = (atomically . readTChan) <<~ (netMessagesPush . netMessager)
+waitNetPushMessage :: PushSide -> Assistant (NetMessage)
+waitNetPushMessage side = (atomically . readTChan)
+	<<~ (getSide side . netMessagesPush . netMessager)
 
 {- Remotes using the XMPP transport have urls like xmpp::user@host -}
 isXMPPRemote :: Remote -> Bool