only start ref change watcher thread once per P2P connection

This is more efficient. Note that the peer will get CHANGED messages for
all refs changed since the connection opened, even if those changes
happened before it sent NOTIFYCHANGE.

RemoteDaemon/Transport/Tor.hs

@@ -10,6 +10,7 @@ module RemoteDaemon.Transport.Tor (server) where
 import Common
 import qualified Annex
 import Annex.Concurrent
+import Annex.ChangedRefs
 import RemoteDaemon.Types
 import RemoteDaemon.Common
 import Utility.Tor
@@ -71,12 +72,18 @@ maxConnections :: Int
 maxConnections = 10
 
 serveClient :: TransportHandle -> UUID -> Repo -> TBQueue Handle -> IO ()
-serveClient th u r q = bracket setup cleanup go
+serveClient th u r q = bracket setup cleanup start
   where
-	setup = atomically $ readTBQueue q
-	cleanup = hClose
-	go h = do
+	setup = do
+		h <- atomically $ readTBQueue q
 		debugM "remotedaemon" "serving a Tor connection"
+		return h
+	
+	cleanup h = do
+		debugM "remotedaemon" "done with Tor connection"
+		hClose h
+
+	start h = do
 		-- Avoid doing any work in the liftAnnex, since only one
 		-- can run at a time.
 		st <- liftAnnex th dupState
@@ -92,16 +99,18 @@ serveClient th u r q = bracket setup cleanup go
 				}
 			v <- liftIO $ runNetProto conn $ serveAuth u
 			case v of
-				Right (Just theiruuid) -> void $ do
-					v' <- runFullProto (Serving theiruuid) conn $
-						serveAuthed u
-					case v' of
-						Right () -> return ()
-						Left e -> liftIO $ debugM "remotedaemon" ("Tor connection error: " ++ e)
+				Right (Just theiruuid) -> authed conn theiruuid
 				Right Nothing -> liftIO $
 					debugM "remotedaemon" "Tor connection failed to authenticate"
 				Left e -> liftIO $
 					debugM "remotedaemon" ("Tor connection error before authentication: " ++ e)
 		-- Merge the duplicated state back in.
 		liftAnnex th $ mergeState st'
-		debugM "remotedaemon" "done with Tor connection"
+	
+	authed conn theiruuid = 
+		bracket watchChangedRefs (liftIO . stopWatchingChangedRefs) $ \crh -> do
+			v' <- runFullProto (Serving theiruuid crh) conn $
+				serveAuthed u
+			case v' of
+				Right () -> return ()
+				Left e -> liftIO $ debugM "remotedaemon" ("Tor connection error: " ++ e)