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.

P2P/Annex.hs

@@ -25,10 +25,8 @@ import Utility.Metered
 
 import Control.Monad.Free
 
--- When we're serving a peer, we know their uuid, and can use it to update
--- transfer logs.
 data RunMode
-	= Serving UUID
+	= Serving UUID ChangedRefsHandle
 	| Client
 
 -- Full interpreter for Proto, that can receive and send objects.
@@ -115,18 +113,17 @@ runLocal runmode runner a = case a of
 				protoaction False
 				next
 			Right _ -> runner next
-	WaitRefChange next -> do
+	WaitRefChange next -> case runmode of
-		v <- tryNonAsync $ bracket
+		Serving _ h -> do
-			watchChangedRefs
+			v <- tryNonAsync $ liftIO $ waitChangedRefs h
-			(liftIO . stopWatchingChangedRefs)
+			case v of
-			(liftIO . waitChangedRefs)
+				Left e -> return (Left (show e))
-		case v of
+				Right changedrefs -> runner (next changedrefs)
-			Left e -> return (Left (show e))
+		_ -> return $ Left "change notification not implemented for client"
-			Right changedrefs -> runner (next changedrefs)
   where
 	transfer mk k af ta = case runmode of
 		-- Update transfer logs when serving.
-		Serving theiruuid -> 
+		Serving theiruuid _ -> 
 			mk theiruuid k af noRetry ta noNotification
 		-- Transfer logs are updated higher in the stack when
 		-- a client.

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
+	setup = do
-	cleanup = hClose
+		h <- atomically $ readTBQueue q
-	go h = do
 		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
+				Right (Just theiruuid) -> authed conn theiruuid
-					v' <- runFullProto (Serving theiruuid) conn $
-						serveAuthed u
-					case v' of
-						Right () -> return ()
-						Left e -> liftIO $ debugM "remotedaemon" ("Tor connection error: " ++ e)
 				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)