(squash commit) launch handleLocalResponse in GM

htlcswitch/switch.go

@@ -246,12 +246,6 @@ type Switch struct {
 	// This will be retrieved by the registered links atomically.
 	bestHeight uint32
 
-	// TODO(yy): remove handleLocalResponseWG, once handleLocalResponse runs
-	// without a goroutine. Currently we can't run handleLocalResponse in
-	// gm, since if gm is stopping, the goroutine won't start and it is
-	// unclear if it safe to skip handleLocalResponse.
-	handleLocalResponseWG sync.WaitGroup
-
 	// gm starts and stops tasks in goroutines and waits for them.
 	gm *fn.GoroutineManager
 
@@ -957,8 +951,6 @@ func (s *Switch) getLocalLink(pkt *htlcPacket, htlc *lnwire.UpdateAddHTLC) (
 //
 // NOTE: This method MUST be spawned as a goroutine.
 func (s *Switch) handleLocalResponse(pkt *htlcPacket) {
-	defer s.handleLocalResponseWG.Done()
-
 	attemptID := pkt.incomingHTLCID
 
 	// The error reason will be unencypted in case this a local
@@ -2025,9 +2017,6 @@ func (s *Switch) Stop() error {
 	// Ask running goroutines to stop and wait for them.
 	s.gm.Stop()
 
-	// TODO(yy): remove this, when s.handleLocalResponseWG is removed.
-	s.handleLocalResponseWG.Wait()
-
 	// Wait until all active goroutines have finished exiting before
 	// stopping the mailboxes, otherwise the mailbox map could still be
 	// accessed and modified.
@@ -3054,8 +3043,12 @@ func (s *Switch) handlePacketSettle(packet *htlcPacket) error {
 	// NOTE: `closeCircuit` modifies the state of `packet`.
 	if localHTLC {
 		// TODO(yy): remove the goroutine and send back the error here.
-		s.handleLocalResponseWG.Add(1)
-		go s.handleLocalResponse(packet)
+		err = s.gm.Go(func(ctx context.Context) {
+			s.handleLocalResponse(packet)
+		})
+		if err != nil {
+			return err
+		}
 
 		// If this is a locally initiated HTLC, there's no need to
 		// forward it so we exit.
@@ -3110,8 +3103,12 @@ func (s *Switch) handlePacketFail(packet *htlcPacket,
 	// NOTE: `closeCircuit` modifies the state of `packet`.
 	if packet.incomingChanID == hop.Source {
 		// TODO(yy): remove the goroutine and send back the error here.
-		s.handleLocalResponseWG.Add(1)
-		go s.handleLocalResponse(packet)
+		err = s.gm.Go(func(ctx context.Context) {
+			s.handleLocalResponse(packet)
+		})
+		if err != nil {
+			return err
+		}
 
 		// If this is a locally initiated HTLC, there's no need to
 		// forward it so we exit.