htlcswitch: in event of duplicate link add, prefer newer link

htlcswitch/switch.go

@@ -1723,11 +1723,11 @@ func (s *Switch) AddLink(link ChannelLink) error {
 
 	chanID := link.ChanID()
 
-	// First, ensure that this link is not already active in the switch.
+	// If a link already exists, then remove the prior one so we can
+	// replace it with this fresh instance.
 	_, err := s.getLink(chanID)
 	if err == nil {
-		return fmt.Errorf("unable to add ChannelLink(%v), already "+
+		s.removeLink(chanID)
-			"active", chanID)
 	}
 
 	// Get and attach the mailbox for this link, which buffers packets in

htlcswitch/switch_test.go

@@ -25,65 +25,6 @@ func genPreimage() ([32]byte, error) {
 	return preimage, nil
 }
 
-// TestSwitchAddDuplicateLink tests that the switch will reject duplicate links
-// for both pending and live links. It also tests that we can successfully
-// add a link after having removed it.
-func TestSwitchAddDuplicateLink(t *testing.T) {
-	t.Parallel()
-
-	alicePeer, err := newMockServer(t, "alice", nil)
-	if err != nil {
-		t.Fatalf("unable to create alice server: %v", err)
-	}
-
-	s, err := initSwitchWithDB(nil)
-	if err != nil {
-		t.Fatalf("unable to init switch: %v", err)
-	}
-	if err := s.Start(); err != nil {
-		t.Fatalf("unable to start switch: %v", err)
-	}
-	defer s.Stop()
-
-	chanID1, _, aliceChanID, _ := genIDs()
-
-	pendingChanID := lnwire.ShortChannelID{}
-
-	aliceChannelLink := newMockChannelLink(
-		s, chanID1, pendingChanID, alicePeer, false,
-	)
-	if err := s.AddLink(aliceChannelLink); err != nil {
-		t.Fatalf("unable to add alice link: %v", err)
-	}
-
-	// Alice should have a pending link, adding again should fail.
-	if err := s.AddLink(aliceChannelLink); err == nil {
-		t.Fatalf("adding duplicate link should have failed")
-	}
-
-	// Update the short chan id of the channel, so that the link goes live.
-	aliceChannelLink.setLiveShortChanID(aliceChanID)
-	err = s.UpdateShortChanID(chanID1)
-	if err != nil {
-		t.Fatalf("unable to update alice short_chan_id: %v", err)
-	}
-
-	// Alice should have a live link, adding again should fail.
-	if err := s.AddLink(aliceChannelLink); err == nil {
-		t.Fatalf("adding duplicate link should have failed")
-	}
-
-	// Remove the live link to ensure the indexes are cleared.
-	if err := s.RemoveLink(chanID1); err != nil {
-		t.Fatalf("unable to remove alice link: %v", err)
-	}
-
-	// Alice has no links, adding should succeed.
-	if err := s.AddLink(aliceChannelLink); err != nil {
-		t.Fatalf("unable to add alice link: %v", err)
-	}
-}
-
 // TestSwitchSendPending checks the inability of htlc switch to forward adds
 // over pending links, and the UpdateShortChanID makes a pending link live.
 func TestSwitchSendPending(t *testing.T) {

peer.go

@@ -1529,8 +1529,8 @@ out:
 				chainEvents, currentHeight, false)
 			if err != nil {
 				peerLog.Errorf("can't register new channel "+
-					"link(%v) with NodeKey(%x)", chanPoint,
+					"link(%v) with NodeKey(%x): %v", chanPoint,
-					p.PubKey())
+					p.PubKey(), err)
 			}
 
 			close(newChanReq.done)