channelnotifier+discover+invoices: return error in Stop functions

In order to be consistent with other sub systems an error is now
returned from the Stop functions.
This also allows writing a generic cleanup mechanism to stop all
sub systems in case of a failure.

channelnotifier/channelnotifier.go

@@ -86,10 +86,12 @@ func (c *ChannelNotifier) Start() error {
 }
 
 // Stop signals the notifier for a graceful shutdown.
-func (c *ChannelNotifier) Stop() {
+func (c *ChannelNotifier) Stop() error {
+	var err error
 	c.stopped.Do(func() {
-		c.ntfnServer.Stop()
+		err = c.ntfnServer.Stop()
 	})
+	return err
 }
 
 // SubscribeChannelEvents returns a subscribe.Client that will receive updates

discovery/gossiper.go

@@ -461,8 +461,9 @@ func (d *AuthenticatedGossiper) start() error {
 }
 
 // Stop signals any active goroutines for a graceful closure.
-func (d *AuthenticatedGossiper) Stop() {
+func (d *AuthenticatedGossiper) Stop() error {
 	d.stopped.Do(d.stop)
+	return nil
 }
 
 func (d *AuthenticatedGossiper) stop() {

funding/manager.go

@@ -675,12 +675,14 @@ func (f *Manager) start() error {
 
 // Stop signals all helper goroutines to execute a graceful shutdown. This
 // method will block until all goroutines have exited.
-func (f *Manager) Stop() {
+func (f *Manager) Stop() error {
 	f.stopped.Do(func() {
 		log.Info("Funding manager shutting down")
 		close(f.quit)
 		f.wg.Wait()
 	})
+
+	return nil
 }
 
 // nextPendingChanID returns the next free pending channel ID to be used to

funding/manager_test.go

@@ -484,7 +484,9 @@ func createTestFundingManager(t *testing.T, privKey *btcec.PrivateKey,
 func recreateAliceFundingManager(t *testing.T, alice *testNode) {
 	// Stop the old fundingManager before creating a new one.
 	close(alice.shutdownChannel)
-	alice.fundingMgr.Stop()
+	if err := alice.fundingMgr.Stop(); err != nil {
+		t.Fatalf("failed stop funding manager: %v", err)
+	}
 
 	aliceMsgChan := make(chan lnwire.Message)
 	aliceAnnounceChan := make(chan lnwire.Message)
@@ -622,8 +624,12 @@ func tearDownFundingManagers(t *testing.T, a, b *testNode) {
 	close(a.shutdownChannel)
 	close(b.shutdownChannel)
 
-	a.fundingMgr.Stop()
+	if err := a.fundingMgr.Stop(); err != nil {
-	b.fundingMgr.Stop()
+		t.Fatalf("failed stop funding manager: %v", err)
+	}
+	if err := b.fundingMgr.Stop(); err != nil {
+		t.Fatalf("failed stop funding manager: %v", err)
+	}
 	os.RemoveAll(a.testDir)
 	os.RemoveAll(b.testDir)
 }
@@ -1502,7 +1508,9 @@ func TestFundingManagerRestartBehavior(t *testing.T) {
 	// implementation, and expect it to retry sending the fundingLocked
 	// message. We'll explicitly shut down Alice's funding manager to
 	// prevent a race when overriding the sendMessage implementation.
-	alice.fundingMgr.Stop()
+	if err := alice.fundingMgr.Stop(); err != nil {
+		t.Fatalf("failed stop funding manager: %v", err)
+	}
 	bob.sendMessage = workingSendMessage
 	recreateAliceFundingManager(t, alice)
 

htlcswitch/htlcnotifier.go

@@ -87,12 +87,14 @@ func (h *HtlcNotifier) Start() error {
 }
 
 // Stop signals the notifier for a graceful shutdown.
-func (h *HtlcNotifier) Stop() {
+func (h *HtlcNotifier) Stop() error {
+	var err error
 	h.stopped.Do(func() {
-		if err := h.ntfnServer.Stop(); err != nil {
+		if err = h.ntfnServer.Stop(); err != nil {
 			log.Warnf("error stopping htlc notifier: %v", err)
 		}
 	})
+	return err
 }
 
 // SubscribeHtlcEvents returns a subscribe.Client that will receive updates

htlcswitch/switch_test.go

@@ -2867,19 +2867,31 @@ func testHtcNotifier(t *testing.T, testOpts []serverOption, iterations int,
 	if err := aliceNotifier.Start(); err != nil {
 		t.Fatalf("could not start alice notifier")
 	}
-	defer aliceNotifier.Stop()
+	defer func() {
+		if err := aliceNotifier.Stop(); err != nil {
+			t.Fatalf("failed to stop alice notifier: %v", err)
+		}
+	}()
 
 	bobNotifier := NewHtlcNotifier(mockTime)
 	if err := bobNotifier.Start(); err != nil {
 		t.Fatalf("could not start bob notifier")
 	}
-	defer bobNotifier.Stop()
+	defer func() {
+		if err := bobNotifier.Stop(); err != nil {
+			t.Fatalf("failed to stop bob notifier: %v", err)
+		}
+	}()
 
 	carolNotifier := NewHtlcNotifier(mockTime)
 	if err := carolNotifier.Start(); err != nil {
 		t.Fatalf("could not start carol notifier")
 	}
-	defer carolNotifier.Stop()
+	defer func() {
+		if err := carolNotifier.Stop(); err != nil {
+			t.Fatalf("failed to stop carol notifier: %v", err)
+		}
+	}()
 
 	// Create a notifier server option which will set our htlc notifiers
 	// for the three hop network.

invoices/invoiceregistry.go

@@ -237,7 +237,7 @@ func (i *InvoiceRegistry) Start() error {
 	// delete them.
 	err = i.scanInvoicesOnStart()
 	if err != nil {
-		i.Stop()
+		_ = i.Stop()
 		return err
 	}
 
@@ -245,12 +245,13 @@ func (i *InvoiceRegistry) Start() error {
 }
 
 // Stop signals the registry for a graceful shutdown.
-func (i *InvoiceRegistry) Stop() {
+func (i *InvoiceRegistry) Stop() error {
 	i.expiryWatcher.Stop()
 
 	close(i.quit)
 
 	i.wg.Wait()
+	return nil
 }
 
 // invoiceEvent represents a new event that has modified on invoice on disk.

invoices/invoiceregistry_test.go

@@ -527,7 +527,11 @@ func TestCancelHoldInvoice(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer registry.Stop()
+	defer func() {
+		if err := registry.Stop(); err != nil {
+			t.Fatalf("failed to stop invoice registry: %v", err)
+		}
+	}()
 
 	// Add the invoice.
 	_, err = registry.AddInvoice(testHodlInvoice, testInvoicePaymentHash)
@@ -1005,7 +1009,9 @@ func TestInvoiceExpiryWithRegistry(t *testing.T) {
 
 	// Give some time to the watcher to cancel everything.
 	time.Sleep(500 * time.Millisecond)
-	registry.Stop()
+	if err = registry.Stop(); err != nil {
+		t.Fatalf("failed to stop invoice registry: %v", err)
+	}
 
 	// Create the expected cancellation set before the final check.
 	expectedCancellations = append(

invoices/test_utils_test.go

@@ -215,7 +215,9 @@ func newTestContext(t *testing.T) *testContext {
 		clock:    clock,
 		t:        t,
 		cleanup: func() {
-			registry.Stop()
+			if err = registry.Stop(); err != nil {
+				t.Fatalf("failed to stop invoice registry: %v", err)
+			}
 			cleanup()
 		},
 	}

peernotifier/peernotifier.go

@@ -49,11 +49,13 @@ func (p *PeerNotifier) Start() error {
 }
 
 // Stop signals the notifier for a graceful shutdown.
-func (p *PeerNotifier) Stop() {
+func (p *PeerNotifier) Stop() error {
+	var err error
 	p.stopped.Do(func() {
 		log.Info("Stopping PeerNotifier")
-		p.ntfnServer.Stop()
+		err = p.ntfnServer.Stop()
 	})
+	return err
 }
 
 // SubscribePeerEvents returns a subscribe.Client that will receive updates