routing: shutdown chanrouter correctly.

chainntnfs/bitcoindnotify/bitcoind.go

@@ -151,7 +151,12 @@ func (b *BitcoindNotifier) Stop() error {
 
 		close(epochClient.epochChan)
 	}
-	b.txNotifier.TearDown()
+
+	// The txNotifier is only initialized in the start method therefore we
+	// need to make sure we don't access a nil pointer here.
+	if b.txNotifier != nil {
+		b.txNotifier.TearDown()
+	}
 
 	// Stop the mempool notifier.
 	b.memNotifier.TearDown()

chainntnfs/neutrinonotify/neutrino.go

@@ -152,7 +152,12 @@ func (n *NeutrinoNotifier) Stop() error {
 
 		close(epochClient.epochChan)
 	}
-	n.txNotifier.TearDown()
+
+	// The txNotifier is only initialized in the start method therefore we
+	// need to make sure we don't access a nil pointer here.
+	if n.txNotifier != nil {
+		n.txNotifier.TearDown()
+	}
 
 	return nil
 }

chanfitness/chaneventstore.go

@@ -12,7 +12,9 @@ package chanfitness
 
 import (
 	"errors"
+	"fmt"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/btcsuite/btcd/wire"
@@ -48,6 +50,9 @@ var (
 // ChannelEventStore maintains a set of event logs for the node's channels to
 // provide insight into the performance and health of channels.
 type ChannelEventStore struct {
+	started atomic.Bool
+	stopped atomic.Bool
+
 	cfg *Config
 
 	// peers tracks all of our currently monitored peers and their channels.
@@ -142,7 +147,11 @@ func NewChannelEventStore(config *Config) *ChannelEventStore {
 // information from the store. If this function fails, it cancels its existing
 // subscriptions and returns an error.
 func (c *ChannelEventStore) Start() error {
-	log.Info("ChannelEventStore starting")
+	log.Info("ChannelEventStore starting...")
+
+	if c.started.Swap(true) {
+		return fmt.Errorf("ChannelEventStore started more than once")
+	}
 
 	// Create a subscription to channel events.
 	channelClient, err := c.cfg.SubscribeChannelEvents()
@@ -198,21 +207,36 @@ func (c *ChannelEventStore) Start() error {
 		cancel:         cancel,
 	})
 
+	log.Debug("ChannelEventStore started")
+
 	return nil
 }
 
 // Stop terminates all goroutines started by the event store.
-func (c *ChannelEventStore) Stop() {
+func (c *ChannelEventStore) Stop() error {
 	log.Info("ChannelEventStore shutting down...")
-	defer log.Debug("ChannelEventStore shutdown complete")
+
+	if c.stopped.Swap(true) {
+		return fmt.Errorf("ChannelEventStore stopped more than once")
+	}
 
 	// Stop the consume goroutine.
 	close(c.quit)
 	c.wg.Wait()
 
 	// Stop the ticker after the goroutine reading from it has exited, to
 	// avoid a race.
-	c.cfg.FlapCountTicker.Stop()
+	var err error
+	if c.cfg.FlapCountTicker == nil {
+		err = fmt.Errorf("ChannelEventStore FlapCountTicker not " +
+			"initialized")
+	} else {
+		c.cfg.FlapCountTicker.Stop()
+	}
+
+	log.Debugf("ChannelEventStore shutdown complete")
+
+	return err
 }
 
 // addChannel checks whether we are already tracking a channel's peer, creates a

discovery/gossiper.go

@@ -753,7 +753,12 @@ func (d *AuthenticatedGossiper) stop() {
 	log.Debug("Authenticated Gossiper is stopping")
 	defer log.Debug("Authenticated Gossiper stopped")
 
-	d.blockEpochs.Cancel()
+	// `blockEpochs` is only initialized in the start routine so we make
+	// sure we don't panic here in the case where the `Stop` method is
+	// called when the `Start` method does not complete.
+	if d.blockEpochs != nil {
+		d.blockEpochs.Cancel()
+	}
 
 	d.syncMgr.Stop()
 

docs/release-notes/release-notes-0.18.3.md

@@ -35,6 +35,10 @@
 
 * [Fixed a bug](https://github.com/lightningnetwork/lnd/pull/8896) that caused
   LND to use a default fee rate for the batch channel opening flow.
+
+* [Fixed](https://github.com/lightningnetwork/lnd/pull/8497) a case where LND
+  would not shut down properly when interrupted via e.g. SIGTERM. Moreover, LND
+  now shutsdown correctly in case one subsystem fails to startup.
 
 * The fee limit for payments [was made
   compatible](https://github.com/lightningnetwork/lnd/pull/8941) with inbound

graph/builder.go

@@ -300,6 +300,8 @@ func (b *Builder) Start() error {
 	b.wg.Add(1)
 	go b.networkHandler()
 
+	log.Debug("Builder started")
+
 	return nil
 }
 
@@ -312,7 +314,6 @@ func (b *Builder) Stop() error {
 	}
 
 	log.Info("Builder shutting down...")
-	defer log.Debug("Builder shutdown complete")
 
 	// Our filtered chain view could've only been started if
 	// AssumeChannelValid isn't present.
@@ -325,6 +326,8 @@ func (b *Builder) Stop() error {
 	close(b.quit)
 	b.wg.Wait()
 
+	log.Debug("Builder shutdown complete")
+
 	return nil
 }
 

htlcswitch/interceptable_switch.go

@@ -4,6 +4,7 @@ import (
 	"crypto/sha256"
 	"fmt"
 	"sync"
+	"sync/atomic"
 
 	"github.com/go-errors/errors"
 	"github.com/lightningnetwork/lnd/chainntnfs"
@@ -33,6 +34,9 @@ var (
 // Settle - routes UpdateFulfillHTLC to the originating link.
 // Fail - routes UpdateFailHTLC to the originating link.
 type InterceptableSwitch struct {
+	started atomic.Bool
+	stopped atomic.Bool
+
 	// htlcSwitch is the underline switch
 	htlcSwitch *Switch
 
@@ -201,6 +205,12 @@ func (s *InterceptableSwitch) SetInterceptor(
 }
 
 func (s *InterceptableSwitch) Start() error {
+	log.Info("InterceptableSwitch starting...")
+
+	if s.started.Swap(true) {
+		return fmt.Errorf("InterceptableSwitch started more than once")
+	}
+
 	blockEpochStream, err := s.notifier.RegisterBlockEpochNtfn(nil)
 	if err != nil {
 		return err
@@ -217,14 +227,28 @@ func (s *InterceptableSwitch) Start() error {
 		}
 	}()
 
+	log.Debug("InterceptableSwitch started")
+
 	return nil
 }
 
 func (s *InterceptableSwitch) Stop() error {
+	log.Info("InterceptableSwitch shutting down...")
+
+	if s.stopped.Swap(true) {
+		return fmt.Errorf("InterceptableSwitch stopped more than once")
+	}
+
 	close(s.quit)
 	s.wg.Wait()
 
-	s.blockEpochStream.Cancel()
+	// We need to check whether the start routine run and initialized the
+	// `blockEpochStream`.
+	if s.blockEpochStream != nil {
+		s.blockEpochStream.Cancel()
+	}
+
+	log.Debug("InterceptableSwitch shutdown complete")
 
 	return nil
 }

htlcswitch/link.go

@@ -562,14 +562,18 @@ func (l *channelLink) Stop() {
 	}
 
 	// Ensure the channel for the timer is drained.
-	if !l.updateFeeTimer.Stop() {
-		select {
-		case <-l.updateFeeTimer.C:
-		default:
+	if l.updateFeeTimer != nil {
+		if !l.updateFeeTimer.Stop() {
+			select {
+			case <-l.updateFeeTimer.C:
+			default:
+			}
 		}
 	}
 
-	l.hodlQueue.Stop()
+	if l.hodlQueue != nil {
+		l.hodlQueue.Stop()
+	}
 
 	close(l.quit)
 	l.wg.Wait()

invoices/invoiceregistry.go

@@ -101,6 +101,9 @@ func (r *htlcReleaseEvent) Less(other queue.PriorityQueueItem) bool {
 // created by the daemon. The registry is a thin wrapper around a map in order
 // to ensure that all updates/reads are thread safe.
 type InvoiceRegistry struct {
+	started atomic.Bool
+	stopped atomic.Bool
+
 	sync.RWMutex
 
 	nextClientID uint32 // must be used atomically
@@ -213,42 +216,66 @@ func (i *InvoiceRegistry) scanInvoicesOnStart(ctx context.Context) error {
 
 // Start starts the registry and all goroutines it needs to carry out its task.
 func (i *InvoiceRegistry) Start() error {
-	// Start InvoiceExpiryWatcher and prepopulate it with existing active
-	// invoices.
-	err := i.expiryWatcher.Start(func(hash lntypes.Hash, force bool) error {
-		return i.cancelInvoiceImpl(context.Background(), hash, force)
-	})
+	var err error
+
+	log.Info("InvoiceRegistry starting...")
+
+	if i.started.Swap(true) {
+		return fmt.Errorf("InvoiceRegistry started more than once")
+	}
+	// Start InvoiceExpiryWatcher and prepopulate it with existing
+	// active invoices.
+	err = i.expiryWatcher.Start(
+		func(hash lntypes.Hash, force bool) error {
+			return i.cancelInvoiceImpl(
+				context.Background(), hash, force,
+			)
+		})
 	if err != nil {
 		return err
 	}
 
-	log.Info("InvoiceRegistry starting")
-
 	i.wg.Add(1)
 	go i.invoiceEventLoop()
 
-	// Now scan all pending and removable invoices to the expiry watcher or
-	// delete them.
+	// Now scan all pending and removable invoices to the expiry
+	// watcher or delete them.
 	err = i.scanInvoicesOnStart(context.Background())
 	if err != nil {
 		_ = i.Stop()
-		return err
 	}
 
-	return nil
+	log.Debug("InvoiceRegistry started")
+
+	return err
 }
 
 // Stop signals the registry for a graceful shutdown.
 func (i *InvoiceRegistry) Stop() error {
+	log.Info("InvoiceRegistry shutting down...")
+
+	if i.stopped.Swap(true) {
+		return fmt.Errorf("InvoiceRegistry stopped more than once")
+	}
+
 	log.Info("InvoiceRegistry shutting down...")
 	defer log.Debug("InvoiceRegistry shutdown complete")
 
-	i.expiryWatcher.Stop()
+	var err error
+	if i.expiryWatcher == nil {
+		err = fmt.Errorf("InvoiceRegistry expiryWatcher is not " +
+			"initialized")
+	} else {
+		i.expiryWatcher.Stop()
+	}
 
 	close(i.quit)
 
 	i.wg.Wait()
-	return nil
+
+	log.Debug("InvoiceRegistry shutdown complete")
+
+	return err
 }
 
 // invoiceEvent represents a new event that has modified on invoice on disk.

lnd.go

@@ -674,11 +674,33 @@ func Main(cfg *Config, lisCfg ListenerCfg, implCfg *ImplementationCfg,
 		bestHeight)
 
 	// With all the relevant chains initialized, we can finally start the
-	// server itself.
-	if err := server.Start(); err != nil {
+	// server itself. We start the server in an asynchronous goroutine so
+	// that we are able to interrupt and shutdown the daemon gracefully in
+	// case the startup of the subservers do not behave as expected.
+	errChan := make(chan error)
+	go func() {
+		errChan <- server.Start()
+	}()
+
+	defer func() {
+		err := server.Stop()
+		if err != nil {
+			ltndLog.Warnf("Stopping the server including all "+
+				"its subsystems failed with %v", err)
+		}
+	}()
+
+	select {
+	case err := <-errChan:
+		if err == nil {
+			break
+		}
+
 		return mkErr("unable to start server: %v", err)
+
+	case <-interceptor.ShutdownChannel():
+		return nil
 	}
-	defer server.Stop()
 
 	// We transition the server state to Active, as the server is up.
 	interceptorChain.SetServerActive()

lnwallet/chainfee/estimator.go

@@ -884,7 +884,9 @@ func (w *WebAPIEstimator) Stop() error {
 		return nil
 	}
 
-	w.updateFeeTicker.Stop()
+	if w.updateFeeTicker != nil {
+		w.updateFeeTicker.Stop()
+	}
 
 	close(w.quit)
 	w.wg.Wait()