multi: Add atomic start/stop functions.

Make sure that each subsystem only starts and stop once. This makes
sure we don't close e.g. quit channels twice.

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()
@@ -198,13 +207,18 @@ 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)
@@ -213,6 +227,10 @@ func (c *ChannelEventStore) Stop() {
 	// Stop the ticker after the goroutine reading from it has exited, to
 	// avoid a race.
 	c.cfg.FlapCountTicker.Stop()
+
+	log.Debugf("ChannelEventStore shutdown complete")
+
+	return nil
 }
 
 // addChannel checks whether we are already tracking a channel's peer, creates a

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
@@ -217,15 +227,25 @@ 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()
 
+	log.Debug("InterceptableSwitch shutdown complete")
+
 	return nil
 }
 

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
@@ -213,33 +216,48 @@ 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")
 
@@ -248,6 +266,9 @@ func (i *InvoiceRegistry) Stop() error {
 	close(i.quit)
 
 	i.wg.Wait()
+
+	log.Debug("InvoiceRegistry shutdown complete")
+
 	return nil
 }
 

sweep/fee_bumper.go

@@ -261,6 +261,9 @@ type TxPublisherConfig struct {
 // until the tx is confirmed or the fee rate reaches the maximum fee rate
 // specified by the caller.
 type TxPublisher struct {
+	started atomic.Bool
+	stopped atomic.Bool
+
 	wg sync.WaitGroup
 
 	// cfg specifies the configuration of the TxPublisher.
@@ -666,7 +669,10 @@ type monitorRecord struct {
 // off the monitor loop.
 func (t *TxPublisher) Start() error {
 	log.Info("TxPublisher starting...")
-	defer log.Debugf("TxPublisher started")
+
+	if t.started.Swap(true) {
+		return fmt.Errorf("TxPublisher started more than once")
+	}
 
 	blockEvent, err := t.cfg.Notifier.RegisterBlockEpochNtfn(nil)
 	if err != nil {
@@ -676,17 +682,26 @@ func (t *TxPublisher) Start() error {
 	t.wg.Add(1)
 	go t.monitor(blockEvent)
 
+	log.Debugf("TxPublisher started")
+
 	return nil
 }
 
 // Stop stops the publisher and waits for the monitor loop to exit.
-func (t *TxPublisher) Stop() {
+func (t *TxPublisher) Stop() error {
 	log.Info("TxPublisher stopping...")
-	defer log.Debugf("TxPublisher stopped")
+
+	if t.stopped.Swap(true) {
+		return fmt.Errorf("TxPublisher stopped more than once")
+	}
 
 	close(t.quit)
-
 	t.wg.Wait()
+
+	log.Debug("TxPublisher stopped")
+
+	return nil
+
 }
 
 // monitor is the main loop driven by new blocks. Whevenr a new block arrives,