discovery: thread contexts through sync manager

Here, we remove one context.TODO() by threading a context through to the
SyncManager.

discovery/gossiper.go

@@ -678,7 +678,7 @@ func (d *AuthenticatedGossiper) start(ctx context.Context) error {
 		return err
 	}
 
-	d.syncMgr.Start()
+	d.syncMgr.Start(ctx)
 
 	d.banman.start()
 

discovery/sync_manager.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/lnpeer"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/routing/route"
@@ -200,8 +201,9 @@ type SyncManager struct {
 	// number of queries.
 	rateLimiter *rate.Limiter
 
-	wg   sync.WaitGroup
+	wg     sync.WaitGroup
-	quit chan struct{}
+	quit   chan struct{}
+	cancel fn.Option[context.CancelFunc]
 }
 
 // newSyncManager constructs a new SyncManager backed by the given config.
@@ -246,10 +248,13 @@ func newSyncManager(cfg *SyncManagerCfg) *SyncManager {
 }
 
 // Start starts the SyncManager in order to properly carry out its duties.
-func (m *SyncManager) Start() {
+func (m *SyncManager) Start(ctx context.Context) {
 	m.start.Do(func() {
+		ctx, cancel := context.WithCancel(ctx)
+		m.cancel = fn.Some(cancel)
+
 		m.wg.Add(1)
-		go m.syncerHandler()
+		go m.syncerHandler(ctx)
 	})
 }
 
@@ -259,6 +264,7 @@ func (m *SyncManager) Stop() {
 		log.Debugf("SyncManager is stopping")
 		defer log.Debugf("SyncManager stopped")
 
+		m.cancel.WhenSome(func(fn context.CancelFunc) { fn() })
 		close(m.quit)
 		m.wg.Wait()
 
@@ -282,7 +288,7 @@ func (m *SyncManager) Stop() {
 //     much of the public network as possible.
 //
 // NOTE: This must be run as a goroutine.
-func (m *SyncManager) syncerHandler() {
+func (m *SyncManager) syncerHandler(ctx context.Context) {
 	defer m.wg.Done()
 
 	m.cfg.RotateTicker.Resume()
@@ -380,7 +386,7 @@ func (m *SyncManager) syncerHandler() {
 			}
 			m.syncersMu.Unlock()
 
-			s.Start(context.TODO())
+			s.Start(ctx)
 
 			// Once we create the GossipSyncer, we'll signal to the
 			// caller that they can proceed since the SyncManager's

discovery/sync_manager_test.go

@@ -2,6 +2,7 @@ package discovery
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"io"
 	"reflect"
@@ -82,7 +83,7 @@ func TestSyncManagerNumActiveSyncers(t *testing.T) {
 	}
 
 	syncMgr := newPinnedTestSyncManager(numActiveSyncers, pinnedSyncers)
-	syncMgr.Start()
+	syncMgr.Start(context.Background())
 	defer syncMgr.Stop()
 
 	// First we'll start by adding the pinned syncers. These should
@@ -134,7 +135,7 @@ func TestSyncManagerNewActiveSyncerAfterDisconnect(t *testing.T) {
 
 	// We'll create our test sync manager to have two active syncers.
 	syncMgr := newTestSyncManager(2)
-	syncMgr.Start()
+	syncMgr.Start(context.Background())
 	defer syncMgr.Stop()
 
 	// The first will be an active syncer that performs a historical sync
@@ -187,7 +188,7 @@ func TestSyncManagerRotateActiveSyncerCandidate(t *testing.T) {
 
 	// We'll create our sync manager with three active syncers.
 	syncMgr := newTestSyncManager(1)
-	syncMgr.Start()
+	syncMgr.Start(context.Background())
 	defer syncMgr.Stop()
 
 	// The first syncer registered always performs a historical sync.
@@ -235,7 +236,7 @@ func TestSyncManagerNoInitialHistoricalSync(t *testing.T) {
 	t.Parallel()
 
 	syncMgr := newTestSyncManager(0)
-	syncMgr.Start()
+	syncMgr.Start(context.Background())
 	defer syncMgr.Stop()
 
 	// We should not expect any messages from the peer.
@@ -269,7 +270,7 @@ func TestSyncManagerInitialHistoricalSync(t *testing.T) {
 		t.Fatal("expected graph to not be considered as synced")
 	}
 
-	syncMgr.Start()
+	syncMgr.Start(context.Background())
 	defer syncMgr.Stop()
 
 	// We should expect to see a QueryChannelRange message with a
@@ -338,7 +339,7 @@ func TestSyncManagerHistoricalSyncOnReconnect(t *testing.T) {
 	t.Parallel()
 
 	syncMgr := newTestSyncManager(2)
-	syncMgr.Start()
+	syncMgr.Start(context.Background())
 	defer syncMgr.Stop()
 
 	// We should expect to see a QueryChannelRange message with a
@@ -372,7 +373,7 @@ func TestSyncManagerForceHistoricalSync(t *testing.T) {
 	t.Parallel()
 
 	syncMgr := newTestSyncManager(1)
-	syncMgr.Start()
+	syncMgr.Start(context.Background())
 	defer syncMgr.Stop()
 
 	// We should expect to see a QueryChannelRange message with a
@@ -410,7 +411,7 @@ func TestSyncManagerGraphSyncedAfterHistoricalSyncReplacement(t *testing.T) {
 	t.Parallel()
 
 	syncMgr := newTestSyncManager(1)
-	syncMgr.Start()
+	syncMgr.Start(context.Background())
 	defer syncMgr.Stop()
 
 	// We should expect to see a QueryChannelRange message with a
@@ -468,7 +469,7 @@ func TestSyncManagerWaitUntilInitialHistoricalSync(t *testing.T) {
 	// We'll start by creating our test sync manager which will hold up to
 	// 2 active syncers.
 	syncMgr := newTestSyncManager(numActiveSyncers)
-	syncMgr.Start()
+	syncMgr.Start(context.Background())
 	defer syncMgr.Stop()
 
 	// We'll go ahead and create our syncers.