Merge pull request #2932 from wpaulino/sync-manager-improvements

discovery: SyncManager improvements

discovery/gossiper.go

@@ -306,12 +306,11 @@ func New(cfg Config, selfKey *btcec.PublicKey) *AuthenticatedGossiper {
 		channelMtx:              multimutex.NewMutex(),
 		recentRejects:           make(map[uint64]struct{}),
 		syncMgr: newSyncManager(&SyncManagerCfg{
-			ChainHash:                 cfg.ChainHash,
-			ChanSeries:                cfg.ChanSeries,
-			RotateTicker:              cfg.RotateTicker,
-			HistoricalSyncTicker:      cfg.HistoricalSyncTicker,
-			ActiveSyncerTimeoutTicker: cfg.ActiveSyncerTimeoutTicker,
-			NumActiveSyncers:          cfg.NumActiveSyncers,
+			ChainHash:            cfg.ChainHash,
+			ChanSeries:           cfg.ChanSeries,
+			RotateTicker:         cfg.RotateTicker,
+			HistoricalSyncTicker: cfg.HistoricalSyncTicker,
+			NumActiveSyncers:     cfg.NumActiveSyncers,
 		}),
 	}
 

discovery/gossiper_test.go

@@ -741,17 +741,16 @@ func createTestCtx(startHeight uint32) (*testCtx, func(), error) {
 			c := make(chan struct{})
 			return c
 		},
-		Router:                    router,
-		TrickleDelay:              trickleDelay,
-		RetransmitDelay:           retransmitDelay,
-		ProofMatureDelta:          proofMatureDelta,
-		WaitingProofStore:         waitingProofStore,
-		MessageStore:              newMockMessageStore(),
-		RotateTicker:              ticker.NewForce(DefaultSyncerRotationInterval),
-		HistoricalSyncTicker:      ticker.NewForce(DefaultHistoricalSyncInterval),
-		ActiveSyncerTimeoutTicker: ticker.NewForce(DefaultActiveSyncerTimeout),
-		NumActiveSyncers:          3,
-		AnnSigner:                 &mockSigner{nodeKeyPriv1},
+		Router:               router,
+		TrickleDelay:         trickleDelay,
+		RetransmitDelay:      retransmitDelay,
+		ProofMatureDelta:     proofMatureDelta,
+		WaitingProofStore:    waitingProofStore,
+		MessageStore:         newMockMessageStore(),
+		RotateTicker:         ticker.NewForce(DefaultSyncerRotationInterval),
+		HistoricalSyncTicker: ticker.NewForce(DefaultHistoricalSyncInterval),
+		NumActiveSyncers:     3,
+		AnnSigner:            &mockSigner{nodeKeyPriv1},
 	}, nodeKeyPub1)
 
 	if err := gossiper.Start(); err != nil {
@@ -1480,20 +1479,19 @@ func TestSignatureAnnouncementRetryAtStartup(t *testing.T) {
 	// the message to the peer.
 	ctx.gossiper.Stop()
 	gossiper := New(Config{
-		Notifier:                  ctx.gossiper.cfg.Notifier,
-		Broadcast:                 ctx.gossiper.cfg.Broadcast,
-		NotifyWhenOnline:          ctx.gossiper.reliableSender.cfg.NotifyWhenOnline,
-		NotifyWhenOffline:         ctx.gossiper.reliableSender.cfg.NotifyWhenOffline,
-		Router:                    ctx.gossiper.cfg.Router,
-		TrickleDelay:              trickleDelay,
-		RetransmitDelay:           retransmitDelay,
-		ProofMatureDelta:          proofMatureDelta,
-		WaitingProofStore:         ctx.gossiper.cfg.WaitingProofStore,
-		MessageStore:              ctx.gossiper.cfg.MessageStore,
-		RotateTicker:              ticker.NewForce(DefaultSyncerRotationInterval),
-		HistoricalSyncTicker:      ticker.NewForce(DefaultHistoricalSyncInterval),
-		ActiveSyncerTimeoutTicker: ticker.NewForce(DefaultActiveSyncerTimeout),
-		NumActiveSyncers:          3,
+		Notifier:             ctx.gossiper.cfg.Notifier,
+		Broadcast:            ctx.gossiper.cfg.Broadcast,
+		NotifyWhenOnline:     ctx.gossiper.reliableSender.cfg.NotifyWhenOnline,
+		NotifyWhenOffline:    ctx.gossiper.reliableSender.cfg.NotifyWhenOffline,
+		Router:               ctx.gossiper.cfg.Router,
+		TrickleDelay:         trickleDelay,
+		RetransmitDelay:      retransmitDelay,
+		ProofMatureDelta:     proofMatureDelta,
+		WaitingProofStore:    ctx.gossiper.cfg.WaitingProofStore,
+		MessageStore:         ctx.gossiper.cfg.MessageStore,
+		RotateTicker:         ticker.NewForce(DefaultSyncerRotationInterval),
+		HistoricalSyncTicker: ticker.NewForce(DefaultHistoricalSyncInterval),
+		NumActiveSyncers:     3,
 	}, ctx.gossiper.selfKey)
 	if err != nil {
 		t.Fatalf("unable to recreate gossiper: %v", err)

discovery/mock_test.go

@@ -1,6 +1,7 @@
 package discovery
 
 import (
+	"errors"
 	"net"
 	"sync"
 
@@ -30,6 +31,7 @@ func (p *mockPeer) SendMessage(_ bool, msgs ...lnwire.Message) error {
 		select {
 		case p.sentMsgs <- msg:
 		case <-p.quit:
+			return errors.New("peer disconnected")
 		}
 	}
 

discovery/sync_manager_test.go

@@ -30,11 +30,10 @@ func randPeer(t *testing.T, quit chan struct{}) *mockPeer {
 func newTestSyncManager(numActiveSyncers int) *SyncManager {
 	hID := lnwire.ShortChannelID{BlockHeight: latestKnownHeight}
 	return newSyncManager(&SyncManagerCfg{
-		ChanSeries:                newMockChannelGraphTimeSeries(hID),
-		RotateTicker:              ticker.NewForce(DefaultSyncerRotationInterval),
-		HistoricalSyncTicker:      ticker.NewForce(DefaultHistoricalSyncInterval),
-		ActiveSyncerTimeoutTicker: ticker.NewForce(DefaultActiveSyncerTimeout),
-		NumActiveSyncers:          numActiveSyncers,
+		ChanSeries:           newMockChannelGraphTimeSeries(hID),
+		RotateTicker:         ticker.NewForce(DefaultSyncerRotationInterval),
+		HistoricalSyncTicker: ticker.NewForce(DefaultHistoricalSyncInterval),
+		NumActiveSyncers:     numActiveSyncers,
 	})
 }
 
@@ -57,21 +56,22 @@ func TestSyncManagerNumActiveSyncers(t *testing.T) {
 	for i := 0; i < numActiveSyncers; i++ {
 		peer := randPeer(t, syncMgr.quit)
 		syncMgr.InitSyncState(peer)
+		s := assertSyncerExistence(t, syncMgr, peer)
 
 		// The first syncer registered always attempts a historical
 		// sync.
 		if i == 0 {
-			assertTransitionToChansSynced(t, syncMgr, peer, true)
+			assertTransitionToChansSynced(t, s, peer)
 		}
-
-		assertPassiveSyncerTransition(t, syncMgr, peer)
-		assertSyncerStatus(t, syncMgr, peer, chansSynced, ActiveSync)
+		assertActiveGossipTimestampRange(t, peer)
+		assertSyncerStatus(t, s, chansSynced, ActiveSync)
 	}
 
 	for i := 0; i < numSyncers-numActiveSyncers; i++ {
 		peer := randPeer(t, syncMgr.quit)
 		syncMgr.InitSyncState(peer)
-		assertSyncerStatus(t, syncMgr, peer, chansSynced, PassiveSync)
+		s := assertSyncerExistence(t, syncMgr, peer)
+		assertSyncerStatus(t, s, chansSynced, PassiveSync)
 	}
 }
 
@@ -80,39 +80,52 @@ func TestSyncManagerNumActiveSyncers(t *testing.T) {
 func TestSyncManagerNewActiveSyncerAfterDisconnect(t *testing.T) {
 	t.Parallel()
 
-	// We'll create our test sync manager to only have one active syncer.
-	syncMgr := newTestSyncManager(1)
+	// We'll create our test sync manager to have two active syncers.
+	syncMgr := newTestSyncManager(2)
 	syncMgr.Start()
 	defer syncMgr.Stop()
 
-	// peer1 will represent an active syncer that performs a historical
-	// sync since it is the first registered peer with the SyncManager.
-	peer1 := randPeer(t, syncMgr.quit)
-	syncMgr.InitSyncState(peer1)
-	assertTransitionToChansSynced(t, syncMgr, peer1, true)
-	assertPassiveSyncerTransition(t, syncMgr, peer1)
+	// The first will be an active syncer that performs a historical sync
+	// since it is the first one registered with the SyncManager.
+	historicalSyncPeer := randPeer(t, syncMgr.quit)
+	syncMgr.InitSyncState(historicalSyncPeer)
+	historicalSyncer := assertSyncerExistence(t, syncMgr, historicalSyncPeer)
+	assertTransitionToChansSynced(t, historicalSyncer, historicalSyncPeer)
+	assertActiveGossipTimestampRange(t, historicalSyncPeer)
+	assertSyncerStatus(t, historicalSyncer, chansSynced, ActiveSync)
+
+	// Then, we'll create the second active syncer, which is the one we'll
+	// disconnect.
+	activeSyncPeer := randPeer(t, syncMgr.quit)
+	syncMgr.InitSyncState(activeSyncPeer)
+	activeSyncer := assertSyncerExistence(t, syncMgr, activeSyncPeer)
+	assertActiveGossipTimestampRange(t, activeSyncPeer)
+	assertSyncerStatus(t, activeSyncer, chansSynced, ActiveSync)
 
 	// It will then be torn down to simulate a disconnection. Since there
 	// are no other candidate syncers available, the active syncer won't be
 	// replaced.
-	syncMgr.PruneSyncState(peer1.PubKey())
+	syncMgr.PruneSyncState(activeSyncPeer.PubKey())
 
 	// Then, we'll start our active syncer again, but this time we'll also
 	// have a passive syncer available to replace the active syncer after
 	// the peer disconnects.
-	syncMgr.InitSyncState(peer1)
-	assertPassiveSyncerTransition(t, syncMgr, peer1)
+	syncMgr.InitSyncState(activeSyncPeer)
+	activeSyncer = assertSyncerExistence(t, syncMgr, activeSyncPeer)
+	assertActiveGossipTimestampRange(t, activeSyncPeer)
+	assertSyncerStatus(t, activeSyncer, chansSynced, ActiveSync)
 
 	// Create our second peer, which should be initialized as a passive
 	// syncer.
-	peer2 := randPeer(t, syncMgr.quit)
-	syncMgr.InitSyncState(peer2)
-	assertSyncerStatus(t, syncMgr, peer2, chansSynced, PassiveSync)
+	newActiveSyncPeer := randPeer(t, syncMgr.quit)
+	syncMgr.InitSyncState(newActiveSyncPeer)
+	newActiveSyncer := assertSyncerExistence(t, syncMgr, newActiveSyncPeer)
+	assertSyncerStatus(t, newActiveSyncer, chansSynced, PassiveSync)
 
 	// Disconnect our active syncer, which should trigger the SyncManager to
 	// replace it with our passive syncer.
-	syncMgr.PruneSyncState(peer1.PubKey())
-	assertPassiveSyncerTransition(t, syncMgr, peer2)
+	go syncMgr.PruneSyncState(activeSyncPeer.PubKey())
+	assertPassiveSyncerTransition(t, newActiveSyncer, newActiveSyncPeer)
 }
 
 // TestSyncManagerRotateActiveSyncerCandidate tests that we can successfully
@@ -128,19 +141,22 @@ func TestSyncManagerRotateActiveSyncerCandidate(t *testing.T) {
 	// The first syncer registered always performs a historical sync.
 	activeSyncPeer := randPeer(t, syncMgr.quit)
 	syncMgr.InitSyncState(activeSyncPeer)
-	assertTransitionToChansSynced(t, syncMgr, activeSyncPeer, true)
-	assertPassiveSyncerTransition(t, syncMgr, activeSyncPeer)
+	activeSyncer := assertSyncerExistence(t, syncMgr, activeSyncPeer)
+	assertTransitionToChansSynced(t, activeSyncer, activeSyncPeer)
+	assertActiveGossipTimestampRange(t, activeSyncPeer)
+	assertSyncerStatus(t, activeSyncer, chansSynced, ActiveSync)
 
 	// We'll send a tick to force a rotation. Since there aren't any
 	// candidates, none of the active syncers will be rotated.
 	syncMgr.cfg.RotateTicker.(*ticker.Force).Force <- time.Time{}
 	assertNoMsgSent(t, activeSyncPeer)
-	assertSyncerStatus(t, syncMgr, activeSyncPeer, chansSynced, ActiveSync)
+	assertSyncerStatus(t, activeSyncer, chansSynced, ActiveSync)
 
 	// We'll then go ahead and add a passive syncer.
 	passiveSyncPeer := randPeer(t, syncMgr.quit)
 	syncMgr.InitSyncState(passiveSyncPeer)
-	assertSyncerStatus(t, syncMgr, passiveSyncPeer, chansSynced, PassiveSync)
+	passiveSyncer := assertSyncerExistence(t, syncMgr, passiveSyncPeer)
+	assertSyncerStatus(t, passiveSyncer, chansSynced, PassiveSync)
 
 	// We'll force another rotation - this time, since we have a passive
 	// syncer available, they should be rotated.
@@ -149,7 +165,7 @@ func TestSyncManagerRotateActiveSyncerCandidate(t *testing.T) {
 	// The transition from an active syncer to a passive syncer causes the
 	// peer to send out a new GossipTimestampRange in the past so that they
 	// don't receive new graph updates.
-	assertActiveSyncerTransition(t, syncMgr, activeSyncPeer)
+	assertActiveSyncerTransition(t, activeSyncer, activeSyncPeer)
 
 	// The transition from a passive syncer to an active syncer causes the
 	// peer to send a new GossipTimestampRange with the current timestamp to
@@ -158,13 +174,54 @@ func TestSyncManagerRotateActiveSyncerCandidate(t *testing.T) {
 	// machine, starting from its initial syncingChans state. We'll then
 	// need to transition it to its final chansSynced state to ensure the
 	// next syncer is properly started in the round-robin.
-	assertPassiveSyncerTransition(t, syncMgr, passiveSyncPeer)
+	assertPassiveSyncerTransition(t, passiveSyncer, passiveSyncPeer)
 }
 
-// TestSyncManagerHistoricalSync ensures that we only attempt a single
-// historical sync during the SyncManager's startup, and that we can routinely
-// force historical syncs whenever the HistoricalSyncTicker fires.
-func TestSyncManagerHistoricalSync(t *testing.T) {
+// TestSyncManagerInitialHistoricalSync ensures that we only attempt a single
+// historical sync during the SyncManager's startup. If the peer corresponding
+// to the initial historical syncer disconnects, we should attempt to find a
+// replacement.
+func TestSyncManagerInitialHistoricalSync(t *testing.T) {
+	t.Parallel()
+
+	syncMgr := newTestSyncManager(0)
+	syncMgr.Start()
+	defer syncMgr.Stop()
+
+	// We should expect to see a QueryChannelRange message with a
+	// FirstBlockHeight of the genesis block, signaling that an initial
+	// historical sync is being attempted.
+	peer := randPeer(t, syncMgr.quit)
+	syncMgr.InitSyncState(peer)
+	assertMsgSent(t, peer, &lnwire.QueryChannelRange{
+		FirstBlockHeight: 0,
+		NumBlocks:        math.MaxUint32,
+	})
+
+	// If an additional peer connects, then another historical sync should
+	// not be attempted.
+	finalHistoricalPeer := randPeer(t, syncMgr.quit)
+	syncMgr.InitSyncState(finalHistoricalPeer)
+	finalHistoricalSyncer := assertSyncerExistence(t, syncMgr, finalHistoricalPeer)
+	assertNoMsgSent(t, finalHistoricalPeer)
+
+	// If we disconnect the peer performing the initial historical sync, a
+	// new one should be chosen.
+	syncMgr.PruneSyncState(peer.PubKey())
+	assertTransitionToChansSynced(t, finalHistoricalSyncer, finalHistoricalPeer)
+
+	// Once the initial historical sync has succeeded, another one should
+	// not be attempted by disconnecting the peer who performed it.
+	extraPeer := randPeer(t, syncMgr.quit)
+	syncMgr.InitSyncState(extraPeer)
+	assertNoMsgSent(t, extraPeer)
+	syncMgr.PruneSyncState(finalHistoricalPeer.PubKey())
+	assertNoMsgSent(t, extraPeer)
+}
+
+// TestSyncManagerForceHistoricalSync ensures that we can perform routine
+// historical syncs whenever the HistoricalSyncTicker fires.
+func TestSyncManagerForceHistoricalSync(t *testing.T) {
 	t.Parallel()
 
 	syncMgr := newTestSyncManager(0)
@@ -197,190 +254,64 @@ func TestSyncManagerHistoricalSync(t *testing.T) {
 	})
 }
 
-// TestSyncManagerRoundRobinQueue ensures that any subsequent active syncers can
-// only be started after the previous one has completed its state machine.
-func TestSyncManagerRoundRobinQueue(t *testing.T) {
+// TestSyncManagerWaitUntilInitialHistoricalSync ensures that no GossipSyncers
+// are initialized as ActiveSync until the initial historical sync has been
+// completed. Once it does, the pending GossipSyncers should be transitioned to
+// ActiveSync.
+func TestSyncManagerWaitUntilInitialHistoricalSync(t *testing.T) {
 	t.Parallel()
 
-	const numActiveSyncers = 3
+	const numActiveSyncers = 2
 
-	// We'll start by creating our sync manager with support for three
-	// active syncers.
+	// We'll start by creating our test sync manager which will hold up to
+	// 2 active syncers.
 	syncMgr := newTestSyncManager(numActiveSyncers)
 	syncMgr.Start()
 	defer syncMgr.Stop()
 
+	// We'll go ahead and create our syncers.
 	peers := make([]*mockPeer, 0, numActiveSyncers)
-
-	// The first syncer registered always attempts a historical sync.
-	firstPeer := randPeer(t, syncMgr.quit)
-	syncMgr.InitSyncState(firstPeer)
-	peers = append(peers, firstPeer)
-	assertTransitionToChansSynced(t, syncMgr, firstPeer, true)
-
-	// After completing the historical sync, a sync transition to ActiveSync
-	// should happen. It should transition immediately since it has no
-	// dependents.
-	assertActiveGossipTimestampRange(t, firstPeer)
-
-	// We'll create the remaining numActiveSyncers. These will be queued in
-	// the round robin since the first syncer has yet to reach chansSynced.
-	queuedPeers := make([]*mockPeer, 0, numActiveSyncers-1)
-	for i := 0; i < numActiveSyncers-1; i++ {
+	syncers := make([]*GossipSyncer, 0, numActiveSyncers)
+	for i := 0; i < numActiveSyncers; i++ {
 		peer := randPeer(t, syncMgr.quit)
-		syncMgr.InitSyncState(peer)
 		peers = append(peers, peer)
-		queuedPeers = append(queuedPeers, peer)
-	}
 
-	// Ensure they cannot transition without sending a GossipTimestampRange
-	// message first.
-	for _, peer := range queuedPeers {
-		assertNoMsgSent(t, peer)
-	}
-
-	// Transition the first syncer to chansSynced, which should allow the
-	// second to transition next.
-	assertTransitionToChansSynced(t, syncMgr, firstPeer, false)
-
-	// assertSyncerTransitioned ensures the target peer's syncer is the only
-	// that has transitioned.
-	assertSyncerTransitioned := func(target *mockPeer) {
-		t.Helper()
-
-		for _, peer := range peers {
-			if peer.PubKey() != target.PubKey() {
-				assertNoMsgSent(t, peer)
-				continue
-			}
-
-			assertActiveGossipTimestampRange(t, target)
-		}
-	}
-
-	// For each queued syncer, we'll ensure they have transitioned to an
-	// ActiveSync type and reached their final chansSynced state to allow
-	// the next one to transition.
-	for _, peer := range queuedPeers {
-		assertSyncerTransitioned(peer)
-		assertTransitionToChansSynced(t, syncMgr, peer, false)
-	}
-}
-
-// TestSyncManagerRoundRobinTimeout ensures that if we timeout while waiting for
-// an active syncer to reach its final chansSynced state, then we will go on to
-// start the next.
-func TestSyncManagerRoundRobinTimeout(t *testing.T) {
-	t.Parallel()
-
-	// Create our sync manager with support for two active syncers.
-	syncMgr := newTestSyncManager(2)
-	syncMgr.Start()
-	defer syncMgr.Stop()
-
-	// peer1 will be the first peer we start, which will time out and cause
-	// peer2 to start.
-	peer1 := randPeer(t, syncMgr.quit)
-	peer2 := randPeer(t, syncMgr.quit)
-
-	// The first syncer registered always attempts a historical sync.
-	syncMgr.InitSyncState(peer1)
-	assertTransitionToChansSynced(t, syncMgr, peer1, true)
-
-	// We assume the syncer for peer1 has transitioned once we see it send a
-	// lnwire.GossipTimestampRange message.
-	assertActiveGossipTimestampRange(t, peer1)
-
-	// We'll then create the syncer for peer2. This should cause it to be
-	// queued so that it starts once the syncer for peer1 is done.
-	syncMgr.InitSyncState(peer2)
-	assertNoMsgSent(t, peer2)
-
-	// Send a force tick to pretend the sync manager has timed out waiting
-	// for peer1's syncer to reach chansSynced.
-	syncMgr.cfg.ActiveSyncerTimeoutTicker.(*ticker.Force).Force <- time.Time{}
-
-	// Finally, ensure that the syncer for peer2 has transitioned.
-	assertActiveGossipTimestampRange(t, peer2)
-}
-
-// TestSyncManagerRoundRobinStaleSyncer ensures that any stale active syncers we
-// are currently waiting for or are queued up to start are properly removed and
-// stopped.
-func TestSyncManagerRoundRobinStaleSyncer(t *testing.T) {
-	t.Parallel()
-
-	const numActiveSyncers = 4
-
-	// We'll create and start our sync manager with some active syncers.
-	syncMgr := newTestSyncManager(numActiveSyncers)
-	syncMgr.Start()
-	defer syncMgr.Stop()
-
-	peers := make([]*mockPeer, 0, numActiveSyncers)
-
-	// The first syncer registered always attempts a historical sync.
-	firstPeer := randPeer(t, syncMgr.quit)
-	syncMgr.InitSyncState(firstPeer)
-	peers = append(peers, firstPeer)
-	assertTransitionToChansSynced(t, syncMgr, firstPeer, true)
-
-	// After completing the historical sync, a sync transition to ActiveSync
-	// should happen. It should transition immediately since it has no
-	// dependents.
-	assertActiveGossipTimestampRange(t, firstPeer)
-	assertMsgSent(t, firstPeer, &lnwire.QueryChannelRange{
-		FirstBlockHeight: startHeight,
-		NumBlocks:        math.MaxUint32 - startHeight,
-	})
-
-	// We'll create the remaining numActiveSyncers. These will be queued in
-	// the round robin since the first syncer has yet to reach chansSynced.
-	queuedPeers := make([]*mockPeer, 0, numActiveSyncers-1)
-	for i := 0; i < numActiveSyncers-1; i++ {
-		peer := randPeer(t, syncMgr.quit)
 		syncMgr.InitSyncState(peer)
-		peers = append(peers, peer)
-		queuedPeers = append(queuedPeers, peer)
-	}
+		s := assertSyncerExistence(t, syncMgr, peer)
+		syncers = append(syncers, s)
 
-	// Ensure they cannot transition without sending a GossipTimestampRange
-	// message first.
-	for _, peer := range queuedPeers {
-		assertNoMsgSent(t, peer)
-	}
-
-	// assertSyncerTransitioned ensures the target peer's syncer is the only
-	// that has transitioned.
-	assertSyncerTransitioned := func(target *mockPeer) {
-		t.Helper()
-
-		for _, peer := range peers {
-			if peer.PubKey() != target.PubKey() {
-				assertNoMsgSent(t, peer)
-				continue
-			}
-
-			assertPassiveSyncerTransition(t, syncMgr, target)
-		}
-	}
-
-	// We'll then remove the syncers in the middle to cover the case where
-	// they are queued up in the sync manager's pending list.
-	for i, peer := range peers {
-		if i == 0 || i == len(peers)-1 {
+		// The first one always attempts a historical sync. We won't
+		// transition it to chansSynced to ensure the remaining syncers
+		// aren't started as active.
+		if i == 0 {
+			assertSyncerStatus(t, s, syncingChans, PassiveSync)
 			continue
 		}
 
-		syncMgr.PruneSyncState(peer.PubKey())
+		// The rest should remain in a passive and chansSynced state,
+		// and they should be queued to transition to active once the
+		// initial historical sync is completed.
+		assertNoMsgSent(t, peer)
+		assertSyncerStatus(t, s, chansSynced, PassiveSync)
 	}
 
-	// We'll then remove the syncer we are currently waiting for. This
-	// should prompt the last syncer to start since it is the only one left
-	// pending. We'll do this in a goroutine since the peer behind the new
-	// active syncer will need to send out its new GossipTimestampRange.
-	go syncMgr.PruneSyncState(peers[0].PubKey())
-	assertSyncerTransitioned(peers[len(peers)-1])
+	// To ensure we don't transition any pending active syncers that have
+	// previously disconnected, we'll disconnect the last one.
+	stalePeer := peers[numActiveSyncers-1]
+	syncMgr.PruneSyncState(stalePeer.PubKey())
+
+	// Then, we'll complete the initial historical sync by transitioning the
+	// historical syncer to its final chansSynced state. This should trigger
+	// all of the pending active syncers to transition, except for the one
+	// we disconnected.
+	assertTransitionToChansSynced(t, syncers[0], peers[0])
+	for i, s := range syncers {
+		if i == numActiveSyncers-1 {
+			assertNoMsgSent(t, peers[i])
+			continue
+		}
+		assertPassiveSyncerTransition(t, s, peers[i])
+	}
 }
 
 // assertNoMsgSent is a helper function that ensures a peer hasn't sent any
@@ -423,7 +354,7 @@ func assertActiveGossipTimestampRange(t *testing.T, peer *mockPeer) {
 	var msgSent lnwire.Message
 	select {
 	case msgSent = <-peer.sentMsgs:
-	case <-time.After(time.Second):
+	case <-time.After(2 * time.Second):
 		t.Fatalf("expected peer %x to send lnwire.GossipTimestampRange "+
 			"message", peer.PubKey())
 	}
@@ -443,10 +374,9 @@ func assertActiveGossipTimestampRange(t *testing.T, peer *mockPeer) {
 	}
 }
 
-// assertSyncerStatus asserts that the gossip syncer for the given peer matches
-// the expected sync state and type.
-func assertSyncerStatus(t *testing.T, syncMgr *SyncManager, peer *mockPeer,
-	syncState syncerState, syncType SyncerType) {
+// assertSyncerExistence asserts that a GossipSyncer exists for the given peer.
+func assertSyncerExistence(t *testing.T, syncMgr *SyncManager,
+	peer *mockPeer) *GossipSyncer {
 
 	t.Helper()
 
@@ -455,19 +385,29 @@ func assertSyncerStatus(t *testing.T, syncMgr *SyncManager, peer *mockPeer,
 		t.Fatalf("gossip syncer for peer %x not found", peer.PubKey())
 	}
 
+	return s
+}
+
+// assertSyncerStatus asserts that the gossip syncer for the given peer matches
+// the expected sync state and type.
+func assertSyncerStatus(t *testing.T, s *GossipSyncer, syncState syncerState,
+	syncType SyncerType) {
+
+	t.Helper()
+
 	// We'll check the status of our syncer within a WaitPredicate as some
 	// sync transitions might cause this to be racy.
 	err := lntest.WaitNoError(func() error {
 		state := s.syncState()
 		if s.syncState() != syncState {
 			return fmt.Errorf("expected syncState %v for peer "+
-				"%x, got %v", syncState, peer.PubKey(), state)
+				"%x, got %v", syncState, s.cfg.peerPub, state)
 		}
 
 		typ := s.SyncType()
 		if s.SyncType() != syncType {
 			return fmt.Errorf("expected syncType %v for peer "+
-				"%x, got %v", syncType, peer.PubKey(), typ)
+				"%x, got %v", syncType, s.cfg.peerPub, typ)
 		}
 
 		return nil
@@ -479,28 +419,17 @@ func assertSyncerStatus(t *testing.T, syncMgr *SyncManager, peer *mockPeer,
 
 // assertTransitionToChansSynced asserts the transition of an ActiveSync
 // GossipSyncer to its final chansSynced state.
-func assertTransitionToChansSynced(t *testing.T, syncMgr *SyncManager,
-	peer *mockPeer, historicalSync bool) {
-
+func assertTransitionToChansSynced(t *testing.T, s *GossipSyncer, peer *mockPeer) {
 	t.Helper()
 
-	s, ok := syncMgr.GossipSyncer(peer.PubKey())
-	if !ok {
-		t.Fatalf("gossip syncer for peer %x not found", peer.PubKey())
-	}
-
-	firstBlockHeight := uint32(startHeight)
-	if historicalSync {
-		firstBlockHeight = 0
-	}
 	assertMsgSent(t, peer, &lnwire.QueryChannelRange{
-		FirstBlockHeight: firstBlockHeight,
-		NumBlocks:        math.MaxUint32 - firstBlockHeight,
+		FirstBlockHeight: 0,
+		NumBlocks:        math.MaxUint32,
 	})
 
 	s.ProcessQueryMsg(&lnwire.ReplyChannelRange{Complete: 1}, nil)
 
-	chanSeries := syncMgr.cfg.ChanSeries.(*mockChannelGraphTimeSeries)
+	chanSeries := s.cfg.channelSeries.(*mockChannelGraphTimeSeries)
 
 	select {
 	case <-chanSeries.filterReq:
@@ -525,25 +454,22 @@ func assertTransitionToChansSynced(t *testing.T, syncMgr *SyncManager,
 
 // assertPassiveSyncerTransition asserts that a gossip syncer goes through all
 // of its expected steps when transitioning from passive to active.
-func assertPassiveSyncerTransition(t *testing.T, syncMgr *SyncManager,
-	peer *mockPeer) {
+func assertPassiveSyncerTransition(t *testing.T, s *GossipSyncer, peer *mockPeer) {
 
 	t.Helper()
 
 	assertActiveGossipTimestampRange(t, peer)
-	assertTransitionToChansSynced(t, syncMgr, peer, false)
+	assertSyncerStatus(t, s, chansSynced, ActiveSync)
 }
 
 // assertActiveSyncerTransition asserts that a gossip syncer goes through all of
 // its expected steps when transitioning from active to passive.
-func assertActiveSyncerTransition(t *testing.T, syncMgr *SyncManager,
-	peer *mockPeer) {
-
+func assertActiveSyncerTransition(t *testing.T, s *GossipSyncer, peer *mockPeer) {
 	t.Helper()
 
 	assertMsgSent(t, peer, &lnwire.GossipTimestampRange{
 		FirstTimestamp: uint32(zeroTimestamp.Unix()),
 		TimestampRange: 0,
 	})
-	assertSyncerStatus(t, syncMgr, peer, chansSynced, PassiveSync)
+	assertSyncerStatus(t, s, chansSynced, PassiveSync)
 }

discovery/syncer.go

@@ -18,16 +18,23 @@ import (
 type SyncerType uint8
 
 const (
-	// ActiveSync denotes that a gossip syncer should exercise its default
-	// behavior. This includes reconciling the set of missing graph updates
-	// with the remote peer _and_ receiving new updates from them.
+	// ActiveSync denotes that a gossip syncer:
+	//
+	// 1. Should not attempt to synchronize with the remote peer for
+	//    missing channels.
+	// 2. Should respond to queries from the remote peer.
+	// 3. Should receive new updates from the remote peer.
+	//
+	// They are started in a chansSynced state in order to accomplish their
+	// responsibilities above.
 	ActiveSync SyncerType = iota
 
 	// PassiveSync denotes that a gossip syncer:
 	//
-	//   1. Should not attempt to query the remote peer for graph updates.
-	//   2. Should respond to queries from the remote peer.
-	//   3. Should not receive new updates from the remote peer.
+	// 1. Should not attempt to synchronize with the remote peer for
+	//    missing channels.
+	// 2. Should respond to queries from the remote peer.
+	// 3. Should not receive new updates from the remote peer.
 	//
 	// They are started in a chansSynced state in order to accomplish their
 	// responsibilities above.
@@ -161,6 +168,14 @@ type syncTransitionReq struct {
 	errChan     chan error
 }
 
+// historicalSyncReq encapsulates a request for a gossip syncer to perform a
+// historical sync.
+type historicalSyncReq struct {
+	// doneChan is a channel that serves as a signal and is closed to ensure
+	// the historical sync is attempted by the time we return to the caller.
+	doneChan chan struct{}
+}
+
 // gossipSyncerCfg is a struct that packages all the information a GossipSyncer
 // needs to carry out its duties.
 type gossipSyncerCfg struct {
@@ -246,7 +261,7 @@ type GossipSyncer struct {
 	// gossip syncer to perform a historical sync. Theese can only be done
 	// once the gossip syncer is in a chansSynced state to ensure its state
 	// machine behaves as expected.
-	historicalSyncReqs chan struct{}
+	historicalSyncReqs chan *historicalSyncReq
 
 	// genHistoricalChanRangeQuery when true signals to the gossip syncer
 	// that it should request the remote peer for all of its known channel
@@ -315,7 +330,7 @@ func newGossipSyncer(cfg gossipSyncerCfg) *GossipSyncer {
 		cfg:                cfg,
 		rateLimiter:        rateLimiter,
 		syncTransitionReqs: make(chan *syncTransitionReq),
-		historicalSyncReqs: make(chan struct{}),
+		historicalSyncReqs: make(chan *historicalSyncReq),
 		gossipMsgs:         make(chan lnwire.Message, 100),
 		quit:               make(chan struct{}),
 	}
@@ -515,8 +530,8 @@ func (g *GossipSyncer) channelGraphSyncer() {
 			case req := <-g.syncTransitionReqs:
 				req.errChan <- g.handleSyncTransition(req)
 
-			case <-g.historicalSyncReqs:
-				g.handleHistoricalSync()
+			case req := <-g.historicalSyncReqs:
+				g.handleHistoricalSync(req)
 
 			case <-g.quit:
 				return
@@ -1128,7 +1143,6 @@ func (g *GossipSyncer) handleSyncTransition(req *syncTransitionReq) error {
 	var (
 		firstTimestamp time.Time
 		timestampRange uint32
-		newState       syncerState
 	)
 
 	switch req.newSyncType {
@@ -1137,11 +1151,6 @@ func (g *GossipSyncer) handleSyncTransition(req *syncTransitionReq) error {
 	case ActiveSync:
 		firstTimestamp = time.Now()
 		timestampRange = math.MaxUint32
-		newState = syncingChans
-
-		// We'll set genHistoricalChanRangeQuery to false since in order
-		// to not perform another historical sync if we previously have.
-		g.genHistoricalChanRangeQuery = false
 
 	// If a PassiveSync transition has been requested, then we should no
 	// longer receive any new updates from the remote peer. We can do this
@@ -1150,7 +1159,6 @@ func (g *GossipSyncer) handleSyncTransition(req *syncTransitionReq) error {
 	case PassiveSync:
 		firstTimestamp = zeroTimestamp
 		timestampRange = 0
-		newState = chansSynced
 
 	default:
 		return fmt.Errorf("unhandled sync transition %v",
@@ -1162,7 +1170,6 @@ func (g *GossipSyncer) handleSyncTransition(req *syncTransitionReq) error {
 		return fmt.Errorf("unable to send local update horizon: %v", err)
 	}
 
-	g.setSyncState(newState)
 	g.setSyncType(req.newSyncType)
 
 	return nil
@@ -1184,22 +1191,33 @@ func (g *GossipSyncer) SyncType() SyncerType {
 // NOTE: This can only be done once the gossip syncer has reached its final
 // chansSynced state.
 func (g *GossipSyncer) historicalSync() error {
+	done := make(chan struct{})
+
 	select {
-	case g.historicalSyncReqs <- struct{}{}:
-		return nil
+	case g.historicalSyncReqs <- &historicalSyncReq{
+		doneChan: done,
+	}:
 	case <-time.After(syncTransitionTimeout):
 		return ErrSyncTransitionTimeout
 	case <-g.quit:
 		return ErrGossiperShuttingDown
 	}
+
+	select {
+	case <-done:
+		return nil
+	case <-g.quit:
+		return ErrGossiperShuttingDown
+	}
 }
 
 // handleHistoricalSync handles a request to the gossip syncer to perform a
 // historical sync.
-func (g *GossipSyncer) handleHistoricalSync() {
+func (g *GossipSyncer) handleHistoricalSync(req *historicalSyncReq) {
 	// We'll go back to our initial syncingChans state in order to request
 	// the remote peer to give us all of the channel IDs they know of
 	// starting from the genesis block.
 	g.genHistoricalChanRangeQuery = true
 	g.setSyncState(syncingChans)
+	close(req.doneChan)
 }

discovery/syncer_test.go

@@ -2014,8 +2014,7 @@ func TestGossipSyncerSyncTransitions(t *testing.T) {
 				syncState := g.syncState()
 				if syncState != chansSynced {
 					t.Fatalf("expected syncerState %v, "+
-						"got %v", chansSynced,
-						syncState)
+						"got %v", chansSynced, syncState)
 				}
 			},
 		},
@@ -2037,21 +2036,10 @@ func TestGossipSyncerSyncTransitions(t *testing.T) {
 					TimestampRange: math.MaxUint32,
 				})
 
-				// The local update horizon should be followed
-				// by a QueryChannelRange message sent to the
-				// remote peer requesting all channels it
-				// knows of from the highest height the syncer
-				// knows of.
-				assertMsgSent(t, msgChan, &lnwire.QueryChannelRange{
-					FirstBlockHeight: startHeight,
-					NumBlocks:        math.MaxUint32 - startHeight,
-				})
-
 				syncState := g.syncState()
-				if syncState != waitingQueryRangeReply {
+				if syncState != chansSynced {
 					t.Fatalf("expected syncerState %v, "+
-						"got %v", waitingQueryRangeReply,
-						syncState)
+						"got %v", chansSynced, syncState)
 				}
 			},
 		},

server.go

@@ -673,23 +673,22 @@ func newServer(listenAddrs []net.Addr, chanDB *channeldb.DB, cc *chainControl,
 	}
 
 	s.authGossiper = discovery.New(discovery.Config{
-		Router:                    s.chanRouter,
-		Notifier:                  s.cc.chainNotifier,
-		ChainHash:                 *activeNetParams.GenesisHash,
-		Broadcast:                 s.BroadcastMessage,
-		ChanSeries:                chanSeries,
-		NotifyWhenOnline:          s.NotifyWhenOnline,
-		NotifyWhenOffline:         s.NotifyWhenOffline,
-		ProofMatureDelta:          0,
-		TrickleDelay:              time.Millisecond * time.Duration(cfg.TrickleDelay),
-		RetransmitDelay:           time.Minute * 30,
-		WaitingProofStore:         waitingProofStore,
-		MessageStore:              gossipMessageStore,
-		AnnSigner:                 s.nodeSigner,
-		RotateTicker:              ticker.New(discovery.DefaultSyncerRotationInterval),
-		HistoricalSyncTicker:      ticker.New(cfg.HistoricalSyncInterval),
-		ActiveSyncerTimeoutTicker: ticker.New(discovery.DefaultActiveSyncerTimeout),
-		NumActiveSyncers:          cfg.NumGraphSyncPeers,
+		Router:               s.chanRouter,
+		Notifier:             s.cc.chainNotifier,
+		ChainHash:            *activeNetParams.GenesisHash,
+		Broadcast:            s.BroadcastMessage,
+		ChanSeries:           chanSeries,
+		NotifyWhenOnline:     s.NotifyWhenOnline,
+		NotifyWhenOffline:    s.NotifyWhenOffline,
+		ProofMatureDelta:     0,
+		TrickleDelay:         time.Millisecond * time.Duration(cfg.TrickleDelay),
+		RetransmitDelay:      time.Minute * 30,
+		WaitingProofStore:    waitingProofStore,
+		MessageStore:         gossipMessageStore,
+		AnnSigner:            s.nodeSigner,
+		RotateTicker:         ticker.New(discovery.DefaultSyncerRotationInterval),
+		HistoricalSyncTicker: ticker.New(cfg.HistoricalSyncInterval),
+		NumActiveSyncers:     cfg.NumGraphSyncPeers,
 	},
 		s.identityPriv.PubKey(),
 	)