rpc: Add PendingOpenChannel to SubscribeChannelEvents

This commit adds PendingOpenChannel to SubscribeChannelEvents stream in
the gRPC API.
This is useful for keeping track of channel openings that Autopilot does.
It can also be used for the non-initator side of a channel opening to keep
track of channel openings.

channelnotifier/channelnotifier.go

@@ -20,6 +20,13 @@ type ChannelNotifier struct {
 	chanDB *channeldb.DB
 }
 
+// PendingOpenChannelEvent represents a new event where a new channel has
+// entered a pending open state.
+type PendingOpenChannelEvent struct {
+	// ChannelPoint is the channelpoint for the new channel.
+	ChannelPoint *wire.OutPoint
+}
+
 // OpenChannelEvent represents a new event where a channel goes from pending
 // open to open.
 type OpenChannelEvent struct {
@@ -82,6 +89,16 @@ func (c *ChannelNotifier) SubscribeChannelEvents() (*subscribe.Client, error) {
 	return c.ntfnServer.Subscribe()
 }
 
+// NotifyPendingOpenChannelEvent notifies the channelEventNotifier goroutine that a
+// new channel is pending.
+func (c *ChannelNotifier) NotifyPendingOpenChannelEvent(chanPoint wire.OutPoint) {
+	event := PendingOpenChannelEvent{ChannelPoint: &chanPoint}
+
+	if err := c.ntfnServer.SendUpdate(event); err != nil {
+		log.Warnf("Unable to send pending open channel update: %v", err)
+	}
+}
+
 // NotifyOpenChannelEvent notifies the channelEventNotifier goroutine that a
 // channel has gone from pending open to open.
 func (c *ChannelNotifier) NotifyOpenChannelEvent(chanPoint wire.OutPoint) {

fundingmanager.go

@@ -363,6 +363,10 @@ type fundingConfig struct {
 	// and on the requesting node's public key that returns a bool which tells
 	// the funding manager whether or not to accept the channel.
 	OpenChannelPredicate chanacceptor.ChannelAcceptor
+
+	// NotifyPendingOpenChannelEvent informs the ChannelNotifier when channels
+	// enter a pending state.
+	NotifyPendingOpenChannelEvent func(wire.OutPoint)
 }
 
 // fundingManager acts as an orchestrator/bridge between the wallet's
@@ -1691,6 +1695,10 @@ func (f *fundingManager) handleFundingCreated(fmsg *fundingCreatedMsg) {
 	f.localDiscoverySignals[channelID] = make(chan struct{})
 	f.localDiscoveryMtx.Unlock()
 
+	// Inform the ChannelNotifier that the channel has entered
+	// pending open state.
+	f.cfg.NotifyPendingOpenChannelEvent(fundingOut)
+
 	// At this point we have sent our last funding message to the
 	// initiating peer before the funding transaction will be broadcast.
 	// With this last message, our job as the responder is now complete.
@@ -1835,6 +1843,9 @@ func (f *fundingManager) handleFundingSigned(fmsg *fundingSignedMsg) {
 
 	select {
 	case resCtx.updates <- upd:
+		// Inform the ChannelNotifier that the channel has entered
+		// pending open state.
+		f.cfg.NotifyPendingOpenChannelEvent(*fundingPoint)
 	case <-f.quit:
 		return
 	}

fundingmanager_test.go

@@ -376,11 +376,12 @@ func createTestFundingManager(t *testing.T, privKey *btcec.PrivateKey,
 			publTxChan <- txn
 			return nil
 		},
-		ZombieSweeperInterval:  1 * time.Hour,
-		ReservationTimeout:     1 * time.Nanosecond,
-		MaxPendingChannels:     DefaultMaxPendingChannels,
-		NotifyOpenChannelEvent: func(wire.OutPoint) {},
-		OpenChannelPredicate:   chainedAcceptor,
+		ZombieSweeperInterval:         1 * time.Hour,
+		ReservationTimeout:            1 * time.Nanosecond,
+		MaxPendingChannels:            DefaultMaxPendingChannels,
+		NotifyOpenChannelEvent:        func(wire.OutPoint) {},
+		OpenChannelPredicate:          chainedAcceptor,
+		NotifyPendingOpenChannelEvent: func(wire.OutPoint) {},
 	}
 
 	for _, op := range options {

lnrpc/rpc.proto

@@ -1930,6 +1930,7 @@ message ChannelEventUpdate {
         ChannelCloseSummary closed_channel = 2 [ json_name = "closed_channel" ];
         ChannelPoint active_channel = 3 [ json_name = "active_channel" ];
         ChannelPoint inactive_channel = 4 [ json_name = "inactive_channel" ];
+        PendingUpdate pending_open_channel = 6 [json_name = "pending_open_channel"];
     }
 
     enum UpdateType {
@@ -1937,6 +1938,7 @@ message ChannelEventUpdate {
          CLOSED_CHANNEL = 1;
          ACTIVE_CHANNEL = 2;
          INACTIVE_CHANNEL = 3;
+         PENDING_OPEN_CHANNEL = 4;
     }
 
     UpdateType type = 5 [ json_name = "type" ];

lnrpc/rpc.swagger.json

@@ -1467,7 +1467,8 @@
         "OPEN_CHANNEL",
         "CLOSED_CHANNEL",
         "ACTIVE_CHANNEL",
-        "INACTIVE_CHANNEL"
+        "INACTIVE_CHANNEL",
+        "PENDING_OPEN_CHANNEL"
       ],
       "default": "OPEN_CHANNEL"
     },
@@ -2149,6 +2150,9 @@
         "inactive_channel": {
           "$ref": "#/definitions/lnrpcChannelPoint"
         },
+        "pending_open_channel": {
+          "$ref": "#/definitions/lnrpcPendingUpdate"
+        },
         "type": {
           "$ref": "#/definitions/ChannelEventUpdateUpdateType"
         }

lntest/itest/lnd_test.go

@@ -6460,25 +6460,34 @@ func testBasicChannelCreationAndUpdates(net *lntest.NetworkHarness, t *harnessTe
 	// Since each of the channels just became open, Bob and Alice should
 	// each receive an open and an active notification for each channel.
 	var numChannelUpds int
-	const totalNtfns = 2 * numChannels
+	const totalNtfns = 3 * numChannels
 	verifyOpenUpdatesReceived := func(sub channelSubscription) error {
 		numChannelUpds = 0
 		for numChannelUpds < totalNtfns {
 			select {
 			case update := <-sub.updateChan:
 				switch update.Type {
-				case lnrpc.ChannelEventUpdate_ACTIVE_CHANNEL:
-					if numChannelUpds%2 != 1 {
-						return fmt.Errorf("expected open" +
-							"channel ntfn, got active " +
+				case lnrpc.ChannelEventUpdate_PENDING_OPEN_CHANNEL:
+					if numChannelUpds%3 != 0 {
+						return fmt.Errorf("expected " +
+							"open or active" +
+							"channel ntfn, got pending open " +
 							"channel ntfn instead")
 					}
 				case lnrpc.ChannelEventUpdate_OPEN_CHANNEL:
-					if numChannelUpds%2 != 0 {
-						return fmt.Errorf("expected active" +
+					if numChannelUpds%3 != 1 {
+						return fmt.Errorf("expected " +
+							"pending open or active" +
 							"channel ntfn, got open" +
 							"channel ntfn instead")
 					}
+				case lnrpc.ChannelEventUpdate_ACTIVE_CHANNEL:
+					if numChannelUpds%3 != 2 {
+						return fmt.Errorf("expected " +
+							"pending open or open" +
+							"channel ntfn, got active " +
+							"channel ntfn instead")
+					}
 				default:
 					return fmt.Errorf("update type mismatch: "+
 						"expected open or active channel "+

rpcserver.go

@@ -3187,6 +3187,16 @@ func (r *rpcServer) SubscribeChannelEvents(req *lnrpc.ChannelEventSubscription,
 		case e := <-channelEventSub.Updates():
 			var update *lnrpc.ChannelEventUpdate
 			switch event := e.(type) {
+			case channelnotifier.PendingOpenChannelEvent:
+				update = &lnrpc.ChannelEventUpdate{
+					Type: lnrpc.ChannelEventUpdate_PENDING_OPEN_CHANNEL,
+					Channel: &lnrpc.ChannelEventUpdate_PendingOpenChannel{
+						PendingOpenChannel: &lnrpc.PendingUpdate{
+							Txid:        event.ChannelPoint.Hash[:],
+							OutputIndex: event.ChannelPoint.Index,
+						},
+					},
+				}
 			case channelnotifier.OpenChannelEvent:
 				channel, err := createRPCOpenChannel(r, graph,
 					event.Channel, true)
@@ -5601,7 +5611,9 @@ func (r *rpcServer) SubscribeChannelBackups(req *lnrpc.ChannelBackupSubscription
 			switch e.(type) {
 
 			// We only care about new/closed channels, so we'll
-			// skip any events for active/inactive channels.
+			// skip any events for pending/active/inactive channels.
+			case channelnotifier.PendingOpenChannelEvent:
+				continue
 			case channelnotifier.ActiveChannelEvent:
 				continue
 			case channelnotifier.InactiveChannelEvent:

server.go

@@ -1113,13 +1113,14 @@ func newServer(listenAddrs []net.Addr, chanDB *channeldb.DB,
 			// channel bandwidth.
 			return uint16(input.MaxHTLCNumber / 2)
 		},
-		ZombieSweeperInterval:  1 * time.Minute,
-		ReservationTimeout:     10 * time.Minute,
-		MinChanSize:            btcutil.Amount(cfg.MinChanSize),
-		MaxPendingChannels:     cfg.MaxPendingChannels,
-		RejectPush:             cfg.RejectPush,
-		NotifyOpenChannelEvent: s.channelNotifier.NotifyOpenChannelEvent,
-		OpenChannelPredicate:   chanPredicate,
+		ZombieSweeperInterval:         1 * time.Minute,
+		ReservationTimeout:            10 * time.Minute,
+		MinChanSize:                   btcutil.Amount(cfg.MinChanSize),
+		MaxPendingChannels:            cfg.MaxPendingChannels,
+		RejectPush:                    cfg.RejectPush,
+		NotifyOpenChannelEvent:        s.channelNotifier.NotifyOpenChannelEvent,
+		OpenChannelPredicate:          chanPredicate,
+		NotifyPendingOpenChannelEvent: s.channelNotifier.NotifyPendingOpenChannelEvent,
 	})
 	if err != nil {
 		return nil, err