routing: remove sourceNode from routingGraph interface

In this commit, we further reduce the routingGraph interface and this
time we make it more node-agnostic so that it can be backed by any graph
and not one with a concept of "sourceNode".

routing/graph.go

@@ -18,9 +18,6 @@ type routingGraph interface {
 	forEachNodeChannel(nodePub route.Vertex,
 		cb func(channel *channeldb.DirectedChannel) error) error
 
-	// sourceNode returns the source node of the graph.
-	sourceNode() route.Vertex
-
 	// fetchNodeFeatures returns the features of the given node.
 	fetchNodeFeatures(nodePub route.Vertex) (*lnwire.FeatureVector, error)
 }
@@ -73,13 +70,6 @@ func (g *CachedGraph) forEachNodeChannel(nodePub route.Vertex,
 	return g.graph.ForEachNodeDirectedChannel(g.tx, nodePub, cb)
 }
 
-// sourceNode returns the source node of the graph.
-//
-// NOTE: Part of the routingGraph interface.
-func (g *CachedGraph) sourceNode() route.Vertex {
-	return g.source
-}
-
 // fetchNodeFeatures returns the features of the given node. If the node is
 // unknown, assume no additional features are supported.
 //
@@ -99,7 +89,7 @@ func (g *CachedGraph) FetchAmountPairCapacity(nodeFrom, nodeTo route.Vertex,
 	//
 	// Note: Inbound fees are not used here because this method is only used
 	// by a deprecated router rpc.
-	u := newNodeEdgeUnifier(g.sourceNode(), nodeTo, false, nil)
+	u := newNodeEdgeUnifier(g.source, nodeTo, false, nil)
 
 	err := u.addGraphPolicies(g)
 	if err != nil {

routing/integrated_routing_context_test.go

@@ -200,7 +200,7 @@ func (c *integratedRoutingContext) testPayment(maxParts uint32,
 	}
 
 	session, err := newPaymentSession(
-		&payment, getBandwidthHints,
+		&payment, c.graph.source.pubkey, getBandwidthHints,
 		func() (routingGraph, func(), error) {
 			return c.graph, func() {}, nil
 		},

routing/pathfind.go

@@ -48,7 +48,7 @@ const (
 
 // pathFinder defines the interface of a path finding algorithm.
 type pathFinder = func(g *graphParams, r *RestrictParams,
-	cfg *PathFindingConfig, source, target route.Vertex,
+	cfg *PathFindingConfig, self, source, target route.Vertex,
 	amt lnwire.MilliSatoshi, timePref float64, finalHtlcExpiry int32) (
 	[]*unifiedEdge, float64, error)
 
@@ -521,8 +521,9 @@ func getOutgoingBalance(node route.Vertex, outgoingChans map[uint64]struct{},
 // path and accurately check the amount to forward at every node against the
 // available bandwidth.
 func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
-	source, target route.Vertex, amt lnwire.MilliSatoshi, timePref float64,
-	finalHtlcExpiry int32) ([]*unifiedEdge, float64, error) {
+	self, source, target route.Vertex, amt lnwire.MilliSatoshi,
+	timePref float64, finalHtlcExpiry int32) ([]*unifiedEdge, float64,
+	error) {
 
 	// Pathfinding can be a significant portion of the total payment
 	// latency, especially on low-powered devices. Log several metrics to
@@ -583,8 +584,6 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 
 	// If we are routing from ourselves, check that we have enough local
 	// balance available.
-	self := g.graph.sourceNode()
-
 	if source == self {
 		max, total, err := getOutgoingBalance(
 			self, outgoingChanMap, g.bandwidthHints, g.graph,

routing/pathfind_test.go

@@ -3218,7 +3218,8 @@ func dbFindPath(graph *channeldb.ChannelGraph,
 			bandwidthHints:  bandwidthHints,
 			graph:           routingGraph,
 		},
-		r, cfg, source, target, amt, timePref, finalHtlcExpiry,
+		r, cfg, sourceNode.PubKeyBytes, source, target, amt, timePref,
+		finalHtlcExpiry,
 	)
 
 	return route, err

routing/payment_session.go

@@ -163,6 +163,8 @@ type PaymentSession interface {
 // loop if payment attempts take long enough. An additional set of edges can
 // also be provided to assist in reaching the payment's destination.
 type paymentSession struct {
+	selfNode route.Vertex
+
 	additionalEdges map[route.Vertex][]AdditionalEdge
 
 	getBandwidthHints func(routingGraph) (bandwidthHints, error)
@@ -192,7 +194,7 @@ type paymentSession struct {
 }
 
 // newPaymentSession instantiates a new payment session.
-func newPaymentSession(p *LightningPayment,
+func newPaymentSession(p *LightningPayment, selfNode route.Vertex,
 	getBandwidthHints func(routingGraph) (bandwidthHints, error),
 	getRoutingGraph func() (routingGraph, func(), error),
 	missionControl MissionController, pathFindingConfig PathFindingConfig) (
@@ -206,6 +208,7 @@ func newPaymentSession(p *LightningPayment,
 	logPrefix := fmt.Sprintf("PaymentSession(%x):", p.Identifier())
 
 	return &paymentSession{
+		selfNode:          selfNode,
 		additionalEdges:   edges,
 		getBandwidthHints: getBandwidthHints,
 		payment:           p,
@@ -296,8 +299,6 @@ func (p *paymentSession) RequestRoute(maxAmt, feeLimit lnwire.MilliSatoshi,
 
 		p.log.Debugf("pathfinding for amt=%v", maxAmt)
 
-		sourceVertex := routingGraph.sourceNode()
-
 		// Find a route for the current amount.
 		path, _, err := p.pathFinder(
 			&graphParams{
@@ -306,7 +307,7 @@ func (p *paymentSession) RequestRoute(maxAmt, feeLimit lnwire.MilliSatoshi,
 				graph:           routingGraph,
 			},
 			restrictions, &p.pathFindingConfig,
-			sourceVertex, p.payment.Target,
+			p.selfNode, p.selfNode, p.payment.Target,
 			maxAmt, p.payment.TimePref, finalHtlcExpiry,
 		)
 
@@ -384,7 +385,7 @@ func (p *paymentSession) RequestRoute(maxAmt, feeLimit lnwire.MilliSatoshi,
 		// this into a route by applying the time-lock and fee
 		// requirements.
 		route, err := newRoute(
-			sourceVertex, path, height,
+			p.selfNode, path, height,
 			finalHopParams{
 				amt:         maxAmt,
 				totalAmt:    p.payment.Amount,

routing/payment_session_source.go

@@ -73,8 +73,8 @@ func (m *SessionSource) NewPaymentSession(p *LightningPayment) (
 	}
 
 	session, err := newPaymentSession(
-		p, getBandwidthHints, m.getRoutingGraph,
-		m.MissionControl, m.PathFindingConfig,
+		p, m.SourceNode.PubKeyBytes, getBandwidthHints,
+		m.getRoutingGraph, m.MissionControl, m.PathFindingConfig,
 	)
 	if err != nil {
 		return nil, err

routing/payment_session_test.go

@@ -115,7 +115,7 @@ func TestUpdateAdditionalEdge(t *testing.T) {
 
 	// Create the paymentsession.
 	session, err := newPaymentSession(
-		payment,
+		payment, route.Vertex{},
 		func(routingGraph) (bandwidthHints, error) {
 			return &mockBandwidthHints{}, nil
 		},
@@ -195,7 +195,7 @@ func TestRequestRoute(t *testing.T) {
 	}
 
 	session, err := newPaymentSession(
-		payment,
+		payment, route.Vertex{},
 		func(routingGraph) (bandwidthHints, error) {
 			return &mockBandwidthHints{}, nil
 		},
@@ -211,9 +211,9 @@ func TestRequestRoute(t *testing.T) {
 
 	// Override pathfinder with a mock.
 	session.pathFinder = func(_ *graphParams, r *RestrictParams,
-		_ *PathFindingConfig, _, _ route.Vertex, _ lnwire.MilliSatoshi,
-		_ float64, _ int32) ([]*unifiedEdge, float64,
-		error) {
+		_ *PathFindingConfig, _, _, _ route.Vertex,
+		_ lnwire.MilliSatoshi, _ float64, _ int32) ([]*unifiedEdge,
+		float64, error) {
 
 		// We expect find path to receive a cltv limit excluding the
 		// final cltv delta (including the block padding).

routing/router.go

@@ -2148,8 +2148,9 @@ func (r *ChannelRouter) FindRoute(req *RouteRequest) (*route.Route, float64,
 			bandwidthHints:  bandwidthHints,
 			graph:           r.cachedGraph,
 		},
-		req.Restrictions, &r.cfg.PathFindingConfig, req.Source,
-		req.Target, req.Amount, req.TimePreference, finalHtlcExpiry,
+		req.Restrictions, &r.cfg.PathFindingConfig,
+		r.selfNode.PubKeyBytes, req.Source, req.Target, req.Amount,
+		req.TimePreference, finalHtlcExpiry,
 	)
 	if err != nil {
 		return nil, 0, err