router: return probability from findPath

The returned probability can then be used in QueryRoutes to not having
to reconstruct the probability.

lnrpc/routerrpc/router_backend.go

@@ -57,7 +57,7 @@ type RouterBackend struct {
 		restrictions *routing.RestrictParams,
 		destCustomRecords record.CustomSet,
 		routeHints map[route.Vertex][]*channeldb.CachedEdgePolicy,
-		finalExpiry uint16) (*route.Route, error)
+		finalExpiry uint16) (*route.Route, float64, error)
 
 	MissionControl MissionControl
 
@@ -325,7 +325,7 @@ func (r *RouterBackend) QueryRoutes(ctx context.Context,
 	// Query the channel router for a possible path to the destination that
 	// can carry `in.Amt` satoshis _including_ the total fee required on
 	// the route.
-	route, err := r.FindRoute(
+	route, _, err := r.FindRoute(
 		sourcePubKey, targetPubKey, amt, in.TimePref, restrictions,
 		customRecords, routeHintEdges, finalCLTVDelta,
 	)

lnrpc/routerrpc/router_backend_test.go

@@ -126,7 +126,7 @@ func testQueryRoutes(t *testing.T, useMissionControl bool, useMsat bool,
 		amt lnwire.MilliSatoshi, _ float64,
 		restrictions *routing.RestrictParams, _ record.CustomSet,
 		routeHints map[route.Vertex][]*channeldb.CachedEdgePolicy,
-		finalExpiry uint16) (*route.Route, error) {
+		finalExpiry uint16) (*route.Route, float64, error) {
 
 		if int64(amt) != amtSat*1000 {
 			t.Fatal("unexpected amount")
@@ -187,7 +187,9 @@ func testQueryRoutes(t *testing.T, useMissionControl bool, useMsat bool,
 		}
 
 		hops := []*route.Hop{{}}
-		return route.NewRouteFromHops(amt, 144, source, hops)
+		route, err := route.NewRouteFromHops(amt, 144, source, hops)
+
+		return route, expectedProb, err
 	}
 
 	backend := &RouterBackend{

lnrpc/routerrpc/router_server.go

@@ -366,7 +366,7 @@ func (s *Server) EstimateRouteFee(ctx context.Context,
 	// restriction for the default CLTV limit, otherwise we can find a route
 	// that exceeds it and is useless to us.
 	mc := s.cfg.RouterBackend.MissionControl
-	route, err := s.cfg.Router.FindRoute(
+	route, _, err := s.cfg.Router.FindRoute(
 		s.cfg.RouterBackend.SelfNode, destNode, amtMsat, 0,
 		&routing.RestrictParams{
 			FeeLimit:          feeLimit,

routing/pathfind.go

@@ -43,7 +43,7 @@ const (
 type pathFinder = func(g *graphParams, r *RestrictParams,
 	cfg *PathFindingConfig, source, target route.Vertex,
 	amt lnwire.MilliSatoshi, timePref float64, finalHtlcExpiry int32) (
-	[]*channeldb.CachedEdgePolicy, error)
+	[]*channeldb.CachedEdgePolicy, float64, error)
 
 var (
 	// DefaultAttemptCost is the default fixed virtual cost in path finding
@@ -427,7 +427,7 @@ func getOutgoingBalance(node route.Vertex, outgoingChans map[uint64]struct{},
 // available bandwidth.
 func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 	source, target route.Vertex, amt lnwire.MilliSatoshi, timePref float64,
-	finalHtlcExpiry int32) ([]*channeldb.CachedEdgePolicy, error) {
+	finalHtlcExpiry int32) ([]*channeldb.CachedEdgePolicy, float64, error) {
 
 	// Pathfinding can be a significant portion of the total payment
 	// latency, especially on low-powered devices. Log several metrics to
@@ -448,7 +448,7 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 		var err error
 		features, err = g.graph.fetchNodeFeatures(target)
 		if err != nil {
-			return nil, err
+			return nil, 0, err
 		}
 	}
 
@@ -457,14 +457,14 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 	err := feature.ValidateRequired(features)
 	if err != nil {
 		log.Warnf("Pathfinding destination node features: %v", err)
-		return nil, errUnknownRequiredFeature
+		return nil, 0, errUnknownRequiredFeature
 	}
 
 	// Ensure that all transitive dependencies are set.
 	err = feature.ValidateDeps(features)
 	if err != nil {
 		log.Warnf("Pathfinding destination node features: %v", err)
-		return nil, errMissingDependentFeature
+		return nil, 0, errMissingDependentFeature
 	}
 
 	// Now that we know the feature vector is well formed, we'll proceed in
@@ -476,7 +476,7 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 	if len(r.DestCustomRecords) > 0 &&
 		!features.HasFeature(lnwire.TLVOnionPayloadOptional) {
 
-		return nil, errNoTlvPayload
+		return nil, 0, errNoTlvPayload
 	}
 
 	// If the caller has a payment address to attach, check that our
@@ -484,7 +484,7 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 	if r.PaymentAddr != nil &&
 		!features.HasFeature(lnwire.PaymentAddrOptional) {
 
-		return nil, errNoPaymentAddr
+		return nil, 0, errNoPaymentAddr
 	}
 
 	// If the caller needs to send custom records, check that our
@@ -492,7 +492,7 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 	if r.Metadata != nil &&
 		!features.HasFeature(lnwire.TLVOnionPayloadOptional) {
 
-		return nil, errNoTlvPayload
+		return nil, 0, errNoTlvPayload
 	}
 
 	// Set up outgoing channel map for quicker access.
@@ -513,19 +513,19 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 			self, outgoingChanMap, g.bandwidthHints, g.graph,
 		)
 		if err != nil {
-			return nil, err
+			return nil, 0, err
 		}
 
 		// If the total outgoing balance isn't sufficient, it will be
 		// impossible to complete the payment.
 		if total < amt {
-			return nil, errInsufficientBalance
+			return nil, 0, errInsufficientBalance
 		}
 
 		// If there is only not enough capacity on a single route, it
 		// may still be possible to complete the payment by splitting.
 		if max < amt {
-			return nil, errNoPathFound
+			return nil, 0, errNoPathFound
 		}
 	}
 
@@ -611,8 +611,8 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 
 	// Validate time preference value.
 	if math.Abs(timePref) > 1 {
-		return nil, fmt.Errorf("time preference %v out of range [-1, 1]",
-			timePref)
+		return nil, 0, fmt.Errorf("time preference %v out of range "+
+			"[-1, 1]", timePref)
 	}
 
 	// Scale to avoid the extremes -1 and 1 which run into infinity issues.
@@ -856,7 +856,7 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 
 		err := u.addGraphPolicies(g.graph)
 		if err != nil {
-			return nil, err
+			return nil, 0, err
 		}
 
 		for _, reverseEdge := range additionalEdgesWithSrc[pivot] {
@@ -895,7 +895,7 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 			// Get feature vector for fromNode.
 			fromFeatures, err := getGraphFeatures(fromNode)
 			if err != nil {
-				return nil, err
+				return nil, 0, err
 			}
 
 			// If there are no valid features, skip this node.
@@ -934,7 +934,7 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 		if !ok {
 			// If the node doesn't have a next hop it means we
 			// didn't find a path.
-			return nil, errNoPathFound
+			return nil, 0, errNoPathFound
 		}
 
 		// Add the next hop to the list of path edges.
@@ -968,7 +968,7 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 		distance[source].probability, len(pathEdges),
 		distance[source].amountToReceive-amt)
 
-	return pathEdges, nil
+	return pathEdges, distance[source].probability, nil
 }
 
 // getProbabilityBasedDist converts a weight into a distance that takes into

routing/pathfind_test.go

@@ -2291,7 +2291,7 @@ func TestPathFindSpecExample(t *testing.T) {
 	// Query for a route of 4,999,999 mSAT to carol.
 	carol := ctx.aliases["C"]
 	const amt lnwire.MilliSatoshi = 4999999
-	route, err := ctx.router.FindRoute(
+	route, _, err := ctx.router.FindRoute(
 		bobNode.PubKeyBytes, carol, amt, 0, noRestrictions, nil, nil,
 		MinCLTVDelta,
 	)
@@ -2341,7 +2341,7 @@ func TestPathFindSpecExample(t *testing.T) {
 	}
 
 	// We'll now request a route from A -> B -> C.
-	route, err = ctx.router.FindRoute(
+	route, _, err = ctx.router.FindRoute(
 		source.PubKeyBytes, carol, amt, 0, noRestrictions, nil, nil,
 		MinCLTVDelta,
 	)
@@ -3117,7 +3117,7 @@ func dbFindPath(graph *channeldb.ChannelGraph,
 		}
 	}()
 
-	return findPath(
+	route, _, err := findPath(
 		&graphParams{
 			additionalEdges: additionalEdges,
 			bandwidthHints:  bandwidthHints,
@@ -3125,4 +3125,6 @@ func dbFindPath(graph *channeldb.ChannelGraph,
 		},
 		r, cfg, source, target, amt, timePref, finalHtlcExpiry,
 	)
+
+	return route, err
 }

routing/payment_session.go

@@ -297,7 +297,7 @@ func (p *paymentSession) RequestRoute(maxAmt, feeLimit lnwire.MilliSatoshi,
 		sourceVertex := routingGraph.sourceNode()
 
 		// Find a route for the current amount.
-		path, err := p.pathFinder(
+		path, _, err := p.pathFinder(
 			&graphParams{
 				additionalEdges: p.additionalEdges,
 				bandwidthHints:  bandwidthHints,

routing/payment_session_test.go

@@ -209,11 +209,10 @@ func TestRequestRoute(t *testing.T) {
 	}
 
 	// Override pathfinder with a mock.
-	session.pathFinder = func(
-		g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
-		source, target route.Vertex, amt lnwire.MilliSatoshi,
-		timePref float64,
-		finalHtlcExpiry int32) ([]*channeldb.CachedEdgePolicy, error) {
+	session.pathFinder = func(_ *graphParams, r *RestrictParams,
+		_ *PathFindingConfig, _, _ route.Vertex, _ lnwire.MilliSatoshi,
+		_ float64, _ int32) ([]*channeldb.CachedEdgePolicy, float64,
+		error) {
 
 		// We expect find path to receive a cltv limit excluding the
 		// final cltv delta (including the block padding).
@@ -232,7 +231,7 @@ func TestRequestRoute(t *testing.T) {
 			},
 		}
 
-		return path, nil
+		return path, 1.0, nil
 	}
 
 	route, err := session.RequestRoute(

routing/router.go

@@ -1752,11 +1752,10 @@ type routingMsg struct {
 // particular target destination to which it is able to send `amt` after
 // factoring in channel capacities and cumulative fees along the route.
 func (r *ChannelRouter) FindRoute(source, target route.Vertex,
-	amt lnwire.MilliSatoshi, timePref float64,
-	restrictions *RestrictParams,
+	amt lnwire.MilliSatoshi, timePref float64, restrictions *RestrictParams,
 	destCustomRecords record.CustomSet,
 	routeHints map[route.Vertex][]*channeldb.CachedEdgePolicy,
-	finalExpiry uint16) (*route.Route, error) {
+	finalExpiry uint16) (*route.Route, float64, error) {
 
 	log.Debugf("Searching for path to %v, sending %v", target, amt)
 
@@ -1766,14 +1765,14 @@ func (r *ChannelRouter) FindRoute(source, target route.Vertex,
 		r.cachedGraph, r.selfNode.PubKeyBytes, r.cfg.GetLink,
 	)
 	if err != nil {
-		return nil, err
+		return nil, 0, err
 	}
 
 	// We'll fetch the current block height so we can properly calculate the
 	// required HTLC time locks within the route.
 	_, currentHeight, err := r.cfg.Chain.GetBestBlock()
 	if err != nil {
-		return nil, err
+		return nil, 0, err
 	}
 
 	// Now that we know the destination is reachable within the graph, we'll
@@ -1782,10 +1781,10 @@ func (r *ChannelRouter) FindRoute(source, target route.Vertex,
 
 	// Validate time preference.
 	if timePref < -1 || timePref > 1 {
-		return nil, errors.New("time preference out of range")
+		return nil, 0, errors.New("time preference out of range")
 	}
 
-	path, err := findPath(
+	path, probability, err := findPath(
 		&graphParams{
 			additionalEdges: routeHints,
 			bandwidthHints:  bandwidthHints,
@@ -1796,7 +1795,7 @@ func (r *ChannelRouter) FindRoute(source, target route.Vertex,
 		source, target, amt, timePref, finalHtlcExpiry,
 	)
 	if err != nil {
-		return nil, err
+		return nil, 0, err
 	}
 
 	// Create the route with absolute time lock values.
@@ -1810,7 +1809,7 @@ func (r *ChannelRouter) FindRoute(source, target route.Vertex,
 		},
 	)
 	if err != nil {
-		return nil, err
+		return nil, 0, err
 	}
 
 	go log.Tracef("Obtained path to send %v to %x: %v",
@@ -1819,7 +1818,7 @@ func (r *ChannelRouter) FindRoute(source, target route.Vertex,
 		}),
 	)
 
-	return route, nil
+	return route, probability, nil
 }
 
 // generateNewSessionKey generates a new ephemeral private key to be used for a

routing/router_test.go

@@ -268,7 +268,7 @@ func TestFindRoutesWithFeeLimit(t *testing.T) {
 		CltvLimit:         math.MaxUint32,
 	}
 
-	route, err := ctx.router.FindRoute(
+	route, _, err := ctx.router.FindRoute(
 		ctx.router.selfNode.PubKeyBytes,
 		target, paymentAmt, 0, restrictions, nil, nil,
 		MinCLTVDelta,
@@ -1554,7 +1554,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 	targetNode := priv2.PubKey()
 	var targetPubKeyBytes route.Vertex
 	copy(targetPubKeyBytes[:], targetNode.SerializeCompressed())
-	_, err = ctx.router.FindRoute(
+	_, _, err = ctx.router.FindRoute(
 		ctx.router.selfNode.PubKeyBytes,
 		targetPubKeyBytes, paymentAmt, 0, noRestrictions, nil, nil,
 		MinCLTVDelta,
@@ -1595,7 +1595,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 
 	// Should still be able to find the route, and the info should be
 	// updated.
-	_, err = ctx.router.FindRoute(
+	_, _, err = ctx.router.FindRoute(
 		ctx.router.selfNode.PubKeyBytes,
 		targetPubKeyBytes, paymentAmt, 0, noRestrictions, nil, nil,
 		MinCLTVDelta,