routing: use capacity in pathfinding

Extends the pathfinder with a capacity argument for later usage.

In tests, the inserted testCapacity has no effect, but will be used
later to estimate reduced probabilities from it.

lnrpc/routerrpc/router_backend.go

@@ -103,7 +103,7 @@ type MissionControl interface {
 	// GetProbability is expected to return the success probability of a
 	// payment from fromNode to toNode.
 	GetProbability(fromNode, toNode route.Vertex,
-		amt lnwire.MilliSatoshi) float64
+		amt lnwire.MilliSatoshi, capacity btcutil.Amount) float64
 
 	// ResetHistory resets the history of MissionControl returning it to a
 	// state as if no payment attempts have been made.
@@ -258,7 +258,8 @@ func (r *RouterBackend) QueryRoutes(ctx context.Context,
 	restrictions := &routing.RestrictParams{
 		FeeLimit: feeLimit,
 		ProbabilitySource: func(fromNode, toNode route.Vertex,
-			amt lnwire.MilliSatoshi) float64 {
+			amt lnwire.MilliSatoshi,
+			capacity btcutil.Amount) float64 {
 
 			if _, ok := ignoredNodes[fromNode]; ok {
 				return 0
@@ -277,7 +278,7 @@ func (r *RouterBackend) QueryRoutes(ctx context.Context,
 			}
 
 			return r.MissionControl.GetProbability(
-				fromNode, toNode, amt,
+				fromNode, toNode, amt, capacity,
 			)
 		},
 		DestCustomRecords: record.CustomSet(in.DestCustomRecords),
@@ -362,7 +363,7 @@ func (r *RouterBackend) getSuccessProbability(rt *route.Route) float64 {
 		toNode := hop.PubKeyBytes
 
 		probability := r.MissionControl.GetProbability(
-			fromNode, toNode, amtToFwd,
+			fromNode, toNode, amtToFwd, 0,
 		)
 
 		successProb *= probability

lnrpc/routerrpc/router_backend_test.go

@@ -145,18 +145,18 @@ func testQueryRoutes(t *testing.T, useMissionControl bool, useMsat bool,
 		}
 
 		if restrictions.ProbabilitySource(route.Vertex{2},
-			route.Vertex{1}, 0,
+			route.Vertex{1}, 0, 0,
 		) != 0 {
 			t.Fatal("expecting 0% probability for ignored edge")
 		}
 
 		if restrictions.ProbabilitySource(ignoreNodeVertex,
-			route.Vertex{6}, 0,
+			route.Vertex{6}, 0, 0,
 		) != 0 {
 			t.Fatal("expecting 0% probability for ignored node")
 		}
 
-		if restrictions.ProbabilitySource(node1, node2, 0) != 0 {
+		if restrictions.ProbabilitySource(node1, node2, 0, 0) != 0 {
 			t.Fatal("expecting 0% probability for ignored pair")
 		}
 
@@ -181,7 +181,7 @@ func testQueryRoutes(t *testing.T, useMissionControl bool, useMsat bool,
 			expectedProb = testMissionControlProb
 		}
 		if restrictions.ProbabilitySource(route.Vertex{4},
-			route.Vertex{5}, 0,
+			route.Vertex{5}, 0, 0,
 		) != expectedProb {
 			t.Fatal("expecting 100% probability")
 		}
@@ -239,7 +239,7 @@ type mockMissionControl struct {
 }
 
 func (m *mockMissionControl) GetProbability(fromNode, toNode route.Vertex,
-	amt lnwire.MilliSatoshi) float64 {
+	amt lnwire.MilliSatoshi, capacity btcutil.Amount) float64 {
 
 	return testMissionControlProb
 }

lnrpc/routerrpc/router_server.go

@@ -710,7 +710,7 @@ func (s *Server) QueryProbability(ctx context.Context,
 	amt := lnwire.MilliSatoshi(req.AmtMsat)
 
 	mc := s.cfg.RouterBackend.MissionControl
-	prob := mc.GetProbability(fromNode, toNode, amt)
+	prob := mc.GetProbability(fromNode, toNode, amt, 0)
 	history := mc.GetPairHistorySnapshot(fromNode, toNode)
 
 	return &QueryProbabilityResponse{