Merge pull request #1203 from Roasbeef/router-view-switch

routing+server: add new QueryBandwidth method to reduce outbound fail…

routing/missioncontrol.go

@@ -4,6 +4,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/coreos/bbolt"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/roasbeef/btcd/btcec"
@@ -57,6 +58,8 @@ type missionControl struct {
 
 	selfNode *channeldb.LightningNode
 
+	queryBandwidth func(*channeldb.ChannelEdgeInfo) lnwire.MilliSatoshi
+
 	sync.Mutex
 
 	// TODO(roasbeef): further counters, if vertex continually unavailable,
@@ -68,13 +71,15 @@ type missionControl struct {
 // newMissionControl returns a new instance of missionControl.
 //
 // TODO(roasbeef): persist memory
-func newMissionControl(g *channeldb.ChannelGraph,
-	selfNode *channeldb.LightningNode) *missionControl {
+func newMissionControl(
+	g *channeldb.ChannelGraph, selfNode *channeldb.LightningNode,
+	qb func(*channeldb.ChannelEdgeInfo) lnwire.MilliSatoshi) *missionControl {
 
 	return &missionControl{
 		failedEdges:    make(map[uint64]time.Time),
 		failedVertexes: make(map[Vertex]time.Time),
 		selfNode:       selfNode,
+		queryBandwidth: qb,
 		graph:          g,
 	}
 }
@@ -157,6 +162,8 @@ type paymentSession struct {
 
 	additionalEdges map[Vertex][]*channeldb.ChannelEdgePolicy
 
+	bandwidthHints map[uint64]lnwire.MilliSatoshi
+
 	mc *missionControl
 }
 
@@ -165,7 +172,7 @@ type paymentSession struct {
 // in order to populate additional edges to explore when finding a path to the
 // payment's destination.
 func (m *missionControl) NewPaymentSession(routeHints [][]HopHint,
-	target *btcec.PublicKey) *paymentSession {
+	target *btcec.PublicKey) (*paymentSession, error) {
 
 	viewSnapshot := m.GraphPruneView()
 
@@ -210,11 +217,62 @@ func (m *missionControl) NewPaymentSession(routeHints [][]HopHint,
 		}
 	}
 
+	// We'll also obtain a set of bandwidthHints from the lower layer for
+	// each of our outbound channels. This will allow the path finding to
+	// skip any links that aren't active or just don't have enough
+	// bandwidth to carry the payment.
+	sourceNode, err := m.graph.SourceNode()
+	if err != nil {
+		return nil, err
+	}
+	bandwidthHints, err := generateBandwidthHints(
+		sourceNode, m.queryBandwidth,
+	)
+	if err != nil {
+		return nil, err
+	}
+
 	return &paymentSession{
 		pruneViewSnapshot: viewSnapshot,
 		additionalEdges:   edges,
+		bandwidthHints:    bandwidthHints,
 		mc:                m,
+	}, nil
+}
+
+// generateBandwidthHints is a helper function that's utilized the main
+// findPath function in order to obtain hints from the lower layer w.r.t to the
+// available bandwidth of edges on the network. Currently, we'll only obtain
+// bandwidth hints for the edges we directly have open ourselves. Obtaining
+// these hints allows us to reduce the number of extraneous attempts as we can
+// skip channels that are inactive, or just don't have enough bandwidth to
+// carry the payment.
+func generateBandwidthHints(sourceNode *channeldb.LightningNode,
+	queryBandwidth func(*channeldb.ChannelEdgeInfo) lnwire.MilliSatoshi) (map[uint64]lnwire.MilliSatoshi, error) {
+
+	// First, we'll collect the set of outbound edges from the target
+	// source node.
+	var localChans []*channeldb.ChannelEdgeInfo
+	err := sourceNode.ForEachChannel(nil, func(tx *bolt.Tx,
+		edgeInfo *channeldb.ChannelEdgeInfo,
+		_, _ *channeldb.ChannelEdgePolicy) error {
+
+		localChans = append(localChans, edgeInfo)
+		return nil
+	})
+	if err != nil {
+		return nil, err
 	}
+
+	// Now that we have all of our outbound edges, we'll populate the set
+	// of bandwidth hints, querying the lower switch layer for the most up
+	// to date values.
+	bandwidthHints := make(map[uint64]lnwire.MilliSatoshi)
+	for _, localChan := range localChans {
+		bandwidthHints[localChan.ChannelID] = queryBandwidth(localChan)
+	}
+
+	return bandwidthHints, nil
 }
 
 // ReportVertexFailure adds a vertex to the graph prune view after a client
@@ -285,7 +343,7 @@ func (p *paymentSession) RequestRoute(payment *LightningPayment,
 	path, err := findPath(
 		nil, p.mc.graph, p.additionalEdges, p.mc.selfNode,
 		payment.Target, pruneView.vertexes, pruneView.edges,
-		payment.Amount,
+		payment.Amount, p.bandwidthHints,
 	)
 	if err != nil {
 		return nil, err

routing/pathfind.go

@@ -458,7 +458,8 @@ func findPath(tx *bolt.Tx, graph *channeldb.ChannelGraph,
 	additionalEdges map[Vertex][]*channeldb.ChannelEdgePolicy,
 	sourceNode *channeldb.LightningNode, target *btcec.PublicKey,
 	ignoredNodes map[Vertex]struct{}, ignoredEdges map[uint64]struct{},
-	amt lnwire.MilliSatoshi) ([]*ChannelHop, error) {
+	amt lnwire.MilliSatoshi,
+	bandwidthHints map[uint64]lnwire.MilliSatoshi) ([]*ChannelHop, error) {
 
 	var err error
 	if tx == nil {
@@ -516,7 +517,7 @@ func findPath(tx *bolt.Tx, graph *channeldb.ChannelGraph,
 	// processEdge is a helper closure that will be used to make sure edges
 	// satisfy our specific requirements.
 	processEdge := func(edge *channeldb.ChannelEdgePolicy,
-		capacity btcutil.Amount, pivot Vertex) {
+		bandwidth lnwire.MilliSatoshi, pivot Vertex) {
 
 		v := Vertex(edge.Node.PubKeyBytes)
 
@@ -547,7 +548,7 @@ func findPath(tx *bolt.Tx, graph *channeldb.ChannelGraph,
 		// this edge. We'll also shave off irrelevant edges by adding
 		// the sufficient capacity of an edge and clearing their
 		// min-htlc amount to our relaxation condition.
-		if tempDist < distance[v].dist && capacity >= amt.ToSatoshis() &&
+		if tempDist < distance[v].dist && bandwidth >= amt &&
 			amt >= edge.MinHTLC && edge.TimeLockDelta != 0 {
 
 			distance[v] = nodeWithDist{
@@ -558,7 +559,7 @@ func findPath(tx *bolt.Tx, graph *channeldb.ChannelGraph,
 			prev[v] = edgeWithPrev{
 				edge: &ChannelHop{
 					ChannelEdgePolicy: edge,
-					Capacity:          capacity,
+					Capacity:          bandwidth.ToSatoshis(),
 				},
 				prevNode: pivot,
 			}
@@ -606,7 +607,20 @@ func findPath(tx *bolt.Tx, graph *channeldb.ChannelGraph,
 			edgeInfo *channeldb.ChannelEdgeInfo,
 			outEdge, _ *channeldb.ChannelEdgePolicy) error {
 
-			processEdge(outEdge, edgeInfo.Capacity, pivot)
+			// We'll query the lower layer to see if we can obtain
+			// any more up to date information concerning the
+			// bandwidth of this edge.
+			edgeBandwidth, ok := bandwidthHints[edgeInfo.ChannelID]
+			if !ok {
+				// If we don't have a hint for this edge, then
+				// we'll just use the known Capacity as the
+				// available bandwidth.
+				edgeBandwidth = lnwire.NewMSatFromSatoshis(
+					edgeInfo.Capacity,
+				)
+			}
+
+			processEdge(outEdge, edgeBandwidth, pivot)
 
 			// TODO(roasbeef): return min HTLC as error in end?
 
@@ -622,7 +636,7 @@ func findPath(tx *bolt.Tx, graph *channeldb.ChannelGraph,
 		// routing hint due to having enough capacity for the payment
 		// and use the payment amount as its capacity.
 		for _, edge := range additionalEdges[bestNode.PubKeyBytes] {
-			processEdge(edge, amt.ToSatoshis(), pivot)
+			processEdge(edge, amt, pivot)
 		}
 	}
 
@@ -681,7 +695,8 @@ func findPath(tx *bolt.Tx, graph *channeldb.ChannelGraph,
 // algorithm in a block box manner.
 func findPaths(tx *bolt.Tx, graph *channeldb.ChannelGraph,
 	source *channeldb.LightningNode, target *btcec.PublicKey,
-	amt lnwire.MilliSatoshi, numPaths uint32) ([][]*ChannelHop, error) {
+	amt lnwire.MilliSatoshi, numPaths uint32,
+	bandwidthHints map[uint64]lnwire.MilliSatoshi) ([][]*ChannelHop, error) {
 
 	ignoredEdges := make(map[uint64]struct{})
 	ignoredVertexes := make(map[Vertex]struct{})
@@ -698,7 +713,7 @@ func findPaths(tx *bolt.Tx, graph *channeldb.ChannelGraph,
 	// satoshis along the path before fees are calculated.
 	startingPath, err := findPath(
 		tx, graph, nil, source, target, ignoredVertexes, ignoredEdges,
-		amt,
+		amt, bandwidthHints,
 	)
 	if err != nil {
 		log.Errorf("Unable to find path: %v", err)
@@ -773,6 +788,7 @@ func findPaths(tx *bolt.Tx, graph *channeldb.ChannelGraph,
 			spurPath, err := findPath(
 				tx, graph, nil, spurNode, target,
 				ignoredVertexes, ignoredEdges, amt,
+				bandwidthHints,
 			)
 
 			// If we weren't able to find a path, we'll continue to

routing/pathfind_test.go

@@ -313,7 +313,7 @@ func TestBasicGraphPathFinding(t *testing.T) {
 	target := aliases["sophon"]
 	path, err := findPath(
 		nil, graph, nil, sourceNode, target, ignoredVertexes,
-		ignoredEdges, paymentAmt,
+		ignoredEdges, paymentAmt, nil,
 	)
 	if err != nil {
 		t.Fatalf("unable to find path: %v", err)
@@ -455,7 +455,7 @@ func TestBasicGraphPathFinding(t *testing.T) {
 	target = aliases["luoji"]
 	path, err = findPath(
 		nil, graph, nil, sourceNode, target, ignoredVertexes,
-		ignoredEdges, paymentAmt,
+		ignoredEdges, paymentAmt, nil,
 	)
 	if err != nil {
 		t.Fatalf("unable to find route: %v", err)
@@ -541,7 +541,7 @@ func TestPathFindingWithAdditionalEdges(t *testing.T) {
 	// We should now be able to find a path from roasbeef to doge.
 	path, err := findPath(
 		nil, graph, additionalEdges, sourceNode, dogePubKey, nil, nil,
-		paymentAmt,
+		paymentAmt, nil,
 	)
 	if err != nil {
 		t.Fatalf("unable to find private path to doge: %v", err)
@@ -578,6 +578,7 @@ func TestKShortestPathFinding(t *testing.T) {
 	target := aliases["luoji"]
 	paths, err := findPaths(
 		nil, graph, sourceNode, target, paymentAmt, 100,
+		nil,
 	)
 	if err != nil {
 		t.Fatalf("unable to find paths between roasbeef and "+
@@ -629,7 +630,7 @@ func TestNewRoutePathTooLong(t *testing.T) {
 	target := aliases["ursula"]
 	_, err = findPath(
 		nil, graph, nil, sourceNode, target, ignoredVertexes,
-		ignoredEdges, paymentAmt,
+		ignoredEdges, paymentAmt, nil,
 	)
 	if err != nil {
 		t.Fatalf("path should have been found")
@@ -640,7 +641,7 @@ func TestNewRoutePathTooLong(t *testing.T) {
 	target = aliases["vincent"]
 	path, err := findPath(
 		nil, graph, nil, sourceNode, target, ignoredVertexes,
-		ignoredEdges, paymentAmt,
+		ignoredEdges, paymentAmt, nil,
 	)
 	if err == nil {
 		t.Fatalf("should not have been able to find path, supposed to be "+
@@ -682,7 +683,7 @@ func TestPathNotAvailable(t *testing.T) {
 
 	_, err = findPath(
 		nil, graph, nil, sourceNode, unknownNode, ignoredVertexes,
-		ignoredEdges, 100,
+		ignoredEdges, 100, nil,
 	)
 	if !IsError(err, ErrNoPathFound) {
 		t.Fatalf("path shouldn't have been found: %v", err)
@@ -718,7 +719,7 @@ func TestPathInsufficientCapacity(t *testing.T) {
 	payAmt := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin)
 	_, err = findPath(
 		nil, graph, nil, sourceNode, target, ignoredVertexes,
-		ignoredEdges, payAmt,
+		ignoredEdges, payAmt, nil,
 	)
 	if !IsError(err, ErrNoPathFound) {
 		t.Fatalf("graph shouldn't be able to support payment: %v", err)
@@ -748,7 +749,7 @@ func TestRouteFailMinHTLC(t *testing.T) {
 	payAmt := lnwire.MilliSatoshi(10)
 	_, err = findPath(
 		nil, graph, nil, sourceNode, target, ignoredVertexes,
-		ignoredEdges, payAmt,
+		ignoredEdges, payAmt, nil,
 	)
 	if !IsError(err, ErrNoPathFound) {
 		t.Fatalf("graph shouldn't be able to support payment: %v", err)
@@ -778,7 +779,7 @@ func TestRouteFailDisabledEdge(t *testing.T) {
 	payAmt := lnwire.NewMSatFromSatoshis(10000)
 	_, err = findPath(
 		nil, graph, nil, sourceNode, target, ignoredVertexes,
-		ignoredEdges, payAmt,
+		ignoredEdges, payAmt, nil,
 	)
 	if err != nil {
 		t.Fatalf("unable to find path: %v", err)
@@ -799,7 +800,7 @@ func TestRouteFailDisabledEdge(t *testing.T) {
 	// failure as it is no longer eligible.
 	_, err = findPath(
 		nil, graph, nil, sourceNode, target, ignoredVertexes,
-		ignoredEdges, payAmt,
+		ignoredEdges, payAmt, nil,
 	)
 	if !IsError(err, ErrNoPathFound) {
 		t.Fatalf("graph shouldn't be able to support payment: %v", err)

routing/router.go

@@ -163,6 +163,14 @@ type Config struct {
 	// GraphPruneInterval is used as an interval to determine how often we
 	// should examine the channel graph to garbage collect zombie channels.
 	GraphPruneInterval time.Duration
+
+	// QueryBandwidth is a method that allows the router to query the lower
+	// link layer to determine the up to date available bandwidth at a
+	// prospective link to be traversed. If the  link isn't available, then
+	// a value of zero should be returned. Otherwise, the current up to
+	// date knowledge of the available bandwidth of the link should be
+	// returned.
+	QueryBandwidth func(edge *channeldb.ChannelEdgeInfo) lnwire.MilliSatoshi
 }
 
 // routeTuple is an entry within the ChannelRouter's route cache. We cache
@@ -283,18 +291,23 @@ func New(cfg Config) (*ChannelRouter, error) {
 		return nil, err
 	}
 
-	return &ChannelRouter{
+	r := &ChannelRouter{
 		cfg:               &cfg,
 		networkUpdates:    make(chan *routingMsg),
 		topologyClients:   make(map[uint64]*topologyClient),
 		ntfnClientUpdates: make(chan *topologyClientUpdate),
-		missionControl:    newMissionControl(cfg.Graph, selfNode),
 		channelEdgeMtx:    multimutex.NewMutex(),
 		selfNode:          selfNode,
 		routeCache:        make(map[routeTuple][]*Route),
 		rejectCache:       make(map[uint64]struct{}),
 		quit:              make(chan struct{}),
-	}, nil
+	}
+
+	r.missionControl = newMissionControl(
+		cfg.Graph, selfNode, cfg.QueryBandwidth,
+	)
+
+	return r, nil
 }
 
 // Start launches all the goroutines the ChannelRouter requires to carry out
@@ -1352,6 +1365,16 @@ func (r *ChannelRouter) FindRoutes(target *btcec.PublicKey,
 		return nil, err
 	}
 
+	// Before we open the db transaction below, we'll attempt to obtain a
+	// set of bandwidth hints that can help us eliminate certain routes
+	// early on in the path finding process.
+	bandwidthHints, err := generateBandwidthHints(
+		r.selfNode, r.cfg.QueryBandwidth,
+	)
+	if err != nil {
+		return nil, err
+	}
+
 	tx, err := r.cfg.Graph.Database().Begin(false)
 	if err != nil {
 		tx.Rollback()
@@ -1363,6 +1386,7 @@ func (r *ChannelRouter) FindRoutes(target *btcec.PublicKey,
 	// our source to the destination.
 	shortestPaths, err := findPaths(
 		tx, r.cfg.Graph, r.selfNode, target, amt, numPaths,
+		bandwidthHints,
 	)
 	if err != nil {
 		tx.Rollback()
@@ -1567,9 +1591,13 @@ func (r *ChannelRouter) SendPayment(payment *LightningPayment) ([32]byte, *Route
 	// Before starting the HTLC routing attempt, we'll create a fresh
 	// payment session which will report our errors back to mission
 	// control.
-	paySession := r.missionControl.NewPaymentSession(
+	paySession, err := r.missionControl.NewPaymentSession(
 		payment.RouteHints, payment.Target,
 	)
+	if err != nil {
+		return preImage, nil, fmt.Errorf("unable to create payment "+
+			"session: %v", err)
+	}
 
 	// We'll continue until either our payment succeeds, or we encounter a
 	// critical error during path finding.

routing/router_test.go

@@ -128,6 +128,9 @@ func createTestCtx(startingHeight uint32, testGraph ...string) (*testCtx, func()
 		},
 		ChannelPruneExpiry: time.Hour * 24,
 		GraphPruneInterval: time.Hour * 2,
+		QueryBandwidth: func(e *channeldb.ChannelEdgeInfo) lnwire.MilliSatoshi {
+			return lnwire.NewMSatFromSatoshis(e.Capacity)
+		},
 	})
 	if err != nil {
 		return nil, nil, fmt.Errorf("unable to create router %v", err)
@@ -1617,7 +1620,7 @@ func TestFindPathFeeWeighting(t *testing.T) {
 	// path even though the direct path has a higher potential time lock.
 	path, err := findPath(
 		nil, ctx.graph, nil, sourceNode, target, ignoreVertex,
-		ignoreEdge, amt,
+		ignoreEdge, amt, nil,
 	)
 	if err != nil {
 		t.Fatalf("unable to find path: %v", err)

server.go

@@ -351,6 +351,35 @@ func newServer(listenAddrs []string, chanDB *channeldb.DB, cc *chainControl,
 		},
 		ChannelPruneExpiry: time.Duration(time.Hour * 24 * 14),
 		GraphPruneInterval: time.Duration(time.Hour),
+		QueryBandwidth: func(edge *channeldb.ChannelEdgeInfo) lnwire.MilliSatoshi {
+			// If we aren't on either side of this edge, then we'll
+			// just thread through the capacity of the edge as we
+			// know it.
+			if !bytes.Equal(edge.NodeKey1Bytes[:], selfNode.PubKeyBytes[:]) &&
+				!bytes.Equal(edge.NodeKey2Bytes[:], selfNode.PubKeyBytes[:]) {
+
+				return lnwire.NewMSatFromSatoshis(edge.Capacity)
+			}
+
+			cid := lnwire.NewChanIDFromOutPoint(&edge.ChannelPoint)
+			link, err := s.htlcSwitch.GetLink(cid)
+			if err != nil {
+				// If the link isn't online, then we'll report
+				// that it has zero bandwidth to the router.
+				return 0
+			}
+
+			// If the link is found within the switch, but it isn't
+			// yet eligible to forward any HTLCs, then we'll treat
+			// it as if it isn't online in the first place.
+			if !link.EligibleToForward() {
+				return 0
+			}
+
+			// Otherwise, we'll return the current best estimate
+			// for the available bandwidth for the link.
+			return link.Bandwidth()
+		},
 	})
 	if err != nil {
 		return nil, fmt.Errorf("can't create router: %v", err)