routing: abstract path finding behind mission control

In this commit, from the PoV of the SendPayment method we now delegate
all path finding+verification to missionControl. This change doesn’t
materially affect anything, it simply expands the abstraction to make
way for future features that more heavily utilize mission control.

routing/missioncontrol.go

@@ -3,6 +3,8 @@ package routing
 import (
 	"sync"
 	"time"
+
+	"github.com/lightningnetwork/lnd/channeldb"
 )
 
 const (
@@ -49,6 +51,10 @@ type missionControl struct {
 	// to that particular vertex.
 	failedVertexes map[vertex]time.Time
 
+	graph *channeldb.ChannelGraph
+
+	selfNode *channeldb.LightningNode
+
 	sync.Mutex
 
 	// TODO(roasbeef): further counters, if vertex continually unavailable,
@@ -60,8 +66,12 @@ type missionControl struct {
 // newMissionControl returns a new instance of missionControl.
 //
 // TODO(roasbeef): persist memory
-func newMissionControl() *missionControl {
+func newMissionControl(g *channeldb.ChannelGraph,
+	s *channeldb.LightningNode) *missionControl {
+
 	return &missionControl{
+		graph:          g,
+		selfNode:       s,
 		failedEdges:    make(map[uint64]time.Time),
 		failedVertexes: make(map[vertex]time.Time),
 	}
@@ -92,6 +102,45 @@ func (m *missionControl) ReportChannelFailure(e uint64) {
 	m.Unlock()
 }
 
+// RequestRoute returns a route which is likely to be capable for successfully
+// routing the specified HTLC payment to the target node. Initially the first
+// set of paths returned from this method may encounter routing failure along
+// the way, however as more payments are sent, mission control will start to
+// build an up to date view of the network itself. With each payment a new area
+// will be explored, which feeds into the recommendations made for routing.
+//
+// NOTE: This function is safe for concurrent access.
+func (m *missionControl) RequestRoute(payment *LightningPayment,
+	height uint32) (*Route, error) {
+
+	// First, we'll query mission control for it's current recommendation
+	// on the edges/vertexes to ignore during path finding.
+	pruneView := m.GraphPruneView()
+
+	// TODO(roasbeef): sync logic amongst dist sys
+
+	// Taking into account this prune view, we'll attempt to locate a path
+	// to our destination, respecting the recommendations from
+	// missionControl.
+	path, err := findPath(nil, m.graph, m.selfNode, payment.Target,
+		pruneView.vertexes, pruneView.edges, payment.Amount)
+	if err != nil {
+		return nil, err
+	}
+
+	// With the next candidate path found, we'll attempt to turn this into
+	// a route by applying the time-lock and fee requirements.
+	sourceVertex := newVertex(m.selfNode.PubKey)
+	route, err := newRoute(payment.Amount, sourceVertex, path, height)
+	if err != nil {
+		// TODO(roasbeef): return which edge/vertex didn't work
+		// out
+		return nil, err
+	}
+
+	return route, err
+}
+
 // GraphPruneView returns a new graphPruneView instance which is to be
 // consulted during path finding. If a vertex/edge is found within the returned
 // prune view, it is to be ignored as a goroutine has had issues routing

routing/router.go

@@ -234,7 +234,7 @@ func New(cfg Config) (*ChannelRouter, error) {
 		networkUpdates:    make(chan *routingMsg),
 		topologyClients:   make(map[uint64]*topologyClient),
 		ntfnClientUpdates: make(chan *topologyClientUpdate),
-		missionControl:    newMissionControl(),
+		missionControl:    newMissionControl(cfg.Graph, selfNode),
 		routeCache:        make(map[routeTuple][]*Route),
 		quit:              make(chan struct{}),
 	}, nil
@@ -1189,19 +1189,13 @@ func (r *ChannelRouter) SendPayment(payment *LightningPayment) ([32]byte, *Route
 
 	// We'll continue until either our payment succeeds, or we encounter a
 	// critical error during path finding.
-	sourceVertex := newVertex(r.selfNode.PubKey)
 	for {
-		// First, we'll query mission control for it's current
-		// recommendation on the edges/vertexes to ignore during path
-		// finding.
-		pruneView := r.missionControl.GraphPruneView()
-
-		// Taking into account this prune view, we'll attempt to locate
-		// a path to our destination, respecting the recommendations
-		// from missionControl.
-		path, err := findPath(nil, r.cfg.Graph, r.selfNode,
-			payment.Target, pruneView.vertexes, pruneView.edges,
-			payment.Amount)
+		// We'll kick things off by requesting a new route from mission
+		// control, which will incoroporate the current best known
+		// state of the channel graph and our past HTLC routing
+		// successes/failures.
+		route, err := r.missionControl.RequestRoute(payment,
+			uint32(currentHeight))
 		if err != nil {
 			// If we're unable to successfully make a payment using
 			// any of the routes we've found, then return an error.
@@ -1214,17 +1208,6 @@ func (r *ChannelRouter) SendPayment(payment *LightningPayment) ([32]byte, *Route
 			return preImage, nil, err
 		}
 
-		// With the next candiate path found, we'll attempt to turn
-		// this into a route by applying the time-lock and fee
-		// requirements.
-		route, err := newRoute(payment.Amount, sourceVertex, path,
-			uint32(currentHeight))
-		if err != nil {
-			// TODO(roasbeef): return which edge/vertex didn't work
-			// out
-			return preImage, nil, err
-		}
-
 		log.Tracef("Attempting to send payment %x, using route: %v",
 			payment.PaymentHash, newLogClosure(func() string {
 				return spew.Sdump(route)