autopilot: convert Peer to route.Vertex

In preparation for removing the ForEachNode/ForEachChannel call pattern,
we refactor the autopilot subserver by simplifying the `ChannelEdge`
such that it no longer returns the `Node` type which has a
`ForEachChannel` method on it. The aim is to completely remove the
`ForEachChannel` usage.

autopilot/graph.go

@@ -106,9 +106,7 @@ func (d *dbNode) ForEachChannel(ctx context.Context,
 		edge := ChannelEdge{
 			ChanID:   lnwire.NewShortChanIDFromInt(ep.ChannelID),
 			Capacity: ei.Capacity,
-			Peer: &dbNode{
+			Peer:     node.Node().PubKeyBytes,
-				tx: node,
-			},
 		}
 
 		return cb(ctx, edge)
@@ -198,9 +196,7 @@ func (nc dbNodeCached) ForEachChannel(ctx context.Context,
 		edge := ChannelEdge{
 			ChanID:   lnwire.NewShortChanIDFromInt(cid),
 			Capacity: channel.Capacity,
-			Peer: dbNodeCached{
+			Peer:     channel.OtherNode,
-				node: channel.OtherNode,
-			},
 		}
 
 		if err := cb(ctx, edge); err != nil {

autopilot/interface.go

@@ -72,7 +72,7 @@ type ChannelEdge struct {
 
 	// Peer is the peer that this channel creates an edge to in the channel
 	// graph.
-	Peer Node
+	Peer route.Vertex
 }
 
 // ChannelGraph in an interface that represents a traversable channel graph.

autopilot/prefattach_test.go

@@ -175,8 +175,8 @@ func TestPrefAttachmentSelectTwoVertexes(t *testing.T) {
 			// The candidates should be amongst the two edges
 			// created above.
 			for nodeID, candidate := range candidates {
-				edge1Pub := edge1.Peer.PubKey()
+				edge1Pub := edge1.Peer
-				edge2Pub := edge2.Peer.PubKey()
+				edge2Pub := edge2.Peer
 
 				switch {
 				case bytes.Equal(nodeID[:], edge1Pub[:]):
@@ -228,7 +228,7 @@ func TestPrefAttachmentSelectGreedyAllocation(t *testing.T) {
 			)
 			require.NoError(t1, err)
 
-			peerPubBytes := edge1.Peer.PubKey()
+			peerPubBytes := edge1.Peer
 			peerPub, err := btcec.ParsePubKey(peerPubBytes[:])
 			require.NoError(t1, err)
 
@@ -535,18 +535,12 @@ func (d *testDBGraph) addRandChannel(node1, node2 *btcec.PublicKey,
 	return &ChannelEdge{
 			ChanID:   chanID,
 			Capacity: capacity,
-			Peer: &dbNode{tx: &testNodeTx{
+			Peer:     vertex1.PubKeyBytes,
-				db:   d,
-				node: vertex1,
-			}},
 		},
 		&ChannelEdge{
 			ChanID:   chanID,
 			Capacity: capacity,
-			Peer: &dbNode{tx: &testNodeTx{
+			Peer:     vertex2.PubKeyBytes,
-				db:   d,
-				node: vertex2,
-			}},
 		},
 		nil
 }
@@ -692,14 +686,14 @@ func (m *memChannelGraph) addRandChannel(node1, node2 *btcec.PublicKey,
 	edge1 := ChannelEdge{
 		ChanID:   randChanID(),
 		Capacity: capacity,
-		Peer:     vertex2,
+		Peer:     vertex2.PubKey(),
 	}
 	vertex1.chans = append(vertex1.chans, edge1)
 
 	edge2 := ChannelEdge{
 		ChanID:   randChanID(),
 		Capacity: capacity,
-		Peer:     vertex1,
+		Peer:     vertex1.PubKey(),
 	}
 	vertex2.chans = append(vertex2.chans, edge2)
 

autopilot/simple_graph.go

@@ -1,6 +1,10 @@
 package autopilot
 
-import "context"
+import (
+	"context"
+
+	"github.com/lightningnetwork/lnd/routing/route"
+)
 
 // diameterCutoff is used to discard nodes in the diameter calculation.
 // It is the multiplier for the eccentricity of the highest-degree node,
@@ -31,8 +35,8 @@ func NewSimpleGraph(ctx context.Context, g ChannelGraph) (*SimpleGraph, error) {
 	// The returned index is then used to create a simplified adjacency list
 	// where each node is identified by its index instead of its pubkey, and
 	// also to create a mapping from node index to node pubkey.
-	getNodeIndex := func(node Node) int {
+	getNodeIndex := func(node route.Vertex) int {
-		key := NodeID(node.PubKey())
+		key := NodeID(node)
 		nodeIndex, ok := nodes[key]
 
 		if !ok {
@@ -47,7 +51,7 @@ func NewSimpleGraph(ctx context.Context, g ChannelGraph) (*SimpleGraph, error) {
 	// Iterate over each node and each channel and update the adj and the
 	// node index.
 	err := g.ForEachNode(ctx, func(ctx context.Context, node Node) error {
-		u := getNodeIndex(node)
+		u := getNodeIndex(node.PubKey())
 
 		return node.ForEachChannel(
 			ctx, func(_ context.Context,