graph/db: let ForEachNodeCached maybe fetch node addresses

Here we adjust the ForEachNodeCached graph DB method to pass in a node's
addresses into the provided call-back if requested. This will allow us
to improve the performance of node/channel iteration in the autopilot
subserver.

graph/db/graph.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"net"
 	"sync"
 	"sync/atomic"
 	"testing"
@@ -248,15 +249,21 @@ func (c *ChannelGraph) GraphSession(cb func(graph NodeTraverser) error,
 // graph, executing the passed callback with each node encountered.
 //
 // NOTE: The callback contents MUST not be modified.
-func (c *ChannelGraph) ForEachNodeCached(ctx context.Context,
-	cb func(node route.Vertex, chans map[uint64]*DirectedChannel) error,
-	reset func()) error {
+func (c *ChannelGraph) ForEachNodeCached(ctx context.Context, withAddrs bool,
+	cb func(ctx context.Context, node route.Vertex, addrs []net.Addr,
+		chans map[uint64]*DirectedChannel) error, reset func()) error {
 
-	if c.graphCache != nil {
-		return c.graphCache.ForEachNode(cb)
+	if !withAddrs && c.graphCache != nil {
+		return c.graphCache.ForEachNode(
+			func(node route.Vertex,
+				channels map[uint64]*DirectedChannel) error {
+
+				return cb(ctx, node, nil, channels)
+			},
+		)
 	}
 
-	return c.V1Store.ForEachNodeCached(ctx, cb, reset)
+	return c.V1Store.ForEachNodeCached(ctx, withAddrs, cb, reset)
 }
 
 // AddLightningNode adds a vertex/node to the graph database. If the node is not