graph: remove unused ForEachNode method from Builder

And from various interfaces where it is not needed.

Author: ellemouton

graph/builder.go

@@ -1555,18 +1555,6 @@ func (b *Builder) FetchLightningNode(
 	return b.cfg.Graph.FetchLightningNode(node)
 }
 
-// ForEachNode is used to iterate over every node in router topology.
-//
-// NOTE: This method is part of the ChannelGraphSource interface.
-func (b *Builder) ForEachNode(
-	cb func(*models.LightningNode) error) error {
-
-	return b.cfg.Graph.ForEachNode(
-		func(_ kvdb.RTx, n *models.LightningNode) error {
-			return cb(n)
-		})
-}
-
 // ForAllOutgoingChannels is used to iterate over all outgoing channels owned by
 // the router.
 //

graph/interfaces.go

@@ -85,9 +85,6 @@ type ChannelGraphSource interface {
 	// public key. channeldb.ErrGraphNodeNotFound is returned if the node
 	// doesn't exist within the graph.
 	FetchLightningNode(route.Vertex) (*models.LightningNode, error)
-
-	// ForEachNode is used to iterate over every node in the known graph.
-	ForEachNode(func(node *models.LightningNode) error) error
 }
 
 // DB is an interface describing a persisted Lightning Network graph.
@@ -241,12 +238,6 @@ type DB interface {
 	FetchLightningNode(nodePub route.Vertex) (*models.LightningNode,
 		error)
 
-	// ForEachNode iterates through all the stored vertices/nodes in the
-	// graph, executing the passed callback with each node encountered. If
-	// the callback returns an error, then the transaction is aborted and
-	// the iteration stops early.
-	ForEachNode(cb func(kvdb.RTx, *models.LightningNode) error) error
-
 	// ForEachNodeChannel iterates through all channels of the given node,
 	// executing the passed callback with an edge info structure and the
 	// policies of each end of the channel. The first edge policy is the