multi: move ChannelGraphSource interface

... to the new `graph` package in preparation for the implementation of
the interface being moved to this new package.

routing/router.go

@@ -24,6 +24,7 @@ import (
 	"github.com/lightningnetwork/lnd/channeldb/models"
 	"github.com/lightningnetwork/lnd/clock"
 	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/graph"
 	"github.com/lightningnetwork/lnd/htlcswitch"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/kvdb"
@@ -127,82 +128,6 @@ var (
 	ErrSkipTempErr = errors.New("cannot skip temp error for non-MPP")
 )
 
-// ChannelGraphSource represents the source of information about the topology
-// of the lightning network. It's responsible for the addition of nodes, edges,
-// applying edge updates, and returning the current block height with which the
-// topology is synchronized.
-type ChannelGraphSource interface {
-	// AddNode is used to add information about a node to the router
-	// database. If the node with this pubkey is not present in an existing
-	// channel, it will be ignored.
-	AddNode(node *channeldb.LightningNode,
-		op ...batch.SchedulerOption) error
-
-	// AddEdge is used to add edge/channel to the topology of the router,
-	// after all information about channel will be gathered this
-	// edge/channel might be used in construction of payment path.
-	AddEdge(edge *models.ChannelEdgeInfo,
-		op ...batch.SchedulerOption) error
-
-	// AddProof updates the channel edge info with proof which is needed to
-	// properly announce the edge to the rest of the network.
-	AddProof(chanID lnwire.ShortChannelID,
-		proof *models.ChannelAuthProof) error
-
-	// UpdateEdge is used to update edge information, without this message
-	// edge considered as not fully constructed.
-	UpdateEdge(policy *models.ChannelEdgePolicy,
-		op ...batch.SchedulerOption) error
-
-	// IsStaleNode returns true if the graph source has a node announcement
-	// for the target node with a more recent timestamp. This method will
-	// also return true if we don't have an active channel announcement for
-	// the target node.
-	IsStaleNode(node route.Vertex, timestamp time.Time) bool
-
-	// IsPublicNode determines whether the given vertex is seen as a public
-	// node in the graph from the graph's source node's point of view.
-	IsPublicNode(node route.Vertex) (bool, error)
-
-	// IsKnownEdge returns true if the graph source already knows of the
-	// passed channel ID either as a live or zombie edge.
-	IsKnownEdge(chanID lnwire.ShortChannelID) bool
-
-	// IsStaleEdgePolicy returns true if the graph source has a channel
-	// edge for the passed channel ID (and flags) that have a more recent
-	// timestamp.
-	IsStaleEdgePolicy(chanID lnwire.ShortChannelID, timestamp time.Time,
-		flags lnwire.ChanUpdateChanFlags) bool
-
-	// MarkEdgeLive clears an edge from our zombie index, deeming it as
-	// live.
-	MarkEdgeLive(chanID lnwire.ShortChannelID) error
-
-	// ForAllOutgoingChannels is used to iterate over all channels
-	// emanating from the "source" node which is the center of the
-	// star-graph.
-	ForAllOutgoingChannels(cb func(tx kvdb.RTx,
-		c *models.ChannelEdgeInfo,
-		e *models.ChannelEdgePolicy) error) error
-
-	// CurrentBlockHeight returns the block height from POV of the router
-	// subsystem.
-	CurrentBlockHeight() (uint32, error)
-
-	// GetChannelByID return the channel by the channel id.
-	GetChannelByID(chanID lnwire.ShortChannelID) (
-		*models.ChannelEdgeInfo, *models.ChannelEdgePolicy,
-		*models.ChannelEdgePolicy, error)
-
-	// FetchLightningNode attempts to look up a target node by its identity
-	// public key. channeldb.ErrGraphNodeNotFound is returned if the node
-	// doesn't exist within the graph.
-	FetchLightningNode(route.Vertex) (*channeldb.LightningNode, error)
-
-	// ForEachNode is used to iterate over every node in the known graph.
-	ForEachNode(func(node *channeldb.LightningNode) error) error
-}
-
 // PaymentAttemptDispatcher is used by the router to send payment attempts onto
 // the network, and receive their results.
 type PaymentAttemptDispatcher interface {
@@ -499,7 +424,7 @@ type ChannelRouter struct {
 
 // A compile time check to ensure ChannelRouter implements the
 // ChannelGraphSource interface.
-var _ ChannelGraphSource = (*ChannelRouter)(nil)
+var _ graph.ChannelGraphSource = (*ChannelRouter)(nil)
 
 // New creates a new instance of the ChannelRouter with the specified
 // configuration parameters. As part of initialization, if the router detects