multi: move ChannelGraphSource interface

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

graph/interfaces.go

@@ -0,0 +1,90 @@
+package graph
+
+import (
+	"time"
+
+	"github.com/lightningnetwork/lnd/batch"
+	"github.com/lightningnetwork/lnd/channeldb"
+	"github.com/lightningnetwork/lnd/channeldb/models"
+	"github.com/lightningnetwork/lnd/kvdb"
+	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/lightningnetwork/lnd/routing/route"
+)
+
+// 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.
+//
+//nolint:interfacebloat
+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
+}