htlcswitch+peer: embed ChannelUpdateHandler in ChannelLink

GetLink, GetLinksByInterface now use ChannelUpdateHandler.

htlcswitch/interfaces.go

@@ -57,6 +57,39 @@ type packetHandler interface {
 	handleLocalAddPacket(*htlcPacket) error
 }
 
+// ChannelUpdateHandler is an interface that provides methods that allow
+// sending lnwire.Message to the underlying link as well as querying state.
+type ChannelUpdateHandler interface {
+	// HandleChannelUpdate handles the htlc requests as settle/add/fail
+	// which sent to us from remote peer we have a channel with.
+	//
+	// NOTE: This function MUST be non-blocking (or block as little as
+	// possible).
+	HandleChannelUpdate(lnwire.Message)
+
+	// ChanID returns the channel ID for the channel link. The channel ID
+	// is a more compact representation of a channel's full outpoint.
+	ChanID() lnwire.ChannelID
+
+	// Bandwidth returns the amount of milli-satoshis which current link
+	// might pass through channel link. The value returned from this method
+	// represents the up to date available flow through the channel. This
+	// takes into account any forwarded but un-cleared HTLC's, and any
+	// HTLC's which have been set to the over flow queue.
+	Bandwidth() lnwire.MilliSatoshi
+
+	// EligibleToForward returns a bool indicating if the channel is able
+	// to actively accept requests to forward HTLC's. A channel may be
+	// active, but not able to forward HTLC's if it hasn't yet finalized
+	// the pre-channel operation protocol with the remote peer. The switch
+	// will use this function in forwarding decisions accordingly.
+	EligibleToForward() bool
+
+	// MayAddOutgoingHtlc returns an error if we may not add an outgoing
+	// htlc to the channel.
+	MayAddOutgoingHtlc() error
+}
+
 // ChannelLink is an interface which represents the subsystem for managing the
 // incoming htlc requests, applying the changes to the channel, and also
 // propagating/forwarding it to htlc switch.
@@ -81,20 +114,12 @@ type ChannelLink interface {
 	// Embed the packetHandler interface.
 	packetHandler
 
-	// HandleChannelUpdate handles the htlc requests as settle/add/fail
-	// which sent to us from remote peer we have a channel with.
-	//
-	// NOTE: This function MUST be non-blocking (or block as little as
-	// possible).
-	HandleChannelUpdate(lnwire.Message)
+	// Embed the ChannelUpdateHandler interface.
+	ChannelUpdateHandler
 
 	// ChannelPoint returns the channel outpoint for the channel link.
 	ChannelPoint() *wire.OutPoint
 
-	// ChanID returns the channel ID for the channel link. The channel ID
-	// is a more compact representation of a channel's full outpoint.
-	ChanID() lnwire.ChannelID
-
 	// ShortChanID returns the short channel ID for the channel link. The
 	// short channel ID encodes the exact location in the main chain that
 	// the original funding output can be found.
@@ -129,13 +154,6 @@ type ChannelLink interface {
 	CheckHtlcTransit(payHash [32]byte, amt lnwire.MilliSatoshi,
 		timeout uint32, heightNow uint32) *LinkError
 
-	// Bandwidth returns the amount of milli-satoshis which current link
-	// might pass through channel link. The value returned from this method
-	// represents the up to date available flow through the channel. This
-	// takes into account any forwarded but un-cleared HTLC's, and any
-	// HTLC's which have been set to the over flow queue.
-	Bandwidth() lnwire.MilliSatoshi
-
 	// Stats return the statistics of channel link. Number of updates,
 	// total sent/received milli-satoshis.
 	Stats() (uint64, lnwire.MilliSatoshi, lnwire.MilliSatoshi)
@@ -144,17 +162,6 @@ type ChannelLink interface {
 	// the channel link opened.
 	Peer() lnpeer.Peer
 
-	// EligibleToForward returns a bool indicating if the channel is able
-	// to actively accept requests to forward HTLC's. A channel may be
-	// active, but not able to forward HTLC's if it hasn't yet finalized
-	// the pre-channel operation protocol with the remote peer. The switch
-	// will use this function in forwarding decisions accordingly.
-	EligibleToForward() bool
-
-	// MayAddOutgoingHtlc returns an error if we may not add an outgoing
-	// htlc to the channel.
-	MayAddOutgoingHtlc() error
-
 	// AttachMailBox delivers an active MailBox to the link. The MailBox may
 	// have buffered messages.
 	AttachMailBox(MailBox)

htlcswitch/switch.go

@@ -2022,7 +2022,9 @@ func (s *Switch) addLiveLink(link ChannelLink) {
 
 // GetLink is used to initiate the handling of the get link command. The
 // request will be propagated/handled to/in the main goroutine.
-func (s *Switch) GetLink(chanID lnwire.ChannelID) (ChannelLink, error) {
+func (s *Switch) GetLink(chanID lnwire.ChannelID) (ChannelUpdateHandler,
+	error) {
+
 	s.indexMtx.RLock()
 	defer s.indexMtx.RUnlock()
 
@@ -2164,11 +2166,26 @@ func (s *Switch) UpdateShortChanID(chanID lnwire.ChannelID) error {
 
 // GetLinksByInterface fetches all the links connected to a particular node
 // identified by the serialized compressed form of its public key.
-func (s *Switch) GetLinksByInterface(hop [33]byte) ([]ChannelLink, error) {
+func (s *Switch) GetLinksByInterface(hop [33]byte) ([]ChannelUpdateHandler,
+	error) {
+
 	s.indexMtx.RLock()
 	defer s.indexMtx.RUnlock()
 
-	return s.getLinks(hop)
+	var handlers []ChannelUpdateHandler
+
+	links, err := s.getLinks(hop)
+	if err != nil {
+		return nil, err
+	}
+
+	// Range over the returned []ChannelLink to convert them into
+	// []ChannelUpdateHandler.
+	for _, link := range links {
+		handlers = append(handlers, link)
+	}
+
+	return handlers, nil
 }
 
 // getLinks is function which returns the channel links of the peer by hop