htlcswitch+channeldb: add htlcidx to fwding log

In this commit we add htlcindex field to the forwardingevent
struct, which is persisted alongside the other event fields.

Author: Abdulkbk

channeldb/forwarding_log.go

@@ -25,11 +25,11 @@ const (
 	// is as follows:
 	//
 	//  * 8 byte incoming chan ID || 8 byte outgoing chan ID || 8 byte value in
-	//    || 8 byte value out
+	//    || 8 byte value out || 8 byte htlc index
 	//
 	// From the value in and value out, callers can easily compute the
 	// total fee extract from a forwarding event.
-	forwardingEventSize = 32
+	forwardingEventSize = 40
 
 	// MaxResponseEvents is the max number of forwarding events that will
 	// be returned by a single query response. This size was selected to
@@ -78,6 +78,10 @@ type ForwardingEvent struct {
 	// AmtOut is the amount of the outgoing HTLC. Subtracting the incoming
 	// amount from this gives the total fees for this payment circuit.
 	AmtOut lnwire.MilliSatoshi
+
+	// HtlcIndex is the index of the HTLC in the channel. This is used to
+	// match the HTLC in the channel with the HTLC in the forwarding log.
+	HtlcIndex uint64
 }
 
 // encodeForwardingEvent writes out the target forwarding event to the passed
@@ -86,6 +90,7 @@ type ForwardingEvent struct {
 func encodeForwardingEvent(w io.Writer, f *ForwardingEvent) error {
 	return WriteElements(
 		w, f.IncomingChanID, f.OutgoingChanID, f.AmtIn, f.AmtOut,
+		f.HtlcIndex,
 	)
 }
 
@@ -96,6 +101,7 @@ func encodeForwardingEvent(w io.Writer, f *ForwardingEvent) error {
 func decodeForwardingEvent(r io.Reader, f *ForwardingEvent) error {
 	return ReadElements(
 		r, &f.IncomingChanID, &f.OutgoingChanID, &f.AmtIn, &f.AmtOut,
+		&f.HtlcIndex,
 	)
 }
 

channeldb/forwarding_log_test.go

@@ -41,6 +41,7 @@ func TestForwardingLogBasicStorageAndQuery(t *testing.T) {
 			OutgoingChanID: lnwire.NewShortChanIDFromInt(uint64(rand.Int63())),
 			AmtIn:          lnwire.MilliSatoshi(rand.Int63()),
 			AmtOut:         lnwire.MilliSatoshi(rand.Int63()),
+			HtlcIndex:      uint64(i),
 		}
 
 		timestamp = timestamp.Add(time.Minute * 10)
@@ -109,6 +110,7 @@ func TestForwardingLogQueryOptions(t *testing.T) {
 			OutgoingChanID: lnwire.NewShortChanIDFromInt(uint64(rand.Int63())),
 			AmtIn:          lnwire.MilliSatoshi(rand.Int63()),
 			AmtOut:         lnwire.MilliSatoshi(rand.Int63()),
+			HtlcIndex:      uint64(i),
 		}
 
 		endTime = endTime.Add(time.Minute * 10)
@@ -208,6 +210,7 @@ func TestForwardingLogQueryLimit(t *testing.T) {
 			OutgoingChanID: lnwire.NewShortChanIDFromInt(uint64(rand.Int63())),
 			AmtIn:          lnwire.MilliSatoshi(rand.Int63()),
 			AmtOut:         lnwire.MilliSatoshi(rand.Int63()),
+			HtlcIndex:      uint64(i),
 		}
 
 		endTime = endTime.Add(time.Minute * 10)
@@ -317,6 +320,7 @@ func TestForwardingLogStoreEvent(t *testing.T) {
 			OutgoingChanID: lnwire.NewShortChanIDFromInt(uint64(rand.Int63())),
 			AmtIn:          lnwire.MilliSatoshi(rand.Int63()),
 			AmtOut:         lnwire.MilliSatoshi(rand.Int63()),
+			HtlcIndex:      uint64(i),
 		}
 	}
 

htlcswitch/switch.go

@@ -3074,6 +3074,7 @@ func (s *Switch) handlePacketSettle(packet *htlcPacket) error {
 				OutgoingChanID: circuit.Outgoing.ChanID,
 				AmtIn:          circuit.IncomingAmount,
 				AmtOut:         circuit.OutgoingAmount,
+				HtlcIndex:      circuit.Incoming.HtlcID,
 			},
 		)
 		s.fwdEventMtx.Unlock()