routing: remove paymentFailure pointer

This introduces an option instead to signal whether there was a failure
for result interpretation.

routing/missioncontrol.go

@@ -276,7 +276,7 @@ type paymentResult struct {
 
 // newPaymentResult constructs a new paymentResult.
 func newPaymentResult(id uint64, rt *mcRoute, timeFwd, timeReply time.Time,
-	failure *paymentFailure) *paymentResult {
+	failure fn.Option[paymentFailure]) *paymentResult {
 
 	result := &paymentResult{
 		id: id,
@@ -289,11 +289,13 @@ func newPaymentResult(id uint64, rt *mcRoute, timeFwd, timeReply time.Time,
 		route: tlv.NewRecordT[tlv.TlvType2](*rt),
 	}
 
-	if failure != nil {
-		result.failure = tlv.SomeRecordT(
-			tlv.NewRecordT[tlv.TlvType3](*failure),
-		)
-	}
+	failure.WhenSome(
+		func(f paymentFailure) {
+			result.failure = tlv.SomeRecordT(
+				tlv.NewRecordT[tlv.TlvType3](f),
+			)
+		},
+	)
 
 	return result
 }
@@ -621,7 +623,7 @@ func (m *MissionControl) ReportPaymentFail(paymentID uint64, rt *route.Route,
 
 	result := newPaymentResult(
 		paymentID, extractMCRoute(rt), timestamp, timestamp,
-		newPaymentFailure(failureSourceIdx, failure),
+		fn.Some(newPaymentFailure(failureSourceIdx, failure)),
 	)
 
 	return m.processPaymentResult(result)
@@ -635,7 +637,8 @@ func (m *MissionControl) ReportPaymentSuccess(paymentID uint64,
 	timestamp := m.cfg.clock.Now()
 
 	result := newPaymentResult(
-		paymentID, extractMCRoute(rt), timestamp, timestamp, nil,
+		paymentID, extractMCRoute(rt), timestamp, timestamp,
+		fn.None[paymentFailure](),
 	)
 
 	_, err := m.processPaymentResult(result)
@@ -832,13 +835,13 @@ func (n *namespacedDB) purge() error {
 // failure with unknown details. Otherwise, the index and failure message are
 // used to populate the info field of the paymentFailure.
 func newPaymentFailure(sourceIdx *int,
-	failureMsg lnwire.FailureMessage) *paymentFailure {
+	failureMsg lnwire.FailureMessage) paymentFailure {
 
 	if sourceIdx == nil {
-		return &paymentFailure{}
+		return paymentFailure{}
 	}
 
-	return &paymentFailure{
+	return paymentFailure{
 		sourceIdx: tlv.SomeRecordT(
 			tlv.NewPrimitiveRecord[tlv.TlvType0](
 				uint8(*sourceIdx),

routing/missioncontrol_store_test.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/btcsuite/btcwallet/walletdb"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/kvdb"
 	"github.com/lightningnetwork/lnd/lntest/wait"
 	"github.com/lightningnetwork/lnd/lnwire"
@@ -85,19 +86,19 @@ func TestMissionControlStore(t *testing.T) {
 
 	result1 := newPaymentResult(
 		99, mcStoreTestRoute, testTime, testTime,
-		newPaymentFailure(
+		fn.Some(newPaymentFailure(
 			&failureSourceIdx,
 			lnwire.NewFailIncorrectDetails(100, 1000),
-		),
+		)),
 	)
 
 	result2 := newPaymentResult(
 		2, mcStoreTestRoute, testTime.Add(time.Hour),
 		testTime.Add(time.Hour),
-		newPaymentFailure(
+		fn.Some(newPaymentFailure(
 			&failureSourceIdx,
 			lnwire.NewFailIncorrectDetails(100, 1000),
-		),
+		)),
 	)
 
 	// Store result.
@@ -134,7 +135,7 @@ func TestMissionControlStore(t *testing.T) {
 	)
 	result3.id = 3
 	result3.failure = tlv.SomeRecordT(
-		tlv.NewRecordT[tlv.TlvType3](*newPaymentFailure(
+		tlv.NewRecordT[tlv.TlvType3](newPaymentFailure(
 			&failureSourceIdx, &lnwire.FailMPPTimeout{},
 		)),
 	)
@@ -153,7 +154,7 @@ func TestMissionControlStore(t *testing.T) {
 	// Also demonstrate the persistence of a success result.
 	result4 := newPaymentResult(
 		5, mcStoreTestRoute, testTime.Add(3*time.Hour),
-		testTime.Add(3*time.Hour), nil,
+		testTime.Add(3*time.Hour), fn.None[paymentFailure](),
 	)
 	store.AddResult(result4)
 	require.NoError(t, store.storeResults())
@@ -186,7 +187,10 @@ func TestMissionControlStoreFlushing(t *testing.T) {
 		return newPaymentResult(
 			lastID, mcStoreTestRoute, testTime.Add(-time.Hour),
 			testTime,
-			newPaymentFailure(&failureSourceIdx, failureDetails),
+			fn.Some(newPaymentFailure(
+				&failureSourceIdx,
+				failureDetails,
+			)),
 		)
 	}
 
@@ -287,10 +291,10 @@ func BenchmarkMissionControlStoreFlushing(b *testing.B) {
 				result := newPaymentResult(
 					lastID, mcStoreTestRoute, testTimeFwd,
 					testTime,
-					newPaymentFailure(
+					fn.Some(newPaymentFailure(
 						&failureSourceIdx,
 						failureDetails,
-					),
+					)),
 				)
 				store.AddResult(result)
 			}
@@ -305,10 +309,10 @@ func BenchmarkMissionControlStoreFlushing(b *testing.B) {
 				results[i] = newPaymentResult(
 					0, mcStoreTestRoute, testTimeFwd,
 					testTime,
-					newPaymentFailure(
+					fn.Some(newPaymentFailure(
 						&failureSourceIdx,
 						failureDetails,
-					),
+					)),
 				)
 			}
 

routing/result_interpretation_test.go

@@ -732,7 +732,7 @@ func TestResultInterpretation(t *testing.T) {
 		t.Run(testCase.name, func(t *testing.T) {
 			var failure fn.Option[paymentFailure]
 			if !testCase.success {
-				failure = fn.Some(*newPaymentFailure(
+				failure = fn.Some(newPaymentFailure(
 					&testCase.failureSrcIdx,
 					testCase.failure,
 				))