routing/payment_session: make NewPaymentSession take payment directly

This commit moves supplying of the information in the LightningPayment
to the initialization of the paymentSession, away from every call to
RequestRoute.

Instead the paymentSession will store this information internally, as it
doesn't change between payment attempts.

This is done to rid the RequestRoute call of the LightingPayment
argument, as for SendToRoute calls, it is not needed to supply the next
route.

routing/mock_test.go

@@ -10,7 +10,6 @@ import (
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/routing/route"
-	"github.com/lightningnetwork/lnd/zpay32"
 )
 
 type mockPaymentAttemptDispatcher struct {
@@ -78,8 +77,8 @@ type mockPaymentSessionSource struct {
 
 var _ PaymentSessionSource = (*mockPaymentSessionSource)(nil)
 
-func (m *mockPaymentSessionSource) NewPaymentSession(routeHints [][]zpay32.HopHint,
-	target route.Vertex) (PaymentSession, error) {
+func (m *mockPaymentSessionSource) NewPaymentSession(
+	_ *LightningPayment) (PaymentSession, error) {
 
 	return &mockPaymentSession{m.routes}, nil
 }
@@ -123,9 +122,7 @@ type mockPaymentSession struct {
 
 var _ PaymentSession = (*mockPaymentSession)(nil)
 
-func (m *mockPaymentSession) RequestRoute(payment *LightningPayment,
-	height uint32, finalCltvDelta uint16) (*route.Route, error) {
-
+func (m *mockPaymentSession) RequestRoute(height uint32) (*route.Route, error) {
 	if len(m.routes) == 0 {
 		return nil, fmt.Errorf("no routes")
 	}

routing/payment_lifecycle.go

@@ -34,7 +34,6 @@ type paymentLifecycle struct {
 	paySession    PaymentSession
 	timeoutChan   <-chan time.Time
 	currentHeight int32
-	finalCLTVDelta uint16
 	attempt       *channeldb.HTLCAttemptInfo
 	circuit       *sphinx.Circuit
 	lastError     error
@@ -267,9 +266,7 @@ func (p *paymentLifecycle) createNewPaymentAttempt() (lnwire.ShortChannelID,
 	}
 
 	// Create a new payment attempt from the given payment session.
-	rt, err := p.paySession.RequestRoute(
-		p.payment, uint32(p.currentHeight), p.finalCLTVDelta,
-	)
+	rt, err := p.paySession.RequestRoute(uint32(p.currentHeight))
 	if err != nil {
 		log.Warnf("Failed to find route for payment %x: %v",
 			p.payment.PaymentHash, err)

routing/payment_session.go

@@ -24,8 +24,7 @@ var (
 type PaymentSession interface {
 	// RequestRoute returns the next route to attempt for routing the
 	// specified HTLC payment to the target node.
-	RequestRoute(payment *LightningPayment,
-		height uint32, finalCltvDelta uint16) (*route.Route, error)
+	RequestRoute(height uint32) (*route.Route, error)
 }
 
 // paymentSession is used during an HTLC routings session to prune the local
@@ -43,6 +42,8 @@ type paymentSession struct {
 
 	sessionSource *SessionSource
 
+	payment *LightningPayment
+
 	preBuiltRoute      *route.Route
 	preBuiltRouteTried bool
 
@@ -58,8 +59,7 @@ type paymentSession struct {
 //
 // NOTE: This function is safe for concurrent access.
 // NOTE: Part of the PaymentSession interface.
-func (p *paymentSession) RequestRoute(payment *LightningPayment,
-	height uint32, finalCltvDelta uint16) (*route.Route, error) {
+func (p *paymentSession) RequestRoute(height uint32) (*route.Route, error) {
 
 	switch {
 
@@ -77,12 +77,13 @@ func (p *paymentSession) RequestRoute(payment *LightningPayment,
 
 	// Add BlockPadding to the finalCltvDelta so that the receiving node
 	// does not reject the HTLC if some blocks are mined while it's in-flight.
+	finalCltvDelta := p.payment.FinalCLTVDelta
 	finalCltvDelta += BlockPadding
 
 	// We need to subtract the final delta before passing it into path
 	// finding. The optimal path is independent of the final cltv delta and
 	// the path finding algorithm is unaware of this value.
-	cltvLimit := payment.CltvLimit - uint32(finalCltvDelta)
+	cltvLimit := p.payment.CltvLimit - uint32(finalCltvDelta)
 
 	// TODO(roasbeef): sync logic amongst dist sys
 
@@ -93,13 +94,13 @@ func (p *paymentSession) RequestRoute(payment *LightningPayment,
 
 	restrictions := &RestrictParams{
 		ProbabilitySource: ss.MissionControl.GetProbability,
-		FeeLimit:          payment.FeeLimit,
-		OutgoingChannelID: payment.OutgoingChannelID,
-		LastHop:           payment.LastHop,
+		FeeLimit:          p.payment.FeeLimit,
+		OutgoingChannelID: p.payment.OutgoingChannelID,
+		LastHop:           p.payment.LastHop,
 		CltvLimit:         cltvLimit,
-		DestCustomRecords: payment.DestCustomRecords,
-		DestFeatures:      payment.DestFeatures,
-		PaymentAddr:       payment.PaymentAddr,
+		DestCustomRecords: p.payment.DestCustomRecords,
+		DestFeatures:      p.payment.DestFeatures,
+		PaymentAddr:       p.payment.PaymentAddr,
 	}
 
 	// We'll also obtain a set of bandwidthHints from the lower layer for
@@ -122,8 +123,8 @@ func (p *paymentSession) RequestRoute(payment *LightningPayment,
 			bandwidthHints:  bandwidthHints,
 		},
 		restrictions, &ss.PathFindingConfig,
-		ss.SelfNode.PubKeyBytes, payment.Target,
-		payment.Amount, finalHtlcExpiry,
+		ss.SelfNode.PubKeyBytes, p.payment.Target,
+		p.payment.Amount, finalHtlcExpiry,
 	)
 	if err != nil {
 		return nil, err
@@ -135,10 +136,10 @@ func (p *paymentSession) RequestRoute(payment *LightningPayment,
 	route, err := newRoute(
 		sourceVertex, path, height,
 		finalHopParams{
-			amt:         payment.Amount,
+			amt:         p.payment.Amount,
 			cltvDelta:   finalCltvDelta,
-			records:     payment.DestCustomRecords,
-			paymentAddr: payment.PaymentAddr,
+			records:     p.payment.DestCustomRecords,
+			paymentAddr: p.payment.PaymentAddr,
 		},
 	)
 	if err != nil {

routing/payment_session_source.go

@@ -47,10 +47,10 @@ type SessionSource struct {
 // view from Mission Control. An optional set of routing hints can be provided
 // in order to populate additional edges to explore when finding a path to the
 // payment's destination.
-func (m *SessionSource) NewPaymentSession(routeHints [][]zpay32.HopHint,
-	target route.Vertex) (PaymentSession, error) {
+func (m *SessionSource) NewPaymentSession(p *LightningPayment) (
+	PaymentSession, error) {
 
-	edges, err := RouteHintsToEdges(routeHints, target)
+	edges, err := RouteHintsToEdges(p.RouteHints, p.Target)
 	if err != nil {
 		return nil, err
 	}
@@ -70,6 +70,7 @@ func (m *SessionSource) NewPaymentSession(routeHints [][]zpay32.HopHint,
 		additionalEdges:   edges,
 		getBandwidthHints: getBandwidthHints,
 		sessionSource:     m,
+		payment:           p,
 		pathFinder:        findPath,
 	}, nil
 }

routing/payment_session_test.go

@@ -44,16 +44,6 @@ func TestRequestRoute(t *testing.T) {
 		},
 	}
 
-	session := &paymentSession{
-		getBandwidthHints: func() (map[uint64]lnwire.MilliSatoshi,
-			error) {
-
-			return nil, nil
-		},
-		sessionSource: sessionSource,
-		pathFinder:    findPath,
-	}
-
 	cltvLimit := uint32(30)
 	finalCltvDelta := uint16(8)
 
@@ -62,7 +52,18 @@ func TestRequestRoute(t *testing.T) {
 		FinalCLTVDelta: finalCltvDelta,
 	}
 
-	route, err := session.RequestRoute(payment, height, finalCltvDelta)
+	session := &paymentSession{
+		getBandwidthHints: func() (map[uint64]lnwire.MilliSatoshi,
+			error) {
+
+			return nil, nil
+		},
+		sessionSource: sessionSource,
+		payment:       payment,
+		pathFinder:    findPath,
+	}
+
+	route, err := session.RequestRoute(height)
 	if err != nil {
 		t.Fatal(err)
 	}

routing/router.go

@@ -159,8 +159,7 @@ type PaymentSessionSource interface {
 	// routes to the given target. An optional set of routing hints can be
 	// provided in order to populate additional edges to explore when
 	// finding a path to the payment's destination.
-	NewPaymentSession(routeHints [][]zpay32.HopHint,
-		target route.Vertex) (PaymentSession, error)
+	NewPaymentSession(p *LightningPayment) (PaymentSession, error)
 
 	// NewPaymentSessionForRoute creates a new paymentSession instance that
 	// is just used for failure reporting to missioncontrol, and will only
@@ -1677,9 +1676,7 @@ func (r *ChannelRouter) preparePayment(payment *LightningPayment) (
 	// Before starting the HTLC routing attempt, we'll create a fresh
 	// payment session which will report our errors back to mission
 	// control.
-	paySession, err := r.cfg.SessionSource.NewPaymentSession(
-		payment.RouteHints, payment.Target,
-	)
+	paySession, err := r.cfg.SessionSource.NewPaymentSession(payment)
 	if err != nil {
 		return nil, err
 	}
@@ -1817,7 +1814,6 @@ func (r *ChannelRouter) sendPayment(
 		payment:       payment,
 		paySession:    paySession,
 		currentHeight: currentHeight,
-		finalCLTVDelta: uint16(payment.FinalCLTVDelta),
 		attempt:       existingAttempt,
 		circuit:       nil,
 		lastError:     nil,