multi: move payment related code into own package

This commit moves most of the code into its own package. It is
the smallest code move possible without moving import cycles and
keeping the changes to the code base as small as possible during
refactor.

routing/control_tower.go

@@ -6,6 +6,7 @@ import (
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/multimutex"
+	paymentsdb "github.com/lightningnetwork/lnd/payments/db"
 	"github.com/lightningnetwork/lnd/queue"
 )
 
@@ -13,23 +14,23 @@ import (
 // the payment lifecycle.
 type DBMPPayment interface {
 	// GetState returns the current state of the payment.
-	GetState() *channeldb.MPPaymentState
+	GetState() *paymentsdb.MPPaymentState
 
 	// Terminated returns true if the payment is in a final state.
 	Terminated() bool
 
 	// GetStatus returns the current status of the payment.
-	GetStatus() channeldb.PaymentStatus
+	GetStatus() paymentsdb.PaymentStatus
 
 	// NeedWaitAttempts specifies whether the payment needs to wait for the
 	// outcome of an attempt.
 	NeedWaitAttempts() (bool, error)
 
 	// GetHTLCs returns all HTLCs of this payment.
-	GetHTLCs() []channeldb.HTLCAttempt
+	GetHTLCs() []paymentsdb.HTLCAttempt
 
 	// InFlightHTLCs returns all HTLCs that are in flight.
-	InFlightHTLCs() []channeldb.HTLCAttempt
+	InFlightHTLCs() []paymentsdb.HTLCAttempt
 
 	// AllowMoreAttempts is used to decide whether we can safely attempt
 	// more HTLCs for a given payment state. Return an error if the payment
@@ -38,7 +39,7 @@ type DBMPPayment interface {
 
 	// TerminalInfo returns the settled HTLC attempt or the payment's
 	// failure reason.
-	TerminalInfo() (*channeldb.HTLCAttempt, *channeldb.FailureReason)
+	TerminalInfo() (*paymentsdb.HTLCAttempt, *channeldb.FailureReason)
 }
 
 // ControlTower tracks all outgoing payments made, whose primary purpose is to
@@ -57,7 +58,7 @@ type ControlTower interface {
 	DeleteFailedAttempts(lntypes.Hash) error
 
 	// RegisterAttempt atomically records the provided HTLCAttemptInfo.
-	RegisterAttempt(lntypes.Hash, *channeldb.HTLCAttemptInfo) error
+	RegisterAttempt(lntypes.Hash, *paymentsdb.HTLCAttemptInfo) error
 
 	// SettleAttempt marks the given attempt settled with the preimage. If
 	// this is a multi shard payment, this might implicitly mean the the
@@ -67,12 +68,12 @@ type ControlTower interface {
 	// error to prevent us from making duplicate payments to the same
 	// payment hash. The provided preimage is atomically saved to the DB
 	// for record keeping.
-	SettleAttempt(lntypes.Hash, uint64, *channeldb.HTLCSettleInfo) (
-		*channeldb.HTLCAttempt, error)
+	SettleAttempt(lntypes.Hash, uint64, *paymentsdb.HTLCSettleInfo) (
+		*paymentsdb.HTLCAttempt, error)
 
 	// FailAttempt marks the given payment attempt failed.
-	FailAttempt(lntypes.Hash, uint64, *channeldb.HTLCFailInfo) (
-		*channeldb.HTLCAttempt, error)
+	FailAttempt(lntypes.Hash, uint64, *paymentsdb.HTLCFailInfo) (
+		*paymentsdb.HTLCAttempt, error)
 
 	// FetchPayment fetches the payment corresponding to the given payment
 	// hash.
@@ -87,7 +88,7 @@ type ControlTower interface {
 	FailPayment(lntypes.Hash, channeldb.FailureReason) error
 
 	// FetchInFlightPayments returns all payments with status InFlight.
-	FetchInFlightPayments() ([]*channeldb.MPPayment, error)
+	FetchInFlightPayments() ([]*paymentsdb.MPPayment, error)
 
 	// SubscribePayment subscribes to updates for the payment with the given
 	// hash. A first update with the current state of the payment is always
@@ -151,7 +152,7 @@ func (s *controlTowerSubscriberImpl) Updates() <-chan interface{} {
 // controlTower is persistent implementation of ControlTower to restrict
 // double payment sending.
 type controlTower struct {
-	db *channeldb.KVPaymentsDB
+	db *paymentsdb.KVPaymentsDB
 
 	// subscriberIndex is used to provide a unique id for each subscriber
 	// to all payments. This is used to easily remove the subscriber when
@@ -168,7 +169,7 @@ type controlTower struct {
 }
 
 // NewControlTower creates a new instance of the controlTower.
-func NewControlTower(db *channeldb.KVPaymentsDB) ControlTower {
+func NewControlTower(db *paymentsdb.KVPaymentsDB) ControlTower {
 	return &controlTower{
 		db: db,
 		subscribersAllPayments: make(
@@ -215,7 +216,7 @@ func (p *controlTower) DeleteFailedAttempts(paymentHash lntypes.Hash) error {
 // RegisterAttempt atomically records the provided HTLCAttemptInfo to the
 // DB.
 func (p *controlTower) RegisterAttempt(paymentHash lntypes.Hash,
-	attempt *channeldb.HTLCAttemptInfo) error {
+	attempt *paymentsdb.HTLCAttemptInfo) error {
 
 	p.paymentsMtx.Lock(paymentHash)
 	defer p.paymentsMtx.Unlock(paymentHash)
@@ -235,8 +236,8 @@ func (p *controlTower) RegisterAttempt(paymentHash lntypes.Hash,
 // this is a multi shard payment, this might implicitly mean the the
 // full payment succeeded.
 func (p *controlTower) SettleAttempt(paymentHash lntypes.Hash,
-	attemptID uint64, settleInfo *channeldb.HTLCSettleInfo) (
-	*channeldb.HTLCAttempt, error) {
+	attemptID uint64, settleInfo *paymentsdb.HTLCSettleInfo) (
+	*paymentsdb.HTLCAttempt, error) {
 
 	p.paymentsMtx.Lock(paymentHash)
 	defer p.paymentsMtx.Unlock(paymentHash)
@@ -254,8 +255,8 @@ func (p *controlTower) SettleAttempt(paymentHash lntypes.Hash,
 
 // FailAttempt marks the given payment attempt failed.
 func (p *controlTower) FailAttempt(paymentHash lntypes.Hash,
-	attemptID uint64, failInfo *channeldb.HTLCFailInfo) (
-	*channeldb.HTLCAttempt, error) {
+	attemptID uint64, failInfo *paymentsdb.HTLCFailInfo) (
+	*paymentsdb.HTLCAttempt, error) {
 
 	p.paymentsMtx.Lock(paymentHash)
 	defer p.paymentsMtx.Unlock(paymentHash)
@@ -303,7 +304,9 @@ func (p *controlTower) FailPayment(paymentHash lntypes.Hash,
 }
 
 // FetchInFlightPayments returns all payments with status InFlight.
-func (p *controlTower) FetchInFlightPayments() ([]*channeldb.MPPayment, error) {
+func (p *controlTower) FetchInFlightPayments() ([]*paymentsdb.MPPayment,
+	error) {
+
 	return p.db.FetchInFlightPayments()
 }
 
@@ -386,7 +389,7 @@ func (p *controlTower) SubscribeAllPayments() (ControlTowerSubscriber, error) {
 // be executed atomically (by means of a lock) with the database update to
 // guarantee consistency of the notifications.
 func (p *controlTower) notifySubscribers(paymentHash lntypes.Hash,
-	event *channeldb.MPPayment) {
+	event *paymentsdb.MPPayment) {
 
 	// Get all subscribers for this payment.
 	p.subscribersMtx.Lock()