Initial approach

lib/service/checkpayments.go

@@ -12,15 +12,17 @@ import (
 	"github.com/lightningnetwork/lnd/lnrpc/routerrpc"
 )
 
+func (svc *LndhubService) GetAllPendingPayments(ctx context.Context) ([]models.Invoice, error) {
+    payments := []models.Invoice{}
+    err := svc.DB.NewSelect().Model(&payments).Where("state = 'initialized'").Where("type = 'outgoing'").Where("r_hash != ''").Where("created_at >= (now() - interval '2 weeks') ").Scan(ctx)
+    return payments, err
+}
 func (svc *LndhubService) CheckAllPendingOutgoingPayments(ctx context.Context) (err error) {
-	//check database for all pending payments
-	pendingPayments := []models.Invoice{}
-	//since this part is synchronously executed before the main server starts, we should not get into race conditions
-	//only fetch invoices from the last 2 weeks which should be a safe timeframe for hodl invoices to avoid refetching old invoices again and again
-	err = svc.DB.NewSelect().Model(&pendingPayments).Where("state = 'initialized'").Where("type = 'outgoing'").Where("r_hash != ''").Where("created_at >= (now() - interval '2 weeks') ").Scan(ctx)
+    pendingPayments, err := svc.GetAllPendingPayments(ctx)
     if err != nil {
         return err
     }
+
 	svc.Logger.Infof("Found %d pending payments", len(pendingPayments))
 	//call trackoutgoingpaymentstatus for each one
 	var wg sync.WaitGroup
@@ -39,6 +41,13 @@ func (svc *LndhubService) CheckAllPendingOutgoingPayments(ctx context.Context) (
 	return nil
 }
 
+func (svc *LndhubService) GetTransactionEntryByInvoiceId(ctx context.Context, id int64) (models.TransactionEntry, error) {
+    entry := models.TransactionEntry{}
+
+    err := svc.DB.NewSelect().Model(&entry).Where("invoice_id = ?", id).Limit(1).Scan(ctx)
+    return entry, err
+}
+
 // Should be called in a goroutine as the tracking can potentially take a long time
 func (svc *LndhubService) TrackOutgoingPaymentstatus(ctx context.Context, invoice *models.Invoice) {
 	//ask lnd using TrackPaymentV2 by hash of payment
@@ -55,8 +64,7 @@ func (svc *LndhubService) TrackOutgoingPaymentstatus(ctx context.Context, invoic
 		svc.Logger.Errorf("Error tracking payment %s: %s", invoice.RHash, err.Error())
 		return
 	}
-	//fetch the tx entry for the invoice
-	entry := models.TransactionEntry{}
+
 	//call HandleFailedPayment or HandleSuccesfulPayment
 	for {
 		payment, err := paymentTracker.Recv()
@@ -64,7 +72,7 @@ func (svc *LndhubService) TrackOutgoingPaymentstatus(ctx context.Context, invoic
 			svc.Logger.Errorf("Error tracking payment with hash %s: %s", invoice.RHash, err.Error())
 			return
 		}
-		err = svc.DB.NewSelect().Model(&entry).Where("invoice_id = ?", invoice.ID).Limit(1).Scan(ctx)
+        entry, err := svc.GetTransactionEntryByInvoiceId(ctx, invoice.ID)
 		if err != nil {
 			svc.Logger.Errorf("Error tracking payment %s: %s", invoice.RHash, err.Error())
 			return

lib/service/config.go

@@ -46,6 +46,7 @@ type Config struct {
 	RabbitMQLndInvoiceExchange       string  `envconfig:"RABBITMQ_LND_INVOICE_EXCHANGE" default:"lnd_invoice"`
 	RabbitMQInvoiceConsumerQueueName string  `envconfig:"RABBITMQ_INVOICE_CONSUMER_QUEUE_NAME" default:"lnd_invoice_consumer"`
 	SubscriptionConsumerType         string  `envconfig:"SUBSCRIPTION_CONSUMER_TYPE" default:"grpc"`
+	FinalizePendingPaymentsWith      string  `envconfig:"FINALIZE_PAYMENTS_WITH" default:"native"`
 	Branding                         BrandingConfig
 }
 

main.go

@@ -156,6 +156,15 @@ func main() {
 	}
 	logger.Infof("Connected to LND: %s - %s", getInfo.Alias, getInfo.IdentityPubkey)
 
+	svc := &service.LndhubService{
+		Config:         c,
+		DB:             dbConn,
+		LndClient:      lndClient,
+		Logger:         logger,
+		IdentityPubkey: getInfo.IdentityPubkey,
+		InvoicePubSub:  service.NewPubsub(),
+	}
+
 	// If no RABBITMQ_URI was provided we will not attempt to create a client
 	// No rabbitmq features will be available in this case.
 	var rabbitmqClient rabbitmq.Client
@@ -165,6 +174,7 @@ func main() {
 			rabbitmq.WithLndInvoiceExchange(c.RabbitMQLndInvoiceExchange),
 			rabbitmq.WithLndHubInvoiceExchange(c.RabbitMQLndhubInvoiceExchange),
 			rabbitmq.WithLndInvoiceConsumerQueueName(c.RabbitMQInvoiceConsumerQueueName),
+			rabbitmq.WithLndHubService(svc),
 		)
 		if err != nil {
 			logger.Fatal(err)
@@ -174,15 +184,7 @@ func main() {
 		defer rabbitmqClient.Close()
 	}
 
-	svc := &service.LndhubService{
-		Config:         c,
-		DB:             dbConn,
-		LndClient:      lndClient,
-		RabbitMQClient: rabbitmqClient,
-		Logger:         logger,
-		IdentityPubkey: getInfo.IdentityPubkey,
-		InvoicePubSub:  service.NewPubsub(),
-	}
+	svc.RabbitMQClient = rabbitmqClient
 
 	logMw := createLoggingMiddleware(logger)
 	// strict rate limit for requests for sending payments
@@ -230,10 +232,20 @@ func main() {
 	// A goroutine will be spawned for each one
 	backgroundWg.Add(1)
 	go func() {
+		switch svc.Config.FinalizePendingPaymentsWith {
+		case "rabbitmq":
+			err = svc.RabbitMQClient.FinalizeInitializedPayments(backGroundCtx)
+			if err != nil {
+				svc.Logger.Error(err)
+			}
+
+		default:
 			err = svc.CheckAllPendingOutgoingPayments(backGroundCtx)
 			if err != nil {
 				svc.Logger.Error(err)
 			}
+		}
+
 		svc.Logger.Info("Pending payment check routines done")
 		backgroundWg.Done()
 	}()

rabbitmq/rabbitmq.go

@@ -4,10 +4,12 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"os"
 	"sync"
+	"time"
 
 	"github.com/getAlby/lndhub.go/db/models"
 	"github.com/getsentry/sentry-go"
@@ -39,12 +41,21 @@ type (
 type Client interface {
 	SubscribeToLndInvoices(context.Context, IncomingInvoiceHandler) error
 	StartPublishInvoices(context.Context, SubscribeToInvoicesFunc, EncodeOutgoingInvoiceFunc) error
+	FinalizeInitializedPayments(context.Context) error
 	// Close will close all connections to rabbitmq
 	Close() error
 }
 
+type LndHubService interface {
+	HandleFailedPayment(context.Context, *models.Invoice, models.TransactionEntry, error) error
+	HandleSuccessfulPayment(context.Context, *models.Invoice, models.TransactionEntry) error
+	GetAllPendingPayments(context.Context) ([]models.Invoice, error)
+	GetTransactionEntryByInvoiceId(context.Context, int64) (models.TransactionEntry, error)
+}
+
 type DefaultClient struct {
 	conn          *amqp.Connection
+	lndHubService LndHubService
 
 	// It is recommended that, when possible, publishers and consumers
 	// use separate connections so that consumers are isolated from potential
@@ -55,7 +66,9 @@ type DefaultClient struct {
 	logger *lecho.Logger
 
 	lndInvoiceConsumerQueueName string
+	lndPaymentConsumerQueueName string
 	lndInvoiceExchange          string
+	lndPaymentExchange          string
 	lndHubInvoiceExchange       string
 }
 
@@ -85,6 +98,12 @@ func WithLogger(logger *lecho.Logger) ClientOption {
 	}
 }
 
+func WithLndHubService(svc LndHubService) ClientOption {
+	return func(client *DefaultClient) {
+		client.lndHubService = svc
+	}
+}
+
 // Dial sets up a connection to rabbitmq with two channels that are ready to produce and consume
 func Dial(uri string, options ...ClientOption) (Client, error) {
 	conn, err := amqp.Dial(uri)
@@ -128,6 +147,171 @@ func Dial(uri string, options ...ClientOption) (Client, error) {
 
 func (client *DefaultClient) Close() error { return client.conn.Close() }
 
+func (client *DefaultClient) FinalizeInitializedPayments(ctx context.Context) error {
+	// Sanity check
+	if client.lndHubService == nil {
+		return errors.New("no LndHubService provided to rabbitmqClient")
+	}
+
+	err := client.publishChannel.ExchangeDeclare(
+		client.lndPaymentExchange,
+		// topic is a type of exchange that allows routing messages to different queue's bases on a routing key
+		"topic",
+		// Durable and Non-Auto-Deleted exchanges will survive server restarts and remain
+		// declared when there are no remaining bindings.
+		true,
+		false,
+		// Non-Internal exchange's accept direct publishing
+		false,
+		// Nowait: We set this to false as we want to wait for a server response
+		// to check whether the exchange was created succesfully
+		false,
+		nil,
+	)
+	if err != nil {
+		return err
+	}
+
+	queue, err := client.consumeChannel.QueueDeclare(
+		client.lndPaymentConsumerQueueName,
+		// Durable and Non-Auto-Deleted queues will survive server restarts and remain
+		// declared when there are no remaining bindings.
+		true,
+		false,
+		// None-Exclusive means other consumers can consume from this queue.
+		// Messages from queues are spread out and load balanced between consumers.
+		// So multiple lndhub.go instances will spread the load of invoices between them
+		false,
+		// Nowait: We set this to false as we want to wait for a server response
+		// to check whether the queue was created successfully
+		false,
+		nil,
+	)
+	if err != nil {
+		return err
+	}
+
+	err = client.consumeChannel.QueueBind(
+		queue.Name,
+		"payment.outgoing.#",
+		client.lndPaymentExchange,
+		// Nowait: We set this to false as we want to wait for a server response
+		// to check whether the queue was created successfully
+		false,
+		nil,
+	)
+	if err != nil {
+		return err
+	}
+
+	deliveryChan, err := client.consumeChannel.Consume(
+		queue.Name,
+		"",
+		false,
+		false,
+		false,
+		false,
+		nil,
+	)
+	if err != nil {
+		return err
+	}
+
+	getInvoicesTable := func(ctx context.Context) (map[string]models.Invoice, error) {
+		invoicesByHash := map[string]models.Invoice{}
+		pendingInvoices, err := client.lndHubService.GetAllPendingPayments(ctx)
+
+		if err != nil {
+			return invoicesByHash, err
+		}
+
+		for _, invoice := range pendingInvoices {
+			invoicesByHash[invoice.RHash] = invoice
+		}
+		return invoicesByHash, nil
+	}
+
+	pendingInvoices, err := getInvoicesTable(ctx)
+	if err != nil {
+		return err
+	}
+
+	for {
+		select {
+		case <-ctx.Done():
+			return context.Canceled
+		case delivery, ok := <-deliveryChan:
+			// Shortcircuit if no pending invoices are left
+			if len(pendingInvoices) == 0 {
+				break
+			}
+
+			if !ok {
+				return err
+			}
+
+			payment := lnrpc.Payment{}
+
+			err := json.Unmarshal(delivery.Body, &payment)
+			if err != nil {
+				delivery.Nack(false, false)
+
+				continue
+			}
+
+			ticker := time.NewTicker(time.Hour)
+			defer ticker.Stop()
+
+			// Check if paymentHash corresponds to one of the pending invoices
+			if invoice, ok := pendingInvoices[payment.PaymentHash]; ok == true {
+				switch payment.Status {
+				case lnrpc.Payment_SUCCEEDED:
+					t, err := client.lndHubService.GetTransactionEntryByInvoiceId(ctx, invoice.ID)
+					if err != nil {
+						delivery.Nack(false, true)
+
+						continue
+					}
+
+					if err = client.lndHubService.HandleSuccessfulPayment(ctx, &invoice, t); err != nil {
+						delivery.Nack(false, true)
+
+						continue
+					}
+
+				case lnrpc.Payment_FAILED:
+					t, err := client.lndHubService.GetTransactionEntryByInvoiceId(ctx, invoice.ID)
+					if err != nil {
+						delivery.Nack(false, true)
+
+						continue
+					}
+
+					if err = client.lndHubService.HandleFailedPayment(ctx, &invoice, t, fmt.Errorf(payment.FailureReason.String())); err != nil {
+						delivery.Nack(false, true)
+
+						continue
+					}
+				}
+			}
+
+            // Refresh the pending invoice table after each tick
+			select {
+			case <-ticker.C:
+				invoices, err := getInvoicesTable(ctx)
+				pendingInvoices = invoices
+                if err != nil {
+                    return err
+                }
+			}
+
+			delivery.Ack(false)
+		}
+
+		return nil
+	}
+}
+
 func (client *DefaultClient) SubscribeToLndInvoices(ctx context.Context, handler IncomingInvoiceHandler) error {
 	err := client.publishChannel.ExchangeDeclare(
 		client.lndInvoiceExchange,