make mempool fee estimation optional

chain/default_fee_estimator.go

@@ -0,0 +1,22 @@
+package chain
+
+import "context"
+
+type DefaultFeeEstimator struct {
+	targetConf uint32
+}
+
+func NewDefaultFeeEstimator(targetConf uint32) *DefaultFeeEstimator {
+	return &DefaultFeeEstimator{
+		targetConf: targetConf,
+	}
+}
+
+func (e *DefaultFeeEstimator) EstimateFeeRate(
+	context.Context,
+	FeeStrategy,
+) (*FeeEstimation, error) {
+	return &FeeEstimation{
+		TargetConf: &e.targetConf,
+	}, nil
+}

chain/fee_estimator.go

@@ -1,6 +1,9 @@
 package chain
 
-import "context"
+import (
+	"context"
+	"fmt"
+)
 
 type FeeStrategy int
 
@@ -13,7 +16,20 @@ const (
 )
 
 type FeeEstimation struct {
-	SatPerVByte float64
+	SatPerVByte *float64
+	TargetConf  *uint32
+}
+
+func (f *FeeEstimation) String() string {
+	feeStr := "<nil>"
+	confStr := "<nil>"
+	if f.SatPerVByte != nil {
+		feeStr = fmt.Sprintf("%.5f", *f.SatPerVByte)
+	}
+	if f.TargetConf != nil {
+		confStr = fmt.Sprintf("%v", *f.TargetConf)
+	}
+	return fmt.Sprintf("satPerVbyte %s, targetConf %s", feeStr, confStr)
 }
 
 type FeeEstimator interface {

interceptor/intercept_handler.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"context"
 	"encoding/hex"
-	"fmt"
 	"log"
 	"math/big"
 	"time"
@@ -354,32 +353,23 @@ func (i *Interceptor) openChannel(paymentHash, destination []byte, incomingAmoun
 		capacity++
 	}
 
-	var targetConf *uint32
-	confStr := "<nil>"
-	var feeEstimation *float64
-	feeStr := "<nil>"
-	if i.feeEstimator != nil {
 	fee, err := i.feeEstimator.EstimateFeeRate(
 		context.Background(),
 		i.feeStrategy,
 	)
-		if err == nil {
+	if err != nil || fee == nil {
-			feeEstimation = &fee.SatPerVByte
-			feeStr = fmt.Sprintf("%.5f", *feeEstimation)
-		} else {
 		log.Printf("Error estimating chain fee, fallback to target conf: %v", err)
-			targetConf = &i.config.TargetConf
+		fee = &chain.FeeEstimation{
-			confStr = fmt.Sprintf("%v", *targetConf)
+			TargetConf: &i.config.TargetConf,
 		}
 	}
 
 	log.Printf(
-		"Opening zero conf channel. Paymenthash: %x, Destination: %x, capacity: %v, fee: %s, targetConf: %s",
+		"Opening zero conf channel. Paymenthash: %x, Destination: %x, capacity: %v, fee: %s",
 		paymentHash,
 		destination,
 		capacity,
-		feeStr,
+		fee.String(),
-		confStr,
 	)
 	channelPoint, err := i.client.OpenChannel(&lightning.OpenChannelRequest{
 		Destination:    destination,
@@ -387,8 +377,8 @@ func (i *Interceptor) openChannel(paymentHash, destination []byte, incomingAmoun
 		MinConfs:       i.config.MinConfs,
 		IsPrivate:      true,
 		IsZeroConf:     true,
-		FeeSatPerVByte: feeEstimation,
+		FeeSatPerVByte: fee.SatPerVByte,
-		TargetConf:     targetConf,
+		TargetConf:     fee.TargetConf,
 	})
 	if err != nil {
 		log.Printf("paymenthash %x, client.OpenChannelSync(%x, %v) error: %v", paymentHash, destination, capacity, err)

lsps2/intercept_handler.go

@@ -3,7 +3,6 @@ package lsps2
 import (
 	"context"
 	"encoding/hex"
-	"fmt"
 	"log"
 	"math"
 	"strings"
@@ -414,23 +413,14 @@ func (i *Interceptor) ensureChannelOpen(payment *paymentState) {
 			return
 		}
 
-		var targetConf *uint32
-		confStr := "<nil>"
-		var feeEstimation *float64
-		feeStr := "<nil>"
-		if i.feeEstimator != nil {
 		fee, err := i.feeEstimator.EstimateFeeRate(
 			context.Background(),
 			i.config.FeeStrategy,
 		)
-			if err == nil {
+		if err != nil || fee == nil {
-				feeEstimation = &fee.SatPerVByte
+			log.Printf("Error estimating chain fee, fallback to target conf: %v", err)
-				feeStr = fmt.Sprintf("%.5f", *feeEstimation)
+			fee = &chain.FeeEstimation{
-			} else {
+				TargetConf: &i.config.TargetConf,
-				log.Printf("Error estimating chain fee, fallback to target "+
-					"conf: %v", err)
-				targetConf = &i.config.TargetConf
-				confStr = fmt.Sprintf("%v", *targetConf)
 			}
 		}
 
@@ -439,11 +429,10 @@ func (i *Interceptor) ensureChannelOpen(payment *paymentState) {
 
 		log.Printf(
 			"LSPS2: Opening zero conf channel. Destination: %x, capacity: %v, "+
-				"fee: %s, targetConf: %s",
+				"fee: %s",
 			destination,
 			capacity,
-			feeStr,
+			fee.String(),
-			confStr,
 		)
 
 		channelPoint, err := i.client.OpenChannel(&lightning.OpenChannelRequest{
@@ -452,8 +441,8 @@ func (i *Interceptor) ensureChannelOpen(payment *paymentState) {
 			MinConfs:       i.config.MinConfs,
 			IsPrivate:      true,
 			IsZeroConf:     true,
-			FeeSatPerVByte: feeEstimation,
+			FeeSatPerVByte: fee.SatPerVByte,
-			TargetConf:     targetConf,
+			TargetConf:     fee.TargetConf,
 		})
 		if err != nil {
 			log.Printf(

main.go

@@ -59,16 +59,6 @@ func main() {
 		log.Fatalf("failed to create nodes service: %v", err)
 	}
 
-	mempoolUrl := os.Getenv("MEMPOOL_API_BASE_URL")
-	if mempoolUrl == "" {
-		log.Fatalf("No mempool url configured.")
-	}
-
-	feeEstimator, err := mempool.NewMempoolClient(mempoolUrl)
-	if err != nil {
-		log.Fatalf("failed to initialize mempool client: %v", err)
-	}
-
 	var feeStrategy chain.FeeStrategy
 	envFeeStrategy := os.Getenv("MEMPOOL_PRIORITY")
 	switch strings.ToLower(envFeeStrategy) {
@@ -85,7 +75,17 @@ func main() {
 	default:
 		feeStrategy = chain.FeeStrategyEconomy
 	}
+
+	var mempoolClient *mempool.MempoolClient
+	mempoolUrl := os.Getenv("MEMPOOL_API_BASE_URL")
+	if mempoolUrl != "" {
+		mempoolClient, err = mempool.NewMempoolClient(mempoolUrl)
+		if err != nil {
+			log.Fatalf("failed to initialize mempool client: %v", err)
+		}
+
 		log.Printf("using mempool api for fee estimation: %v, fee strategy: %v:%v", mempoolUrl, envFeeStrategy, feeStrategy)
+	}
 
 	databaseUrl := os.Getenv("DATABASE_URL")
 	pool, err := postgresql.PgConnect(databaseUrl)
@@ -111,6 +111,13 @@ func main() {
 	var interceptors []interceptor.HtlcInterceptor
 	for _, node := range nodes {
 		var htlcInterceptor interceptor.HtlcInterceptor
+		var feeEstimator chain.FeeEstimator
+		if mempoolClient == nil {
+			feeEstimator = chain.NewDefaultFeeEstimator(node.NodeConfig.TargetConf)
+		} else {
+			feeEstimator = mempoolClient
+		}
+
 		if node.NodeConfig.Lnd != nil {
 			client, err := lnd.NewLndClient(node.NodeConfig.Lnd)
 			if err != nil {

mempool/mempool_client.go

@@ -85,6 +85,6 @@ func (m *MempoolClient) EstimateFeeRate(
 	}
 
 	return &chain.FeeEstimation{
-		SatPerVByte: rate,
+		SatPerVByte: &rate,
 	}, nil
 }