lnd: make MailboxDeliveryTimeout configurable

config.go

@@ -444,6 +444,8 @@ type Config struct {
 
 	Sweeper *lncfg.Sweeper `group:"sweeper" namespace:"sweeper"`
 
+	Htlcswitch *lncfg.Htlcswitch `group:"htlcswitch" namespace:"htlcswitch"`
+
 	// LogWriter is the root logger that all of the daemon's subloggers are
 	// hooked up to.
 	LogWriter *build.RotatingLogWriter
@@ -462,6 +464,8 @@ type Config struct {
 }
 
 // DefaultConfig returns all default values for the Config struct.
+//
+// nolint:lll
 func DefaultConfig() Config {
 	return Config{
 		LndDir:            DefaultLndDir,
@@ -643,6 +647,9 @@ func DefaultConfig() Config {
 		Sweeper: &lncfg.Sweeper{
 			BatchWindowDuration: sweep.DefaultBatchWindowDuration,
 		},
+		Htlcswitch: &lncfg.Htlcswitch{
+			MailboxDeliveryTimeout: htlcswitch.DefaultMailboxDeliveryTimeout,
+		},
 	}
 }
 
@@ -1660,6 +1667,7 @@ func ValidateConfig(cfg Config, interceptor signal.Interceptor, fileParser,
 		cfg.RPCMiddleware,
 		cfg.RemoteSigner,
 		cfg.Sweeper,
+		cfg.Htlcswitch,
 	)
 	if err != nil {
 		return nil, err

lncfg/htlcswitch.go

@@ -0,0 +1,34 @@
+package lncfg
+
+import (
+	"fmt"
+	"time"
+)
+
+var (
+	// MaxMailboxDeliveryTimeout specifies the max allowed timeout value.
+	// This value is derived from the itest `async_bidirectional_payments`,
+	// where both side send 483 payments at the same time to stress test
+	// lnd.
+	MaxMailboxDeliveryTimeout = 2 * time.Minute
+)
+
+// nolint:lll
+type Htlcswitch struct {
+	MailboxDeliveryTimeout time.Duration `long:"mailboxdeliverytimeout" description:"The timeout value when delivering HTLCs to a channel link. Setting this value too small will result in local payment failures if large number of payments are sent over a short period."`
+}
+
+// Validate checks the values configured for htlcswitch.
+func (h *Htlcswitch) Validate() error {
+	if h.MailboxDeliveryTimeout <= 0 {
+		return fmt.Errorf("mailboxdeliverytimeout must be positive")
+	}
+
+	if h.MailboxDeliveryTimeout > MaxMailboxDeliveryTimeout {
+		return fmt.Errorf("mailboxdeliverytimeout: %v exceeds "+
+			"maximum: %v", h.MailboxDeliveryTimeout,
+			MaxMailboxDeliveryTimeout)
+	}
+
+	return nil
+}

sample-lnd.conf

@@ -1423,3 +1423,10 @@ litecoin.node=ltcd
 ; window to allow more inputs to be added and thereby lower the fee per input.
 ; sweeper.batchwindowduration=30s
 
+[htlcswitch]
+
+; The timeout value when delivering HTLCs to a channel link. Setting this value
+; too small will result in local payment failures if large number of payments
+; are sent over a short period.
+; htlcswitch.mailboxdeliverytimeout=60s
+

server.go

@@ -658,7 +658,7 @@ func newServer(cfg *Config, listenAddrs []net.Addr,
 		AllowCircularRoute:     cfg.AllowCircularRoute,
 		RejectHTLC:             cfg.RejectHTLC,
 		Clock:                  clock.NewDefaultClock(),
-		MailboxDeliveryTimeout: htlcswitch.DefaultMailboxDeliveryTimeout,
+		MailboxDeliveryTimeout: cfg.Htlcswitch.MailboxDeliveryTimeout,
 		DustThreshold:          thresholdMSats,
 		SignAliasUpdate:        s.signAliasUpdate,
 		IsAlias:                aliasmgr.IsAlias,