lnd: make MailboxDeliveryTimeout configurable

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
+}