From e6bebc4fe7dc571d011057c4dc100e1675ba4a8f Mon Sep 17 00:00:00 2001
From: yyforyongyu <yy2452@columbia.edu>
Date: Thu, 20 Oct 2022 19:37:31 +0800
Subject: [PATCH] lnd: make `MailboxDeliveryTimeout` configurable

---
 config.go           |  8 ++++++++
 lncfg/htlcswitch.go | 34 ++++++++++++++++++++++++++++++++++
 sample-lnd.conf     |  7 +++++++
 server.go           |  2 +-
 4 files changed, 50 insertions(+), 1 deletion(-)
 create mode 100644 lncfg/htlcswitch.go

diff --git a/config.go b/config.go
index 57b0f5f3d..ef187e6a6 100644
--- a/config.go
+++ b/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
diff --git a/lncfg/htlcswitch.go b/lncfg/htlcswitch.go
new file mode 100644
index 000000000..4fdc85749
--- /dev/null
+++ b/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
+}
diff --git a/sample-lnd.conf b/sample-lnd.conf
index 3afa98586..a06342ece 100644
--- a/sample-lnd.conf
+++ b/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
+
diff --git a/server.go b/server.go
index a425937c0..a722a16f8 100644
--- a/server.go
+++ b/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,