multi: add new config options to tune gossip msg allocated bandwidth

We go with the defaults of if no values are set.

config.go

@@ -707,6 +707,8 @@ func DefaultConfig() Config {
 			ChannelUpdateInterval: discovery.DefaultChannelUpdateInterval,
 			SubBatchDelay:         discovery.DefaultSubBatchDelay,
 			AnnouncementConf:      discovery.DefaultProofMatureDelta,
+			MsgRateBytes:          discovery.DefaultMsgBytesPerSecond,
+			MsgBurstBytes:         discovery.DefaultMsgBytesBurst,
 		},
 		Invoices: &lncfg.Invoices{
 			HoldExpiryDelta: lncfg.DefaultHoldInvoiceExpiryDelta,

discovery/gossiper.go

@@ -390,6 +390,14 @@ type Config struct {
 	// spent-ness of channel outpoints. For neutrino, this saves long
 	// rescans from blocking initial usage of the daemon.
 	AssumeChannelValid bool
+
+	// MsgRateBytes is the rate limit for the number of bytes per second
+	// that we'll allocate to outbound gossip messages.
+	MsgRateBytes uint64
+
+	// MsgBurstBytes is the allotted burst amount in bytes. This is the
+	// number of starting tokens in our token bucket algorithm.
+	MsgBurstBytes uint64
 }
 
 // processedNetworkMsg is a wrapper around networkMsg and a boolean. It is
@@ -584,6 +592,8 @@ func New(cfg Config, selfKeyDesc *keychain.KeyDescriptor) *AuthenticatedGossiper
 		BestHeight:               gossiper.latestHeight,
 		PinnedSyncers:            cfg.PinnedSyncers,
 		IsStillZombieChannel:     cfg.IsStillZombieChannel,
+		AllotedMsgBytesPerSecond: cfg.MsgRateBytes,
+		AllotedMsgBytesBurst:     cfg.MsgBurstBytes,
 	})
 
 	gossiper.reliableSender = newReliableSender(&reliableSenderCfg{

lncfg/gossip.go

@@ -5,6 +5,7 @@ import (
 	"time"
 
 	"github.com/lightningnetwork/lnd/discovery"
+	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/routing/route"
 )
 
@@ -32,6 +33,10 @@ type Gossip struct {
 	SubBatchDelay time.Duration `long:"sub-batch-delay" description:"The duration to wait before sending the next announcement batch if there are multiple. Use a small value if there are a lot announcements and they need to be broadcast quickly."`
 
 	AnnouncementConf uint32 `long:"announcement-conf" description:"The number of confirmations required before processing channel announcements."`
+
+	MsgRateBytes uint64 `long:"msg-rate-bytes" description:"The maximum number of bytes of gossip messages that will be sent per second. This is a global limit that applies to all peers."`
+
+	MsgBurstBytes uint64 `long:"msg-burst-bytes" description:"The maximum number of bytes of gossip messages that will be sent in a burst. This is a global limit that applies to all peers. This value should be set to something greater than 130 KB"`
 }
 
 // Parse the pubkeys for the pinned syncers.
@@ -58,6 +63,11 @@ func (g *Gossip) Validate() error {
 			"%v", g.AnnouncementConf, minAnnouncementConf)
 	}
 
+	if g.MsgBurstBytes < lnwire.MaxSliceLength {
+		return fmt.Errorf("msg-burst-bytes=%v must be at least %v",
+			g.MsgBurstBytes, lnwire.MaxSliceLength)
+	}
+
 	return nil
 }
 

sample-lnd.conf

@@ -1746,6 +1746,17 @@
 ; The number of confirmations required before processing channel announcements.
 ; gossip.announcement-conf=6
 
+; The allotted bandwidth rate expressed in bytes/second that will be allocated
+; towards outbound gossip messages. Realized rates above this value will be 
+; throttled. This value is shared across all peers.
+; gossip.msg-rate-bytes=102400
+
+; The amount of bytes of gossip messages that can be sent at a given time. This
+; is used as the amount of tokens in the token bucket algorithm. This value
+; MUST be set to something about 65 KB, otherwise a single max sized message
+; can never be sent.
+; gossip.msg-burst-bytes=204800
+
 [invoices]
 
 ; If a hold invoice has accepted htlcs that reach their expiry height and are

server.go

@@ -1188,6 +1188,8 @@ func newServer(cfg *Config, listenAddrs []net.Addr,
 		IsStillZombieChannel:    s.graphBuilder.IsZombieChannel,
 		ScidCloser:              scidCloserMan,
 		AssumeChannelValid:      cfg.Routing.AssumeChannelValid,
+		MsgRateBytes:            cfg.Gossip.MsgRateBytes,
+		MsgBurstBytes:           cfg.Gossip.MsgBurstBytes,
 	}, nodeKeyDesc)
 
 	accessCfg := &accessManConfig{