multi: make tower MaxUpdates configurable

This is helpful in an itest environment where we want to quickly
saturate a session.

lncfg/wtclient.go

@@ -22,6 +22,10 @@ type WtClient struct {
 	// of blocks to wait after the last channel of a session is closed
 	// before sending the DeleteSession message to the tower server.
 	SessionCloseRange uint32 `long:"session-close-range" description:"The range over which to choose a random number of blocks to wait after the last channel of a session is closed before sending the DeleteSession message to the tower server. Set to 1 for no delay."`
+
+	// MaxUpdates is the maximum number of updates to be backed up in a
+	// single tower sessions.
+	MaxUpdates uint16 `long:"max-updates" description:"The maximum number of updates to be backed up in a single session."`
 }
 
 // Validate ensures the user has provided a valid configuration.

sample-lnd.conf

@@ -1004,6 +1004,9 @@ litecoin.node=ltcd
 ; along with reduced privacy from the tower server.
 ; wtclient.session-close-range=10
 
+; The maximum number of updates to include in a tower session.
+; wtclient.max-updates=1024
+
 [healthcheck]
 
 ; The number of times we should attempt to query our chain backend before

server.go

@@ -1497,6 +1497,10 @@ func newServer(cfg *Config, listenAddrs []net.Addr,
 			policy.SweepFeeRate = sweepRateSatPerVByte.FeePerKWeight()
 		}
 
+		if cfg.WtClient.MaxUpdates != 0 {
+			policy.MaxUpdates = cfg.WtClient.MaxUpdates
+		}
+
 		sessionCloseRange := uint32(wtclient.DefaultSessionCloseRange)
 		if cfg.WtClient.SessionCloseRange != 0 {
 			sessionCloseRange = cfg.WtClient.SessionCloseRange