multi: add block cache size config

This commit adds block cache size to the main lnd config along with the
chainreg config.

chainreg/chainregistry.go

@@ -73,6 +73,9 @@ type Config struct {
 	// RemoteChanDB is a pointer to the remote backing channel database.
 	RemoteChanDB *channeldb.DB
 
+	// BlockCacheSize is the size (in bytes) of blocks kept in memory.
+	BlockCacheSize uint64
+
 	// PrivateWalletPw is the private wallet password to the underlying
 	// btcwallet instance.
 	PrivateWalletPw []byte

config.go

@@ -101,6 +101,10 @@ const (
 	// initiated the channel closure.
 	defaultCoopCloseTargetConfs = 6
 
+	// defaultBlockCacheSize is the size (in bytes) of blocks that will be
+	// keep in memory if no size is specified.
+	defaultBlockCacheSize uint64 = 20 * 1024 * 1024 // 20 MB
+
 	// defaultHostSampleInterval is the default amount of time that the
 	// HostAnnouncer will wait between DNS resolutions to check if the
 	// backing IP of a host has changed.
@@ -273,6 +277,8 @@ type Config struct {
 	LtcdMode      *lncfg.Btcd     `group:"ltcd" namespace:"ltcd"`
 	LitecoindMode *lncfg.Bitcoind `group:"litecoind" namespace:"litecoind"`
 
+	BlockCacheSize uint64 `long:"blockcachesize" description:"The maximum capacity of the block cache"`
+
 	Autopilot *lncfg.AutoPilot `group:"Autopilot" namespace:"autopilot"`
 
 	Tor *lncfg.Tor `group:"Tor" namespace:"tor"`
@@ -434,6 +440,7 @@ func DefaultConfig() Config {
 			UserAgentName:    neutrino.UserAgentName,
 			UserAgentVersion: neutrino.UserAgentVersion,
 		},
+		BlockCacheSize:     defaultBlockCacheSize,
 		UnsafeDisconnect:   true,
 		MaxPendingChannels: lncfg.DefaultMaxPendingChannels,
 		NoSeedBackup:       defaultNoSeedBackup,

lnd.go

@@ -546,6 +546,7 @@ func Main(cfg *Config, lisCfg ListenerCfg, interceptor signal.Interceptor) error
 		Dialer: func(addr string) (net.Conn, error) {
 			return cfg.net.Dial("tcp", addr, cfg.ConnectionTimeout)
 		},
+		BlockCacheSize: cfg.BlockCacheSize,
 	}
 
 	activeChainControl, cleanup, err := chainreg.NewChainControl(chainControlCfg)

sample-lnd.conf

@@ -224,6 +224,12 @@
 ; The target location of the channel backup file.
 ; backupfilepath=~/.lnd/data/chain/bitcoin/simnet/channel.backup
 
+; The maximum capacity of the block cache in bytes. Increasing this will result
+; in more blocks being kept in memory but will increase performance when the
+; same block is required multiple times.
+; The example value below is 40 MB (1024 * 1024 * 40)
+; blockcachesize=41943040
+
 ; Optional URL for external fee estimation. If no URL is specified, the method
 ; for fee estimation will depend on the chosen backend and network. Must be set
 ; for neutrino on mainnet.