Merge pull request #2417 from cfromknecht/min-backoff

server: configurable min backoff

config.go

@@ -53,6 +53,7 @@ const (
 	defaultInactiveChanTimeout = 20 * time.Minute
 	defaultMaxLogFiles         = 3
 	defaultMaxLogFileSize      = 10
+	defaultMinBackoff          = time.Second
 	defaultMaxBackoff          = time.Hour
 
 	defaultTorSOCKSPort            = 9050
@@ -197,6 +198,7 @@ type config struct {
 	ExternalIPs      []net.Addr
 	DisableListen    bool          `long:"nolisten" description:"Disable listening for incoming peer connections"`
 	NAT              bool          `long:"nat" description:"Toggle NAT traversal support (using either UPnP or NAT-PMP) to automatically advertise your external IP address to the network -- NOTE this does not support devices behind multiple NATs"`
+	MinBackoff       time.Duration `long:"minbackoff" description:"Shortest backoff when reconnecting to persistent peers. Valid time units are {s, m, h}."`
 	MaxBackoff       time.Duration `long:"maxbackoff" description:"Longest backoff when reconnecting to persistent peers. Valid time units are {s, m, h}."`
 
 	DebugLevel string `short:"d" long:"debuglevel" description:"Logging level for all subsystems {trace, debug, info, warn, error, critical} -- You may also specify <subsystem>=<level>,<subsystem2>=<level>,... to set the log level for individual subsystems -- Use show to list available subsystems"`
@@ -300,6 +302,7 @@ func loadConfig() (*config, error) {
 		},
 		MaxPendingChannels: defaultMaxPendingChannels,
 		NoSeedBackup:       defaultNoSeedBackup,
+		MinBackoff:         defaultMinBackoff,
 		MaxBackoff:         defaultMaxBackoff,
 		SubRPCServers: &subRPCServerConfigs{
 			SignRPC: &signrpc.Config{},
@@ -959,6 +962,13 @@ func loadConfig() (*config, error) {
 		}
 	}
 
+	// Ensure that the specified minimum backoff is below or equal to the
+	// maximum backoff.
+	if cfg.MinBackoff > cfg.MaxBackoff {
+		return nil, fmt.Errorf("maxbackoff must be greater than " +
+			"minbackoff")
+	}
+
 	// Finally, ensure that the user's color is correctly formatted,
 	// otherwise the server will not be able to start after the unlocking
 	// the wallet.

server.go

@@ -49,10 +49,6 @@ const (
 	// connected to.
 	defaultMinPeers = 3
 
-	// defaultBackoff is the starting point for exponential backoff for
-	// reconnecting to persistent peers.
-	defaultBackoff = time.Second
-
 	// defaultStableConnDuration is a floor under which all reconnection
 	// attempts will apply exponential randomized backoff. Connections
 	// durations exceeding this value will be eligible to have their
@@ -1752,7 +1748,7 @@ func (s *server) establishPersistentConnections() error {
 		// persistent connection with.
 		s.persistentPeers[pubStr] = struct{}{}
 		if _, ok := s.persistentPeersBackoff[pubStr]; !ok {
-			s.persistentPeersBackoff[pubStr] = defaultBackoff
+			s.persistentPeersBackoff[pubStr] = cfg.MinBackoff
 		}
 
 		for _, address := range nodeAddr.addresses {
@@ -2023,7 +2019,7 @@ func (s *server) nextPeerBackoff(pubStr string,
 	backoff, ok := s.persistentPeersBackoff[pubStr]
 	if !ok {
 		// If an existing backoff was unknown, use the default.
-		return defaultBackoff
+		return cfg.MinBackoff
 	}
 
 	// If the peer failed to start properly, we'll just use the previous
@@ -2045,17 +2041,17 @@ func (s *server) nextPeerBackoff(pubStr string,
 	// reduce the timeout duration by the length of the connection after
 	// applying randomized exponential backoff. We'll only apply this in the
 	// case that:
-	//   reb(curBackoff) - connDuration > defaultBackoff
+	//   reb(curBackoff) - connDuration > cfg.MinBackoff
 	relaxedBackoff := computeNextBackoff(backoff) - connDuration
-	if relaxedBackoff > defaultBackoff {
+	if relaxedBackoff > cfg.MinBackoff {
 		return relaxedBackoff
 	}
 
-	// Lastly, if reb(currBackoff) - connDuration <= defaultBackoff, meaning
+	// Lastly, if reb(currBackoff) - connDuration <= cfg.MinBackoff, meaning
 	// the stable connection lasted much longer than our previous backoff.
 	// To reward such good behavior, we'll reconnect after the default
 	// timeout.
-	return defaultBackoff
+	return cfg.MinBackoff
 }
 
 // shouldDropConnection determines if our local connection to a remote peer
@@ -2711,7 +2707,7 @@ func (s *server) ConnectToPeer(addr *lnwire.NetAddress, perm bool) error {
 
 		s.persistentPeers[targetPub] = struct{}{}
 		if _, ok := s.persistentPeersBackoff[targetPub]; !ok {
-			s.persistentPeersBackoff[targetPub] = defaultBackoff
+			s.persistentPeersBackoff[targetPub] = cfg.MinBackoff
 		}
 		s.persistentConnReqs[targetPub] = append(
 			s.persistentConnReqs[targetPub], connReq)