TCP Keepalives

Enabled TCP keepalive packets to determine if the connection is still
valid, and terminate if needed. It also helps with maintaining idle
connections.

Default to 300 seconds and can be changed by:

    CONFIG SET keepalive 300

addresses #145: clients not being cleaned up properly

controller/config.go

@@ -20,9 +20,10 @@ const (
 	ProtectedMode = "protected-mode"
 	MaxMemory     = "maxmemory"
 	AutoGC        = "autogc"
+	KeepAlive     = "keepalive"
 )
 
-var validProperties = []string{RequirePass, LeaderAuth, ProtectedMode, MaxMemory, AutoGC}
+var validProperties = []string{RequirePass, LeaderAuth, ProtectedMode, MaxMemory, AutoGC, KeepAlive}
 
 // Config is a tile38 config
 type Config struct {
@@ -44,6 +45,8 @@ type Config struct {
 	MaxMemory      int    `json:"-"`
 	AutoGCP        string `json:"autogc,omitempty"`
 	AutoGC         uint64 `json:"-"`
+	KeepAliveP     string `json:"keepalive,omitempty"`
+	KeepAlive      int    `json:"-"`
 }
 
 func (c *Controller) loadConfig() error {
@@ -74,6 +77,9 @@ func (c *Controller) loadConfig() error {
 	if err := c.setConfigProperty(AutoGC, c.config.AutoGCP, true); err != nil {
 		return err
 	}
+	if err := c.setConfigProperty(KeepAlive, c.config.KeepAliveP, true); err != nil {
+		return err
+	}
 	return nil
 }
 
@@ -161,7 +167,19 @@ func (c *Controller) setConfigProperty(name, value string, fromLoad bool) error
 		default:
 			invalid = true
 		}
+	case KeepAlive:
+		if value == "" {
+			c.config.KeepAlive = 300
+		} else {
+			keepalive, err := strconv.ParseUint(value, 10, 64)
+			if err != nil {
+				invalid = true
+			} else {
+				c.config.KeepAlive = int(keepalive)
+			}
+		}
 	}
+
 	if invalid {
 		return fmt.Errorf("Invalid argument '%s' for CONFIG SET '%s'", value, name)
 	}
@@ -192,6 +210,8 @@ func (c *Controller) getConfigProperty(name string) string {
 		return c.config.ProtectedMode
 	case MaxMemory:
 		return formatMemSize(c.config.MaxMemory)
+	case KeepAlive:
+		return strconv.FormatUint(uint64(c.config.KeepAlive), 10)
 	}
 }
 
@@ -216,6 +236,7 @@ func (c *Controller) writeConfig(writeProperties bool) error {
 		c.config.ProtectedModeP = c.config.ProtectedMode
 		c.config.MaxMemoryP = formatMemSize(c.config.MaxMemory)
 		c.config.AutoGCP = strconv.FormatUint(c.config.AutoGC, 10)
+		c.config.KeepAliveP = strconv.FormatUint(uint64(c.config.KeepAlive), 10)
 	}
 	var data []byte
 	data, err = json.MarshalIndent(c.config, "", "\t")

controller/controller.go

@@ -227,8 +227,17 @@ func ListenAndServeEx(host string, port int, dir string, ln *net.Listener, http
 		return is
 	}
 	var clientId uint64
+
 	opened := func(conn *server.Conn) {
 		c.mu.Lock()
+		if c.config.KeepAlive > 0 {
+			err := conn.SetKeepAlive(
+				time.Duration(c.config.KeepAlive) * time.Second)
+			if err != nil {
+				log.Warnf("could not set keepalive for connection: %v",
+					conn.RemoteAddr().String())
+			}
+		}
 		clientId++
 		c.conns[conn] = &clientConn{
 			id:     clientId,

controller/server/server.go

@@ -45,6 +45,16 @@ type Conn struct {
 	Authenticated bool
 }
 
+func (conn Conn) SetKeepAlive(period time.Duration) error {
+	if tcp, ok := conn.Conn.(*net.TCPConn); ok {
+		if err := tcp.SetKeepAlive(true); err != nil {
+			return err
+		}
+		return tcp.SetKeepAlivePeriod(period)
+	}
+	return nil
+}
+
 var errCloseHTTP = errors.New("close http")
 
 // ListenAndServe starts a tile38 server at the specified address.