fix (dot/telemetry): NoTelemetry flag stops telemetry

dot/node.go

@@ -345,9 +345,7 @@ func NewNode(cfg *Config, ks *keystore.GlobalKeystore, stopFunc func()) (*Node,
 		return nil, err
 	}
 
-	if cfg.Global.NoTelemetry {
-		return node, nil
-	}
+	telemetry.GetInstance().Initialise(!cfg.Global.NoTelemetry)
 
 	telemetry.GetInstance().AddConnections(gd.TelemetryEndpoints)
 	genesisHash := stateSrvc.Block.GenesisHash()

dot/telemetry/telemetry.go

@@ -45,15 +45,26 @@ type Handler struct {
 	sendMessageTimeout time.Duration
 }
 
+// Instance interface that telemetry handler instance needs to implement
+type Instance interface {
+	AddConnections(conns []*genesis.TelemetryEndpoint)
+	SendMessage(msg Message) error
+	startListening()
+	Initialise(enabled bool)
+}
+
 var (
 	once            sync.Once
-	handlerInstance *Handler
+	handlerInstance Instance
+
+	enabled    = true // enabled by default
+	initilised sync.Once
 )
 
 const defaultMessageTimeout = time.Second
 
 // GetInstance singleton pattern to for accessing TelemetryHandler
-func GetInstance() *Handler { //nolint
+func GetInstance() Instance {
 	if handlerInstance == nil {
 		once.Do(
 			func() {
@@ -65,9 +76,21 @@ func GetInstance() *Handler { //nolint
 				go handlerInstance.startListening()
 			})
 	}
+	if !enabled {
+		return &NoopHandler{}
+	}
+
 	return handlerInstance
 }
 
+// Initialise function to set if telemetry is enabled
+func (h *Handler) Initialise(_enabled bool) {
+	initilised.Do(
+		func() {
+			enabled = _enabled
+		})
+}
+
 // AddConnections adds the given telemetry endpoint as listeners that will receive telemetry data
 func (h *Handler) AddConnections(conns []*genesis.TelemetryEndpoint) {
 	for _, v := range conns {
@@ -290,3 +313,20 @@ func NewNetworkStateTM(host libp2phost.Host, peerInfos []common.PeerInfo) *Netwo
 func (tm *NetworkStateTM) messageType() string {
 	return tm.Msg
 }
+
+// NoopHandler struct no op handling (ignoring) telemetry messages
+type NoopHandler struct {
+}
+
+// Initialise function to set if telemetry is enabled
+func (h *NoopHandler) Initialise(enabled bool) {}
+
+func (h *NoopHandler) startListening() {}
+
+// SendMessage no op for telemetry send message function
+func (h *NoopHandler) SendMessage(msg Message) error {
+	return nil
+}
+
+// AddConnections no op for telemetry add connections function
+func (h *NoopHandler) AddConnections(conns []*genesis.TelemetryEndpoint) {}

dot/telemetry/telemetry_test.go

@@ -128,6 +128,39 @@ func TestListenerConcurrency(t *testing.T) {
 	}
 }
 
+func TestDisableInstance(t *testing.T) {
+	const qty = 1000
+	var wg sync.WaitGroup
+	wg.Add(qty)
+
+	resultCh = make(chan []byte)
+	for i := 0; i < qty; i++ {
+		if i == qty/2 {
+			GetInstance().Initialise(false)
+		}
+		go func() {
+			bh := common.MustHexToHash("0x07b749b6e20fd5f1159153a2e790235018621dd06072a62bcd25e8576f6ff5e6")
+			GetInstance().SendMessage(NewBlockImportTM(&bh, big.NewInt(2), "NetworkInitialSync"))
+			wg.Done()
+		}()
+	}
+	wg.Wait()
+	counter := 0
+	tk := time.NewTicker(time.Second * 2)
+main:
+	for {
+		select {
+		case <-tk.C:
+			break main
+		case <-resultCh:
+			counter++
+		}
+	}
+	tk.Stop()
+
+	require.LessOrEqual(t, counter, qty/2)
+}
+
 // TestInfiniteListener starts loop that print out data received on websocket ws://localhost:8001/
 //  this can be useful to see what data is sent to telemetry server
 func TestInfiniteListener(t *testing.T) {