beacon/light: fix shutdown issues (ethereum#29946)

* beacon/light/request: add server test for event after unsubscribe

* beacon/light/api: fixed double stream.Close()

* beacon/light/request: add checks for nil event callback function

* beacon/light/request: unlock server mutex while unsubscribing from parent

beacon/light/api/light_api.go

@@ -494,9 +494,6 @@ func (api *BeaconLightApi) StartHeadListener(listener HeadEventListener) func()
 
 		for {
 			select {
-			case <-ctx.Done():
-				stream.Close()
-
 			case event, ok := <-stream.Events:
 				if !ok {
 					log.Trace("Event stream closed")

beacon/light/request/server.go

@@ -186,10 +186,14 @@ func (s *serverWithTimeout) eventCallback(event Event) {
 			// call will just do nothing
 			timer.Stop()
 			delete(s.timeouts, id)
-			s.childEventCb(event)
+			if s.childEventCb != nil {
+				s.childEventCb(event)
+			}
 		}
 	default:
-		s.childEventCb(event)
+		if s.childEventCb != nil {
+			s.childEventCb(event)
+		}
 	}
 }
 
@@ -211,25 +215,27 @@ func (s *serverWithTimeout) startTimeout(reqData RequestResponse) {
 			delete(s.timeouts, id)
 			childEventCb := s.childEventCb
 			s.lock.Unlock()
-			childEventCb(Event{Type: EvFail, Data: reqData})
+			if childEventCb != nil {
+				childEventCb(Event{Type: EvFail, Data: reqData})
+			}
 		})
 		childEventCb := s.childEventCb
 		s.lock.Unlock()
-		childEventCb(Event{Type: EvTimeout, Data: reqData})
+		if childEventCb != nil {
+			childEventCb(Event{Type: EvTimeout, Data: reqData})
+		}
 	})
 }
 
 // unsubscribe stops all goroutines associated with the server.
 func (s *serverWithTimeout) unsubscribe() {
 	s.lock.Lock()
-	defer s.lock.Unlock()
-
 	for _, timer := range s.timeouts {
 		if timer != nil {
 			timer.Stop()
 		}
 	}
-	s.childEventCb = nil
+	s.lock.Unlock()
 	s.parent.Unsubscribe()
 }
 
@@ -328,10 +334,10 @@ func (s *serverWithLimits) eventCallback(event Event) {
 	}
 	childEventCb := s.childEventCb
 	s.lock.Unlock()
-	if passEvent {
+	if passEvent && childEventCb != nil {
 		childEventCb(event)
 	}
-	if sendCanRequestAgain {
+	if sendCanRequestAgain && childEventCb != nil {
 		childEventCb(Event{Type: EvCanRequestAgain})
 	}
 }
@@ -347,13 +353,12 @@ func (s *serverWithLimits) sendRequest(request Request) (reqId ID) {
 // unsubscribe stops all goroutines associated with the server.
 func (s *serverWithLimits) unsubscribe() {
 	s.lock.Lock()
-	defer s.lock.Unlock()
-
 	if s.delayTimer != nil {
 		s.delayTimer.Stop()
 		s.delayTimer = nil
 	}
 	s.childEventCb = nil
+	s.lock.Unlock()
 	s.serverWithTimeout.unsubscribe()
 }
 
@@ -383,7 +388,7 @@ func (s *serverWithLimits) canRequestNow() bool {
 	}
 	childEventCb := s.childEventCb
 	s.lock.Unlock()
-	if sendCanRequestAgain {
+	if sendCanRequestAgain && childEventCb != nil {
 		childEventCb(Event{Type: EvCanRequestAgain})
 	}
 	return canRequest
@@ -415,7 +420,7 @@ func (s *serverWithLimits) delay(delay time.Duration) {
 		}
 		childEventCb := s.childEventCb
 		s.lock.Unlock()
-		if sendCanRequestAgain {
+		if sendCanRequestAgain && childEventCb != nil {
 			childEventCb(Event{Type: EvCanRequestAgain})
 		}
 	})

beacon/light/request/server_test.go

@@ -51,6 +51,7 @@ func TestServerEvents(t *testing.T) {
 	expEvent(EvFail)
 	rs.eventCb(Event{Type: EvResponse, Data: RequestResponse{ID: 1, Request: testRequest, Response: testResponse}})
 	expEvent(nil)
+	srv.unsubscribe()
 }
 
 func TestServerParallel(t *testing.T) {
@@ -129,9 +130,7 @@ func TestServerEventRateLimit(t *testing.T) {
 	srv := NewServer(rs, clock)
 	var eventCount int
 	srv.subscribe(func(event Event) {
-		if !event.IsRequestEvent() {
-			eventCount++
-		}
+		eventCount++
 	})
 	expEvents := func(send, expAllowed int) {
 		eventCount = 0
@@ -147,6 +146,30 @@ func TestServerEventRateLimit(t *testing.T) {
 	expEvents(5, 1)
 	clock.Run(maxServerEventRate * maxServerEventBuffer * 2)
 	expEvents(maxServerEventBuffer+5, maxServerEventBuffer)
+	srv.unsubscribe()
+}
+
+func TestServerUnsubscribe(t *testing.T) {
+	rs := &testRequestServer{}
+	clock := &mclock.Simulated{}
+	srv := NewServer(rs, clock)
+	var eventCount int
+	srv.subscribe(func(event Event) {
+		eventCount++
+	})
+	eventCb := rs.eventCb
+	eventCb(Event{Type: testEventType})
+	if eventCount != 1 {
+		t.Errorf("Server event callback not called before unsubscribe")
+	}
+	srv.unsubscribe()
+	if rs.eventCb != nil {
+		t.Errorf("Server event callback not removed after unsubscribe")
+	}
+	eventCb(Event{Type: testEventType})
+	if eventCount != 1 {
+		t.Errorf("Server event callback called after unsubscribe")
+	}
 }
 
 type testRequestServer struct {
@@ -156,4 +179,4 @@ type testRequestServer struct {
 func (rs *testRequestServer) Name() string                  { return "" }
 func (rs *testRequestServer) Subscribe(eventCb func(Event)) { rs.eventCb = eventCb }
 func (rs *testRequestServer) SendRequest(ID, Request)       {}
-func (rs *testRequestServer) Unsubscribe()                  {}
+func (rs *testRequestServer) Unsubscribe()                  { rs.eventCb = nil }