beacon/light: ensure EvRequest before SendRequest returns

beacon/light/api/api_server.go

@@ -59,8 +59,8 @@ func (s *ApiServer) Subscribe(eventCallback func(event request.Event)) {
 // SendRequest implements request.requestServer.
 func (s *ApiServer) SendRequest(req request.Request) request.ID {
 	id := request.ID(atomic.AddUint64(&s.lastId, 1))
+	s.eventCallback(request.Event{Type: request.EvRequest, Data: request.RequestResponse{ID: id, Request: req}})
 	go func() {
-		s.eventCallback(request.Event{Type: request.EvRequest, Data: request.RequestResponse{ID: id, Request: req}})
 		var resp request.Response
 		switch data := req.(type) {
 		case sync.ReqUpdates:

beacon/light/request/server.go

@@ -55,9 +55,9 @@ const (
 
 // requestServer can send requests in a non-blocking way and feed back events
 // through the event callback. When successfully sending a request it should
-// send back an EvRequest event. When finished, it should send back either
-// EvResponse or EvFail. Additionally, it may also send application-defined
-// events that the Modules can interpret.
+// send back an EvRequest event before returning from SendRequest. When finished,
+// it should send back either EvResponse or EvFail. Additionally, it may also
+// send application-defined events that the Modules can interpret.
 type requestServer interface {
 	Subscribe(eventCallback func(event Event))
 	SendRequest(request Request) ID
@@ -151,6 +151,11 @@ func (s *serverWithTimeout) subscribe(eventCallback func(event Event)) {
 	s.parent.Subscribe(s.eventCallback)
 }
 
+// sendRequest sends a request through the parent (requestServer).
+func (s *serverWithTimeout) sendRequest(request Request) (reqId ID) {
+	return s.parent.SendRequest(request)
+}
+
 // eventCallback is called by parent (requestServer) event subscription.
 func (s *serverWithTimeout) eventCallback(event Event) {
 	s.lock.Lock()
@@ -159,6 +164,7 @@ func (s *serverWithTimeout) eventCallback(event Event) {
 	switch event.Type {
 	case EvRequest:
 		s.startTimeout(event.Data.(RequestResponse))
+		s.childEventCb(event)
 	case EvResponse, EvFail:
 		id := event.Data.(RequestResponse).ID
 		if timer, ok := s.timeouts[id]; ok {
@@ -205,11 +211,6 @@ func (s *serverWithTimeout) startTimeout(reqData RequestResponse) {
 	})
 }
 
-// sendRequest sends a request through the parent (requestServer).
-func (s *serverWithTimeout) sendRequest(request Request) (reqId ID) {
-	return s.parent.SendRequest(request)
-}
-
 // stop stops all goroutines associated with the server.
 func (s *serverWithTimeout) unsubscribe() {
 	s.lock.Lock()
@@ -315,9 +316,8 @@ func (s *serverWithLimits) eventCallback(event Event) {
 // sendRequest sends a request through the parent (serverWithTimeout).
 func (s *serverWithLimits) sendRequest(request Request) (reqId ID) {
 	s.lock.Lock()
-	defer s.lock.Unlock()
-
 	s.pendingCount++
+	s.lock.Unlock()
 	return s.serverWithTimeout.sendRequest(request)
 }
 

cmd/blsync/block_sync.go

@@ -33,8 +33,8 @@ type beaconBlockSync struct {
 	serverHeads  map[request.Server]common.Hash
 	headTracker  headTracker
 
-	lastHeadBlock *capella.BeaconBlock
-	headCh   chan headData
+	lastHeadInfo types.HeadInfo
+	headCh       chan headData
 }
 
 type headData struct {
@@ -55,7 +55,7 @@ func newBeaconBlockSync(headTracker headTracker) *beaconBlockSync {
 		recentBlocks: lru.NewCache[common.Hash, *capella.BeaconBlock](10),
 		locked:       make(map[common.Hash]struct{}),
 		serverHeads:  make(map[request.Server]common.Hash),
-		headCh:  make(chan headData, 1),
+		headCh:       make(chan headData, 1),
 	}
 }
 
@@ -86,18 +86,22 @@ func (s *beaconBlockSync) Process(events []request.Event) {
 	if !ok {
 		return
 	}
-	finality, ok := s.headTracker.ValidatedFinality()	//TODO fetch directly if subscription does not deliver
+	finality, ok := s.headTracker.ValidatedFinality() //TODO fetch directly if subscription does not deliver
 	if !ok || head.Header.Epoch() != finality.Attested.Header.Epoch() {
 		return
 	}
 	validatedHead := head.Header.Hash()
 	headBlock, ok := s.recentBlocks.Get(validatedHead)
-	if !ok || headBlock == s.lastHeadBlock {
+	if !ok {
+		return
+	}
+	headInfo := blockHeadInfo(headBlock)
+	if headInfo == s.lastHeadInfo {
 		return
 	}
 	select {
 	case s.headCh <- headData{block: headBlock, update: finality}:
-		s.lastHeadBlock = headBlock
+		s.lastHeadInfo = headInfo
 	default:
 	}
 }
@@ -122,3 +126,10 @@ func (s *beaconBlockSync) MakeRequest(server request.Server) (request.Request, f
 	}
 	return nil, 0
 }
+
+func blockHeadInfo(block *capella.BeaconBlock) types.HeadInfo {
+	if block == nil {
+		return types.HeadInfo{}
+	}
+	return types.HeadInfo{Slot: uint64(block.Slot), BlockRoot: beaconBlockHash(block)}
+}

cmd/blsync/block_sync_test.go

@@ -103,13 +103,6 @@ func TestBlockSync(t *testing.T) {
 	expHeadBlock(5, testBlock2)
 }
 
-func blockHeadInfo(block *capella.BeaconBlock) types.HeadInfo {
-	if block == nil {
-		return types.HeadInfo{}
-	}
-	return types.HeadInfo{Slot: uint64(block.Slot), BlockRoot: beaconBlockHash(block)}
-}
-
 func blockHeader(block *capella.BeaconBlock) types.Header {
 	return types.Header{
 		Slot:          uint64(block.Slot),