include block in attr event and use stategen (#15213)

* include block in attr event and use stategen

* use no-copy state cache for proposal in same epoch

* only advance to the start of epoch

---------

Co-authored-by: Kasey <kasey@users.noreply.github.com>

beacon-chain/blockchain/execution_engine.go

@@ -184,13 +184,13 @@ func (s *Service) notifyForkchoiceUpdate(ctx context.Context, arg *fcuConfig) (*
 	return payloadID, nil
 }
 
-func firePayloadAttributesEvent(_ context.Context, f event.SubscriberSender, nextSlot primitives.Slot) {
+func firePayloadAttributesEvent(f event.SubscriberSender, block interfaces.ReadOnlySignedBeaconBlock, root [32]byte, nextSlot primitives.Slot) {
 	// the fcu args have differing amounts of completeness based on the code path,
 	// and there is work we only want to do if a client is actually listening to the events beacon api endpoint.
 	// temporary solution: just fire a blank event and fill in the details in the api handler.
 	f.Send(&feed.Event{
 		Type: statefeed.PayloadAttributes,
-		Data: payloadattribute.EventData{ProposalSlot: nextSlot},
+		Data: payloadattribute.EventData{HeadBlock: block, HeadRoot: root, ProposalSlot: nextSlot},
 	})
 }
 

beacon-chain/blockchain/forkchoice_update_execution.go

@@ -102,7 +102,7 @@ func (s *Service) forkchoiceUpdateWithExecution(ctx context.Context, args *fcuCo
 		log.WithError(err).Error("could not save head")
 	}
 
-	go firePayloadAttributesEvent(ctx, s.cfg.StateNotifier.StateFeed(), s.CurrentSlot()+1)
+	go firePayloadAttributesEvent(s.cfg.StateNotifier.StateFeed(), args.headBlock, args.headRoot, s.CurrentSlot()+1)
 
 	// Only need to prune attestations from pool if the head has changed.
 	s.pruneAttsFromPool(s.ctx, args.headState, args.headBlock)

beacon-chain/blockchain/process_block.go

@@ -729,9 +729,13 @@ func (s *Service) lateBlockTasks(ctx context.Context) {
 	attribute := s.getPayloadAttribute(ctx, headState, s.CurrentSlot()+1, headRoot[:])
 	// return early if we are not proposing next slot
 	if attribute.IsEmpty() {
+		headBlock, err := s.headBlock()
+		if err != nil {
+			log.WithError(err).WithField("head_root", headRoot).Error("unable to retrieve head block to fire payload attributes event")
+		}
 		// notifyForkchoiceUpdate fires the payload attribute event. But in this case, we won't
 		// call notifyForkchoiceUpdate, so the event is fired here.
-		go firePayloadAttributesEvent(ctx, s.cfg.StateNotifier.StateFeed(), s.CurrentSlot()+1)
+		go firePayloadAttributesEvent(s.cfg.StateNotifier.StateFeed(), headBlock, headRoot, s.CurrentSlot()+1)
 		return
 	}
 

beacon-chain/rpc/endpoints.go

@@ -1041,6 +1041,7 @@ func (s *Service) eventsEndpoints() []endpoint {
 		HeadFetcher:            s.cfg.HeadFetcher,
 		ChainInfoFetcher:       s.cfg.ChainInfoFetcher,
 		TrackedValidatorsCache: s.cfg.TrackedValidatorsCache,
+		StateGen:               s.cfg.StateGen,
 	}
 
 	const namespace = "events"

beacon-chain/rpc/eth/events/BUILD.bazel

@@ -20,6 +20,7 @@ go_library(
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/core/transition:go_default_library",
         "//beacon-chain/state:go_default_library",
+        "//beacon-chain/state/stategen:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/interfaces:go_default_library",
         "//consensus-types/payload-attribute:go_default_library",
@@ -53,6 +54,7 @@ go_test(
         "//beacon-chain/core/feed/operation:go_default_library",
         "//beacon-chain/core/feed/state:go_default_library",
         "//beacon-chain/state:go_default_library",
+        "//beacon-chain/state/stategen/mock:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/blocks:go_default_library",

beacon-chain/rpc/eth/events/events.go

@@ -681,48 +681,48 @@ var zeroRoot [32]byte
 // needsFill allows tests to provide filled EventData values. An ordinary event data value fired by the blockchain package will have
 // all of the checked fields empty, so the logical short circuit should hit immediately.
 func needsFill(ev payloadattribute.EventData) bool {
-	return ev.HeadState == nil || ev.HeadState.IsNil() || ev.HeadState.LatestBlockHeader() == nil ||
+	return len(ev.ParentBlockHash) == 0 ||
-		ev.HeadBlock == nil || ev.HeadBlock.IsNil() ||
-		ev.HeadRoot == zeroRoot || len(ev.ParentBlockRoot) == 0 || len(ev.ParentBlockHash) == 0 ||
 		ev.Attributer == nil || ev.Attributer.IsEmpty()
 }
 
 func (s *Server) fillEventData(ctx context.Context, ev payloadattribute.EventData) (payloadattribute.EventData, error) {
-	var err error
-
 	if !needsFill(ev) {
 		return ev, nil
 	}
-
+	if ev.HeadBlock == nil || ev.HeadBlock.IsNil() {
-	ev.HeadState, err = s.HeadFetcher.HeadState(ctx)
+		return ev, errors.New("head block is nil")
-	if err != nil {
+	}
-		return ev, errors.Wrap(err, "could not get head state")
+	if ev.HeadRoot == zeroRoot {
+		return ev, errors.New("head root is empty")
 	}
 
-	ev.HeadBlock, err = s.HeadFetcher.HeadBlock(ctx)
+	var err error
-	if err != nil {
+	var st state.BeaconState
-		return ev, errors.Wrap(err, "could not look up head block")
-	}
-	ev.HeadRoot, err = ev.HeadBlock.Block().HashTreeRoot()
-	if err != nil {
-		return ev, errors.Wrap(err, "could not compute head block root")
-	}
-	pr := ev.HeadBlock.Block().ParentRoot()
-	ev.ParentBlockRoot = pr[:]
-
-	hsr, err := ev.HeadState.LatestBlockHeader().HashTreeRoot()
-	if err != nil {
-		return ev, errors.Wrap(err, "could not compute latest block header root")
-	}
 
+	// If head is in the same block as the proposal slot, we can use the "read only" state cache.
 	pse := slots.ToEpoch(ev.ProposalSlot)
-	st := ev.HeadState
+	if slots.ToEpoch(ev.HeadBlock.Block().Slot()) == pse {
-	if slots.ToEpoch(st.Slot()) != pse {
+		st = s.StateGen.StateByRootIfCachedNoCopy(ev.HeadRoot)
-		st, err = transition.ProcessSlotsUsingNextSlotCache(ctx, st, hsr[:], ev.ProposalSlot)
+	}
+	// If st is nil, we couldn't get the state from the cache, or it isn't in the same epoch.
+	if st == nil || st.IsNil() {
+		st, err = s.StateGen.StateByRoot(ctx, ev.HeadRoot)
 		if err != nil {
-			return ev, errors.Wrap(err, "could not run process blocks on head state into the proposal slot epoch")
+			return ev, errors.Wrap(err, "could not get head state")
+		}
+		// double check that we need to process_slots, just in case we got here via a hot state cache miss.
+		if slots.ToEpoch(st.Slot()) == pse {
+			start, err := slots.EpochStart(pse)
+			if err != nil {
+				return ev, errors.Wrap(err, "invalid state slot; could not compute epoch start")
+			}
+			st, err = transition.ProcessSlotsUsingNextSlotCache(ctx, st, ev.HeadRoot[:], start)
+			if err != nil {
+				return ev, errors.Wrap(err, "could not run process blocks on head state into the proposal slot epoch")
+			}
 		}
 	}
+
 	ev.ProposerIndex, err = helpers.BeaconProposerIndexAtSlot(ctx, st, ev.ProposalSlot)
 	if err != nil {
 		return ev, errors.Wrap(err, "failed to compute proposer index")
@@ -743,7 +743,7 @@ func (s *Server) fillEventData(ctx context.Context, ev payloadattribute.EventDat
 	if err != nil {
 		return ev, errors.Wrap(err, "could not get head state slot time")
 	}
-	ev.Attributer, err = s.computePayloadAttributes(ctx, st, hsr, ev.ProposerIndex, uint64(t.Unix()), randao)
+	ev.Attributer, err = s.computePayloadAttributes(ctx, st, ev.HeadRoot, ev.ProposerIndex, uint64(t.Unix()), randao)
 	return ev, err
 }
 
@@ -772,7 +772,7 @@ func (s *Server) payloadAttributesReader(ctx context.Context, ev payloadattribut
 			ProposerIndex:     strconv.FormatUint(uint64(ev.ProposerIndex), 10),
 			ProposalSlot:      strconv.FormatUint(uint64(ev.ProposalSlot), 10),
 			ParentBlockNumber: strconv.FormatUint(ev.ParentBlockNumber, 10),
-			ParentBlockRoot:   hexutil.Encode(ev.ParentBlockRoot),
+			ParentBlockRoot:   hexutil.Encode(ev.HeadRoot[:]),
 			ParentBlockHash:   hexutil.Encode(ev.ParentBlockHash),
 			PayloadAttributes: attributesBytes,
 		})

beacon-chain/rpc/eth/events/events_test.go

@@ -18,6 +18,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/operation"
 	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/state"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/state/stategen/mock"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
@@ -528,9 +529,13 @@ func TestStreamEvents_OperationsEvents(t *testing.T) {
 					Block: b,
 					Slot:  &currentSlot,
 				}
+				headRoot, err := b.Block().HashTreeRoot()
+				require.NoError(t, err)
 
 				stn := mockChain.NewEventFeedWrapper()
 				opn := mockChain.NewEventFeedWrapper()
+				stategen := mock.NewService()
+				stategen.AddStateForRoot(st, headRoot)
 				s := &Server{
 					StateNotifier:          &mockChain.SimpleNotifier{Feed: stn},
 					OperationNotifier:      &mockChain.SimpleNotifier{Feed: opn},
@@ -538,6 +543,7 @@ func TestStreamEvents_OperationsEvents(t *testing.T) {
 					ChainInfoFetcher:       mockChainService,
 					TrackedValidatorsCache: cache.NewTrackedValidatorsCache(),
 					EventWriteTimeout:      testEventWriteTimeout,
+					StateGen:               stategen,
 				}
 				if tc.SetTrackedValidatorsCache != nil {
 					tc.SetTrackedValidatorsCache(s.TrackedValidatorsCache)
@@ -553,11 +559,9 @@ func TestStreamEvents_OperationsEvents(t *testing.T) {
 							ProposerIndex:     0,
 							ProposalSlot:      0,
 							ParentBlockNumber: 0,
-							ParentBlockRoot:   make([]byte, 32),
 							ParentBlockHash:   make([]byte, 32),
-							HeadState:         st,
 							HeadBlock:         b,
-							HeadRoot:          [fieldparams.RootLength]byte{},
+							HeadRoot:          headRoot,
 						},
 					},
 				}
@@ -575,8 +579,6 @@ func TestStreamEvents_OperationsEvents(t *testing.T) {
 func TestFillEventData(t *testing.T) {
 	ctx := context.Background()
 	t.Run("AlreadyFilledData_ShouldShortCircuitWithoutError", func(t *testing.T) {
-		st, err := util.NewBeaconStateBellatrix()
-		require.NoError(t, err)
 		b, err := blocks.NewSignedBeaconBlock(util.HydrateSignedBeaconBlockBellatrix(&eth.SignedBeaconBlockBellatrix{}))
 		require.NoError(t, err)
 		attributor, err := payloadattribute.New(&enginev1.PayloadAttributes{
@@ -584,11 +586,9 @@ func TestFillEventData(t *testing.T) {
 		})
 		require.NoError(t, err)
 		alreadyFilled := payloadattribute.EventData{
-			HeadState:       st,
 			HeadBlock:       b,
 			HeadRoot:        [32]byte{1, 2, 3},
 			Attributer:      attributor,
-			ParentBlockRoot: []byte{1, 2, 3},
 			ParentBlockHash: []byte{4, 5, 6},
 		}
 		srv := &Server{} // No real HeadFetcher needed here since it won't be called.
@@ -612,12 +612,14 @@ func TestFillEventData(t *testing.T) {
 			Timestamp: uint64(time.Now().Unix()),
 		})
 		require.NoError(t, err)
+		headRoot, err := b.Block().HashTreeRoot()
+		require.NoError(t, err)
 		// Create an event data object missing certain fields:
 		partial := payloadattribute.EventData{
-			// The presence of a nil HeadState, nil HeadBlock, zeroed HeadRoot, etc.
-			// will cause fillEventData to try to fill the values.
 			ProposalSlot: 42,         // different epoch from current slot
 			Attributer:   attributor, // Must be Bellatrix or later
+			HeadBlock:    b,
+			HeadRoot:     headRoot,
 		}
 		currentSlot := primitives.Slot(0)
 		// to avoid slot processing
@@ -629,6 +631,8 @@ func TestFillEventData(t *testing.T) {
 			Slot:  &currentSlot,
 		}
 
+		stategen := mock.NewService()
+		stategen.AddStateForRoot(st, headRoot)
 		stn := mockChain.NewEventFeedWrapper()
 		opn := mockChain.NewEventFeedWrapper()
 		srv := &Server{
@@ -638,16 +642,15 @@ func TestFillEventData(t *testing.T) {
 			ChainInfoFetcher:       mockChainService,
 			TrackedValidatorsCache: cache.NewTrackedValidatorsCache(),
 			EventWriteTimeout:      testEventWriteTimeout,
+			StateGen:               stategen,
 		}
 
 		filled, err := srv.fillEventData(ctx, partial)
 		require.NoError(t, err, "expected successful fill of partial event data")
 
 		// Verify that fields have been updated from the mock data:
-		require.NotNil(t, filled.HeadState, "HeadState should be assigned")
 		require.NotNil(t, filled.HeadBlock, "HeadBlock should be assigned")
 		require.NotEqual(t, [32]byte{}, filled.HeadRoot, "HeadRoot should no longer be zero")
-		require.NotEmpty(t, filled.ParentBlockRoot, "ParentBlockRoot should be filled")
 		require.NotEmpty(t, filled.ParentBlockHash, "ParentBlockHash should be filled")
 		require.Equal(t, uint64(0), filled.ParentBlockNumber, "ParentBlockNumber must match mock block")
 

beacon-chain/rpc/eth/events/server.go

@@ -10,6 +10,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/cache"
 	opfeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/operation"
 	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/state/stategen"
 )
 
 // Server defines a server implementation of the http events service,
@@ -23,4 +24,5 @@ type Server struct {
 	KeepAliveInterval      time.Duration
 	EventFeedDepth         int
 	EventWriteTimeout      time.Duration
+	StateGen               stategen.StateManager
 }

beacon-chain/state/stategen/mock/mock.go

@@ -23,8 +23,8 @@ func NewService() *StateManager {
 }
 
 // StateByRootIfCachedNoCopy --
-func (_ *StateManager) StateByRootIfCachedNoCopy(_ [32]byte) state.BeaconState {
+func (m *StateManager) StateByRootIfCachedNoCopy(root [32]byte) state.BeaconState {
-	panic("implement me")
+	return m.StatesByRoot[root]
 }
 
 // Resume --

changelog/kasey_payload-attributes-stategen.md

@@ -0,0 +1,2 @@
+### Fixed
+- Ensure that the `payload_attributes` event has a consistent view of the head state by passing the head block in the event and using stategen to retrieve the corresponding state.

consensus-types/payload-attribute/BUILD.bazel

@@ -10,7 +10,6 @@ go_library(
     importpath = "github.com/OffchainLabs/prysm/v6/consensus-types/payload-attribute",
     visibility = ["//visibility:public"],
     deps = [
-        "//beacon-chain/state:go_default_library",
         "//config/fieldparams:go_default_library",
         "//consensus-types:go_default_library",
         "//consensus-types/blocks:go_default_library",

consensus-types/payload-attribute/types.go

@@ -1,7 +1,6 @@
 package payloadattribute
 
 import (
-	"github.com/OffchainLabs/prysm/v6/beacon-chain/state"
 	field_params "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
@@ -100,10 +99,8 @@ type EventData struct {
 	ProposerIndex     primitives.ValidatorIndex
 	ProposalSlot      primitives.Slot
 	ParentBlockNumber uint64
-	ParentBlockRoot   []byte
 	ParentBlockHash   []byte
 	Attributer        Attributer
-	HeadState         state.BeaconState
 	HeadBlock         interfaces.ReadOnlySignedBeaconBlock
 	HeadRoot          [field_params.RootLength]byte
 }