Utilize next slot cache in block rewards rpc (#13684)

* Utilize next slot cache in block rewards rpc

* msg fix

* tests

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

@@ -15,7 +15,9 @@ go_library(
         "//beacon-chain/core/altair:go_default_library",
         "//beacon-chain/core/blocks:go_default_library",
         "//beacon-chain/core/epoch/precompute:go_default_library",
+        "//beacon-chain/core/transition:go_default_library",
         "//beacon-chain/core/validators:go_default_library",
+        "//beacon-chain/db:go_default_library",
         "//beacon-chain/rpc/eth/shared:go_default_library",
         "//beacon-chain/rpc/lookup:go_default_library",
         "//beacon-chain/state:go_default_library",
@@ -35,7 +37,10 @@ go_library(
 
 go_test(
     name = "go_default_test",
-    srcs = ["handlers_test.go"],
+    srcs = [
+        "handlers_test.go",
+        "service_test.go",
+    ],
     embed = [":go_default_library"],
     deps = [
         "//api/server/structs:go_default_library",
@@ -43,6 +48,8 @@ go_test(
         "//beacon-chain/core/altair:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/core/signing:go_default_library",
+        "//beacon-chain/core/transition:go_default_library",
+        "//beacon-chain/db/testing:go_default_library",
         "//beacon-chain/rpc/testutil:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/stategen/mock:go_default_library",

beacon-chain/rpc/eth/rewards/handlers_test.go

@@ -18,6 +18,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/altair"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/signing"
+	dbutil "github.com/prysmaticlabs/prysm/v5/beacon-chain/db/testing"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/rpc/testutil"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/state"
 	mockstategen "github.com/prysmaticlabs/prysm/v5/beacon-chain/state/stategen/mock"
@@ -192,6 +193,7 @@ func BlockRewardTestSetup(t *testing.T, forkName string) (state.BeaconState, int
 }
 
 func TestBlockRewards(t *testing.T) {
+	db := dbutil.SetupDB(t)
 	phase0block, err := blocks.NewSignedBeaconBlock(util.NewBeaconBlock())
 	require.NoError(t, err)
 	t.Run("phase 0", func(t *testing.T) {
@@ -227,7 +229,10 @@ func TestBlockRewards(t *testing.T) {
 			}},
 			OptimisticModeFetcher: mockChainService,
 			FinalizationFetcher:   mockChainService,
-			BlockRewardFetcher:    &BlockRewardService{Replayer: mockstategen.NewReplayerBuilder(mockstategen.WithMockState(st))},
+			BlockRewardFetcher: &BlockRewardService{
+				Replayer: mockstategen.NewReplayerBuilder(mockstategen.WithMockState(st)),
+				DB:       db,
+			},
 		}
 
 		url := "http://only.the.slot.number.at.the.end.is.important/2"
@@ -260,7 +265,10 @@ func TestBlockRewards(t *testing.T) {
 			}},
 			OptimisticModeFetcher: mockChainService,
 			FinalizationFetcher:   mockChainService,
-			BlockRewardFetcher:    &BlockRewardService{Replayer: mockstategen.NewReplayerBuilder(mockstategen.WithMockState(st))},
+			BlockRewardFetcher: &BlockRewardService{
+				Replayer: mockstategen.NewReplayerBuilder(mockstategen.WithMockState(st)),
+				DB:       db,
+			},
 		}
 
 		url := "http://only.the.slot.number.at.the.end.is.important/2"
@@ -293,7 +301,10 @@ func TestBlockRewards(t *testing.T) {
 			}},
 			OptimisticModeFetcher: mockChainService,
 			FinalizationFetcher:   mockChainService,
-			BlockRewardFetcher:    &BlockRewardService{Replayer: mockstategen.NewReplayerBuilder(mockstategen.WithMockState(st))},
+			BlockRewardFetcher: &BlockRewardService{
+				Replayer: mockstategen.NewReplayerBuilder(mockstategen.WithMockState(st)),
+				DB:       db,
+			},
 		}
 
 		url := "http://only.the.slot.number.at.the.end.is.important/2"
@@ -326,7 +337,10 @@ func TestBlockRewards(t *testing.T) {
 			}},
 			OptimisticModeFetcher: mockChainService,
 			FinalizationFetcher:   mockChainService,
-			BlockRewardFetcher:    &BlockRewardService{Replayer: mockstategen.NewReplayerBuilder(mockstategen.WithMockState(st))},
+			BlockRewardFetcher: &BlockRewardService{
+				Replayer: mockstategen.NewReplayerBuilder(mockstategen.WithMockState(st)),
+				DB:       db,
+			},
 		}
 
 		url := "http://only.the.slot.number.at.the.end.is.important/2"
@@ -715,7 +729,9 @@ func TestSyncCommiteeRewards(t *testing.T) {
 		}},
 		OptimisticModeFetcher: mockChainService,
 		FinalizationFetcher:   mockChainService,
-		BlockRewardFetcher:    &BlockRewardService{Replayer: mockstategen.NewReplayerBuilder(mockstategen.WithMockState(st))},
+		BlockRewardFetcher: &BlockRewardService{
+			Replayer: mockstategen.NewReplayerBuilder(mockstategen.WithMockState(st)),
+			DB:       dbutil.SetupDB(t)},
 	}
 
 	t.Run("ok - filtered vals", func(t *testing.T) {

beacon-chain/rpc/eth/rewards/service.go

@@ -8,7 +8,9 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/api/server/structs"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/altair"
 	coreblocks "github.com/prysmaticlabs/prysm/v5/beacon-chain/core/blocks"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/transition"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/validators"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/db"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/state/stategen"
 	consensusblocks "github.com/prysmaticlabs/prysm/v5/consensus-types/blocks"
@@ -26,6 +28,7 @@ type BlockRewardsFetcher interface {
 // BlockRewardService implements BlockRewardsFetcher and can be declared to access the underlying functions
 type BlockRewardService struct {
 	Replayer stategen.ReplayerBuilder
+	DB       db.HeadAccessDatabase
 }
 
 // GetBlockRewardsData returns the BlockRewards object which is used for the BlockRewardsResponse and ProduceBlockV3.
@@ -124,6 +127,22 @@ func (rs *BlockRewardService) GetStateForRewards(ctx context.Context, blk interf
 	// We want to run several block processing functions that update the proposer's balance.
 	// This will allow us to calculate proposer rewards for each operation (atts, slashings etc).
 	// To do this, we replay the state up to the block's slot, but before processing the block.
+
+	// Try getting the state from the next slot cache first.
+	_, prevSlotRoots, err := rs.DB.BlockRootsBySlot(ctx, slots.PrevSlot(blk.Slot()))
+	if err != nil {
+		return nil, &httputil.DefaultJsonError{
+			Message: "Could not get roots for previous slot: " + err.Error(),
+			Code:    http.StatusInternalServerError,
+		}
+	}
+	for _, r := range prevSlotRoots {
+		s := transition.NextSlotState(r[:], blk.Slot())
+		if s != nil {
+			return s, nil
+		}
+	}
+
 	st, err := rs.Replayer.ReplayerForSlot(slots.PrevSlot(blk.Slot())).ReplayToSlot(ctx, blk.Slot())
 	if err != nil {
 		return nil, &httputil.DefaultJsonError{

beacon-chain/rpc/eth/rewards/service_test.go

@@ -0,0 +1,46 @@
+package rewards
+
+import (
+	"context"
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/transition"
+	dbutil "github.com/prysmaticlabs/prysm/v5/beacon-chain/db/testing"
+	"github.com/prysmaticlabs/prysm/v5/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v5/testing/assert"
+	"github.com/prysmaticlabs/prysm/v5/testing/require"
+	"github.com/prysmaticlabs/prysm/v5/testing/util"
+)
+
+func TestGetStateForRewards_NextSlotCacheHit(t *testing.T) {
+	ctx := context.Background()
+	db := dbutil.SetupDB(t)
+
+	st, err := util.NewBeaconStateDeneb()
+	require.NoError(t, err)
+	b := util.HydrateSignedBeaconBlockDeneb(util.NewBeaconBlockDeneb())
+	parent, err := blocks.NewSignedBeaconBlock(b)
+	require.NoError(t, err)
+	require.NoError(t, db.SaveBlock(ctx, parent))
+
+	r, err := parent.Block().HashTreeRoot()
+	require.NoError(t, err)
+	require.NoError(t, transition.UpdateNextSlotCache(ctx, r[:], st))
+
+	s := &BlockRewardService{
+		Replayer: nil, // setting to nil because replayer must not be invoked
+		DB:       db,
+	}
+	b = util.HydrateSignedBeaconBlockDeneb(util.NewBeaconBlockDeneb())
+	sbb, err := blocks.NewSignedBeaconBlock(b)
+	require.NoError(t, err)
+	sbb.SetSlot(parent.Block().Slot() + 1)
+	result, err := s.GetStateForRewards(ctx, sbb.Block())
+	require.NoError(t, err)
+	_, lcs := transition.LastCachedState()
+	expected, err := lcs.HashTreeRoot(ctx)
+	require.NoError(t, err)
+	actual, err := result.HashTreeRoot(ctx)
+	require.NoError(t, err)
+	assert.DeepEqual(t, expected, actual)
+}

beacon-chain/rpc/service.go

@@ -215,7 +215,7 @@ func NewService(ctx context.Context, cfg *Config) *Service {
 		GenesisTimeFetcher: s.cfg.GenesisTimeFetcher,
 		BlobStorage:        s.cfg.BlobStorage,
 	}
-	rewardFetcher := &rewards.BlockRewardService{Replayer: ch}
+	rewardFetcher := &rewards.BlockRewardService{Replayer: ch, DB: s.cfg.BeaconDB}
 	coreService := &core.Service{
 		HeadFetcher:           s.cfg.HeadFetcher,
 		GenesisTimeFetcher:    s.cfg.GenesisTimeFetcher,