perf(state-transition): reduce amount of withdrawals processed

mod/consensus-types/pkg/types/payload.go

@@ -128,6 +128,16 @@ func (p *ExecutionPayload) DefineSSZ(codec *ssz.Codec) {
 		constants.MaxBytesPerTx,
 	)
 	ssz.DefineSliceOfStaticObjectsContent(codec, &p.Withdrawals, 16)
+
+	// Post Shangai an EL explicitly check that Withdrawals are not nil
+	// (instead empty slices are fine). Currently BeaconKit duly builds
+	// a block with Withdrawals set to empty slice if there are no
+	// withdrawals) but as soon as the block is returned by CometBFT
+	// for verification, the SSZ decoding sets the empty slice to nil.
+	// This code change solves the issue.
+	if p.Withdrawals == nil {
+		p.Withdrawals = make([]*engineprimitives.Withdrawal, 0)
+	}
 }
 
 // MarshalSSZ serializes the ExecutionPayload object into a slice of bytes.

mod/state-transition/pkg/core/state/statedb.go

@@ -225,10 +225,6 @@ func (s *StateDB[
 
 	// Iterate through indices to find the next validators to withdraw.
 	for range bound {
-		var (
-			withdrawal WithdrawalT
-			amount     math.Gwei
-		)
 		validator, err = s.ValidatorByIndex(validatorIndex)
 		if err != nil {
 			return nil, err
@@ -247,24 +243,30 @@ func (s *StateDB[
 
 		// Set the amount of the withdrawal depending on the balance of the
 		// validator.
+		var withdrawal WithdrawalT
 		if validator.IsFullyWithdrawable(balance, epoch) {
-			amount = balance
+			withdrawals = append(withdrawals, withdrawal.New(
+				math.U64(withdrawalIndex),
+				validatorIndex,
+				withdrawalAddress,
+				balance,
+			))
+
+			// Increment the withdrawal index to process the next withdrawal.
+			withdrawalIndex++
 		} else if validator.IsPartiallyWithdrawable(
 			balance, math.Gwei(s.cs.MaxEffectiveBalance()),
 		) {
-			amount = balance - math.Gwei(s.cs.MaxEffectiveBalance())
+			withdrawals = append(withdrawals, withdrawal.New(
+				math.U64(withdrawalIndex),
+				validatorIndex,
+				withdrawalAddress,
+				balance-math.Gwei(s.cs.MaxEffectiveBalance()),
+			))
+
+			// Increment the withdrawal index to process the next withdrawal.
+			withdrawalIndex++
 		}
-		withdrawal = withdrawal.New(
-			math.U64(withdrawalIndex),
-			validatorIndex,
-			withdrawalAddress,
-			amount,
-		)
-
-		withdrawals = append(withdrawals, withdrawal)
-
-		// Increment the withdrawal index to process the next withdrawal.
-		withdrawalIndex++
 
 		// Cap the number of withdrawals to the maximum allowed per payload.
 		//#nosec:G701 // won't overflow in practice.

mod/state-transition/pkg/core/state_processor_staking.go

@@ -23,6 +23,7 @@ package core
 import (
 	"fmt"
 
+	"github.com/berachain/beacon-kit/mod/consensus-types/pkg/types"
 	"github.com/berachain/beacon-kit/mod/errors"
 	"github.com/berachain/beacon-kit/mod/primitives/pkg/common"
 	"github.com/berachain/beacon-kit/mod/primitives/pkg/math"
@@ -131,11 +132,12 @@ func (sp *StateProcessor[
 	}
 
 	// TODO: Modify balance here and then effective balance once per epoch.
-	newBalance := min(
+	updatedBalance := types.ComputeEffectiveBalance(
 		val.GetEffectiveBalance()+dep.GetAmount(),
+		math.Gwei(sp.cs.EffectiveBalanceIncrement()),
 		math.Gwei(sp.cs.MaxEffectiveBalance()),
 	)
-	val.SetEffectiveBalance(newBalance)
+	val.SetEffectiveBalance(updatedBalance)
 	if err = st.UpdateValidatorAtIndex(idx, val); err != nil {
 		return err
 	}

mod/state-transition/pkg/core/state_processor_staking_test.go

@@ -147,23 +147,10 @@ func TestTransitionUpdateValidators(t *testing.T) {
 		StateRoot:     common.Root{},
 		Body: &types.BeaconBlockBody{
 			ExecutionPayload: &types.ExecutionPayload{
-				Timestamp:    10,
-				ExtraData:    []byte("testing"),
-				Transactions: [][]byte{},
-				Withdrawals: []*engineprimitives.Withdrawal{
-					{ // fill empty withdrawals
-						Index:     0,
-						Validator: 0,
-						Address:   emptyAddress,
-						Amount:    0,
-					},
-					{
-						Index:     1,
-						Validator: 1,
-						Address:   emptyAddress,
-						Amount:    0,
-					},
-				},
+				Timestamp:     10,
+				ExtraData:     []byte("testing"),
+				Transactions:  [][]byte{},
+				Withdrawals:   []*engineprimitives.Withdrawal{}, // no withdrawals
 				BaseFeePerGas: math.NewU256(0),
 			},
 			Eth1Data: &types.Eth1Data{},