Simplify ExitedValidatorIndices (#14587)

* fix

* add to comment

* modify test

* remove unused parameter

* changelog

* exclude ejected from exited

* fix linter

---------

Co-authored-by: james-prysm <[email protected]>

Author: saolyn

CHANGELOG.md

@@ -18,7 +18,6 @@ The format is based on Keep a Changelog, and this project adheres to Semantic Ve
 - Updated the `beacon-chain/monitor` package to Electra. [PR](https://github.com/prysmaticlabs/prysm/pull/14562)
 - Added ListAttestationsV2 endpoint.
 - Add ability to rollback node's internal state during processing.
-- Simplified `EjectedValidatorIndices`.
 
 ### Changed
 
@@ -36,6 +35,8 @@ The format is based on Keep a Changelog, and this project adheres to Semantic Ve
 - Updated pgo profile for beacon chain with holesky data. This improves the profile guided
   optimizations in the go compiler.
 - Use read only state when computing the active validator list.
+- Simplified `ExitedValidatorIndices`.
+- Simplified `EjectedValidatorIndices`.
 
 ### Deprecated
 

beacon-chain/core/validators/validator.go

@@ -241,38 +241,16 @@ func SlashedValidatorIndices(epoch primitives.Epoch, validators []*ethpb.Validat
 	return slashed
 }
 
-// ExitedValidatorIndices determines the indices exited during the current epoch.
-func ExitedValidatorIndices(epoch primitives.Epoch, validators []*ethpb.Validator, activeValidatorCount uint64) ([]primitives.ValidatorIndex, error) {
+// ExitedValidatorIndices returns the indices of validators who exited during the specified epoch.
+//
+// A validator is considered to have exited during an epoch if their ExitEpoch equals the epoch and
+// excludes validators that have been ejected.
+// This function simplifies the exit determination by directly checking the validator's ExitEpoch,
+// avoiding the complexities and potential inaccuracies of calculating withdrawable epochs.
+func ExitedValidatorIndices(epoch primitives.Epoch, validators []*ethpb.Validator) ([]primitives.ValidatorIndex, error) {
 	exited := make([]primitives.ValidatorIndex, 0)
-	exitEpochs := make([]primitives.Epoch, 0)
-	for i := 0; i < len(validators); i++ {
-		val := validators[i]
-		if val.ExitEpoch != params.BeaconConfig().FarFutureEpoch {
-			exitEpochs = append(exitEpochs, val.ExitEpoch)
-		}
-	}
-	exitQueueEpoch := primitives.Epoch(0)
-	for _, i := range exitEpochs {
-		if exitQueueEpoch < i {
-			exitQueueEpoch = i
-		}
-	}
-
-	// We use the exit queue churn to determine if we have passed a churn limit.
-	exitQueueChurn := uint64(0)
-	for _, val := range validators {
-		if val.ExitEpoch == exitQueueEpoch {
-			exitQueueChurn++
-		}
-	}
-	churn := helpers.ValidatorExitChurnLimit(activeValidatorCount)
-	if churn < exitQueueChurn {
-		exitQueueEpoch++
-	}
-	withdrawableEpoch := exitQueueEpoch + params.BeaconConfig().MinValidatorWithdrawabilityDelay
 	for i, val := range validators {
-		if val.ExitEpoch == epoch && val.WithdrawableEpoch == withdrawableEpoch &&
-			val.EffectiveBalance > params.BeaconConfig().EjectionBalance {
+		if val.ExitEpoch == epoch && val.EffectiveBalance > params.BeaconConfig().EjectionBalance {
 			exited = append(exited, primitives.ValidatorIndex(i))
 		}
 	}

beacon-chain/core/validators/validator_test.go

@@ -389,19 +389,16 @@ func TestExitedValidatorIndices(t *testing.T) {
 			state: &ethpb.BeaconState{
 				Validators: []*ethpb.Validator{
 					{
-						EffectiveBalance:  params.BeaconConfig().MaxEffectiveBalance,
-						ExitEpoch:         0,
-						WithdrawableEpoch: params.BeaconConfig().MinValidatorWithdrawabilityDelay,
+						EffectiveBalance: params.BeaconConfig().MaxEffectiveBalance,
+						ExitEpoch:        0,
 					},
 					{
-						EffectiveBalance:  params.BeaconConfig().MaxEffectiveBalance,
-						ExitEpoch:         0,
-						WithdrawableEpoch: 10,
+						EffectiveBalance: params.BeaconConfig().MaxEffectiveBalance,
+						ExitEpoch:        10,
 					},
 					{
-						EffectiveBalance:  params.BeaconConfig().MaxEffectiveBalance,
-						ExitEpoch:         0,
-						WithdrawableEpoch: params.BeaconConfig().MinValidatorWithdrawabilityDelay,
+						EffectiveBalance: params.BeaconConfig().MaxEffectiveBalance,
+						ExitEpoch:        0,
 					},
 				},
 			},
@@ -433,11 +430,7 @@ func TestExitedValidatorIndices(t *testing.T) {
 		},
 	}
 	for _, tt := range tests {
-		s, err := state_native.InitializeFromProtoPhase0(tt.state)
-		require.NoError(t, err)
-		activeCount, err := helpers.ActiveValidatorCount(context.Background(), s, time.PrevEpoch(s))
-		require.NoError(t, err)
-		exitedIndices, err := validators.ExitedValidatorIndices(0, tt.state.Validators, activeCount)
+		exitedIndices, err := validators.ExitedValidatorIndices(0, tt.state.Validators)
 		require.NoError(t, err)
 		assert.DeepEqual(t, tt.wanted, exitedIndices)
 	}

beacon-chain/rpc/core/validator.go

@@ -869,16 +869,9 @@ func (s *Service) ValidatorActiveSetChanges(
 		}
 	}
 
-	activeValidatorCount, err := helpers.ActiveValidatorCount(ctx, requestedState, coreTime.CurrentEpoch(requestedState))
-	if err != nil {
-		return nil, &RpcError{
-			Err:    errors.Wrap(err, "could not get active validator count"),
-			Reason: Internal,
-		}
-	}
 	vs := requestedState.Validators()
 	activatedIndices := validators.ActivatedValidatorIndices(coreTime.CurrentEpoch(requestedState), vs)
-	exitedIndices, err := validators.ExitedValidatorIndices(coreTime.CurrentEpoch(requestedState), vs, activeValidatorCount)
+	exitedIndices, err := validators.ExitedValidatorIndices(coreTime.CurrentEpoch(requestedState), vs)
 	if err != nil {
 		return nil, &RpcError{
 			Err:    errors.Wrap(err, "could not determine exited validator indices"),