Electra: beacon-chain/core/helpers (#13921)

* Electra helpers

* Electra helper tests and other fixes

* @terencechain feedback

beacon-chain/core/epoch/epoch_processing.go

@@ -99,7 +99,7 @@ func ProcessRegistryUpdates(ctx context.Context, state state.BeaconState) (state
 	activationEligibilityEpoch := time.CurrentEpoch(state) + 1
 	for idx, validator := range vals {
 		// Process the validators for activation eligibility.
-		if helpers.IsEligibleForActivationQueue(validator) {
+		if helpers.IsEligibleForActivationQueue(validator, currentEpoch) {
 			validator.ActivationEligibilityEpoch = activationEligibilityEpoch
 			if err := state.UpdateValidatorAtIndex(primitives.ValidatorIndex(idx), validator); err != nil {
 				return nil, err

beacon-chain/core/helpers/BUILD.bazel

@@ -12,6 +12,7 @@ go_library(
         "rewards_penalties.go",
         "shuffle.go",
         "sync_committee.go",
+        "validator_churn.go",
         "validators.go",
         "weak_subjectivity.go",
     ],
@@ -56,6 +57,7 @@ go_test(
         "rewards_penalties_test.go",
         "shuffle_test.go",
         "sync_committee_test.go",
+        "validator_churn_test.go",
         "validators_test.go",
         "weak_subjectivity_test.go",
     ],

beacon-chain/core/helpers/validator_churn.go

@@ -0,0 +1,52 @@
+package helpers
+
+import (
+	"github.com/prysmaticlabs/prysm/v5/config/params"
+)
+
+// BalanceChurnLimit for the current active balance, in gwei.
+// New in Electra EIP-7251: https://eips.ethereum.org/EIPS/eip-7251
+//
+// Spec definition:
+//
+//	def get_balance_churn_limit(state: BeaconState) -> Gwei:
+//	    """
+//	    Return the churn limit for the current epoch.
+//	    """
+//	    churn = max(
+//	        MIN_PER_EPOCH_CHURN_LIMIT_ELECTRA,
+//	        get_total_active_balance(state) // CHURN_LIMIT_QUOTIENT
+//	    )
+//	    return churn - churn % EFFECTIVE_BALANCE_INCREMENT
+func BalanceChurnLimit(activeBalanceGwei uint64) uint64 {
+	churn := max(
+		params.BeaconConfig().MinPerEpochChurnLimitElectra,
+		(activeBalanceGwei / params.BeaconConfig().ChurnLimitQuotient),
+	)
+	return churn - churn%params.BeaconConfig().EffectiveBalanceIncrement
+}
+
+// ActivationExitChurnLimit for the current active balance, in gwei.
+// New in Electra EIP-7251: https://eips.ethereum.org/EIPS/eip-7251
+//
+// Spec definition:
+//
+//	def get_activation_exit_churn_limit(state: BeaconState) -> Gwei:
+//	    """
+//	    Return the churn limit for the current epoch dedicated to activations and exits.
+//	    """
+//	    return min(MAX_PER_EPOCH_ACTIVATION_EXIT_CHURN_LIMIT, get_balance_churn_limit(state))
+func ActivationExitChurnLimit(activeBalanceGwei uint64) uint64 {
+	return min(params.BeaconConfig().MaxPerEpochActivationExitChurnLimit, BalanceChurnLimit(activeBalanceGwei))
+}
+
+// ConsolidationChurnLimit for the current active balance, in gwei.
+// New in EIP-7251: https://eips.ethereum.org/EIPS/eip-7251
+//
+// Spec definition:
+//
+//	def get_consolidation_churn_limit(state: BeaconState) -> Gwei:
+//	    return get_balance_churn_limit(state) - get_activation_exit_churn_limit(state)
+func ConsolidationChurnLimit(activeBalanceGwei uint64) uint64 {
+	return BalanceChurnLimit(activeBalanceGwei) - ActivationExitChurnLimit(activeBalanceGwei)
+}

beacon-chain/core/helpers/validator_churn_test.go

@@ -0,0 +1,71 @@
+package helpers_test
+
+import (
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/v5/config/params"
+	"github.com/prysmaticlabs/prysm/v5/testing/assert"
+)
+
+func TestBalanceChurnLimit(t *testing.T) {
+	tests := []struct {
+		name          string
+		activeBalance uint64
+		expected      uint64
+	}{
+		{
+			name:          "less than MIN_PER_EPOCH_CHURN_LIMIT_ELECTRA",
+			activeBalance: 111,
+			expected:      params.BeaconConfig().MinPerEpochChurnLimitElectra,
+		},
+		{
+			name:          "modulo EFFECTIVE_BALANCE_INCREMENT",
+			activeBalance: 111 + params.BeaconConfig().MinPerEpochChurnLimitElectra*params.BeaconConfig().ChurnLimitQuotient,
+			expected:      params.BeaconConfig().MinPerEpochChurnLimitElectra,
+		},
+		{
+			name:          "more than MIN_PER_EPOCH_CHURN_LIMIT_ELECTRA",
+			activeBalance: 2000 * params.BeaconConfig().EffectiveBalanceIncrement * params.BeaconConfig().ChurnLimitQuotient,
+			expected:      2000 * params.BeaconConfig().EffectiveBalanceIncrement,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.expected, helpers.BalanceChurnLimit(tt.activeBalance))
+		})
+	}
+}
+
+func TestActivationExitChurnLimit(t *testing.T) {
+	tests := []struct {
+		name          string
+		activeBalance uint64
+		expected      uint64
+	}{
+		{
+			name:          "less than MAX_PER_EPOCH_ACTIVATION_EXIT_CHURN_LIMIT",
+			activeBalance: 1,
+			expected:      params.BeaconConfig().MinPerEpochChurnLimitElectra,
+		},
+		{
+			name:          "more than MAX_PER_EPOCH_ACTIVATION_EXIT_CHURN_LIMIT",
+			activeBalance: 2000 * params.BeaconConfig().EffectiveBalanceIncrement * params.BeaconConfig().ChurnLimitQuotient,
+			expected:      params.BeaconConfig().MaxPerEpochActivationExitChurnLimit,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.expected, helpers.ActivationExitChurnLimit(tt.activeBalance))
+		})
+	}
+}
+
+// FuzzConsolidationChurnLimit exercises BalanceChurnLimit and ActivationExitChurnLimit
+func FuzzConsolidationChurnLimit(f *testing.F) {
+	f.Fuzz(func(t *testing.T, activeBalance uint64) {
+		helpers.ConsolidationChurnLimit(activeBalance)
+	})
+}