Merge pull request #3659 from ethDreamer/activation_rate_limiting

EIP-7251: Enforce Activation Rate Limit at Fork Transition

Author: ralexstokes

specs/electra/beacon-chain.md

@@ -61,6 +61,7 @@
     - [Updated  `initiate_validator_exit`](#updated--initiate_validator_exit)
     - [New `switch_to_compounding_validator`](#new-switch_to_compounding_validator)
     - [New `queue_excess_active_balance`](#new-queue_excess_active_balance)
+    - [New `queue_entire_balance_and_reset_validator`](#new-queue_entire_balance_and_reset_validator)
     - [New `compute_exit_epoch_and_update_churn`](#new-compute_exit_epoch_and_update_churn)
     - [New `compute_consolidation_epoch_and_update_churn`](#new-compute_consolidation_epoch_and_update_churn)
     - [Updated `slash_validator`](#updated-slash_validator)
@@ -639,6 +640,19 @@ def queue_excess_active_balance(state: BeaconState, index: ValidatorIndex) -> No
         )
 ```
 
+#### New `queue_entire_balance_and_reset_validator`
+```python
+def queue_entire_balance_and_reset_validator(state: BeaconState, index: ValidatorIndex) -> None:
+    balance = state.balances[index]
+    state.balances[index] = 0
+    validator = state.validators[index]
+    validator.effective_balance = 0
+    validator.activation_eligibility_epoch = FAR_FUTURE_EPOCH
+    state.pending_balance_deposits.append(
+        PendingBalanceDeposit(index=index, amount=balance)
+    )
+```
+
 #### New `compute_exit_epoch_and_update_churn`
 
 ```python

specs/electra/fork.md

@@ -159,6 +159,18 @@ def upgrade_to_electra(pre: deneb.BeaconState) -> BeaconState:
     )
 
     # [New in Electra:EIP7251]
+    # add validators that are not yet active to pending balance deposits
+    pre_activation = sorted([
+        index for index, validator in enumerate(post.validators)
+        if validator.activation_epoch == FAR_FUTURE_EPOCH
+    ], key=lambda index: (
+        post.validators[index].activation_eligibility_epoch,
+        index
+    ))
+
+    for index in pre_activation:
+        queue_entire_balance_and_reset_validator(post, ValidatorIndex(index))
+
     # Ensure early adopters of compounding credentials go through the activation churn
     for index, validator in enumerate(post.validators):
         if has_compounding_withdrawal_credential(validator):