Add max epoch activation churn limit (EIP-7514) to Deneb

configs/mainnet.yaml

@@ -87,7 +87,8 @@ EJECTION_BALANCE: 16000000000
 MIN_PER_EPOCH_CHURN_LIMIT: 4
 # 2**16 (= 65,536)
 CHURN_LIMIT_QUOTIENT: 65536
-
+# [New in Deneb:EIP7514] 2**3 (= 8)
+MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT: 8
 
 # Fork choice
 # ---------------------------------------------------------------

configs/minimal.yaml

@@ -82,10 +82,12 @@ INACTIVITY_SCORE_BIAS: 4
 INACTIVITY_SCORE_RECOVERY_RATE: 16
 # 2**4 * 10**9 (= 16,000,000,000) Gwei
 EJECTION_BALANCE: 16000000000
-# 2**2 (= 4)
-MIN_PER_EPOCH_CHURN_LIMIT: 4
+# [customized] more easily demonstrate the difference between this value and the activation churn limit
+MIN_PER_EPOCH_CHURN_LIMIT: 2
 # [customized] scale queue churn at much lower validator counts for testing
 CHURN_LIMIT_QUOTIENT: 32
+# [New in Deneb:EIP7514] [customized]
+MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT: 4
 
 
 # Fork choice

specs/deneb/beacon-chain.md

@@ -16,6 +16,7 @@
 - [Preset](#preset)
   - [Execution](#execution)
 - [Configuration](#configuration)
+  - [Validator cycle](#validator-cycle)
 - [Containers](#containers)
   - [Extended containers](#extended-containers)
     - [`BeaconBlockBody`](#beaconblockbody)
@@ -26,6 +27,7 @@
     - [`kzg_commitment_to_versioned_hash`](#kzg_commitment_to_versioned_hash)
   - [Beacon state accessors](#beacon-state-accessors)
     - [Modified `get_attestation_participation_flag_indices`](#modified-get_attestation_participation_flag_indices)
+    - [New `get_validator_activation_churn_limit`](#new-get_validator_activation_churn_limit)
 - [Beacon chain state transition function](#beacon-chain-state-transition-function)
   - [Execution engine](#execution-engine)
     - [Request data](#request-data)
@@ -40,6 +42,8 @@
     - [Execution payload](#execution-payload)
       - [Modified `process_execution_payload`](#modified-process_execution_payload)
     - [Modified `process_voluntary_exit`](#modified-process_voluntary_exit)
+  - [Epoch processing](#epoch-processing)
+    - [Registry updates](#registry-updates)
 - [Testing](#testing)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
@@ -52,6 +56,7 @@ Deneb is a consensus-layer upgrade containing a number of features. Including:
 * [EIP-4844](https://eips.ethereum.org/EIPS/eip-4844): Shard Blob Transactions scale data-availability of Ethereum in a simple, forwards-compatible manner
 * [EIP-7044](https://eips.ethereum.org/EIPS/eip-7044): Perpetually Valid Signed Voluntary Exits
 * [EIP-7045](https://eips.ethereum.org/EIPS/eip-7045): Increase Max Attestation Inclusion Slot
+* [EIP-7514](https://eips.ethereum.org/EIPS/eip-7514): Add Max Epoch Churn Limit
 
 ## Custom types
 
@@ -89,6 +94,12 @@ and are limited by `MAX_BLOB_GAS_PER_BLOCK // GAS_PER_BLOB`. However the CL limi
 
 ## Configuration
 
+### Validator cycle
+
+| Name | Value |
+| - | - |
+| `MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT` | `uint64(2**3)` (= 8) |
+
 ## Containers
 
 ### Extended containers
@@ -211,6 +222,16 @@ def get_attestation_participation_flag_indices(state: BeaconState,
     return participation_flag_indices
 ```
 
+#### New `get_validator_activation_churn_limit`
+
+```python
+def get_validator_activation_churn_limit(state: BeaconState) -> uint64:
+    """
+    Return the validator activation churn limit for the current epoch.
+    """
+    return min(MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT, get_validator_churn_limit(state))
+```
+
 ## Beacon chain state transition function
 
 ### Execution engine
@@ -415,6 +436,38 @@ def process_voluntary_exit(state: BeaconState, signed_voluntary_exit: SignedVolu
     initiate_validator_exit(state, voluntary_exit.validator_index)
 ```
 
+### Epoch processing
+
+#### Registry updates
+
+*Note*: The function `process_registry_updates` is modified to utilize `get_validator_activation_churn_limit()` to rate limit the activation queue for EIP-7514.
+
+```python
+def process_registry_updates(state: BeaconState) -> None:
+    # Process activation eligibility and ejections
+    for index, validator in enumerate(state.validators):
+        if is_eligible_for_activation_queue(validator):
+            validator.activation_eligibility_epoch = get_current_epoch(state) + 1
+
+        if (
+            is_active_validator(validator, get_current_epoch(state))
+            and validator.effective_balance <= EJECTION_BALANCE
+        ):
+            initiate_validator_exit(state, ValidatorIndex(index))
+
+    # Queue validators eligible for activation and not yet dequeued for activation
+    activation_queue = sorted([
+        index for index, validator in enumerate(state.validators)
+        if is_eligible_for_activation(state, validator)
+        # Order by the sequence of activation_eligibility_epoch setting and then index
+    ], key=lambda index: (state.validators[index].activation_eligibility_epoch, index))
+    # Dequeued validators for activation up to activation churn limit
+    # [Modified in Deneb:EIP7514]
+    for index in activation_queue[:get_validator_activation_churn_limit(state)]:
+        validator = state.validators[index]
+        validator.activation_epoch = compute_activation_exit_epoch(get_current_epoch(state))
+```
+
 ## Testing
 
 *Note*: The function `initialize_beacon_state_from_eth1` is modified for pure Deneb testing only.

tests/core/pyspec/eth2spec/test/context.py

@@ -162,14 +162,34 @@ def default_balances(spec: Spec):
     return [spec.MAX_EFFECTIVE_BALANCE] * num_validators
 
 
-def scaled_churn_balances(spec: Spec):
+def scaled_churn_balances_min_churn_limit(spec: Spec):
     """
     Helper method to create enough validators to scale the churn limit.
     (This is *firmly* over the churn limit -- thus the +2 instead of just +1)
     See the second argument of ``max`` in ``get_validator_churn_limit``.
-    Usage: `@with_custom_state(balances_fn=scaled_churn_balances, ...)`
+    Usage: `@with_custom_state(balances_fn=scaled_churn_balances_min_churn_limit, ...)`
     """
-    num_validators = spec.config.CHURN_LIMIT_QUOTIENT * (2 + spec.config.MIN_PER_EPOCH_CHURN_LIMIT)
+    num_validators = spec.config.CHURN_LIMIT_QUOTIENT * (spec.config.MIN_PER_EPOCH_CHURN_LIMIT + 2)
+    return [spec.MAX_EFFECTIVE_BALANCE] * num_validators
+
+
+def scaled_churn_balances_equal_activation_churn_limit(spec: Spec):
+    """
+    Helper method to create enough validators to scale the churn limit.
+    (This is *firmly* over the churn limit -- thus the +2 instead of just +1)
+    Usage: `@with_custom_state(balances_fn=scaled_churn_balances_exceed_activation_churn_limit, ...)`
+    """
+    num_validators = spec.config.CHURN_LIMIT_QUOTIENT * (spec.config.MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT)
+    return [spec.MAX_EFFECTIVE_BALANCE] * num_validators
+
+
+def scaled_churn_balances_exceed_activation_churn_limit(spec: Spec):
+    """
+    Helper method to create enough validators to scale the churn limit.
+    (This is *firmly* over the churn limit -- thus the +2 instead of just +1)
+    Usage: `@with_custom_state(balances_fn=scaled_churn_balances_exceed_activation_churn_limit, ...)`
+    """
+    num_validators = spec.config.CHURN_LIMIT_QUOTIENT * (spec.config.MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT + 2)
     return [spec.MAX_EFFECTIVE_BALANCE] * num_validators
 
 

tests/core/pyspec/eth2spec/test/deneb/epoch_processing/test_process_registry_updates.py

@@ -0,0 +1,90 @@
+from eth2spec.test.helpers.keys import pubkeys
+from eth2spec.test.helpers.constants import MINIMAL
+from eth2spec.test.context import (
+    with_deneb_and_later,
+    spec_test,
+    spec_state_test,
+    single_phase,
+    with_custom_state,
+    with_presets,
+    scaled_churn_balances_exceed_activation_churn_limit,
+    scaled_churn_balances_equal_activation_churn_limit,
+)
+from eth2spec.test.helpers.epoch_processing import run_epoch_processing_with
+
+
+def run_process_registry_updates(spec, state):
+    yield from run_epoch_processing_with(spec, state, 'process_registry_updates')
+
+
+def run_test_activation_churn_limit(spec, state):
+    mock_activations = spec.get_validator_activation_churn_limit(state) * 2
+
+    validator_count_0 = len(state.validators)
+
+    for i in range(mock_activations):
+        index = validator_count_0 + i
+        validator = spec.Validator(
+            pubkey=pubkeys[index],
+            withdrawal_credentials=spec.ETH1_ADDRESS_WITHDRAWAL_PREFIX + b'\x00' * 11 + b'\x56' * 20,
+            activation_eligibility_epoch=0,
+            activation_epoch=spec.FAR_FUTURE_EPOCH,
+            exit_epoch=spec.FAR_FUTURE_EPOCH,
+            withdrawable_epoch=spec.FAR_FUTURE_EPOCH,
+            effective_balance=spec.MAX_EFFECTIVE_BALANCE,
+        )
+        state.validators.append(validator)
+        state.balances.append(spec.MAX_EFFECTIVE_BALANCE)
+        state.previous_epoch_participation.append(spec.ParticipationFlags(0b0000_0000))
+        state.current_epoch_participation.append(spec.ParticipationFlags(0b0000_0000))
+        state.inactivity_scores.append(0)
+        state.validators[index].activation_epoch = spec.FAR_FUTURE_EPOCH
+
+    churn_limit_0 = spec.get_validator_activation_churn_limit(state)
+
+    yield from run_process_registry_updates(spec, state)
+
+    # Half should churn in first run of registry update
+    for i in range(mock_activations):
+        index = validator_count_0 + i
+        if index < validator_count_0 + churn_limit_0:
+            # The eligible validators within the activation churn limit should have been activated
+            assert state.validators[index].activation_epoch < spec.FAR_FUTURE_EPOCH
+        else:
+            assert state.validators[index].activation_epoch == spec.FAR_FUTURE_EPOCH
+
+
+@with_deneb_and_later
+@with_presets([MINIMAL],
+              reason="mainnet config leads to larger validator set than limit of public/private keys pre-generated")
+@spec_test
+@with_custom_state(balances_fn=scaled_churn_balances_exceed_activation_churn_limit,
+                   threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
+@single_phase
+def test_activation_churn_limit__greater_than_activation_limit(spec, state):
+    assert spec.get_validator_activation_churn_limit(state) == spec.config.MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT
+    assert spec.get_validator_churn_limit(state) > spec.config.MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT
+    yield from run_test_activation_churn_limit(spec, state)
+
+
+@with_deneb_and_later
+@with_presets([MINIMAL],
+              reason="mainnet config leads to larger validator set than limit of public/private keys pre-generated")
+@spec_test
+@with_custom_state(balances_fn=scaled_churn_balances_equal_activation_churn_limit,
+                   threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
+@single_phase
+def test_activation_churn_limit__equal_to_activation_limit(spec, state):
+    assert spec.get_validator_activation_churn_limit(state) == spec.config.MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT
+    assert spec.get_validator_churn_limit(state) == spec.config.MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT
+    yield from run_test_activation_churn_limit(spec, state)
+
+
+@with_deneb_and_later
+@with_presets([MINIMAL],
+              reason="mainnet config leads to larger validator set than limit of public/private keys pre-generated")
+@spec_state_test
+def test_activation_churn_limit__less_than_activation_limit(spec, state):
+    assert spec.get_validator_activation_churn_limit(state) < spec.config.MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT
+    assert spec.get_validator_churn_limit(state) < spec.config.MAX_PER_EPOCH_ACTIVATION_CHURN_LIMIT
+    yield from run_test_activation_churn_limit(spec, state)

tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_voluntary_exit.py

@@ -3,7 +3,8 @@
     spec_state_test,
     always_bls, with_all_phases, with_presets,
     spec_test, single_phase,
-    with_custom_state, scaled_churn_balances,
+    with_custom_state,
+    scaled_churn_balances_min_churn_limit,
 )
 from eth2spec.test.helpers.keys import pubkey_to_privkey
 from eth2spec.test.helpers.voluntary_exits import (
@@ -102,7 +103,8 @@ def test_success_exit_queue__min_churn(spec, state):
 @with_presets([MINIMAL],
               reason="mainnet config leads to larger validator set than limit of public/private keys pre-generated")
 @spec_test
-@with_custom_state(balances_fn=scaled_churn_balances, threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
+@with_custom_state(balances_fn=scaled_churn_balances_min_churn_limit,
+                   threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
 @single_phase
 def test_success_exit_queue__scaled_churn(spec, state):
     churn_limit = spec.get_validator_churn_limit(state)

tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_registry_updates.py

@@ -5,7 +5,7 @@
     spec_test, spec_state_test,
     with_all_phases, single_phase,
     with_custom_state, with_presets,
-    scaled_churn_balances,
+    scaled_churn_balances_min_churn_limit,
 )
 from eth2spec.test.helpers.epoch_processing import run_epoch_processing_with
 
@@ -164,7 +164,8 @@ def test_activation_queue_efficiency_min(spec, state):
 @with_presets([MINIMAL],
               reason="mainnet config leads to larger validator set than limit of public/private keys pre-generated")
 @spec_test
-@with_custom_state(balances_fn=scaled_churn_balances, threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
+@with_custom_state(balances_fn=scaled_churn_balances_min_churn_limit,
+                   threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
 @single_phase
 def test_activation_queue_efficiency_scaled(spec, state):
     assert spec.get_validator_churn_limit(state) > spec.config.MIN_PER_EPOCH_CHURN_LIMIT
@@ -227,7 +228,8 @@ def test_ejection_past_churn_limit_min(spec, state):
 @with_presets([MINIMAL],
               reason="mainnet config leads to larger validator set than limit of public/private keys pre-generated")
 @spec_test
-@with_custom_state(balances_fn=scaled_churn_balances, threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
+@with_custom_state(balances_fn=scaled_churn_balances_min_churn_limit,
+                   threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
 @single_phase
 def test_ejection_past_churn_limit_scaled(spec, state):
     assert spec.get_validator_churn_limit(state) > spec.config.MIN_PER_EPOCH_CHURN_LIMIT
@@ -324,7 +326,8 @@ def test_activation_queue_activation_and_ejection__exceed_churn_limit(spec, stat
 @with_presets([MINIMAL],
               reason="mainnet config leads to larger validator set than limit of public/private keys pre-generated")
 @spec_test
-@with_custom_state(balances_fn=scaled_churn_balances, threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
+@with_custom_state(balances_fn=scaled_churn_balances_min_churn_limit,
+                   threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
 @single_phase
 def test_activation_queue_activation_and_ejection__scaled_churn_limit(spec, state):
     churn_limit = spec.get_validator_churn_limit(state)
@@ -336,7 +339,8 @@ def test_activation_queue_activation_and_ejection__scaled_churn_limit(spec, stat
 @with_presets([MINIMAL],
               reason="mainnet config leads to larger validator set than limit of public/private keys pre-generated")
 @spec_test
-@with_custom_state(balances_fn=scaled_churn_balances, threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
+@with_custom_state(balances_fn=scaled_churn_balances_min_churn_limit,
+                   threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
 @single_phase
 def test_activation_queue_activation_and_ejection__exceed_scaled_churn_limit(spec, state):
     churn_limit = spec.get_validator_churn_limit(state)

tests/generators/epoch_processing/main.py

@@ -32,7 +32,10 @@
     ]}
     capella_mods = combine_mods(_new_capella_mods, bellatrix_mods)
 
-    deneb_mods = capella_mods
+    _new_deneb_mods = {key: 'eth2spec.test.deneb.epoch_processing.test_process_' + key for key in [
+        'registry_updates',
+    ]}
+    deneb_mods = combine_mods(_new_deneb_mods, capella_mods)
 
     eip6110_mods = deneb_mods