diff --git a/specs/core/0_beacon-chain.md b/specs/core/0_beacon-chain.md index f1480fb15..848be29af 100644 --- a/specs/core/0_beacon-chain.md +++ b/specs/core/0_beacon-chain.md @@ -454,6 +454,7 @@ Unless otherwise indicated, code appearing in `this style` is to be interpreted # Validator registry 'validator_registry': [ValidatorRecord], + 'validator_balances': ['uint64'], 'validator_registry_latest_change_slot': 'uint64', 'validator_registry_exit_count': 'uint64', 'validator_registry_delta_chain_tip': 'hash32', # For light clients to track deltas @@ -496,8 +497,6 @@ Unless otherwise indicated, code appearing in `this style` is to be interpreted 'randao_commitment': 'hash32', # Slots the proposer has skipped (i.e. layers of RANDAO expected) 'randao_layers': 'uint64', - # Balance in Gwei - 'balance': 'uint64', # Status code 'status': 'uint64', # Slot when validator last changed status (or 0) @@ -963,11 +962,11 @@ def get_attestation_participants(state: BeaconState, #### `get_effective_balance` ```python -def get_effective_balance(validator: ValidatorRecord) -> int: +def get_effective_balance(state: State, index: int) -> int: """ - Returns the effective balance (also known as "balance at stake") for the ``validator``. + Returns the effective balance (also known as "balance at stake") for a ``validator`` with the given ``index``. """ - return min(validator.balance, MAX_DEPOSIT * GWEI_PER_ETH) + return min(state.validator_balances[index], MAX_DEPOSIT * GWEI_PER_ETH) ``` #### `get_new_validator_registry_delta_chain_tip` @@ -1140,6 +1139,7 @@ def get_initial_beacon_state(initial_validator_deposits: List[Deposit], # Validator registry validator_registry=[], + validator_balances=[], validator_registry_latest_change_slot=INITIAL_SLOT_NUMBER, validator_registry_exit_count=0, validator_registry_delta_chain_tip=ZERO_HASH, @@ -1179,7 +1179,7 @@ def get_initial_beacon_state(initial_validator_deposits: List[Deposit], withdrawal_credentials=deposit.deposit_data.deposit_input.withdrawal_credentials, randao_commitment=deposit.deposit_data.deposit_input.randao_commitment ) - if state.validator_registry[index].balance >= MAX_DEPOSIT * GWEI_PER_ETH: + if get_effective_balance(state, validator_index) == MAX_DEPOSIT * GWEI_PER_ETH: update_validator_status(state, index, ACTIVE) # set initial committee shuffling @@ -1198,9 +1198,11 @@ def get_initial_beacon_state(initial_validator_deposits: List[Deposit], First, a helper function: ```python -def min_empty_validator_index(validators: List[ValidatorRecord], current_slot: int) -> int: - for i, v in enumerate(validators): - if v.balance == 0 and v.latest_status_change_slot + ZERO_BALANCE_VALIDATOR_TTL <= current_slot: +def min_empty_validator_index(validators: List[ValidatorRecord], + validator_balances: List[int], + current_slot: int) -> int: + for i, (v, vbal) in enumerate(zip(validators, validator_balances)): + if vbal == 0 and v.latest_status_change_slot + ZERO_BALANCE_VALIDATOR_TTL <= current_slot: return i return None ``` @@ -1244,25 +1246,25 @@ def process_deposit(state: BeaconState, withdrawal_credentials=withdrawal_credentials, randao_commitment=randao_commitment, randao_layers=0, - balance=deposit, status=PENDING_ACTIVATION, latest_status_change_slot=state.slot, exit_count=0 ) - index = min_empty_validator_index(validators_copy) + index = min_empty_validator_index(state.validator_registry, state.validator_balances, state.slot) if index is None: state.validator_registry.append(validator) - index = len(validators_copy) - 1 + state.validator_balances.append(deposit) + index = len(state.validator_registry) - 1 else: state.validator_registry[index] = validator + state.validator_balances[index] = deposit else: # Increase balance by deposit index = validator_pubkeys.index(pubkey) - validator = state.validator_registry[index] - assert validator.withdrawal_credentials == withdrawal_credentials + assert state.validator_registry[index].withdrawal_credentials == withdrawal_credentials - validator.balance += deposit + state.validator_balances[index] += deposit return index ``` @@ -1344,12 +1346,12 @@ def exit_validator(state: BeaconState, validator.latest_status_change_slot = state.slot if new_status == EXITED_WITH_PENALTY: - state.latest_penalized_exit_balances[state.slot // COLLECTIVE_PENALTY_CALCULATION_PERIOD] += get_effective_balance(validator) + state.latest_penalized_exit_balances[state.slot // COLLECTIVE_PENALTY_CALCULATION_PERIOD] += get_effective_balance(state, index) - whistleblower = state.validator_registry[get_beacon_proposer_index(state, state.slot)] - whistleblower_reward = validator.balance // WHISTLEBLOWER_REWARD_QUOTIENT - whistleblower.balance += whistleblower_reward - validator.balance -= whistleblower_reward + whistleblower_index = get_beacon_proposer_index(state, state.slot) + whistleblower_reward = get_effective_balance(state, index) // WHISTLEBLOWER_REWARD_QUOTIENT + state.validator_balances[whistleblower_index] += whistleblower_reward + state.validator_balances[index] -= whistleblower_reward if prev_status == EXITED_WITHOUT_PENALTY return @@ -1383,8 +1385,8 @@ Below are the processing steps that happen at every slot. ### Block roots -* Let `previous_block_root` be the `hash_tree_root` of the previous beacon block processed in the chain. -* Set `state.latest_block_roots = state.latest_block_roots[1:] + [previous_block_root]`. +* Let `previous_block_root` be the `tree_hash_root` of the previous beacon block processed in the chain. +* Set `state.latest_block_roots[(state.slot - 1) % LATEST_BLOCK_ROOTS_LENGTH] = previous_block_root`. * If `state.slot % LATEST_BLOCK_ROOTS_LENGTH == 0` append `merkle_root(state.latest_block_roots)` to `state.batched_block_roots`. ## Per-block processing @@ -1524,8 +1526,8 @@ The steps below happen when `state.slot % EPOCH_LENGTH == 0`. All [validators](#dfn-validator): -* Let `active_validators = [state.validator_registry[i] for i in get_active_validator_indices(state.validator_registry)]`. -* Let `total_balance = sum([get_effective_balance(v) for v in active_validators])`. +* Let `active_validator_indices = get_active_validator_indices(state.validator_registry)`. +* Let `total_balance = sum([get_effective_balance(state, i) for i in active_validator_indices])`. [Validators](#dfn-Validator) attesting during the current epoch: @@ -1533,42 +1535,37 @@ All [validators](#dfn-validator): * Validators justifying the epoch boundary block at the start of the current epoch: * Let `this_epoch_boundary_attestations = [a for a in this_epoch_attestations if a.data.epoch_boundary_root == get_block_root(state, state.slot-EPOCH_LENGTH) and a.justified_slot == state.justified_slot]`. * Let `this_epoch_boundary_attester_indices` be the union of the [validator](#dfn-validator) index sets given by `[get_attestation_participants(state, a.data, a.participation_bitfield) for a in this_epoch_boundary_attestations]`. - * Let `this_epoch_boundary_attesters = [state.validator_registry[i] for indices in this_epoch_boundary_attester_indices for i in indices]`. - * Let `this_epoch_boundary_attesting_balance = sum([get_effective_balance(v) for v in this_epoch_boundary_attesters])`. + * Let `this_epoch_boundary_attesting_balance = sum([get_effective_balance(state, i) for i in this_epoch_boundary_attester_indices])`. [Validators](#dfn-Validator) attesting during the previous epoch: * Validators that made an attestation during the previous epoch: * Let `previous_epoch_attestations = [a for a in state.latest_attestations if state.slot - 2 * EPOCH_LENGTH <= a.slot < state.slot - EPOCH_LENGTH]`. * Let `previous_epoch_attester_indices` be the union of the validator index sets given by `[get_attestation_participants(state, a.data, a.participation_bitfield) for a in previous_epoch_attestations]`. - * Let `previous_epoch_attesters = [state.validator_registry[i] for indices in previous_epoch_attester_indices for i in indices]`. * Validators targeting the previous justified hash: * Let `previous_epoch_justified_attestations = [a for a in this_epoch_attestations + previous_epoch_attestations if a.justified_slot == state.previous_justified_slot]`. * Let `previous_epoch_justified_attester_indices` be the union of the validator index sets given by `[get_attestation_participants(state, a.data, a.participation_bitfield) for a in previous_epoch_justified_attestations]`. - * Let `previous_epoch_justified_attesters = [state.validator_registry[i] for indices in previous_epoch_justified_attester_indices for i in indices]`. - * Let `previous_epoch_justified_attesting_balance = sum([get_effective_balance(v) for v in previous_epoch_justified_attesters])`. + * Let `previous_epoch_justified_attesting_balance = sum([get_effective_balance(state, i) for i in previous_epoch_justified_attester_indices])`. * Validators justifying the epoch boundary block at the start of the previous epoch: * Let `previous_epoch_boundary_attestations = [a for a in previous_epoch_justified_attestations if a.epoch_boundary_root == get_block_root(state, state.slot - 2 * EPOCH_LENGTH)]`. * Let `previous_epoch_boundary_attester_indices` be the union of the validator index sets given by `[get_attestation_participants(state, a.data, a.participation_bitfield) for a in previous_epoch_boundary_attestations]`. - * Let `previous_epoch_boundary_attesters = [state.validator_registry[i] for indices in previous_epoch_boundary_attester_indices for i in indices]`. - * Let `previous_epoch_boundary_attesting_balance = sum([get_effective_balance(v) for v in previous_epoch_boundary_attesters])`. + * Let `previous_epoch_boundary_attesting_balance = sum([get_effective_balance(state, i) for i in previous_epoch_boundary_attester_indices])`. * Validators attesting to the expected beacon chain head during the previous epoch: * Let `previous_epoch_head_attestations = [a for a in previous_epoch_attestations if a.beacon_block_root == get_block_root(state, a.slot)]`. * Let `previous_epoch_head_attester_indices` be the union of the validator index sets given by `[get_attestation_participants(state, a.data, a.participation_bitfield) for a in previous_epoch_head_attestations]`. - * Let `previous_epoch_head_attesters = [state.validator_registry[i] for indices in previous_epoch_head_attester_indices for i in indices]`. - * Let `previous_epoch_head_attesting_balance = sum([get_effective_balance(v) for v in previous_epoch_head_attesters])`. + * Let `previous_epoch_head_attesting_balance = sum([get_effective_balance(state, i) for i in previous_epoch_head_attester_indices])`. **Note**: `previous_epoch_boundary_attesting_balance` balance might be marginally different than `this_epoch_boundary_attesting_balance` during the previous epoch transition. Due to the tight bound on validator churn each epoch and small per-epoch rewards/penalties, the potential balance difference is very low and only marginally affects consensus safety. For every `shard_committee` in `state.shard_committees_at_slots`: -* Let `attesting_validators(shard_committee, shard_block_root)` be the union of the [validator](#dfn-validator) index sets given by `[get_attestation_participants(state, a.data, a.participation_bitfield) for a in this_epoch_attestations + previous_epoch_attestations if a.shard == shard_committee.shard and a.shard_block_root == shard_block_root]`. -* Let `winning_root(shard_committee)` be equal to the value of `shard_block_root` such that `sum([get_effective_balance(v) for v in attesting_validators(shard_committee, shard_block_root)])` is maximized (ties broken by favoring lower `shard_block_root` values). +* Let `attesting_validator_indices(shard_committee, shard_block_root)` be the union of the [validator](#dfn-validator) index sets given by `[get_attestation_participants(state, a.data, a.participation_bitfield) for a in this_epoch_attestations + previous_epoch_attestations if a.shard == shard_committee.shard and a.shard_block_root == shard_block_root]`. +* Let `winning_root(shard_committee)` be equal to the value of `shard_block_root` such that `sum([get_effective_balance(state, i) for i in attesting_validator_indices(shard_committee, shard_block_root)])` is maximized (ties broken by favoring lower `shard_block_root` values). * Let `attesting_validators(shard_committee)` be equal to `attesting_validators(shard_committee, winning_root(shard_committee))` for convenience. * Let `total_attesting_balance(shard_committee)` be the sum of the balances-at-stake of `attesting_validators(shard_committee)`. -* Let `total_balance(shard_committee) = sum([get_effective_balance(v) for v in shard_committee.committee])`. -* Let `inclusion_slot(v) = a.slot_included` for the attestation `a` where `v` is in `get_attestation_participants(state, a.data, a.participation_bitfield)`. -* Let `inclusion_distance(v) = a.slot_included - a.data.slot` where `a` is the above attestation. +* Let `total_balance(shard_committee) = sum([get_effective_balance(state, i) for i in shard_committee.committee])`. +* Let `inclusion_slot(state, index) = a.slot_included` for the attestation `a` where `index` is in `get_attestation_participants(state, a.data, a.participation_bitfield)`. +* Let `inclusion_distance(state, index) = a.slot_included - a.data.slot` where `a` is the above attestation. * Let `adjust_for_inclusion_distance(magnitude, distance)` be the function below. ```python @@ -1613,8 +1610,8 @@ For every `shard_committee` in `state.shard_committees_at_slots`: First, we define some additional helpers: * Let `base_reward_quotient = BASE_REWARD_QUOTIENT * integer_squareroot(total_balance // GWEI_PER_ETH)`. -* Let `base_reward(v) = get_effective_balance(v) // base_reward_quotient // 4` for any validator `v`. -* Let `inactivity_penalty(v, slots_since_finality) = base_reward(v) + get_effective_balance(v) * slots_since_finality // INACTIVITY_PENALTY_QUOTIENT` for any validator `v`. +* Let `base_reward(state, index) = get_effective_balance(state, index) // base_reward_quotient // 4` for any validator with the given `index`. +* Let `inactivity_penalty(state, index, slots_since_finality) = base_reward(state, index) + get_effective_balance(state, index) * slots_since_finality // INACTIVITY_PENALTY_QUOTIENT` for any validator with the given `index`. #### Justification and finalization @@ -1625,32 +1622,32 @@ Note: When applying penalties in the following balance recalculations implemente Case 1: `slots_since_finality <= 4 * EPOCH_LENGTH`: * Expected FFG source: - * Any [validator](#dfn-validator) `v` in `previous_epoch_justified_attesters` gains `adjust_for_inclusion_distance(base_reward(v) * previous_epoch_justified_attesting_balance // total_balance, inclusion_distance(v))`. - * Any [active validator](#dfn-active-validator) `v` not in `previous_epoch_justified_attesters` loses `base_reward(v)`. + * Any [validator](#dfn-validator) `index` in `previous_epoch_justified_attester_indices` gains `adjust_for_inclusion_distance(base_reward(state, index) * previous_epoch_justified_attesting_balance // total_balance, inclusion_distance(state, index))`. + * Any [active validator](#dfn-active-validator) `v` not in `previous_epoch_justified_attester_indices` loses `base_reward(state, index)`. * Expected FFG target: - * Any [validator](#dfn-validator) `v` in `previous_epoch_boundary_attesters` gains `adjust_for_inclusion_distance(base_reward(v) * previous_epoch_boundary_attesting_balance // total_balance, inclusion_distance(v))`. - * Any [active validator](#dfn-active-validator) `v` not in `previous_epoch_boundary_attesters` loses `base_reward(v)`. + * Any [validator](#dfn-validator) `index` in `previous_epoch_boundary_attester_indices` gains `adjust_for_inclusion_distance(base_reward(state, index) * previous_epoch_boundary_attesting_balance // total_balance, inclusion_distance(state, index))`. + * Any [active validator](#dfn-active-validator) `index` not in `previous_epoch_boundary_attester_indices` loses `base_reward(state, index)`. * Expected beacon chain head: - * Any [validator](#dfn-validator) `v` in `previous_epoch_head_attesters` gains `adjust_for_inclusion_distance(base_reward(v) * previous_epoch_head_attesting_balance // total_balance, inclusion_distance(v))`. - * Any [active validator](#dfn-active-validator) `v` not in `previous_epoch_head_attesters` loses `base_reward(v)`. + * Any [validator](#dfn-validator) `index` in `previous_epoch_head_attester_indices` gains `adjust_for_inclusion_distance(base_reward(state, index) * previous_epoch_head_attesting_balance // total_balance, inclusion_distance(state, index))`. + * Any [active validator](#dfn-active-validator) `index` not in `previous_epoch_head_attester_indices` loses `base_reward(state, index)`. Case 2: `slots_since_finality > 4 * EPOCH_LENGTH`: -* Any [active validator](#dfn-active-validator) `v` not in `previous_epoch_justified_attesters`, loses `inactivity_penalty(v, slots_since_finality)`. -* Any [active validator](#dfn-active-validator) `v` not in `previous_epoch_boundary_attesters`, loses `inactivity_penalty(v, slots_since_finality)`. -* Any [active validator](#dfn-active-validator) `v` not in `previous_epoch_head_attesters`, loses `inactivity_penalty(v, slots_since_finality)`. -* Any [validator](#dfn-validator) with `status == EXITED_WITH_PENALTY`, loses `3 * inactivity_penalty(v, slots_since_finality)`. +* Any [active validator](#dfn-active-validator) `index` not in `previous_epoch_justified_attester_indices`, loses `inactivity_penalty(state, index, slots_since_finality)`. +* Any [active validator](#dfn-active-validator) `index` not in `previous_epoch_boundary_attester_indices`, loses `inactivity_penalty(state, index, slots_since_finality)`. +* Any [active validator](#dfn-active-validator) `index` not in `previous_epoch_head_attester_indices`, loses `inactivity_penalty(state, index, slots_since_finality)`. +* Any [validator](#dfn-validator) `index` with `status == EXITED_WITH_PENALTY`, loses `3 * inactivity_penalty(state, index, slots_since_finality)`. #### Attestation inclusion -For each `v` in `previous_epoch_attesters`, we determine the proposer `proposer_index = get_beacon_proposer_index(state, inclusion_slot(v))` and set `state.validator_registry[proposer_index].balance += base_reward(v) // INCLUDER_REWARD_QUOTIENT`. +For each `index` in `previous_epoch_attester_indices`, we determine the proposer `proposer_index = get_beacon_proposer_index(state, inclusion_slot(state, index))` and set `state.validator_balances[proposer_index] += base_reward(state, index) // INCLUDER_REWARD_QUOTIENT`. #### Crosslinks -For every `shard_committee` in `state.shard_committees_at_slots[:EPOCH_LENGTH]` (i.e. the objects corresponding to the epoch before the current one), for each `v` in `[state.validator_registry[index] for index in shard_committee.committee]`, adjust balances as follows: +For every `shard_committee` in `state.shard_committees_at_slots[:EPOCH_LENGTH]` (i.e. the objects corresponding to the epoch before the current one), for each `index` in `shard_committee.committee`, adjust balances as follows: -* If `v in attesting_validators(shard_committee)`, `v.balance += adjust_for_inclusion_distance(base_reward(v) * total_attesting_balance(shard_committee) // total_balance(shard_committee)), inclusion_distance(v))`. -* If `v not in attesting_validators(shard_committee)`, `v.balance -= base_reward(v)`. +* If `index in attesting_validators(shard_committee)`, `state.validator_balances[index] += adjust_for_inclusion_distance(base_reward(state, index) * total_attesting_balance(shard_committee) // total_balance(shard_committee)), inclusion_distance(state, index))`. +* If `index not in attesting_validators(shard_committee)`, `state.validator_balances[index] -= base_reward(state, index)`. ### Ejections @@ -1663,7 +1660,7 @@ def process_ejections(state: BeaconState) -> None: and eject active validators with balance below ``EJECTION_BALANCE``. """ for index in active_validator_indices(state.validator_registry): - if state.validator_registry[index].balance < EJECTION_BALANCE: + if state.validator_balances[index] < EJECTION_BALANCE: update_validator_status(state, index, new_status=EXITED_WITHOUT_PENALTY) ``` @@ -1685,7 +1682,7 @@ def update_validator_registry(state: BeaconState) -> None: # The active validators active_validator_indices = get_active_validator_indices(state.validator_registry) # The total effective balance of active validators - total_balance = sum([get_effective_balance(v) for i, v in enumerate(validator_registry) if i in active_validator_indices]) + total_balance = sum([get_effective_balance(state, i) for i in active_validator_indices]) # The maximum balance churn in Gwei (for deposits and exits separately) max_balance_churn = max( @@ -1696,9 +1693,9 @@ def update_validator_registry(state: BeaconState) -> None: # Activate validators within the allowable balance churn balance_churn = 0 for index, validator in enumerate(state.validator_registry): - if validator.status == PENDING_ACTIVATION and validator.balance >= MAX_DEPOSIT * GWEI_PER_ETH: + if validator.status == PENDING_ACTIVATION and state.validator_balances[index] >= MAX_DEPOSIT * GWEI_PER_ETH: # Check the balance churn would be within the allowance - balance_churn += get_effective_balance(validator) + balance_churn += get_effective_balance(state, index) if balance_churn > max_balance_churn: break @@ -1710,7 +1707,7 @@ def update_validator_registry(state: BeaconState) -> None: for index, validator in enumerate(state.validator_registry): if validator.status == ACTIVE_PENDING_EXIT: # Check the balance churn would be within the allowance - balance_churn += get_effective_balance(validator) + balance_churn += get_effective_balance(state, index) if balance_churn > max_balance_churn: break @@ -1727,11 +1724,11 @@ def update_validator_registry(state: BeaconState) -> None: ) # Calculate penalties for slashed validators - def to_penalize(v): - return v.status == EXITED_WITH_PENALTY - validators_to_penalize = filter(to_penalize, validator_registry) - for v in validators_to_penalize: - v.balance -= get_effective_balance(v) * min(total_penalties * 3, total_balance) // total_balance + def to_penalize(index): + return state.validator_registry[index].status == EXITED_WITH_PENALTY + validators_to_penalize = filter(to_penalize, range(len(validator_registry))) + for index in validators_to_penalize: + state.validator_balances[index] -= get_effective_balance(state, index) * min(total_penalties * 3, total_balance) // total_balance return validator_registry, latest_penalized_exit_balances, validator_registry_delta_chain_tip ```