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Merge pull request #2399 from ethereum/keep-inactivity-function 

dankrad altair review -- extended and tested
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Danny Ryan 2021-05-12 12:38:26 -06:00 committed by GitHub
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54
specs/altair/beacon-chain.md
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@ -28,7 +28,6 @@
- [`Predicates`](#predicates)
- [`eth2_fast_aggregate_verify`](#eth2_fast_aggregate_verify)
- [Misc](#misc-2)
- [`get_flag_indices_and_weights`](#get_flag_indices_and_weights)
- [`add_flag`](#add_flag)
- [`has_flag`](#has_flag)
- [Beacon state accessors](#beacon-state-accessors)
@ -99,6 +98,7 @@ Altair is the first beacon chain hard fork. Its main features are:
| Name | Value |
| - | - |
| `G2_POINT_AT_INFINITY` | `BLSSignature(b'\xc0' + b'\x00' * 95)` |
| `PARTICIPATION_FLAG_WEIGHTS` | `[TIMELY_HEAD_WEIGHT, TIMELY_SOURCE_WEIGHT, TIMELY_TARGET_WEIGHT]` |
## Configuration
@ -232,20 +232,6 @@ def eth2_fast_aggregate_verify(pubkeys: Sequence[BLSPubkey], message: Bytes32, s
### Misc
#### `get_flag_indices_and_weights`
```python
def get_flag_indices_and_weights() -> Sequence[Tuple[int, uint64]]:
"""
Return paired tuples of participation flag indices along with associated incentivization weights.
"""
return (
(TIMELY_HEAD_FLAG_INDEX, TIMELY_HEAD_WEIGHT),
(TIMELY_SOURCE_FLAG_INDEX, TIMELY_SOURCE_WEIGHT),
(TIMELY_TARGET_FLAG_INDEX, TIMELY_TARGET_WEIGHT),
)
```
#### `add_flag`
```python
@ -277,6 +263,8 @@ def get_next_sync_committee_indices(state: BeaconState) -> Sequence[ValidatorInd
"""
Return the sequence of sync committee indices (which may include duplicate indices)
for the next sync committee, given a ``state`` at a sync committee period boundary.
Note: Committee can contain duplicate indices for small validator sets (< SYNC_COMMITTEE_SIZE + 128)
"""
epoch = Epoch(get_current_epoch(state) + 1)
@ -291,7 +279,7 @@ def get_next_sync_committee_indices(state: BeaconState) -> Sequence[ValidatorInd
candidate_index = active_validator_indices[shuffled_index]
random_byte = hash(seed + uint_to_bytes(uint64(i // 32)))[i % 32]
effective_balance = state.validators[candidate_index].effective_balance
if effective_balance * MAX_RANDOM_BYTE >= MAX_EFFECTIVE_BALANCE * random_byte: # Sample with replacement
if effective_balance * MAX_RANDOM_BYTE >= MAX_EFFECTIVE_BALANCE * random_byte:
sync_committee_indices.append(candidate_index)
i += 1
return sync_committee_indices
@ -312,8 +300,8 @@ def get_next_sync_committee(state: BeaconState) -> SyncCommittee:
returns duplicate indices. Implementations must take care when handling
optimizations relating to aggregation and verification in the presence of duplicates.
Note: This function should only be called at sync committee period boundaries, as
``get_next_sync_committee_indices`` is not stable within a given period.
Note: This function should only be called at sync committee period boundaries by ``process_sync_committee_updates``
as ``get_next_sync_committee_indices`` is not stable within a given period.
"""
indices = get_next_sync_committee_indices(state)
pubkeys = [state.validators[index].pubkey for index in indices]
@ -365,35 +353,31 @@ def get_unslashed_participating_indices(state: BeaconState, flag_index: int, epo
#### `get_flag_index_deltas`
```python
def get_flag_index_deltas(state: BeaconState, flag_index: int, weight: uint64) -> Tuple[Sequence[Gwei], Sequence[Gwei]]:
def get_flag_index_deltas(state: BeaconState, flag_index: int) -> Tuple[Sequence[Gwei], Sequence[Gwei]]:
"""
Return the deltas for a given ``flag_index`` scaled by ``weight`` by scanning through the participation flags.
"""
rewards = [Gwei(0)] * len(state.validators)
penalties = [Gwei(0)] * len(state.validators)
unslashed_participating_indices = get_unslashed_participating_indices(state, flag_index, get_previous_epoch(state))
increment = EFFECTIVE_BALANCE_INCREMENT # Factored out from balances to avoid uint64 overflow
unslashed_participating_increments = get_total_balance(state, unslashed_participating_indices) // increment
active_increments = get_total_active_balance(state) // increment
previous_epoch = get_previous_epoch(state)
unslashed_participating_indices = get_unslashed_participating_indices(state, flag_index, previous_epoch)
weight = PARTICIPATION_FLAG_WEIGHTS[flag_index]
unslashed_participating_balance = get_total_balance(state, unslashed_participating_indices)
unslashed_participating_increments = unslashed_participating_balance // EFFECTIVE_BALANCE_INCREMENT
active_increments = get_total_active_balance(state) // EFFECTIVE_BALANCE_INCREMENT
for index in get_eligible_validator_indices(state):
base_reward = get_base_reward(state, index)
if index in unslashed_participating_indices:
if is_in_inactivity_leak(state):
# This flag reward cancels the inactivity penalty corresponding to the flag index
rewards[index] += Gwei(base_reward * weight // WEIGHT_DENOMINATOR)
else:
if not is_in_inactivity_leak(state):
reward_numerator = base_reward * weight * unslashed_participating_increments
rewards[index] += Gwei(reward_numerator // (active_increments * WEIGHT_DENOMINATOR))
else:
elif flag_index != TIMELY_HEAD_FLAG_INDEX:
penalties[index] += Gwei(base_reward * weight // WEIGHT_DENOMINATOR)
return rewards, penalties
```
#### Modified `get_inactivity_penalty_deltas`
*Note*: The function `get_inactivity_penalty_deltas` is modified in the selection of matching target indices
and the removal of `BASE_REWARDS_PER_EPOCH`.
```python
def get_inactivity_penalty_deltas(state: BeaconState) -> Tuple[Sequence[Gwei], Sequence[Gwei]]:
"""
@ -405,9 +389,6 @@ def get_inactivity_penalty_deltas(state: BeaconState) -> Tuple[Sequence[Gwei], S
previous_epoch = get_previous_epoch(state)
matching_target_indices = get_unslashed_participating_indices(state, TIMELY_TARGET_FLAG_INDEX, previous_epoch)
for index in get_eligible_validator_indices(state):
for (_, weight) in get_flag_indices_and_weights():
# This inactivity penalty cancels the flag reward corresponding to the flag index
penalties[index] += Gwei(get_base_reward(state, index) * weight // WEIGHT_DENOMINATOR)
if index not in matching_target_indices:
penalty_numerator = state.validators[index].effective_balance * state.inactivity_scores[index]
penalty_denominator = INACTIVITY_SCORE_BIAS * INACTIVITY_PENALTY_QUOTIENT_ALTAIR
@ -501,7 +482,7 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
# Update epoch participation flags
proposer_reward_numerator = 0
for index in get_attesting_indices(state, data, attestation.aggregation_bits):
for flag_index, weight in get_flag_indices_and_weights():
for flag_index, weight in enumerate(PARTICIPATION_FLAG_WEIGHTS):
if flag_index in participation_flag_indices and not has_flag(epoch_participation[index], flag_index):
epoch_participation[index] = add_flag(epoch_participation[index], flag_index)
proposer_reward_numerator += get_base_reward(state, index) * weight
@ -643,8 +624,7 @@ def process_rewards_and_penalties(state: BeaconState) -> None:
if get_current_epoch(state) == GENESIS_EPOCH:
return
flag_indices_and_numerators = get_flag_indices_and_weights()
flag_deltas = [get_flag_index_deltas(state, index, numerator) for (index, numerator) in flag_indices_and_numerators]
flag_deltas = [get_flag_index_deltas(state, flag_index) for flag_index in range(len(PARTICIPATION_FLAG_WEIGHTS))]
deltas = flag_deltas + [get_inactivity_penalty_deltas(state)]
for (rewards, penalties) in deltas:
for index in range(len(state.validators)):

28
tests/core/pyspec/eth2spec/test/helpers/rewards.py
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@ -62,13 +62,13 @@ def run_deltas(spec, state):
if is_post_altair(spec):
def get_source_deltas(state):
return spec.get_flag_index_deltas(state, spec.TIMELY_SOURCE_FLAG_INDEX, spec.TIMELY_SOURCE_WEIGHT)
return spec.get_flag_index_deltas(state, spec.TIMELY_SOURCE_FLAG_INDEX)
def get_head_deltas(state):
return spec.get_flag_index_deltas(state, spec.TIMELY_HEAD_FLAG_INDEX, spec.TIMELY_HEAD_WEIGHT)
return spec.get_flag_index_deltas(state, spec.TIMELY_HEAD_FLAG_INDEX)
def get_target_deltas(state):
return spec.get_flag_index_deltas(state, spec.TIMELY_TARGET_FLAG_INDEX, spec.TIMELY_TARGET_WEIGHT)
return spec.get_flag_index_deltas(state, spec.TIMELY_TARGET_FLAG_INDEX)
yield from run_attestation_component_deltas(
spec,
@ -133,14 +133,23 @@ def run_attestation_component_deltas(spec, state, component_delta_fn, matching_a
validator = state.validators[index]
enough_for_reward = has_enough_for_reward(spec, state, index)
if index in matching_indices and not validator.slashed:
if is_post_altair(spec):
if not spec.is_in_inactivity_leak(state) and enough_for_reward:
assert rewards[index] > 0
else:
assert rewards[index] == 0
else:
if enough_for_reward:
assert rewards[index] > 0
else:
assert rewards[index] == 0
assert penalties[index] == 0
else:
assert rewards[index] == 0
if enough_for_reward:
if is_post_altair(spec) and 'head' in deltas_name:
assert penalties[index] == 0
elif enough_for_reward:
assert penalties[index] > 0
else:
assert penalties[index] == 0
@ -225,16 +234,17 @@ def run_get_inactivity_penalty_deltas(spec, state):
if not is_post_altair(spec):
cancel_base_rewards_per_epoch = spec.BASE_REWARDS_PER_EPOCH
base_penalty = cancel_base_rewards_per_epoch * base_reward - spec.get_proposer_reward(state, index)
else:
base_penalty = sum(
base_reward * numerator // spec.WEIGHT_DENOMINATOR
for (_, numerator) in spec.get_flag_indices_and_weights()
)
if not has_enough_for_reward(spec, state, index):
assert penalties[index] == 0
elif index in matching_attesting_indices or not has_enough_for_leak_penalty(spec, state, index):
if is_post_altair(spec):
assert penalties[index] == 0
else:
assert penalties[index] == base_penalty
else:
if is_post_altair(spec):
assert penalties[index] > 0
else:
assert penalties[index] > base_penalty
else: