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Merge pull request #1219 from ethereum/committee-roots 

Compact committee roots
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Danny Ryan 2019-06-29 12:26:45 -05:00 committed by GitHub
parent b21c9cc71b 2857324016
commit e1826aae32
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7 changed files with 52 additions and 39 deletions
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2
configs/constant_presets/mainnet.yaml
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@ -10,7 +10,7 @@ SHARD_COUNT: 1024
# 2**7 (= 128)
TARGET_COMMITTEE_SIZE: 128
# 2**12 (= 4,096)
MAX_INDICES_PER_ATTESTATION: 4096
MAX_VALIDATORS_PER_COMMITTEE: 4096
# 2**2 (= 4)
MIN_PER_EPOCH_CHURN_LIMIT: 4
# 2**16 (= 65,536)

2
configs/constant_presets/minimal.yaml
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@ -9,7 +9,7 @@ SHARD_COUNT: 8
# [customized] unsecure, but fast
TARGET_COMMITTEE_SIZE: 4
# 2**12 (= 4,096)
MAX_INDICES_PER_ATTESTATION: 4096
MAX_VALIDATORS_PER_COMMITTEE: 4096
# 2**2 (= 4)
MIN_PER_EPOCH_CHURN_LIMIT: 4
# 2**16 (= 65,536)

73
specs/core/0_beacon-chain.md
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@ -34,6 +34,7 @@
- [`Eth1Data`](#eth1data)
- [`HistoricalBatch`](#historicalbatch)
- [`DepositData`](#depositdata)
- [`CompactCommittee`](#compactcommittee)
- [`BeaconBlockHeader`](#beaconblockheader)
- [Beacon operations](#beacon-operations)
- [`ProposerSlashing`](#proposerslashing)
@ -69,7 +70,7 @@
- [`get_block_root_at_slot`](#get_block_root_at_slot)
- [`get_block_root`](#get_block_root)
- [`get_randao_mix`](#get_randao_mix)
- [`get_active_index_root`](#get_active_index_root)
- [`get_compact_committees_root`](#get_compact_committees_root)
- [`generate_seed`](#generate_seed)
- [`get_beacon_proposer_index`](#get_beacon_proposer_index)
- [`verify_merkle_branch`](#verify_merkle_branch)
@ -186,7 +187,7 @@ The following values are (non-configurable) constants used throughout the specif
| - | - |
| `SHARD_COUNT` | `2**10` (= 1,024) |
| `TARGET_COMMITTEE_SIZE` | `2**7` (= 128) |
| `MAX_INDICES_PER_ATTESTATION` | `2**12` (= 4,096) |
| `MAX_VALIDATORS_PER_COMMITTEE` | `2**12` (= 4,096) |
| `MIN_PER_EPOCH_CHURN_LIMIT` | `2**2` (= 4) |
| `CHURN_LIMIT_QUOTIENT` | `2**16` (= 65,536) |
| `SHUFFLE_ROUND_COUNT` | `90` |
@ -350,8 +351,8 @@ class AttestationDataAndCustodyBit(Container):
```python
class IndexedAttestation(Container):
custody_bit_0_indices: List[ValidatorIndex, MAX_INDICES_PER_ATTESTATION] # Indices with custody bit equal to 0
custody_bit_1_indices: List[ValidatorIndex, MAX_INDICES_PER_ATTESTATION] # Indices with custody bit equal to 1
custody_bit_0_indices: List[ValidatorIndex, MAX_VALIDATORS_PER_COMMITTEE] # Indices with custody bit equal to 0
custody_bit_1_indices: List[ValidatorIndex, MAX_VALIDATORS_PER_COMMITTEE] # Indices with custody bit equal to 1
data: AttestationData
signature: BLSSignature
```
@ -360,7 +361,7 @@ class IndexedAttestation(Container):
```python
class PendingAttestation(Container):
aggregation_bits: Bitlist[MAX_INDICES_PER_ATTESTATION]
aggregation_bits: Bitlist[MAX_VALIDATORS_PER_COMMITTEE]
data: AttestationData
inclusion_delay: Slot
proposer_index: ValidatorIndex
@ -393,6 +394,14 @@ class DepositData(Container):
signature: BLSSignature
```
#### `CompactCommittee`
```python
class CompactCommittee(Container):
pubkeys: List[Bytes48, MAX_VALIDATORS_PER_COMMITTEE]
compact_validators: List[uint64, MAX_VALIDATORS_PER_COMMITTEE]
```
#### `BeaconBlockHeader`
```python
@ -427,9 +436,9 @@ class AttesterSlashing(Container):
```python
class Attestation(Container):
aggregation_bits: Bitlist[MAX_INDICES_PER_ATTESTATION]
aggregation_bits: Bitlist[MAX_VALIDATORS_PER_COMMITTEE]
data: AttestationData
custody_bits: Bitlist[MAX_INDICES_PER_ATTESTATION]
custody_bits: Bitlist[MAX_VALIDATORS_PER_COMMITTEE]
signature: BLSSignature
```
@ -517,7 +526,7 @@ class BeaconState(Container):
# Shuffling
start_shard: Shard
randao_mixes: Vector[Hash, EPOCHS_PER_HISTORICAL_VECTOR]
active_index_roots: Vector[Hash, EPOCHS_PER_HISTORICAL_VECTOR] # Active registry digests for light clients
compact_committees_roots: Vector[Hash, EPOCHS_PER_HISTORICAL_VECTOR] # Committee digests for light clients
# Slashings
slashings: Vector[Gwei, EPOCHS_PER_SLASHINGS_VECTOR] # Per-epoch sums of slashed effective balances
# Attestations
@ -691,6 +700,9 @@ def get_shard_delta(state: BeaconState, epoch: Epoch) -> int:
```python
def get_epoch_start_shard(state: BeaconState, epoch: Epoch) -> Shard:
"""
Return the start shard of the 0th committee in an epoch.
"""
assert epoch <= get_current_epoch(state) + 1
check_epoch = Epoch(get_current_epoch(state) + 1)
shard = Shard((state.start_shard + get_shard_delta(state, get_current_epoch(state))) % SHARD_COUNT)
@ -744,17 +756,25 @@ def get_randao_mix(state: BeaconState,
return state.randao_mixes[epoch % EPOCHS_PER_HISTORICAL_VECTOR]
```
### `get_active_index_root`
### `get_compact_committees_root`
```python
def get_active_index_root(state: BeaconState,
epoch: Epoch) -> Hash:
def get_compact_committees_root(state: BeaconState, epoch: Epoch) -> Hash:
"""
Return the index root at a recent ``epoch``.
``epoch`` expected to be between
(current_epoch - EPOCHS_PER_HISTORICAL_VECTOR + ACTIVATION_EXIT_DELAY, current_epoch + ACTIVATION_EXIT_DELAY].
Return the compact committee root for the current epoch.
"""
return state.active_index_roots[epoch % EPOCHS_PER_HISTORICAL_VECTOR]
committees = [CompactCommittee() for _ in range(SHARD_COUNT)]
start_shard = get_epoch_start_shard(state, epoch)
for committee_number in range(get_epoch_committee_count(state, epoch)):
shard = Shard((start_shard + committee_number) % SHARD_COUNT)
for index in get_crosslink_committee(state, epoch, shard):
validator = state.validators[index]
committees[shard].pubkeys.append(validator.pubkey)
compact_balance = validator.effective_balance // EFFECTIVE_BALANCE_INCREMENT
# `index` (top 6 bytes) + `slashed` (16th bit) + `compact_balance` (bottom 15 bits)
compact_validator = uint64((index << 16) + (validator.slashed << 15) + compact_balance)
committees[shard].compact_validators.append(compact_validator)
return hash_tree_root(Vector[CompactCommittee, SHARD_COUNT](committees))
```
### `generate_seed`
@ -767,7 +787,7 @@ def generate_seed(state: BeaconState,
"""
return hash(
get_randao_mix(state, Epoch(epoch + EPOCHS_PER_HISTORICAL_VECTOR - MIN_SEED_LOOKAHEAD)) +
get_active_index_root(state, epoch) +
hash_tree_root(List[ValidatorIndex, VALIDATOR_REGISTRY_LIMIT](get_active_validator_indices(state, epoch))) +
int_to_bytes(epoch, length=32)
)
```
@ -867,7 +887,7 @@ def get_crosslink_committee(state: BeaconState, epoch: Epoch, shard: Shard) -> S
```python
def get_attesting_indices(state: BeaconState,
data: AttestationData,
bits: Bitlist[MAX_INDICES_PER_ATTESTATION]) -> Set[ValidatorIndex]:
bits: Bitlist[MAX_VALIDATORS_PER_COMMITTEE]) -> Set[ValidatorIndex]:
"""
Return the set of attesting indices corresponding to ``data`` and ``bitfield``.
"""
@ -946,7 +966,7 @@ def validate_indexed_attestation(state: BeaconState, indexed_attestation: Indexe
# Verify no index has custody bit equal to 1 [to be removed in phase 1]
assert len(bit_1_indices) == 0
# Verify max number of indices
assert len(bit_0_indices) + len(bit_1_indices) <= MAX_INDICES_PER_ATTESTATION
assert len(bit_0_indices) + len(bit_1_indices) <= MAX_VALIDATORS_PER_COMMITTEE
# Verify index sets are disjoint
assert len(set(bit_0_indices).intersection(bit_1_indices)) == 0
# Verify indices are sorted
@ -1148,12 +1168,9 @@ def get_genesis_beacon_state(deposits: Sequence[Deposit], genesis_time: int, eth
validator.activation_epoch = GENESIS_EPOCH
# Populate active_index_roots
genesis_active_index_root = hash_tree_root(
List[ValidatorIndex, VALIDATOR_REGISTRY_LIMIT](get_active_validator_indices(state, GENESIS_EPOCH))
)
genesis_committee_root = get_compact_committees_root(state, GENESIS_EPOCH)
for index in range(EPOCHS_PER_HISTORICAL_VECTOR):
state.active_index_roots[index] = genesis_active_index_root
state.compact_committees_roots[index] = genesis_committee_root
return state
```
@ -1475,7 +1492,7 @@ def process_slashings(state: BeaconState) -> None:
```python
def process_final_updates(state: BeaconState) -> None:
current_epoch = get_current_epoch(state)
next_epoch = current_epoch + 1
next_epoch = Shard(current_epoch + 1)
# Reset eth1 data votes
if (state.slot + 1) % SLOTS_PER_ETH1_VOTING_PERIOD == 0:
state.eth1_data_votes = []
@ -1488,12 +1505,8 @@ def process_final_updates(state: BeaconState) -> None:
# Update start shard
state.start_shard = Shard((state.start_shard + get_shard_delta(state, current_epoch)) % SHARD_COUNT)
# Set active index root
index_root_position = (next_epoch + ACTIVATION_EXIT_DELAY) % EPOCHS_PER_HISTORICAL_VECTOR
state.active_index_roots[index_root_position] = hash_tree_root(
List[ValidatorIndex, VALIDATOR_REGISTRY_LIMIT](
get_active_validator_indices(state, Epoch(next_epoch + ACTIVATION_EXIT_DELAY))
)
)
committee_root_position = (next_epoch + ACTIVATION_EXIT_DELAY) % EPOCHS_PER_HISTORICAL_VECTOR
state.compact_committees_roots[committee_root_position] = get_compact_committees_root(state, next_epoch)
# Reset slashings
state.slashings[next_epoch % EPOCHS_PER_SLASHINGS_VECTOR] = Gwei(0)
# Set randao mix

4
specs/light_client/sync_protocol.md
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@ -31,7 +31,7 @@ We define an "expansion" of an object as an object where a field in an object th
We define two expansions:
* `ExtendedBeaconState`, which is identical to a `BeaconState` except `active_index_roots: List[Bytes32]` is replaced by `active_indices: List[List[ValidatorIndex]]`, where `BeaconState.active_index_roots[i] = hash_tree_root(ExtendedBeaconState.active_indices[i])`.
* `ExtendedBeaconState`, which is identical to a `BeaconState` except `compact_committees_roots: List[Bytes32]` is replaced by `active_indices: List[List[ValidatorIndex]]`, where `BeaconState.compact_committees_roots[i] = hash_tree_root(ExtendedBeaconState.active_indices[i])`.
* `ExtendedBeaconBlock`, which is identical to a `BeaconBlock` except `state_root` is replaced with the corresponding `state: ExtendedBeaconState`.
### `get_active_validator_indices`
@ -40,7 +40,7 @@ Note that there is now a new way to compute `get_active_validator_indices`:
```python
def get_active_validator_indices(state: ExtendedBeaconState, epoch: Epoch) -> List[ValidatorIndex]:
return state.active_indices[epoch % ACTIVE_INDEX_ROOTS_LENGTH]
return state.active_indices[epoch % EPOCHS_PER_HISTORICAL_VECTOR]
```
Note that it takes `state` instead of `state.validators` as an argument. This does not affect its use in `get_shuffled_committee`, because `get_shuffled_committee` has access to the full `state` as one of its arguments.

4
test_libs/pyspec/eth2spec/test/helpers/attestations.py
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@ -67,8 +67,8 @@ def get_valid_attestation(spec, state, slot=None, signed=False):
)
committee_size = len(crosslink_committee)
aggregation_bits = Bitlist[spec.MAX_INDICES_PER_ATTESTATION](*([0] * committee_size))
custody_bits = Bitlist[spec.MAX_INDICES_PER_ATTESTATION](*([0] * committee_size))
aggregation_bits = Bitlist[spec.MAX_VALIDATORS_PER_COMMITTEE](*([0] * committee_size))
custody_bits = Bitlist[spec.MAX_VALIDATORS_PER_COMMITTEE](*([0] * committee_size))
attestation = spec.Attestation(
aggregation_bits=aggregation_bits,
data=attestation_data,

4
test_libs/pyspec/eth2spec/test/helpers/genesis.py
View File

@ -43,9 +43,9 @@ def create_genesis_state(spec, num_validators):
validator.activation_eligibility_epoch = spec.GENESIS_EPOCH
validator.activation_epoch = spec.GENESIS_EPOCH
genesis_active_index_root = hash_tree_root(List[spec.ValidatorIndex, spec.VALIDATOR_REGISTRY_LIMIT](
genesis_compact_committees_root = hash_tree_root(List[spec.ValidatorIndex, spec.VALIDATOR_REGISTRY_LIMIT](
spec.get_active_validator_indices(state, spec.GENESIS_EPOCH)))
for index in range(spec.EPOCHS_PER_HISTORICAL_VECTOR):
state.active_index_roots[index] = genesis_active_index_root
state.compact_committees_roots[index] = genesis_compact_committees_root
return state

2
test_libs/pyspec/eth2spec/test/phase_0/block_processing/test_process_attestation.py
View File

@ -306,7 +306,7 @@ def test_empty_aggregation_bits(spec, state):
attestation = get_valid_attestation(spec, state)
state.slot += spec.MIN_ATTESTATION_INCLUSION_DELAY
attestation.aggregation_bits = Bitlist[spec.MAX_INDICES_PER_ATTESTATION](
attestation.aggregation_bits = Bitlist[spec.MAX_VALIDATORS_PER_COMMITTEE](
*([0b0] * len(attestation.aggregation_bits)))
sign_attestation(spec, state, attestation)