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Update 0_beacon-chain.md

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Justin 2019-04-30 12:27:45 +01:00 committed by GitHub
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specs/core/0_beacon-chain.md
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@ -66,7 +66,6 @@
- [`get_attestation_slot`](#get_attestation_slot)
- [`get_block_root_at_slot`](#get_block_root_at_slot)
- [`get_block_root`](#get_block_root)
- [`get_state_root`](#get_state_root)
- [`get_randao_mix`](#get_randao_mix)
- [`get_active_index_root`](#get_active_index_root)
- [`generate_seed`](#generate_seed)
@ -402,8 +401,8 @@ The types are defined topologically to aid in facilitating an executable version
'aggregation_bitfield': 'bytes',
# Attestation data
'data': AttestationData,
# Inclusion slot
'inclusion_slot': 'uint64',
# Inclusion delay
'inclusion_delay': 'uint64',
# Proposer index
'proposer_index': 'uint64',
}
@ -763,9 +762,9 @@ def get_epoch_start_shard(state: BeaconState, epoch: Epoch) -> Shard:
```python
def get_attestation_slot(state: BeaconState, attestation: Attestation) -> Slot:
epoch = attestation.data.target_epoch
committees_per_slot = get_epoch_committee_count(state, epoch) // SLOTS_PER_EPOCH
offset = (attestation.data.shard + SHARD_COUNT - get_epoch_start_slot(epoch)) % SHARD_COUNT
return get_epoch_start_slot(epoch) + offset // committees_per_slot
committee_count = get_epoch_committee_count(state, epoch)
offset = (attestation.data.shard - get_epoch_start_slot(epoch)) % SHARD_COUNT
return get_epoch_start_slot(epoch) + offset // (committee_count // SLOTS_PER_EPOCH)
```
### `get_block_root_at_slot`
@ -791,18 +790,6 @@ def get_block_root(state: BeaconState,
return get_block_root_at_slot(state, get_epoch_start_slot(epoch))
```
### `get_state_root`
```python
def get_state_root(state: BeaconState,
slot: Slot) -> Bytes32:
"""
Return the state root at a recent ``slot``.
"""
assert slot < state.slot <= slot + SLOTS_PER_HISTORICAL_ROOT
return state.latest_state_roots[slot % SLOTS_PER_HISTORICAL_ROOT]
```
### `get_randao_mix`
```python
@ -847,17 +834,17 @@ def generate_seed(state: BeaconState,
```python
def get_beacon_proposer_index(state: BeaconState) -> ValidatorIndex:
"""
Return the beacon proposer index at ``state.slot``.
Return the current beacon proposer index.
"""
current_epoch = get_current_epoch(state)
committees_per_slot = get_epoch_committee_count(state, current_epoch) // SLOTS_PER_EPOCH
epoch = get_current_epoch(state)
committees_per_slot = get_epoch_committee_count(state, epoch) // SLOTS_PER_EPOCH
offset = committees_per_slot * (state.slot % EPOCH_LENGTH)
first_committee = get_crosslink_committee(state, epoch, offset)
MAX_RANDOM_BYTE = 2**8 - 1
i = 0
while True:
candidate_index = first_committee[(current_epoch + i) % len(first_committee)]
random_byte = hash(generate_seed(state, current_epoch) + int_to_bytes8(i // 32))[i % 32]
candidate_index = first_committee[(epoch + i) % len(first_committee)]
random_byte = hash(generate_seed(state, epoch) + int_to_bytes8(i // 32))[i % 32]
effective_balance = state.validator_registry[candidate_index].effective_balance
if effective_balance * MAX_RANDOM_BYTE >= MAX_EFFECTIVE_BALANCE * random_byte:
return candidate_index
@ -1117,7 +1104,6 @@ Note: All functions in this section mutate `state`.
def initiate_validator_exit(state: BeaconState, index: ValidatorIndex) -> None:
"""
Initiate the validator of the given ``index``.
Note that this function mutates ``state``.
"""
# Return if validator already initiated exit
validator = state.validator_registry[index]
@ -1142,7 +1128,6 @@ def initiate_validator_exit(state: BeaconState, index: ValidatorIndex) -> None:
def slash_validator(state: BeaconState, slashed_index: ValidatorIndex, whistleblower_index: ValidatorIndex=None) -> None:
"""
Slash the validator with index ``slashed_index``.
Note that this function mutates ``state``.
"""
current_epoch = get_current_epoch(state)
initiate_validator_exit(state, slashed_index)
@ -1316,13 +1301,6 @@ def get_winning_crosslink_and_attesting_indices(state: BeaconState, shard: Shard
return winning_crosslink, get_unslashed_attesting_indices(state, get_attestations_for(winning_crosslink))
```
```python
def get_earliest_attestation(state: BeaconState, attestations: List[PendingAttestation], index: ValidatorIndex) -> PendingAttestation:
return min([
a for a in attestations if index in get_attesting_indices(state, a.data, a.aggregation_bitfield)
], key=lambda a: a.inclusion_slot)
```
#### Justification and finalization
Run the following function:
@ -1427,10 +1405,11 @@ def get_attestation_deltas(state: BeaconState) -> Tuple[List[Gwei], List[Gwei]]:
# Proposer and inclusion delay micro-rewards
for index in get_unslashed_attesting_indices(state, matching_source_attestations):
earliest_attestation = get_earliest_attestation(state, matching_source_attestations, index)
rewards[earliest_attestation.proposer_index] += get_base_reward(state, index) // PROPOSER_REWARD_QUOTIENT
inclusion_delay = earliest_attestation.inclusion_slot - get_attestation_slot(state, earliest_attestation)
rewards[index] += get_base_reward(state, index) * MIN_ATTESTATION_INCLUSION_DELAY // inclusion_delay
attestation = min([
a for a in attestations if index in get_attesting_indices(state, a.data, a.aggregation_bitfield)
], key=lambda a: a.inclusion_delay)
rewards[attestation.proposer_index] += get_base_reward(state, index) // PROPOSER_REWARD_QUOTIENT
rewards[index] += get_base_reward(state, index) * MIN_ATTESTATION_INCLUSION_DELAY // attestation.inclusion_delay
# Inactivity penalty
finality_delay = previous_epoch - state.finalized_epoch
@ -1629,6 +1608,8 @@ def process_eth1_data(state: BeaconState, block: BeaconBlock) -> None:
#### Operations
Note: All functions in this section mutate `state`.
##### Proposer slashings
Verify that `len(block.body.proposer_slashings) <= MAX_PROPOSER_SLASHINGS`.
@ -1640,7 +1621,6 @@ def process_proposer_slashing(state: BeaconState,
proposer_slashing: ProposerSlashing) -> None:
"""
Process ``ProposerSlashing`` operation.
Note that this function mutates ``state``.
"""
proposer = state.validator_registry[proposer_slashing.proposer_index]
# Verify that the epoch is the same
@ -1668,7 +1648,6 @@ def process_attester_slashing(state: BeaconState,
attester_slashing: AttesterSlashing) -> None:
"""
Process ``AttesterSlashing`` operation.
Note that this function mutates ``state``.
"""
attestation_1 = attester_slashing.attestation_1
attestation_2 = attester_slashing.attestation_2
@ -1712,10 +1691,9 @@ For each `attestation` in `block.body.attestations`, run the following function:
def process_attestation(state: BeaconState, attestation: Attestation) -> None:
"""
Process ``Attestation`` operation.
Note that this function mutates ``state``.
"""
min_slot = state.slot - SLOTS_PER_EPOCH if get_current_epoch(state) > GENESIS_EPOCH else GENESIS_SLOT
assert min_slot <= get_attestation_slot(state, attestation) <= state.slot - MIN_ATTESTATION_INCLUSION_DELAY
attestation_slot = get_attestation_slot(state, attestation)
assert attestation_slot + MIN_ATTESTATION_INCLUSION_DELAY <= state.slot <= attestation_slot + SLOTS_PER_EPOCH
# Check target epoch, source epoch, source root, and source crosslink
data = attestation.data
@ -1734,7 +1712,7 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
pending_attestation = PendingAttestation(
data=data,
aggregation_bitfield=attestation.aggregation_bitfield,
inclusion_slot=state.slot,
inclusion_delay=state.slot - attestation_slot,
proposer_index=get_beacon_proposer_index(state),
)
if target_epoch == get_current_epoch(state):
@ -1753,7 +1731,6 @@ For each `deposit` in `block.body.deposits`, run the following function:
def process_deposit(state: BeaconState, deposit: Deposit) -> None:
"""
Process an Eth1 deposit, registering a validator or increasing its balance.
Note that this function mutates ``state``.
"""
# Verify the Merkle branch
assert verify_merkle_branch(
@ -1803,7 +1780,6 @@ For each `exit` in `block.body.voluntary_exits`, run the following function:
def process_voluntary_exit(state: BeaconState, exit: VoluntaryExit) -> None:
"""
Process ``VoluntaryExit`` operation.
Note that this function mutates ``state``.
"""
validator = state.validator_registry[exit.validator_index]
# Verify the validator is active
@ -1831,7 +1807,6 @@ For each `transfer` in `block.body.transfers`, run the following function:
def process_transfer(state: BeaconState, transfer: Transfer) -> None:
"""
Process ``Transfer`` operation.
Note that this function mutates ``state``.
"""
# Verify the amount and fee are not individually too big (for anti-overflow purposes)
assert state.balances[transfer.sender] >= max(transfer.amount, transfer.fee)