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Refactor `get_persistent_committee` (#604)

This commit is contained in:
Hsiao-Wei Wang 2019-02-12 19:11:45 +08:00 committed by Justin
parent de90d4475e
commit 41e95cf9ea
1 changed files with 28 additions and 24 deletions
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52
specs/core/1_shard-data-chains.md
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@ -43,42 +43,46 @@ def get_split_offset(list_size: int, chunks: int, index: int) -> int:
return (len(list_size) * index) // chunks return (len(list_size) * index) // chunks
```` ````
#### get_shuffled_committee
```python
def get_shuffled_committee(state: BeaconState,
shard: ShardNumber,
committee_start_epoch: EpochNumber) -> List[ValidatorIndex]:
"""
Return shuffled committee.
"""
validator_indices = get_active_validator_indices(state.validators, committee_start_epoch)
seed = generate_seed(state, committee_start_epoch)
start_offset = get_split_offset(len(validator_indices), SHARD_COUNT, shard)
end_offset = get_split_offset(len(validator_indices), SHARD_COUNT, shard + 1)
return [
validator_indices[get_permuted_index(i, len(validator_indices), seed)]
for i in range(start_offset, end_offset)
]
```
#### get_persistent_committee #### get_persistent_committee
```python ```python
def get_persistent_commmitee(state: BeaconState, def get_persistent_committee(state: BeaconState,
shard: ShardNumber, shard: ShardNumber,
epoch: EpochNumber) -> List[ValidatorIndex]: epoch: EpochNumber) -> List[ValidatorIndex]:
""" """
Returns the persistent committee for the given shard at the given epoch Return the persistent committee for the given ``shard`` at the given ``epoch``.
""" """
earlier_committee_start_epoch = epoch - (epoch % PERSISTENT_COMMITTEE_PERIOD) - PERSISTENT_COMMITTEE_PERIOD * 2
earlier_committee_start = epoch - (epoch % PERSISTENT_COMMITTEE_PERIOD) - PERSISTENT_COMMITTEE_PERIOD * 2 earlier_committee = get_shuffled_committee(state, shard, earlier_committee_start_epoch)
earlier_validator_set = get_active_validator_indices(state.validators, earlier_committee_start)
earlier_seed = generate_seed(state, earlier_committee_start) later_committee_start_epoch = epoch - (epoch % PERSISTENT_COMMITTEE_PERIOD) - PERSISTENT_COMMITTEE_PERIOD
earlier_start_offset = get_split_offset(len(earlier_validator_set), SHARD_COUNT, shard) later_committee = get_shuffled_committee(state, shard, later_committee_start_epoch)
earlier_end_offset = get_split_offset(len(earlier_validator_set), SHARD_COUNT, shard+1)
earlier_committee = [
earlier_validator_set[get_permuted_index(i, len(earlier_validator_set), earlier_seed)]
for i in range(earlier_start_offset, earlier_end_offset)
]
later_committee_start = epoch - (epoch % PERSISTENT_COMMITTEE_PERIOD) - PERSISTENT_COMMITTEE_PERIOD
later_validator_set = get_active_validator_indices(state.validators, later_committee_start)
later_seed = generate_seed(state, later_committee_start)
later_start_offset = get_split_offset(len(later_validator_set), SHARD_COUNT, shard)
later_end_offset = get_split_offset(len(later_validator_set), SHARD_COUNT, shard+1)
later_committee = [
later_validator_set[get_permuted_index(i, len(later_validator_set), later_seed)]
for i in range(later_start_offset, later_end_offset)
]
def get_switchover_epoch(index): def get_switchover_epoch(index):
return ( return (
bytes_to_int(hash(earlier_seed + bytes3(index))[0:8]) % bytes_to_int(hash(earlier_seed + bytes3(index))[0:8]) %
PERSISTENT_COMMITTEE_PERIOD PERSISTENT_COMMITTEE_PERIOD
) )
# Take not-yet-cycled-out validators from earlier committee and already-cycled-in validators from # Take not-yet-cycled-out validators from earlier committee and already-cycled-in validators from
# later committee; return a sorted list of the union of the two, deduplicated # later committee; return a sorted list of the union of the two, deduplicated
return sorted(list(set( return sorted(list(set(