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Merge branch 'master' into vbuterin-patch-19

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specs/core/0_beacon-chain.md
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@ -200,7 +200,6 @@ Unless otherwise indicated, code appearing in `this style` is to be interpreted
| `SEED_LOOKAHEAD` | `2**6` (= 64) | slots | 6.4 minutes | | `SEED_LOOKAHEAD` | `2**6` (= 64) | slots | 6.4 minutes |
| `ENTRY_EXIT_DELAY` | `2**8` (= 256) | slots | 25.6 minutes | | `ENTRY_EXIT_DELAY` | `2**8` (= 256) | slots | 25.6 minutes |
| `POW_RECEIPT_ROOT_VOTING_PERIOD` | `2**10` (= 1,024) | slots | ~1.7 hours | | `POW_RECEIPT_ROOT_VOTING_PERIOD` | `2**10` (= 1,024) | slots | ~1.7 hours |
| `SHARD_PERSISTENT_COMMITTEE_CHANGE_PERIOD` | `2**17` (= 131,072) | slots | ~9 days |
### Reward and penalty quotients ### Reward and penalty quotients
@ -481,8 +480,6 @@ Unless otherwise indicated, code appearing in `this style` is to be interpreted
'latest_randao_mixes': ['hash32'], 'latest_randao_mixes': ['hash32'],
'latest_vdf_outputs': ['hash32'], 'latest_vdf_outputs': ['hash32'],
'shard_committees_at_slots': [[ShardCommittee]], 'shard_committees_at_slots': [[ShardCommittee]],
'persistent_committees': [['uint24']],
'persistent_committee_reassignments': [ShardReassignmentRecord],
# Proof of custody # Proof of custody
# Placeholders for now; ProofOfCustodyChallenge is defined in phase 1, implementers can # Placeholders for now; ProofOfCustodyChallenge is defined in phase 1, implementers can
@ -1069,7 +1066,9 @@ def is_double_vote(attestation_data_1: AttestationData,
Returns True if the provided ``AttestationData`` are slashable Returns True if the provided ``AttestationData`` are slashable
due to a 'double vote'. due to a 'double vote'.
""" """
return attestation_data_1.slot == attestation_data_2.slot target_epoch_1 = attestation_data_1.slot // EPOCH_LENGTH
target_epoch_2 = attestation_data_2.slot // EPOCH_LENGTH
return target_epoch_1 == target_epoch_2
``` ```
#### `is_surround_vote` #### `is_surround_vote`
@ -1084,10 +1083,14 @@ def is_surround_vote(attestation_data_1: AttestationData,
Note: parameter order matters as this function only checks Note: parameter order matters as this function only checks
that ``attestation_data_1`` surrounds ``attestation_data_2``. that ``attestation_data_1`` surrounds ``attestation_data_2``.
""" """
source_epoch_1 = attestation_data_1.justified_slot // EPOCH_LENGTH
source_epoch_2 = attestation_data_2.justified_slot // EPOCH_LENGTH
target_epoch_1 = attestation_data_1.slot // EPOCH_LENGTH
target_epoch_2 = attestation_data_2.slot // EPOCH_LENGTH
return ( return (
(attestation_data_1.justified_slot < attestation_data_2.justified_slot) and (source_epoch_1 < source_epoch_2) and
(attestation_data_2.justified_slot + 1 == attestation_data_2.slot) and (source_epoch_2 + 1 == target_epoch_2) and
(attestation_data_2.slot < attestation_data_1.slot) (target_epoch_2 < target_epoch_1)
) )
``` ```
@ -1170,8 +1173,6 @@ def get_initial_beacon_state(initial_validator_deposits: List[Deposit],
latest_randao_mixes=[ZERO_HASH for _ in range(LATEST_RANDAO_MIXES_LENGTH)], latest_randao_mixes=[ZERO_HASH for _ in range(LATEST_RANDAO_MIXES_LENGTH)],
latest_vdf_outputs=[ZERO_HASH for _ in range(LATEST_RANDAO_MIXES_LENGTH // EPOCH_LENGTH)], latest_vdf_outputs=[ZERO_HASH for _ in range(LATEST_RANDAO_MIXES_LENGTH // EPOCH_LENGTH)],
shard_committees_at_slots=[], shard_committees_at_slots=[],
persistent_committees=[],
persistent_committee_reassignments=[],
# Proof of custody # Proof of custody
poc_challenges=[], poc_challenges=[],
@ -1215,10 +1216,6 @@ def get_initial_beacon_state(initial_validator_deposits: List[Deposit],
initial_shuffling = get_shuffling(ZERO_HASH, state.validator_registry, 0, GENESIS_SLOT) initial_shuffling = get_shuffling(ZERO_HASH, state.validator_registry, 0, GENESIS_SLOT)
state.shard_committees_at_slots = initial_shuffling + initial_shuffling state.shard_committees_at_slots = initial_shuffling + initial_shuffling
# Set initial persistent shuffling
active_validator_indices = get_active_validator_indices(state.validator_registry, state.slot)
state.persistent_committees = split(shuffle(active_validator_indices, ZERO_HASH), SHARD_COUNT)
return state return state
``` ```
@ -1358,14 +1355,6 @@ def exit_validator(state: BeaconState, index: int) -> None:
flag=EXIT, flag=EXIT,
) )
) )
state.validator_registry_exit_count += 1
# Remove validator from persistent committees
for committee in state.persistent_committees:
for i, validator_index in committee:
if validator_index == index:
committee.pop(i)
break
``` ```
```python ```python
@ -1499,9 +1488,9 @@ def verify_merkle_branch(leaf: Hash32, branch: [Hash32], depth: int, index: int,
value = leaf value = leaf
for i in range(depth): for i in range(depth):
if index % 2: if index % 2:
value = hash(branch[i], value) value = hash(branch[i] + value)
else: else:
value = hash(value, branch[i]) value = hash(value + branch[i])
return value == root return value == root
``` ```
@ -1780,33 +1769,6 @@ If a validator registry update does _not_ happen do the following:
* Let `start_shard = state.shard_committees_at_slots[0][0].shard`. * Let `start_shard = state.shard_committees_at_slots[0][0].shard`.
* If `epochs_since_last_registry_change` is an exact power of 2, set `state.shard_committees_at_slots[EPOCH_LENGTH:] = get_shuffling(state.latest_randao_mixes[(state.slot - SEED_LOOKAHEAD) % LATEST_RANDAO_MIXES_LENGTH], state.validator_registry, start_shard, state.slot)`. Note that `start_shard` is not changed from the last epoch. * If `epochs_since_last_registry_change` is an exact power of 2, set `state.shard_committees_at_slots[EPOCH_LENGTH:] = get_shuffling(state.latest_randao_mixes[(state.slot - SEED_LOOKAHEAD) % LATEST_RANDAO_MIXES_LENGTH], state.validator_registry, start_shard, state.slot)`. Note that `start_shard` is not changed from the last epoch.
### Proposer reshuffling
Run the following code to update the shard proposer set:
```python
active_validator_indices = get_active_validator_indices(state.validator_registry, state.slot)
num_validators_to_reshuffle = len(active_validator_indices) // SHARD_PERSISTENT_COMMITTEE_CHANGE_PERIOD
for i in range(num_validators_to_reshuffle):
# Multiplying i to 2 to ensure we have different input to all the required hashes in the shuffling
# and none of the hashes used for entropy in this loop will be the same
validator_index = active_validator_indices[hash(state.latest_randao_mixes[state.slot % LATEST_RANDAO_MIXES_LENGTH] + bytes8(i * 2)) % len(active_validator_indices)]
new_shard = hash(state.latest_randao_mixes[state.slot % LATEST_RANDAO_MIXES_LENGTH] + bytes8(i * 2 + 1)) % SHARD_COUNT
shard_reassignment_record = ShardReassignmentRecord(
validator_index=validator_index,
shard=new_shard,
slot=s + SHARD_PERSISTENT_COMMITTEE_CHANGE_PERIOD
)
state.persistent_committee_reassignments.append(shard_reassignment_record)
while len(state.persistent_committee_reassignments) > 0 and state.persistent_committee_reassignments[0].slot <= s:
reassignment = state.persistent_committee_reassignments.pop(0)
for committee in state.persistent_committees:
if reassignment.validator_index in committee:
committee.pop(committee.index(reassignment.validator_index))
state.persistent_committees[reassignment.shard].append(reassignment.validator_index)
```
### Final updates ### Final updates
* Let `e = state.slot // EPOCH_LENGTH`. Set `state.latest_penalized_exit_balances[(e+1) % LATEST_PENALIZED_EXIT_LENGTH] = state.latest_penalized_exit_balances[e % LATEST_PENALIZED_EXIT_LENGTH]` * Let `e = state.slot // EPOCH_LENGTH`. Set `state.latest_penalized_exit_balances[(e+1) % LATEST_PENALIZED_EXIT_LENGTH] = state.latest_penalized_exit_balances[e % LATEST_PENALIZED_EXIT_LENGTH]`