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Update 0_beacon-chain.md

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Justin 2019-03-12 10:17:34 +00:00 committed by GitHub
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specs/core/0_beacon-chain.md
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@ -335,22 +335,19 @@ The types are defined topologically to aid in facilitating an executable version
```python ```python
{ {
# Slot number # LMD GHOST vote
'slot': 'uint64', 'slot': 'uint64',
# Shard number
'shard': 'uint64',
# Root of the signed beacon block
'beacon_block_root': 'bytes32', 'beacon_block_root': 'bytes32',
# Root of the ancestor at the epoch boundary
'epoch_boundary_root': 'bytes32', # FFG vote
# Data from the shard since the last attestation 'source_epoch': 'uint64',
'source_root': 'bytes32',
'target_root': 'bytes32',
# Crosslink vote
'shard': 'uint64',
'previous_crosslink': Crosslink,
'crosslink_data_root': 'bytes32', 'crosslink_data_root': 'bytes32',
# Last crosslink
'latest_crosslink': Crosslink,
# Last justified epoch in the beacon state
'justified_epoch': 'uint64',
# Hash of the last justified beacon block
'justified_block_root': 'bytes32',
} }
``` ```
@ -612,9 +609,9 @@ The types are defined topologically to aid in facilitating an executable version
'previous_epoch_attestations': [PendingAttestation], 'previous_epoch_attestations': [PendingAttestation],
'current_epoch_attestations': [PendingAttestation], 'current_epoch_attestations': [PendingAttestation],
'previous_justified_epoch': 'uint64', 'previous_justified_epoch': 'uint64',
'justified_epoch': 'uint64', 'current_justified_epoch': 'uint64',
'previous_justified_root': 'bytes32', 'previous_justified_root': 'bytes32',
'justified_root': 'bytes32', 'current_justified_root': 'bytes32',
'justification_bitfield': 'uint64', 'justification_bitfield': 'uint64',
'finalized_epoch': 'uint64', 'finalized_epoch': 'uint64',
@ -1225,8 +1222,8 @@ def is_surround_vote(attestation_data_1: AttestationData,
""" """
Check if ``attestation_data_1`` surrounds ``attestation_data_2``. Check if ``attestation_data_1`` surrounds ``attestation_data_2``.
""" """
source_epoch_1 = attestation_data_1.justified_epoch source_epoch_1 = attestation_data_1.source_epoch
source_epoch_2 = attestation_data_2.justified_epoch source_epoch_2 = attestation_data_2.source_epoch
target_epoch_1 = slot_to_epoch(attestation_data_1.slot) target_epoch_1 = slot_to_epoch(attestation_data_1.slot)
target_epoch_2 = slot_to_epoch(attestation_data_2.slot) target_epoch_2 = slot_to_epoch(attestation_data_2.slot)
@ -1547,9 +1544,9 @@ def get_genesis_beacon_state(genesis_validator_deposits: List[Deposit],
previous_epoch_attestations=[], previous_epoch_attestations=[],
current_epoch_attestations=[], current_epoch_attestations=[],
previous_justified_epoch=GENESIS_EPOCH, previous_justified_epoch=GENESIS_EPOCH,
justified_epoch=GENESIS_EPOCH, current_justified_epoch=GENESIS_EPOCH,
previous_justified_root=ZERO_HASH, previous_justified_root=ZERO_HASH,
justified_root=ZERO_HASH, current_justified_root=ZERO_HASH,
justification_bitfield=0, justification_bitfield=0,
finalized_epoch=GENESIS_EPOCH, finalized_epoch=GENESIS_EPOCH,
@ -1733,7 +1730,7 @@ def get_attesting_balance(state: BeaconState, attestations: List[PendingAttestat
def get_current_epoch_boundary_attestations(state: BeaconState) -> List[PendingAttestation]: def get_current_epoch_boundary_attestations(state: BeaconState) -> List[PendingAttestation]:
return [ return [
a for a in state.current_epoch_attestations a for a in state.current_epoch_attestations
if a.data.epoch_boundary_root == get_block_root(state, get_epoch_start_slot(get_current_epoch(state))) if a.data.target_root == get_block_root(state, get_epoch_start_slot(get_current_epoch(state)))
] ]
``` ```
@ -1741,7 +1738,7 @@ def get_current_epoch_boundary_attestations(state: BeaconState) -> List[PendingA
def get_previous_epoch_boundary_attestations(state: BeaconState) -> List[PendingAttestation]: def get_previous_epoch_boundary_attestations(state: BeaconState) -> List[PendingAttestation]:
return [ return [
a for a in state.previous_epoch_attestations a for a in state.previous_epoch_attestations
if a.data.epoch_boundary_root == get_block_root(state, get_epoch_start_slot(get_previous_epoch(state))) if a.data.target_root == get_block_root(state, get_epoch_start_slot(get_previous_epoch(state)))
] ]
``` ```
@ -1759,7 +1756,7 @@ def get_previous_epoch_matching_head_attestations(state: BeaconState) -> List[Pe
def get_winning_root_and_participants(state: BeaconState, shard: Shard) -> Tuple[Bytes32, List[ValidatorIndex]]: def get_winning_root_and_participants(state: BeaconState, shard: Shard) -> Tuple[Bytes32, List[ValidatorIndex]]:
all_attestations = state.current_epoch_attestations + state.previous_epoch_attestations all_attestations = state.current_epoch_attestations + state.previous_epoch_attestations
valid_attestations = [ valid_attestations = [
a for a in all_attestations if a.data.latest_crosslink == state.latest_crosslinks[shard] a for a in all_attestations if a.data.previous_crosslink == state.latest_crosslinks[shard]
] ]
all_roots = [a.data.crosslink_data_root for a in valid_attestations] all_roots = [a.data.crosslink_data_root for a in valid_attestations]
@ -1802,7 +1799,7 @@ Run the following function:
```python ```python
def update_justification_and_finalization(state: BeaconState) -> None: def update_justification_and_finalization(state: BeaconState) -> None:
new_justified_epoch = state.justified_epoch new_justified_epoch = state.current_justified_epoch
# Rotate the justification bitfield up one epoch to make room for the current epoch # Rotate the justification bitfield up one epoch to make room for the current epoch
state.justification_bitfield <<= 1 state.justification_bitfield <<= 1
# If the previous epoch gets justified, fill the second last bit # If the previous epoch gets justified, fill the second last bit
@ -1826,18 +1823,18 @@ def update_justification_and_finalization(state: BeaconState) -> None:
if (bitfield >> 1) % 4 == 0b11 and state.previous_justified_epoch == current_epoch - 2: if (bitfield >> 1) % 4 == 0b11 and state.previous_justified_epoch == current_epoch - 2:
state.finalized_epoch = state.previous_justified_epoch state.finalized_epoch = state.previous_justified_epoch
# The 1st/2nd/3rd most recent epochs are all justified, the 1st using the 3rd as source # The 1st/2nd/3rd most recent epochs are all justified, the 1st using the 3rd as source
if (bitfield >> 0) % 8 == 0b111 and state.justified_epoch == current_epoch - 2: if (bitfield >> 0) % 8 == 0b111 and state.current_justified_epoch == current_epoch - 2:
state.finalized_epoch = state.justified_epoch state.finalized_epoch = state.current_justified_epoch
# The 1st/2nd most recent epochs are both justified, the 1st using the 2nd as source # The 1st/2nd most recent epochs are both justified, the 1st using the 2nd as source
if (bitfield >> 0) % 4 == 0b11 and state.justified_epoch == current_epoch - 1: if (bitfield >> 0) % 4 == 0b11 and state.current_justified_epoch == current_epoch - 1:
state.finalized_epoch = state.justified_epoch state.finalized_epoch = state.current_justified_epoch
# Rotate justified epochs # Rotate justified epochs
state.previous_justified_epoch = state.justified_epoch state.previous_justified_epoch = state.current_justified_epoch
state.previous_justified_root = state.justified_root state.previous_justified_root = state.current_justified_root
if new_justified_epoch != state.justified_epoch: if new_justified_epoch != state.current_justified_epoch:
state.justified_epoch = new_justified_epoch state.current_justified_epoch = new_justified_epoch
state.justified_root = get_block_root(state, get_epoch_start_slot(new_justified_epoch)) state.current_justified_root = get_block_root(state, get_epoch_start_slot(new_justified_epoch))
``` ```
#### Crosslinks #### Crosslinks
@ -2381,19 +2378,19 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
assert state.slot <= attestation.data.slot + SLOTS_PER_EPOCH assert state.slot <= attestation.data.slot + SLOTS_PER_EPOCH
# Can't submit attestations too quickly # Can't submit attestations too quickly
assert attestation.data.slot + MIN_ATTESTATION_INCLUSION_DELAY <= state.slot assert attestation.data.slot + MIN_ATTESTATION_INCLUSION_DELAY <= state.slot
# Verify that the justified epoch/root is correct # Verify that the justified epoch and root is correct
if slot_to_epoch(attestation.data.slot) >= get_current_epoch(state): if slot_to_epoch(attestation.data.slot) >= get_current_epoch(state):
# Case 1: current epoch attestations # Case 1: current epoch attestations
assert attestation.data.justified_epoch == state.justified_epoch assert attestation.data.source_epoch == state.current_justified_epoch
assert attestation.data.justified_block_root == state.justified_root assert attestation.data.source_root == state.current_justified_root
else: else:
# Case 2: previous epoch attestations # Case 2: previous epoch attestations
assert attestation.data.justified_epoch == state.previous_justified_epoch assert attestation.data.source_epoch == state.previous_justified_epoch
assert attestation.data.justified_block_root == state.previous_justified_root assert attestation.data.source_root == state.previous_justified_root
# Check that the crosslink data is valid # Check that the crosslink data is valid
acceptable_crosslink_data = { acceptable_crosslink_data = {
# Case 1: Latest crosslink matches the one in the state # Case 1: Latest crosslink matches the one in the state
attestation.data.latest_crosslink, attestation.data.previous_crosslink,
# Case 2: State has already been updated, state's latest crosslink matches the crosslink # Case 2: State has already been updated, state's latest crosslink matches the crosslink
# the attestation is trying to create # the attestation is trying to create
Crosslink( Crosslink(