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eth2.0-specs
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update pending header weights after epoch transition, fix committee index loop, fix header processing status assert, add todos for Altair-like shard attestation rewards

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protolambda 2021-05-31 18:55:08 +02:00
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commit 2545c3e2d0
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1 changed files with 42 additions and 32 deletions
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specs/sharding/beacon-chain.md
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@ -251,6 +251,8 @@ class PendingShardHeader(Container):
votes: Bitlist[MAX_VALIDATORS_PER_COMMITTEE]
# Sum of effective balances of votes
weight: Gwei
# When the header was last updated, as reference for weight accuracy
update_slot: Slot
```
### `ShardBlobReference`
@ -538,32 +540,39 @@ def update_pending_shard_work(state: BeaconState, attestation: Attestation) -> N
buffer_index = attestation.data.slot % SHARD_STATE_MEMORY_SLOTS
committee_work = state.shard_buffer[buffer_index][attestation_shard]
# Skip attestation vote accounting if the header is already confirmed
if committee_work.status.selector == CONFIRMED_SHARD_DATA:
# Skip attestation vote accounting if the header is not pending
if committee_work.status.selector != PENDING_SHARD_DATA:
# TODO In Altair: set participation bit flag, if attestation matches winning header.
return
# Note that shard-slot combinations without an assigned committee do not have a pending state
assert shard_info.status.selector == PENDING_SHARD_DATA
current_headers: Sequence[PendingShardHeader] = committee_work.status.value
# Find the corresponding header, abort if it cannot be found
header_index = [header.root for header in current_headers].index(attestation.data.shard_header_root)
# Update votes bitfield in the state
pending_header: PendingShardHeader = current_headers[header_index]
full_committee = get_beacon_committee(state, attestation.data.slot, attestation.data.index)
participants_balance = Gwei(0)
full_committee_balance = Gwei(0)
# The weight may be outdated if it is not the initial weight, and from a previous epoch
if pending_header.weight != 0 and compute_epoch_at_slot(pending_header.update_slot) < get_current_epoch(state):
pending_header.weight = sum(state.validators[index].effective_balance for index, bit
in zip(full_committee, pending_header.votes) if bit)
pending_header.update_slot = state.slot
# Update votes bitfield in the state, update weights
for i, bit in enumerate(attestation.aggregation_bits):
weight = state.validators[full_committee[i]].effective_balance
full_committee_balance += weight
if bit:
if not pending_header.votes[i]:
pending_header.weight += weight
pending_header.votes[i] = True
participants_balance += weight
pending_header.votes[i] = True
# Check if the PendingShardHeader is eligible for expedited confirmation, requiring 2/3 of balance attesting
full_committee_balance = get_total_balance(state, set(full_committee))
if participants_balance * 3 >= full_committee_balance * 2:
if pending_header.weight * 3 >= full_committee_balance * 2:
# TODO In Altair: set participation bit flag for voters of this early winning header
if pending_header.commitment == DataCommitment():
# The committee voted to not confirm anything
state.shard_buffer[buffer_index][attestation_shard].change(
@ -625,6 +634,7 @@ def process_shard_header(state: BeaconState, signed_header: SignedShardBlobHeade
root=header_root,
votes=initial_votes,
weight=0,
update_slot=state.slot,
)
# Include it in the pending list
@ -669,19 +679,18 @@ This epoch transition overrides the Merge epoch transition:
```python
def process_epoch(state: BeaconState) -> None:
process_justification_and_finalization(state)
process_rewards_and_penalties(state)
process_registry_updates(state)
process_slashings(state)
# Sharding
process_pending_shard_confirmations(state)
charge_confirmed_shard_fees(state)
reset_pending_shard_work(state)
# Phase0
process_justification_and_finalization(state)
process_rewards_and_penalties(state)
process_registry_updates(state)
process_slashings(state)
# Final updates
# Phase 0
process_eth1_data_reset(state)
process_effective_balance_updates(state)
process_slashings_reset(state)
@ -711,6 +720,7 @@ def process_pending_shard_confirmations(state: BeaconState) -> None:
committee_work = state.shard_buffer[buffer_index][shard_index]
if committee_work.selector == PENDING_SHARD_DATA:
winning_header = max(committee_work.value, key=lambda header: header.weight)
# TODO In Altair: set participation bit flag of voters for winning header
if winning_header.commitment == DataCommitment():
committee_work.change(selector=UNCONFIRMED_SHARD_DATA, value=None)
else:
@ -768,23 +778,23 @@ def reset_pending_shard_work(state: BeaconState) -> None:
state.shard_buffer[buffer_index] = [ShardWork() for _ in range(active_shards)]
start_shard = get_start_shard(state, slot)
for shard_index in range(state.shard_buffer[buffer_index]):
if start_shard <= shard_index < start_shard + committees_per_slot:
# a committee is available, initialize a pending shard-header list
committee_index = CommitteeIndex(shard_index - start_shard)
committee_length = len(get_beacon_committee(state, slot, committee_index))
state.shard_buffer[buffer_index][shard_index].change(
selector=PENDING_SHARD_DATA,
value=List[PendingShardHeader, MAX_SHARD_HEADERS_PER_SHARD](
PendingShardHeader(
commitment=DataCommitment(),
root=Root(),
votes=Bitlist[MAX_VALIDATORS_PER_COMMITTEE]([0] * committee_length),
weight=0,
)
for committee_index in range(committees_per_slot):
shard = (start_shard + committee_index) % active_shards
# a committee is available, initialize a pending shard-header list
committee_length = len(get_beacon_committee(state, slot, committee_index))
state.shard_buffer[buffer_index][shard].change(
selector=PENDING_SHARD_DATA,
value=List[PendingShardHeader, MAX_SHARD_HEADERS_PER_SHARD](
PendingShardHeader(
commitment=DataCommitment(),
root=Root(),
votes=Bitlist[MAX_VALIDATORS_PER_COMMITTEE]([0] * committee_length),
weight=0,
update_slot=slot,
)
)
# the shard is inactive for this slot otherwise, no committee available, default to UNCONFIRMED_SHARD_DATA.
)
# a shard without committee available defaults to UNCONFIRMED_SHARD_DATA.
```
#### `process_shard_epoch_increment`