Some fixes
This commit is contained in:
Vitalik Buterin
Danny Ryan
parent
7b4a6e8307
commit
4d6dcd15ba
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@ -18,7 +18,7 @@
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- [`AttestationData`](#attestationdata)
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- [`ShardTransition`](#shardtransition)
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- [`Attestation`](#attestation)
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- [`IndexedAttestation`](#indexedattestation)
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- [`AttestationAndCommittee`](#attestationandcommittee)
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- [`CompactCommittee`](#compactcommittee)
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- [`AttestationCustodyBitWrapper`](#attestationcustodybitwrapper)
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- [`PendingAttestation`](#pendingattestation)
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@ -106,7 +106,7 @@ class ShardState(Container):
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slot: Slot
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gasprice: Gwei
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data: Hash
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latest_block_hash: Hash
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latest_block_root: Hash
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```
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### `AttestationData`
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@ -120,6 +120,8 @@ class AttestationData(Container):
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# FFG vote
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source: Checkpoint
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target: Checkpoint
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# Current-slot shard block root
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head_shard_root: Hash
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# Shard transition root
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shard_transition_root: Hash
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```
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@ -150,10 +152,10 @@ class Attestation(Container):
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signature: BLSSignature
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```
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### `IndexedAttestation`
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### `AttestationAndCommittee`
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```python
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class IndexedAttestation(Container):
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class AttestationAndCommittee(Container):
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committee: List[ValidatorIndex, MAX_VALIDATORS_PER_COMMITTEE]
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attestation: Attestation
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```
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@ -239,9 +241,9 @@ def get_light_client_committee(beacon_state: BeaconState, epoch: Epoch) -> Seque
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### `get_indexed_attestation`
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```python
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def get_indexed_attestation(beacon_state: BeaconState, attestation: Attestation) -> IndexedAttestation:
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def get_indexed_attestation(beacon_state: BeaconState, attestation: Attestation) -> AttestationAndCommittee:
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committee = get_beacon_committee(beacon_state, attestation.data.slot, attestation.data.index)
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return IndexedAttestation(committee, attestation)
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return AttestationAndCommittee(committee, attestation)
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```
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### `get_updated_gasprice`
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@ -259,7 +261,7 @@ def get_updated_gasprice(prev_gasprice: Gwei, length: uint8) -> Gwei:
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### `is_valid_indexed_attestation`
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```python
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def is_valid_indexed_attestation(state: BeaconState, indexed_attestation: IndexedAttestation) -> bool:
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def is_valid_indexed_attestation(state: BeaconState, indexed_attestation: AttestationAndCommittee) -> bool:
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"""
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Check if ``indexed_attestation`` has valid indices and signature.
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"""
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@ -303,6 +305,13 @@ def get_offset_slots(state: BeaconState, start_slot: Slot) -> Sequence[Slot]:
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return [start_slot + x for x in SHARD_BLOCK_OFFSETS if start_slot + x < state.slot]
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```
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### `chunks_to_body_root`
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```python
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def chunks_to_body_root(chunks):
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return hash_tree_root(chunks + [EMPTY_CHUNK_ROOT] * (MAX_SHARD_BLOCK_CHUNKS - len(chunks)))
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```
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## Beacon Chain Changes
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### New beacon state fields
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@ -336,7 +345,7 @@ def validate_attestation(state: BeaconState, attestation: Attestation) -> None:
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# Signature check
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assert is_valid_indexed_attestation(state, get_indexed_attestation(state, attestation))
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# Type 1: on-time attestations
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if data.custody_bits != []:
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if attestation.custody_bits != []:
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# Correct slot
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assert data.slot == state.slot
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# Correct data root count
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@ -345,7 +354,7 @@ def validate_attestation(state: BeaconState, attestation: Attestation) -> None:
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assert data.beacon_block_root == get_block_root_at_slot(state, state.slot - 1)
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# Type 2: delayed attestations
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else:
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assert state.slot < data.slot + SLOTS_PER_EPOCH
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assert state.slot - compute_start_slot_at_epoch(slot_to_epoch(data.slot)) < EPOCH_LENGTH
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assert data.shard_transition_root == Hash()
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```
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@ -361,13 +370,10 @@ def apply_shard_transition(state: BeaconState, shard: Shard, transition: ShardTr
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assert len(transition.shard_data_roots) == len(transition.shard_states) == len(transition.shard_block_lengths) == len(offset_slots)
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assert transition.start_slot == start_slot
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def chunks_to_body_root(chunks):
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return hash_tree_root(chunks + [EMPTY_CHUNK_ROOT] * (MAX_SHARD_BLOCK_CHUNKS - len(chunks)))
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# Reonstruct shard headers
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headers = []
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proposers = []
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shard_parent_root = state.shard_states[shard].latest_block_hash
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shard_parent_root = state.shard_states[shard].latest_block_root
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for i in range(len(offset_slots)):
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if any(transition.shard_data_roots):
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headers.append(ShardSignableHeader(
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@ -431,7 +437,10 @@ def process_attestations(state: BeaconState, block: BeaconBlock, attestations: S
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get_total_balance(state, online_indices.intersection(this_shard_committee)) * 2
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and success is False
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):
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# Attestation <-> shard transition consistency
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assert shard_transition_root == hash_tree_root(block.shard_transition)
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assert attestation.data.head_shard_root == chunks_to_body_root(block.shard_transition.shard_data_roots[-1])
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# Apply transition
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apply_shard_transition(state, shard, block.shard_transition)
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# Apply proposer reward and cost
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estimated_attester_reward = sum([get_base_reward(state, attester) for attester in all_participants])
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@ -461,7 +470,7 @@ def process_attestations(state: BeaconState, block: BeaconBlock, attestations: S
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### Misc block post-processing
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```python
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def misc_block_post_process(state: BeaconState, block: BeaconBlock) -> None:
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def verify_shard_transition_false_positives(state: BeaconState, block: BeaconBlock) -> None:
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# Verify that a `shard_transition` in a block is empty if an attestation was not processed for it
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for shard in range(MAX_SHARDS):
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if state.shard_states[shard].slot != state.slot - 1:
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@ -538,7 +547,7 @@ def shard_state_transition(shard: Shard, slot: Slot, pre_state: Hash, previous_b
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## Honest committee member behavior
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Suppose you are a committee member on shard `shard` at slot `current_slot`. Let `state` be the head beacon state you are building on. Three seconds into slot `slot`, run the following procedure:
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Suppose you are a committee member on shard `shard` at slot `current_slot`. Let `state` be the head beacon state you are building on, and let `QUARTER_PERIOD = SECONDS_PER_SLOT // 4`. `2 * QUARTER_PERIOD` seconds into slot `slot`, run the following procedure:
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* Initialize `proposals = []`, `shard_states = []`, `shard_state = state.shard_states[shard][-1]`, `start_slot = shard_state.slot`.
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* For `slot in get_offset_slots(state, start_slot)`, do the following:
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@ -546,6 +555,6 @@ Suppose you are a committee member on shard `shard` at slot `current_slot`. Let
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* If `len(choices) == 0`, do `proposals.append(make_empty_proposal(shard_state, slot))`
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* If `len(choices) == 1`, do `proposals.append(choices[0])`
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* If `len(choices) > 1`, let `winning_proposal` be the proposal with the largest number of total attestations from slots in `state.shard_next_slots[shard]....slot-1` supporting it or any of its descendants, breaking ties by choosing the first proposal locally seen. Do `proposals.append(winning_proposal)`.
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* Set `shard_state = shard_state_transition(shard, slot, shard_state, get_block_root_at_slot(state, state.slot - 1), get_shard_proposer(state, shard, slot), proposals[-1])` and do `shard_states.append(shard_state)`.
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* If `proposals[-1]` is NOT an empty proposal, set `shard_state = shard_state_transition(shard, slot, shard_state, get_block_root_at_slot(state, state.slot - 1), get_shard_proposer(state, shard, slot), proposals[-1])` and do `shard_states.append(shard_state)`. If it is an empty proposal, leave `shard_state` unchanged.
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Make an attestation using `shard_data_roots = [hash_tree_root(proposal) for proposal in proposals]` and `shard_state_roots = shard_states`.
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