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Updates to add new proposals

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Vitalik Buterin 2019-10-29 10:43:13 -07:00 committed by Danny Ryan
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specs/core/1_new_shards.md
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@ -37,21 +37,27 @@ This document describes the shard transition function (data layer only) and the
| - | - | - | - |
| `MAX_SHARDS` | `2**10` (= 1024) |
| `ACTIVE_SHARDS` | `2**6` (= 64) |
| `MAX_CATCHUP_RATIO` | `2**2` (= 4) |
| `ONLINE_PERIOD` | `2**3` (= 8) | epochs | ~51 min |
| `LIGHT_CLIENT_COMMITTEE_SIZE` | `2**7` (= 128) |
| `LIGHT_CLIENT_COMMITTEE_PERIOD` | `2**8` (= 256) | epochs | ~29 hours |
| `SHARD_STATE_ROOT_LENGTH` | `2**7` (= 128) | bytes |
| `SHARD_BLOCK_CHUNK_SIZE` | `2**18` (= 262,144) | |
| `MAX_SHARD_BLOCK_CHUNKS` | `2**2` (= 4) | |
| `BLOCK_SIZE_TARGET` | `3 * 2**16` (= 196,608) | |
| `SHARD_BLOCK_OFFSETS` | `[1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233]` | |
| `MAX_SHARD_BLOCKS_PER_ATTESTATION` | `len(SHARD_BLOCK_OFFSETS)` | |
| `MAX_SHARD_GASPRICE` | `2**14` (= 16,384) | Gwei | |
| `SHARD_GASPRICE_ADJUSTMENT_COEFFICIENT` | `2**3` (= 8) | |
## Containers
### Aliases
| Name | Value |
| - | - |
| `SHARD_STATE_ROOT` | `BytesN[SHARD_STATE_ROOT_LENGTH]` |
### `ShardState`
```python
class ShardState(Container):
slot: Slot
gasprice: Gwei
root: Hash
```
### `AttestationData`
@ -64,55 +70,31 @@ class AttestationData(Container):
# FFG vote
source: Checkpoint
target: Checkpoint
# Shard data
shard_data: AttestationShardData
# Shard transition hash
shard_transition_hash: Hash
```
### `AttestationShardData`
### `ShardTransition`
```python
class AttestationShardData(Container):
# Starting from slot
start_slot: Slot
# Shard block lengths
shard_block_lengths: List[uint8, MAX_CATCHUP_RATIO * MAX_SHARDS]
shard_block_lengths: List[uint8, MAX_SHARD_BLOCKS_PER_ATTESTATION]
# Shard data roots
shard_data_roots: List[Hash, List[Hash, MAX_SHARD_BLOCK_CHUNKS], MAX_CATCHUP_RATIO * MAX_SHARDS]
shard_data_roots: List[Hash, List[Hash, MAX_SHARD_BLOCK_CHUNKS], MAX_SHARD_BLOCKS_PER_ATTESTATION]
# Intermediate state roots
shard_state_roots: List[SHARD_STATE_ROOT, MAX_CATCHUP_RATIO * MAX_SHARDS]
shard_state_roots: List[ShardState, MAX_SHARD_BLOCKS_PER_ATTESTATION]
```
### `ReducedAttestationData`
```python
class ReducedAttestationData(Container):
slot: Slot
index: CommitteeIndex
# LMD GHOST vote
beacon_block_root: Hash
# FFG vote
source: Checkpoint
target: Checkpoint
# Shard data root
shard_data_root: Hash
```
### `Attestation`
```python
class Attestation(Container):
aggregation_bits: Bitlist[MAX_VALIDATORS_PER_COMMITTEE]
data: AttestationData
custody_bits: List[Bitlist[MAX_VALIDATORS_PER_COMMITTEE], MAX_CATCHUP_RATIO * MAX_SHARDS]
signature: BLSSignature
```
### `ReducedAttestation`
```python
class ReducedAttestation(Container):
aggregation_bits: Bitlist[MAX_VALIDATORS_PER_COMMITTEE]
data: ReducedAttestationData
custody_bits: List[Bitlist[MAX_VALIDATORS_PER_COMMITTEE], MAX_CATCHUP_RATIO * MAX_SHARDS]
custody_bits: List[Bitlist[MAX_VALIDATORS_PER_COMMITTEE], MAX_SHARD_BLOCKS_PER_ATTESTATION]
signature: BLSSignature
```
@ -121,8 +103,8 @@ class ReducedAttestation(Container):
```python
class IndexedAttestation(Container):
participants: List[ValidatorIndex, MAX_COMMITTEE_SIZE]
data: ReducedAttestationData
custody_bits: List[Bitlist[MAX_VALIDATORS_PER_COMMITTEE], MAX_CATCHUP_RATIO * MAX_SHARDS]
data: AttestationData
custody_bits: List[Bitlist[MAX_VALIDATORS_PER_COMMITTEE], MAX_SHARD_BLOCKS_PER_ATTESTATION]
signature: BLSSignature
```
@ -199,6 +181,21 @@ def get_indexed_attestation(beacon_state: BeaconState, attestation: Attestation)
return IndexedAttestation(attesting_indices, data, custody_bits, signature)
```
### `update_gasprice`
```python
def update_gasprice(prev_gasprice: Gwei, length: uint8) -> Gwei:
if length > BLOCK_SIZE_TARGET:
delta = prev_gasprice * (length - BLOCK_SIZE_TARGET) // BLOCK_SIZE_TARGET // SHARD_GASPRICE_ADJUSTMENT_COEFFICIENT
return min(prev_gasprice + delta, MAX_SHARD_GASPRICE)
else:
delta = prev_gasprice * (BLOCK_SIZE_TARGET - length) // BLOCK_SIZE_TARGET // SHARD_GASPRICE_ADJUSTMENT_COEFFICIENT
if delta > prev_gasprice - SHARD_GASPRICE_ADJUSTMENT_COEFFICIENT:
return SHARD_GASPRICE_ADJUSTMENT_COEFFICIENT
else:
return prev_gasprice - delta
```
### `is_valid_indexed_attestation`
``python
@ -217,6 +214,7 @@ def is_valid_indexed_attestation(state: BeaconState, indexed_attestation: Indexe
for participant, custody_bits in zip(participants, indexed_attestation.custody_bits):
for i, bit in enumerate(custody_bits):
all_pubkeys.append(state.validators[participant].pubkey)
# Note: only 2N distinct message hashes
all_message_hashes.append(AttestationCustodyBitWrapper(hash_tree_root(indexed_attestation.data), i, bit))
return bls_verify_multiple(
@ -232,9 +230,8 @@ def is_valid_indexed_attestation(state: BeaconState, indexed_attestation: Indexe
### New state variables
```python
shard_state_roots: Vector[SHARD_STATE_ROOT, MAX_SHARDS]
shard_trace_commitments: Vector[Hash, MAX_SHARDS]
shard_next_slots: Vector[Slot, MAX_SHARDS]
shard_transitions: Vector[ShardTransition, MAX_SHARDS]
shard_states: Vector[ShardState, MAX_SHARDS]
online_countdown: Bytes[VALIDATOR_REGISTRY_LIMIT]
current_light_committee: CompactCommittee
next_light_committee: CompactCommittee
@ -254,52 +251,76 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
data = attestation.data
assert data.index < ACTIVE_SHARDS
shard = (data.index + get_start_shard(state, data.slot)) % ACTIVE_SHARDS
proposer_index=get_beacon_proposer_index(state)
# Signature check
committee = get_crosslink_committee(state, get_current_epoch(state), shard)
for bits in attestation.custody_bits + [attestation.aggregation_bits]:
assert bits == len(committee)
assert len(bits) == len(committee)
# Check signature
assert is_valid_indexed_attestation(state, get_indexed_attestation(state, attestation))
# Get attesting indices
attesting_indices = get_attesting_indices(state, attestation.data, attestation.aggregation_bits)
# Prepare pending attestation object
pending_attestation = PendingAttestation(
slot=data.slot,
shard=shard,
aggregation_bits=attestation.aggregation_bits,
inclusion_delay=state.slot - data.slot,
crosslink_success=False,
proposer_index=proposer_index
)
# Type 1: on-time attestations
if data.custody_bits != []:
# Correct start slot
assert data.slot == state.shard_next_slots[shard]
# Correct slot
assert data.slot == state.slot
# Slot the attestation starts counting from
start_slot = state.shard_next_slots[shard]
# Correct data root count
max_catchup = ACTIVE_SHARDS * MAX_CATCHUP_RATIO // get_committee_count(state, state.slot)
assert len(data.shard_data_roots) == len(attestation.custody_bits) == len(data.shard_state_roots) == min(state.slot - data.slot, max_catchup)
offset_slots = [start_slot + x for x in SHARD_BLOCK_OFFSETS if start_slot + x < state.slot]
assert len(attestation.custody_bits) == len(offset_slots)
# Correct parent block root
assert data.beacon_block_root == get_block_root_at_slot(state, state.slot - 1)
# Apply
online_indices = get_online_indices(state)
if get_total_balance(state, online_indices.intersection(attesting_indices)) * 3 >= get_total_balance(state, online_indices) * 2:
# Save trace commitment (used for fraud proofs)
trace = List[Hash, MAX_CATCHUP_RATIO * MAX_SHARDS * 2 + 1]([state.shard_state_roots[shard]])
for data, state in zip(data.shard_data_roots, data.shard_state_roots):
trace.extend([data, state])
state.shard_trace_commitments[shard] = hash_tree_root(trace)
# Save state root and next slot
state.shard_state_roots[shard] = data.shard_state_roots[-1]
state.shard_next_slots[shard] += len(data.shard_data_roots)
# Check correct formatting of shard transition data
transition = block.shard_transitions[shard]
assert data.shard_transition_hash == hash_tree_root(transition)
assert len(transition.shard_data_roots) == len(transition.shard_states) == len(transition.shard_block_lengths) == len(offset_slots)
assert transition.start_slot == start_slot
# Verify correct calculation of gas prices and slots and chunk roots
prev_gasprice = state.shard_states[shard].gasprice
for i in range(len(offset_slots)):
assert transition.shard_states[i].gasprice == update_gasprice(prev_gasprice, transition.shard_block_lengths[i])
assert transition.shard_states[i].slot == offset_slots[i]
assetrt len(transition.shard_data_roots[i]) == transition.shard_block_lengths[i] // SHARD_BLOCK_CHUNK_SIZE
prev_gasprice = transition.shard_states[i].gasprice
# Save updated state
state.shard_states[shard] = data.shard_states[-1]
state.shard_states[shard].slot = state.slot - 1
# Save success (for end-of-epoch rewarding)
pending_attestation.crosslink_success = True
# Reward and cost proposer
estimated_attester_reward = sum([get_base_reward(state, attester) for attester in attesting_indices])
increase_balance(state, proposer, estimated_attester_reward // PROPOSER_REWARD_COEFFICIENT)
for state, length in zip(transition.shard_states, transition.shard_block_lengths):
decrease_balance(state, proposer, state.gasprice * length)
# Type 2: delayed attestations
else:
assert slot_to_epoch(data.slot) in (get_current_epoch(state), get_previous_epoch(state))
assert len(data.shard_data_roots) == len(data.intermediate_state_roots) == 0
assert len(attestation.custody_bits) == 0
for index in attesting_indices:
online_countdown[index] = ONLINE_PERIOD
pending_attestation = PendingAttestation(
slot=data.slot,
shard=shard,
aggregation_bits=attestation.aggregation_bits,
inclusion_delay=state.slot - attestation_slot,
proposer_index=get_beacon_proposer_index(state),
)
if data.target.epoch == get_current_epoch(state):
assert data.source == state.current_justified_checkpoint
@ -309,7 +330,15 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
state.previous_epoch_attestations.append(pending_attestation)
```
Check the length of attestations using `len(block.attestations) <= 4 * get_committee_count(state, state.slot)`.
### Misc block post-processing
```python
def misc_block_post_process(state: BeaconState, block: BeaconBlock):
# Verify that a `shard_transition` in a block is empty if an attestation was not processed for it
for shard in range(MAX_SHARDS):
if state.shard_states[shard].slot != state.slot - 1:
assert block.shard_transition[shard] == ShardTransition()
```
### Light client processing