From afa12caf1f3d2595c79e1a53e901c9639e98f500 Mon Sep 17 00:00:00 2001 From: Hsiao-Wei Wang Date: Sat, 11 Apr 2020 01:12:40 +0800 Subject: [PATCH] Refactor `get_shard_state_transition_result` --- specs/phase1/fraud-proofs.md | 184 +++++++++++++++++++++-------------- 1 file changed, 112 insertions(+), 72 deletions(-) diff --git a/specs/phase1/fraud-proofs.md b/specs/phase1/fraud-proofs.md index 30b94d810..5af904ff5 100644 --- a/specs/phase1/fraud-proofs.md +++ b/specs/phase1/fraud-proofs.md @@ -149,6 +149,118 @@ def compute_shard_data_roots(proposals: Sequence[SignedShardBlock]) -> Sequence[ return [hash_tree_root(proposal.message.body) for proposal in proposals] ``` +```python +def get_proposal_choices_at_slot(beacon_state: BeaconState, + shard_state: ShardState, + slot: Slot, + shard: Shard, + shard_blocks: Sequence[SignedShardBlock], + validate_result: bool=True) -> Sequence[SignedShardBlock]: + choices = [] + beacon_parent_root = get_block_root_at_slot(beacon_state, get_previous_slot(beacon_state.slot)) + proposer_index = get_shard_proposer_index(beacon_state, slot, shard) + shard_blocks_at_slot = [block for block in shard_blocks if block.message.slot == slot] + for block in shard_blocks_at_slot: + temp_shard_state = shard_state.copy() # Not doing the actual state updates here. + # Try to apply state transition to temp_shard_state. + try: + # Verify the proposer_index and signature + assert block.message.proposer_index == proposer_index + if validate_result: + assert verify_shard_block_signature(beacon_state, block) + + shard_state_transition( + beacon_state=beacon_state, + shard=shard, + slot=slot, + shard_state=temp_shard_state, + beacon_parent_root=beacon_parent_root, + signed_block=block, + ) + except Exception: + pass # TODO: throw error in the test helper + else: + choices.append(block) + return choices +``` + +```python +def get_proposal_at_slot(beacon_state: BeaconState, + shard_state: ShardState, + slot: Shard, + shard: Shard, + shard_parent_root: Root, + shard_blocks: Sequence[SignedShardBlock], + validate_result: bool=True) -> Tuple[SignedShardBlock, ShardState, Root]: + beacon_parent_root = get_block_root_at_slot(beacon_state, get_previous_slot(beacon_state.slot)) + proposer_index = get_shard_proposer_index(beacon_state, slot, shard) + shard_state = shard_state.copy() # Don't update the given shard_state + choices = get_proposal_choices_at_slot( + beacon_state=beacon_state, + shard_state=shard_state, + slot=slot, + shard=shard, + shard_blocks=shard_blocks, + validate_result=validate_result, + ) + if len(choices) == 0: + block_header = get_empty_body_block( + shard_parent_root=shard_parent_root, + beacon_parent_root=beacon_parent_root, + slot=slot, + proposer_index=proposer_index, + ) + proposal = SignedShardBlock(message=block_header) + elif len(choices) == 1: + proposal = choices[0] + else: + proposal = get_winning_proposal(beacon_state, choices) + + shard_parent_root = hash_tree_root(proposal.message) + + if not is_empty_body(proposal.message): + # Apply state transition to shard_state. + shard_state_transition( + beacon_state=beacon_state, + shard=shard, + slot=slot, + shard_state=shard_state, + beacon_parent_root=beacon_parent_root, + signed_block=proposal, + ) + + return proposal, shard_state, shard_parent_root +``` + +```python +def get_shard_state_transition_result( + beacon_state: BeaconState, + shard: Shard, + shard_blocks: Sequence[SignedShardBlock], + validate_result: bool=True, +) -> Tuple[Sequence[SignedShardBlock], Sequence[ShardState], Sequence[Root]]: + proposals = [] + shard_states = [] + shard_state = beacon_state.shard_states[shard].copy() + shard_parent_root = beacon_state.shard_states[shard].latest_block_root + for slot in get_offset_slots(beacon_state, shard): + proposal, shard_state, shard_parent_root = get_proposal_at_slot( + beacon_state=beacon_state, + shard_state=shard_state, + slot=slot, + shard=shard, + shard_parent_root=shard_parent_root, + shard_blocks=shard_blocks, + validate_result=validate_result, + ) + shard_states.append(shard_state) + proposals.append(proposal) + + shard_data_roots = compute_shard_data_roots(proposals) + + return proposals, shard_states, shard_data_roots +``` + ### Make attestations Suppose you are a committee member on shard `shard` at slot `current_slot` and you have received shard blocks `shard_blocks`. 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 `current_slot`, run `get_shard_transition(beacon_state, shard, shard_blocks)` to get `shard_transition`. @@ -181,75 +293,3 @@ def get_shard_transition(beacon_state: BeaconState, proposer_signature_aggregate=proposer_signature_aggregate, ) ``` - -```python -def get_shard_state_transition_result( - beacon_state: BeaconState, - shard: Shard, - shard_blocks: Sequence[SignedShardBlock], - validate_result: bool=True, -) -> Tuple[Sequence[SignedShardBlock], Sequence[ShardState], Sequence[Root]]: - proposals = [] - shard_states = [] - shard_state = beacon_state.shard_states[shard].copy() - shard_parent_root = beacon_state.shard_states[shard].latest_block_root - for slot in get_offset_slots(beacon_state, shard): - choices = [] - beacon_parent_root = get_block_root_at_slot(beacon_state, get_previous_slot(beacon_state.slot)) - proposer_index = get_shard_proposer_index(beacon_state, slot, shard) - shard_blocks_at_slot = [block for block in shard_blocks if block.message.slot == slot] - for block in shard_blocks_at_slot: - temp_shard_state = shard_state.copy() # Not doing the actual state updates here. - # Try to apply state transition to temp_shard_state. - try: - # Verify the proposer_index and signature - assert block.message.proposer_index == proposer_index - if validate_result: - assert verify_shard_block_signature(beacon_state, block) - - shard_state_transition( - beacon_state=beacon_state, - shard=shard, - slot=slot, - shard_state=temp_shard_state, - beacon_parent_root=beacon_parent_root, - signed_block=block, - ) - except Exception: - pass # TODO: throw error in the test helper - else: - choices.append(block) - - if len(choices) == 0: - block_header = get_empty_body_block( - shard_parent_root=shard_parent_root, - beacon_parent_root=beacon_parent_root, - slot=slot, - proposer_index=proposer_index, - ) - block = SignedShardBlock(message=block_header) - proposals.append(block) - elif len(choices) == 1: - proposals.append(choices[0]) - else: - proposals.append(get_winning_proposal(beacon_state, choices)) - - shard_parent_root = hash_tree_root(proposals[-1].message) - - if not is_empty_body(proposals[-1].message): - # Apply state transition to shard_state. - shard_state_transition( - beacon_state=beacon_state, - shard=shard, - slot=slot, - shard_state=shard_state, - beacon_parent_root=beacon_parent_root, - signed_block=block, - ) - - shard_states.append(shard_state) - - shard_data_roots = compute_shard_data_roots(proposals) - - return proposals, shard_states, shard_data_roots -```