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Introduce get_epoch_boundary_block

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This commit is contained in:
Roberto Saltini
2023-03-28 15:27:13 +11:00
parent c46c3945fd
commit 201f113b50
1 changed files with 14 additions and 5 deletions
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19
specs/phase0/fork-choice.md
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@@ -192,6 +192,17 @@ def get_ancestor(store: Store, root: Root, slot: Slot) -> Root:
return root
```
#### `get_epoch_boundary_block`
```python
def get_epoch_boundary_block(store: Store, root: Root, epoch: Epoch) -> Root:
"""
Compute the epoch boundary block for epoch ``epoch`` in the chain of block ``root``
"""
epoch_first_slot = compute_start_slot_at_epoch(epoch)
return get_ancestor(store, root, epoch_first_slot)
```
#### `get_weight`
```python
@@ -278,10 +289,9 @@ def filter_block_tree(store: Store, block_root: Root, blocks: Dict[Root, BeaconB
voting_source.epoch + 2 >= current_epoch
)
finalized_slot = compute_start_slot_at_epoch(store.finalized_checkpoint.epoch)
correct_finalized = (
store.finalized_checkpoint.epoch == GENESIS_EPOCH
or store.finalized_checkpoint.root == get_ancestor(store, block_root, finalized_slot)
or store.finalized_checkpoint.root == get_epoch_boundary_block(store, block_root, store.finalized_checkpoint.epoch)
)
# If expected finalized/justified, add to viable block-tree and signal viability to parent.
@@ -442,8 +452,7 @@ def validate_on_attestation(store: Store, attestation: Attestation, is_from_bloc
assert store.blocks[attestation.data.beacon_block_root].slot <= attestation.data.slot
# LMD vote must be consistent with FFG vote target
target_slot = compute_start_slot_at_epoch(target.epoch)
assert target.root == get_ancestor(store, attestation.data.beacon_block_root, target_slot)
assert target.root == get_epoch_boundary_block(store, attestation.data.beacon_block_root, target.epoch)
# Attestations can only affect the fork choice of subsequent slots.
# Delay consideration in the fork choice until their slot is in the past.
@@ -506,7 +515,7 @@ def on_block(store: Store, signed_block: SignedBeaconBlock) -> None:
finalized_slot = compute_start_slot_at_epoch(store.finalized_checkpoint.epoch)
assert block.slot > finalized_slot
# Check block is a descendant of the finalized block at the checkpoint finalized slot
assert get_ancestor(store, block.parent_root, finalized_slot) == store.finalized_checkpoint.root
assert get_epoch_boundary_block(store, block.parent_root, store.finalized_checkpoint.epoch) == store.finalized_checkpoint.root
# Check the block is valid and compute the post-state
state = pre_state.copy()