Introduce compute_shuffling_lookahead_start_slot helper (#5602)

Author: jihoonsong

specs/gloas/fork-choice.md

@@ -41,6 +41,7 @@
   - [Modified `get_latest_message_epoch`](#modified-get_latest_message_epoch)
   - [New `verify_execution_payload_envelope`](#new-verify_execution_payload_envelope)
   - [New `is_valid_dependent_root`](#new-is_valid_dependent_root)
+  - [New `compute_shuffling_lookahead_start_slot`](#new-compute_shuffling_lookahead_start_slot)
   - [Modified `get_attestation_due_ms`](#modified-get_attestation_due_ms)
   - [Modified `get_aggregate_due_ms`](#modified-get_aggregate_due_ms)
   - [Modified `get_sync_message_due_ms`](#modified-get_sync_message_due_ms)
@@ -716,6 +717,15 @@ def is_valid_dependent_root(store: Store, root: Root, dependent_slot: Slot) -> b
     return False
 ```
 
+### New `compute_shuffling_lookahead_start_slot`
+
+```python
+def compute_shuffling_lookahead_start_slot(epoch: Epoch) -> Slot:
+    if epoch <= MIN_SEED_LOOKAHEAD:
+        return GENESIS_SLOT
+    return compute_start_slot_at_epoch(epoch - MIN_SEED_LOOKAHEAD)
+```
+
 ### Modified `get_attestation_due_ms`
 
 ```python

specs/gloas/p2p-interface.md

@@ -26,7 +26,6 @@
   - [New `is_past_slot`](#new-is_past_slot)
   - [New `is_gas_limit_target_compatible`](#new-is_gas_limit_target_compatible)
   - [New `is_bid_compatible_with_head`](#new-is_bid_compatible_with_head)
-  - [New `compute_shuffling_dependent_epoch`](#new-compute_shuffling_dependent_epoch)
   - [New `verify_attestation_payload_status`](#new-verify_attestation_payload_status)
   - [New `verify_block_body_operation_limits`](#new-verify_block_body_operation_limits)
   - [New `verify_execution_requests_limits`](#new-verify_execution_requests_limits)
@@ -380,19 +379,6 @@ def is_bid_compatible_with_head(store: Store, bid: ExecutionPayloadBid) -> bool:
     return builds_on_parent_payload
 ```
 
-### New `compute_shuffling_dependent_epoch`
-
-```python
-def compute_shuffling_dependent_epoch(epoch: Epoch) -> Epoch:
-    """
-    Return the epoch that determines the shuffling for the given ``epoch``.
-    For the first ``MIN_SEED_LOOKAHEAD`` epochs, this is ``GENESIS_EPOCH``.
-    """
-    if epoch <= MIN_SEED_LOOKAHEAD:
-        return GENESIS_EPOCH
-    return epoch - MIN_SEED_LOOKAHEAD
-```
-
 ### New `verify_attestation_payload_status`
 
 ```python
@@ -1093,9 +1079,8 @@ def validate_proposer_preferences_gossip(
         raise GossipIgnore("proposal slot has already started")
 
     # [IGNORE] The proposer for the proposal slot is known
-    lookahead_epoch = compute_shuffling_dependent_epoch(proposal_epoch)
-    lookahead_epoch_start_slot = compute_start_slot_at_epoch(lookahead_epoch)
-    if is_future_slot(store, lookahead_epoch_start_slot, current_time_ms):
+    lookahead_start_slot = compute_shuffling_lookahead_start_slot(proposal_epoch)
+    if is_future_slot(store, lookahead_start_slot, current_time_ms):
         raise GossipIgnore("proposer for the proposal slot is not yet known")
 
     # [IGNORE] The dependent block has been seen (via gossip or non-gossip sources)
@@ -1117,16 +1102,16 @@ def validate_proposer_preferences_gossip(
         raise GossipIgnore("dependent block is not a possible dependent block")
 
     # [REJECT] The validator is the proposer for the given slot in the proposer lookahead
-    lookahead_state = store.block_states[preferences.dependent_root].copy()
-    if lookahead_state.slot < lookahead_epoch_start_slot:
-        process_slots(lookahead_state, lookahead_epoch_start_slot)
-    lookahead_index = preferences.proposal_slot - lookahead_epoch_start_slot
-    if lookahead_state.proposer_lookahead[lookahead_index] != preferences.validator_index:
+    state = store.block_states[preferences.dependent_root].copy()
+    if state.slot < lookahead_start_slot:
+        process_slots(state, lookahead_start_slot)
+    lookahead_index = preferences.proposal_slot - lookahead_start_slot
+    if state.proposer_lookahead[lookahead_index] != preferences.validator_index:
         raise GossipReject("validator is not the proposer for the given slot")
 
     # [REJECT] The signature is valid
-    validator = lookahead_state.validators[preferences.validator_index]
-    domain = get_domain(lookahead_state, DOMAIN_PROPOSER_PREFERENCES, proposal_epoch)
+    validator = state.validators[preferences.validator_index]
+    domain = get_domain(state, DOMAIN_PROPOSER_PREFERENCES, proposal_epoch)
     signing_root = compute_signing_root(preferences, domain)
     if not bls.Verify(validator.pubkey, signing_root, signed_proposer_preferences.signature):
         raise GossipReject("invalid proposer preferences signature")

specs/heze/fork-choice.md

@@ -293,14 +293,15 @@ def on_inclusion_list(store: Store, signed_inclusion_list: SignedInclusionList)
     assert is_valid_dependent_root(store, inclusion_list.dependent_root, dependent_slot)
 
     # Verify the validator is in the inclusion list committee
-    dependent_state = store.block_states[inclusion_list.dependent_root].copy()
-    if dependent_state.slot < inclusion_list.slot:
-        process_slots(dependent_state, inclusion_list.slot)
-    committee = get_inclusion_list_committee(dependent_state, inclusion_list.slot)
+    state = store.block_states[inclusion_list.dependent_root].copy()
+    lookahead_start_slot = compute_shuffling_lookahead_start_slot(epoch)
+    if state.slot < lookahead_start_slot:
+        process_slots(state, lookahead_start_slot)
+    committee = get_inclusion_list_committee(state, inclusion_list.slot)
     assert inclusion_list.validator_index in committee
 
     # Verify the signature
-    assert is_valid_inclusion_list_signature(dependent_state, signed_inclusion_list)
+    assert is_valid_inclusion_list_signature(state, signed_inclusion_list)
 
     # The inclusion list is timely if it arrives in its slot before the deadline
     seconds_since_genesis = store.time - store.genesis_time

tests/core/pyspec/eth_consensus_specs/test/gloas/networking/test_gossip_proposer_preferences.py

@@ -443,28 +443,28 @@ def setup_lookahead_boundary_preferences(spec, state):
     lookahead lower bound for the proposal slot.
     """
     lookahead_epoch = spec.Epoch(spec.MIN_SEED_LOOKAHEAD + 3)
-    lookahead_epoch_start_slot = spec.compute_start_slot_at_epoch(lookahead_epoch)
-    store, blocks = setup_store_with_advanced_state(spec, state, lookahead_epoch_start_slot)
+    lookahead_start_slot = spec.compute_start_slot_at_epoch(lookahead_epoch)
+    store, blocks = setup_store_with_advanced_state(spec, state, lookahead_start_slot)
 
     # The dependent block is the last one before the epoch transition.
     dependent_root = blocks[-2].message.hash_tree_root()
     dependent_state = store.block_states[dependent_root]
     assert spec.get_current_epoch(dependent_state) == spec.Epoch(lookahead_epoch - 1)
 
     lookahead_state = dependent_state.copy()
-    spec.process_slots(lookahead_state, lookahead_epoch_start_slot)
+    spec.process_slots(lookahead_state, lookahead_start_slot)
     proposal_slot = spec.compute_start_slot_at_epoch(
         spec.Epoch(lookahead_epoch + spec.MIN_SEED_LOOKAHEAD)
     )
-    lookahead_index = proposal_slot - lookahead_epoch_start_slot
+    lookahead_index = proposal_slot - lookahead_start_slot
     signed_prefs = build_signed_proposer_preferences(
         spec,
         lookahead_state,
         proposal_slot=proposal_slot,
         validator_index=lookahead_state.proposer_lookahead[lookahead_index],
         dependent_root=dependent_root,
     )
-    return store, blocks, signed_prefs, lookahead_epoch_start_slot
+    return store, blocks, signed_prefs, lookahead_start_slot
 
 
 @with_gloas_and_later
@@ -478,7 +478,7 @@ def test_gossip_proposer_preferences__ignore_outside_lookahead_disparity(spec, s
     anchor_state = state.copy()
     yield "topic", "meta", "proposer_preferences"
 
-    store, blocks, signed_prefs, lookahead_epoch_start_slot = setup_lookahead_boundary_preferences(
+    store, blocks, signed_prefs, lookahead_start_slot = setup_lookahead_boundary_preferences(
         spec, state
     )
 
@@ -489,7 +489,7 @@ def test_gossip_proposer_preferences__ignore_outside_lookahead_disparity(spec, s
     yield get_filename(signed_prefs), signed_prefs
 
     time_ms = (
-        spec.compute_time_at_slot_ms(store, lookahead_epoch_start_slot)
+        spec.compute_time_at_slot_ms(store, lookahead_start_slot)
         - spec.config.MAXIMUM_GOSSIP_CLOCK_DISPARITY
         - 1
     )
@@ -529,7 +529,7 @@ def test_gossip_proposer_preferences__valid_at_lookahead_disparity_edge(spec, st
     anchor_state = state.copy()
     yield "topic", "meta", "proposer_preferences"
 
-    store, blocks, signed_prefs, lookahead_epoch_start_slot = setup_lookahead_boundary_preferences(
+    store, blocks, signed_prefs, lookahead_start_slot = setup_lookahead_boundary_preferences(
         spec, state
     )
 
@@ -540,7 +540,7 @@ def test_gossip_proposer_preferences__valid_at_lookahead_disparity_edge(spec, st
     yield get_filename(signed_prefs), signed_prefs
 
     time_ms = (
-        spec.compute_time_at_slot_ms(store, lookahead_epoch_start_slot)
+        spec.compute_time_at_slot_ms(store, lookahead_start_slot)
         - spec.config.MAXIMUM_GOSSIP_CLOCK_DISPARITY
     )
     yield "current_time_ms", "meta", int(time_ms)
@@ -1020,16 +1020,13 @@ def test_gossip_proposer_preferences__reject_dependent_root_at_lookahead_epoch_s
 
     proposal_slot, validator_index = find_upcoming_proposal_slot(spec, state)
     proposal_epoch = spec.compute_epoch_at_slot(proposal_slot)
-    lookahead_epoch = spec.Epoch(proposal_epoch - spec.MIN_SEED_LOOKAHEAD)
-    lookahead_epoch_start_slot = spec.compute_start_slot_at_epoch(lookahead_epoch)
+    lookahead_start_slot = spec.compute_shuffling_lookahead_start_slot(proposal_epoch)
 
     boundary_block = next(
-        signed_block
-        for signed_block in blocks
-        if signed_block.message.slot == lookahead_epoch_start_slot
+        signed_block for signed_block in blocks if signed_block.message.slot == lookahead_start_slot
     )
     dependent_root = boundary_block.message.hash_tree_root()
-    assert store.block_states[dependent_root].slot == lookahead_epoch_start_slot
+    assert store.block_states[dependent_root].slot == lookahead_start_slot
 
     # Sign valid preferences for the upcoming slot's true proposer, but point
     # dependent_root at the first block whose stored state is exactly at the
@@ -1096,8 +1093,8 @@ def test_gossip_proposer_preferences__ignore_dependent_root_not_possible(spec, s
     # superseded on the only branch.
     proposal_slot, validator_index = find_upcoming_proposal_slot(spec, state)
     proposal_epoch = spec.compute_epoch_at_slot(proposal_slot)
-    lookahead_epoch = spec.Epoch(proposal_epoch - spec.MIN_SEED_LOOKAHEAD)
-    superseded_slot = spec.Slot(spec.compute_start_slot_at_epoch(lookahead_epoch) - 2)
+    lookahead_start_slot = spec.compute_shuffling_lookahead_start_slot(proposal_epoch)
+    superseded_slot = spec.Slot(lookahead_start_slot - 2)
     signed_prefs = build_signed_proposer_preferences(
         spec,
         state,
@@ -1150,13 +1147,12 @@ def test_gossip_proposer_preferences__valid_dependent_root_on_fork(spec, state):
 
     proposal_slot, validator_index = find_upcoming_proposal_slot(spec, state)
     proposal_epoch = spec.compute_epoch_at_slot(proposal_slot)
-    lookahead_epoch = spec.Epoch(proposal_epoch - spec.MIN_SEED_LOOKAHEAD)
-    lookahead_epoch_start_slot = spec.compute_start_slot_at_epoch(lookahead_epoch)
+    lookahead_start_slot = spec.compute_shuffling_lookahead_start_slot(proposal_epoch)
 
     # Fork off two slots before the lookahead epoch start and build a branch
     # whose first block stays before the epoch start and whose second block
     # crosses it.
-    fork_parent_root = spec.get_block_root_at_slot(state, spec.Slot(lookahead_epoch_start_slot - 2))
+    fork_parent_root = spec.get_block_root_at_slot(state, spec.Slot(lookahead_start_slot - 2))
     fork_state = store.block_states[fork_parent_root].copy()
     fork_blocks = []
     for _ in range(2):
@@ -1168,8 +1164,8 @@ def test_gossip_proposer_preferences__valid_dependent_root_on_fork(spec, state):
         store.block_states[block_root] = fork_state.copy()
         fork_blocks.append(signed_fork_block)
     dependent_root = fork_blocks[0].message.hash_tree_root()
-    assert store.blocks[dependent_root].slot == lookahead_epoch_start_slot - 1
-    assert fork_blocks[1].message.slot == lookahead_epoch_start_slot
+    assert store.blocks[dependent_root].slot == lookahead_start_slot - 1
+    assert fork_blocks[1].message.slot == lookahead_start_slot
 
     yield "state", anchor_state
     seen = get_seen(spec)
@@ -1222,7 +1218,7 @@ def test_gossip_proposer_preferences__valid_dependent_root_across_empty_epochs(s
     yield "topic", "meta", "proposer_preferences"
 
     current_epoch = spec.Epoch(spec.MIN_SEED_LOOKAHEAD + 2)
-    lookahead_epoch_start_slot = spec.compute_start_slot_at_epoch(current_epoch)
+    lookahead_start_slot = spec.compute_start_slot_at_epoch(current_epoch)
 
     # Build the canonical chain to the slot before two fully empty epochs.
     first_empty_epoch = spec.Epoch(current_epoch - 2)
@@ -1232,7 +1228,7 @@ def test_gossip_proposer_preferences__valid_dependent_root_across_empty_epochs(s
     dependent_state = state.copy()
 
     # Skip both epochs, then import the first block at the lookahead boundary.
-    boundary_block = build_empty_block(spec, state, slot=lookahead_epoch_start_slot)
+    boundary_block = build_empty_block(spec, state, slot=lookahead_start_slot)
     signed_boundary_block = state_transition_and_sign_block(spec, state, boundary_block)
     boundary_root = signed_boundary_block.message.hash_tree_root()
     store.blocks[boundary_root] = signed_boundary_block.message
@@ -1245,7 +1241,7 @@ def test_gossip_proposer_preferences__valid_dependent_root_across_empty_epochs(s
     assert spec.get_shuffling_dependent_root(store, boundary_root, proposal_epoch) == dependent_root
 
     lookahead_state = dependent_state.copy()
-    spec.process_slots(lookahead_state, lookahead_epoch_start_slot)
+    spec.process_slots(lookahead_state, lookahead_start_slot)
     # Pick a slot that distinguishes the advanced lookahead from the stale
     # lookahead in the dependent block's post-state.
     for slot_offset in range(spec.SLOTS_PER_EPOCH):