diff --git a/pysetup/spec_builders/eip7594.py b/pysetup/spec_builders/eip7594.py index 332937832..dfbc427a7 100644 --- a/pysetup/spec_builders/eip7594.py +++ b/pysetup/spec_builders/eip7594.py @@ -12,6 +12,14 @@ class EIP7594SpecBuilder(BaseSpecBuilder): return f''' from eth2spec.deneb import {preset_name} as deneb ''' + + + @classmethod + def sundry_functions(cls) -> str: + return """ +def retrieve_column_sidecars(beacon_block_root: Root) -> Sequence[DataColumnSidecar]: + return [] +""" @classmethod def hardcoded_custom_type_dep_constants(cls, spec_object) -> str: diff --git a/specs/_features/eip7594/fork-choice.md b/specs/_features/eip7594/fork-choice.md new file mode 100644 index 000000000..cc4caa36c --- /dev/null +++ b/specs/_features/eip7594/fork-choice.md @@ -0,0 +1,122 @@ +# EIP-7594 -- Fork Choice + +## Table of contents + + + + +- [Introduction](#introduction) + - [Helpers](#helpers) + - [Modified `is_data_available`](#modified-is_data_available) + - [New `is_chain_available`](#new-is_chain_available) + - [Modified `get_head`](#modified-get_head) + - [New `is_peer_sampling_required`](#new-is_peer_sampling_required) +- [Updated fork-choice handlers](#updated-fork-choice-handlers) + - [Modified `on_block`](#modified-on_block) + - [Pull-up tip helpers](#pull-up-tip-helpers) + - [Modified `compute_pulled_up_tip`](#modified-compute_pulled_up_tip) + + + + +## Introduction + +This is the modification of the fork choice accompanying EIP-7594. + +### Helpers + +#### Modified `is_data_available` + +```python +def is_data_available(beacon_block_root: Root) -> bool: + # `retrieve_column_sidecars` is implementation and context dependent, replacing `retrieve_blobs_and_proofs`. + # For the given block root, it returns all column sidecars to custody, or raises an exception if they are not available. # The p2p network does not guarantee sidecar retrieval outside of `MIN_EPOCHS_FOR_DATA_COLUMN_SIDECARS_REQUESTS` epochs. + column_sidecars = retrieve_column_sidecars(beacon_block_root) + return all( + verify_data_column_sidecar_kzg_proofs(column_sidecar) + for column_sidecar in column_sidecars + ) +``` + +#### Modified `get_head` + +*Note*: children of the current `head` are required to be available in order to be considered by the fork-choice. + +```python +def get_head(store: Store) -> Root: + # Get filtered block tree that only includes viable branches + blocks = get_filtered_block_tree(store) + # Execute the LMD-GHOST fork choice + head = store.justified_checkpoint.root + while True: + # Get available children for the current slot + children = [ + root for (root, block) in blocks.items() + if ( + block.parent_root == head + and is_data_available(root) + ) + ] + if len(children) == 0: + return head + # Sort by latest attesting balance with ties broken lexicographically + # Ties broken by favoring block with lexicographically higher root + head = max(children, key=lambda root: (get_weight(store, root), root)) +``` + +## Updated fork-choice handlers + +### Modified `on_block` + +*Note*: The blob data availability check is removed. + +```python +def on_block(store: Store, signed_block: SignedBeaconBlock) -> None: + """ + Run ``on_block`` upon receiving a new block. + """ + block = signed_block.message + # Parent block must be known + assert block.parent_root in store.block_states + # Make a copy of the state to avoid mutability issues + state = copy(store.block_states[block.parent_root]) + # Blocks cannot be in the future. If they are, their consideration must be delayed until they are in the past. + assert get_current_slot(store) >= block.slot + + # Check that block is later than the finalized epoch slot (optimization to reduce calls to get_ancestor) + 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 + finalized_checkpoint_block = get_checkpoint_block( + store, + block.parent_root, + store.finalized_checkpoint.epoch, + ) + assert store.finalized_checkpoint.root == finalized_checkpoint_block + + # Check the block is valid and compute the post-state + block_root = hash_tree_root(block) + state_transition(state, signed_block, True) + + # Add new block to the store + store.blocks[block_root] = block + # Add new state for this block to the store + store.block_states[block_root] = state + + # Add block timeliness to the store + time_into_slot = (store.time - store.genesis_time) % SECONDS_PER_SLOT + is_before_attesting_interval = time_into_slot < SECONDS_PER_SLOT // INTERVALS_PER_SLOT + is_timely = get_current_slot(store) == block.slot and is_before_attesting_interval + store.block_timeliness[hash_tree_root(block)] = is_timely + + # Add proposer score boost if the block is timely and not conflicting with an existing block + is_first_block = store.proposer_boost_root == Root() + if is_timely and is_first_block: + store.proposer_boost_root = hash_tree_root(block) + + # Update checkpoints in store if necessary + update_checkpoints(store, state.current_justified_checkpoint, state.finalized_checkpoint) + + # Eagerly compute unrealized justification and finality. + compute_pulled_up_tip(store, block_root) +```