98 lines
3.7 KiB
Markdown
98 lines
3.7 KiB
Markdown
# EIP-7594 -- Fork Choice
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## Table of contents
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<!-- TOC -->
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<!-- START doctoc generated TOC please keep comment here to allow auto update -->
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<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
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- [Introduction](#introduction)
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- [Helpers](#helpers)
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- [Modified `is_data_available`](#modified-is_data_available)
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- [Updated fork-choice handlers](#updated-fork-choice-handlers)
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- [Modified `on_block`](#modified-on_block)
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<!-- END doctoc generated TOC please keep comment here to allow auto update -->
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<!-- /TOC -->
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## Introduction
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This is the modification of the fork choice accompanying EIP-7594.
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## Helpers
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### Modified `is_data_available`
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```python
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def is_data_available(beacon_block_root: Root) -> bool:
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# `retrieve_column_sidecars` is implementation and context dependent, replacing
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# `retrieve_blobs_and_proofs`. For the given block root, it returns all column
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# sidecars to sample, or raises an exception if they are not available.
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# The p2p network does not guarantee sidecar retrieval outside of
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# `MIN_EPOCHS_FOR_DATA_COLUMN_SIDECARS_REQUESTS` epochs.
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column_sidecars = retrieve_column_sidecars(beacon_block_root)
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return all(
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verify_data_column_sidecar_kzg_proofs(column_sidecar)
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for column_sidecar in column_sidecars
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)
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```
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## Updated fork-choice handlers
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### Modified `on_block`
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*Note*: The only modification is that `is_data_available` does not take `blob_kzg_commitments` as input.
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```python
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def on_block(store: Store, signed_block: SignedBeaconBlock) -> None:
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"""
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Run ``on_block`` upon receiving a new block.
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"""
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block = signed_block.message
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# Parent block must be known
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assert block.parent_root in store.block_states
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# Make a copy of the state to avoid mutability issues
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state = copy(store.block_states[block.parent_root])
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# Blocks cannot be in the future. If they are, their consideration must be delayed until they are in the past.
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assert get_current_slot(store) >= block.slot
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# Check that block is later than the finalized epoch slot (optimization to reduce calls to get_ancestor)
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finalized_slot = compute_start_slot_at_epoch(store.finalized_checkpoint.epoch)
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assert block.slot > finalized_slot
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# Check block is a descendant of the finalized block at the checkpoint finalized slot
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finalized_checkpoint_block = get_checkpoint_block(
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store,
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block.parent_root,
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store.finalized_checkpoint.epoch,
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)
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assert store.finalized_checkpoint.root == finalized_checkpoint_block
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# [Modified in EIP7594]
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assert is_data_available(hash_tree_root(block))
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# Check the block is valid and compute the post-state
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block_root = hash_tree_root(block)
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state_transition(state, signed_block, True)
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# Add new block to the store
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store.blocks[block_root] = block
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# Add new state for this block to the store
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store.block_states[block_root] = state
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# Add block timeliness to the store
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time_into_slot = (store.time - store.genesis_time) % SECONDS_PER_SLOT
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is_before_attesting_interval = time_into_slot < SECONDS_PER_SLOT // INTERVALS_PER_SLOT
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is_timely = get_current_slot(store) == block.slot and is_before_attesting_interval
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store.block_timeliness[hash_tree_root(block)] = is_timely
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# Add proposer score boost if the block is timely and not conflicting with an existing block
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is_first_block = store.proposer_boost_root == Root()
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if is_timely and is_first_block:
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store.proposer_boost_root = hash_tree_root(block)
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# Update checkpoints in store if necessary
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update_checkpoints(store, state.current_justified_checkpoint, state.finalized_checkpoint)
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# Eagerly compute unrealized justification and finality.
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compute_pulled_up_tip(store, block_root)
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```
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