diff --git a/configs/mainnet.yaml b/configs/mainnet.yaml index 6d23073b7..0a207b423 100644 --- a/configs/mainnet.yaml +++ b/configs/mainnet.yaml @@ -70,6 +70,11 @@ MIN_PER_EPOCH_CHURN_LIMIT: 4 CHURN_LIMIT_QUOTIENT: 65536 +# Fork choice +# --------------------------------------------------------------- +# 25% +PROPOSER_SCORE_BOOST: 70 + # Deposit contract # --------------------------------------------------------------- # Ethereum PoW Mainnet diff --git a/configs/minimal.yaml b/configs/minimal.yaml index 4f99fce31..508587ee5 100644 --- a/configs/minimal.yaml +++ b/configs/minimal.yaml @@ -69,6 +69,12 @@ MIN_PER_EPOCH_CHURN_LIMIT: 4 CHURN_LIMIT_QUOTIENT: 32 +# Fork choice +# --------------------------------------------------------------- +# 25% +PROPOSER_SCORE_BOOST: 70 + + # Deposit contract # --------------------------------------------------------------- # Ethereum Goerli testnet diff --git a/specs/merge/fork-choice.md b/specs/merge/fork-choice.md index 8c5bc1312..dc392d263 100644 --- a/specs/merge/fork-choice.md +++ b/specs/merge/fork-choice.md @@ -175,6 +175,12 @@ def on_block(store: Store, signed_block: SignedBeaconBlock) -> None: # Add new state for this block to the store store.block_states[hash_tree_root(block)] = state + # Add proposer score boost if the block is timely + time_into_slot = (store.time - store.genesis_time) % SECONDS_PER_SLOT + is_before_attesting_interval = time_into_slot < SECONDS_PER_SLOT // INTERVALS_PER_SLOT + if get_current_slot(store) == block.slot and is_before_attesting_interval: + store.proposer_boost_root = hash_tree_root(block) + # Update justified checkpoint if state.current_justified_checkpoint.epoch > store.justified_checkpoint.epoch: if state.current_justified_checkpoint.epoch > store.best_justified_checkpoint.epoch: diff --git a/specs/phase0/beacon-chain.md b/specs/phase0/beacon-chain.md index 1618aa37c..7172307c6 100644 --- a/specs/phase0/beacon-chain.md +++ b/specs/phase0/beacon-chain.md @@ -169,7 +169,6 @@ We define the following Python custom types for type hinting and readability: | `BLSPubkey` | `Bytes48` | a BLS12-381 public key | | `BLSSignature` | `Bytes96` | a BLS12-381 signature | - ## Constants The following values are (non-configurable) constants used throughout the specification. diff --git a/specs/phase0/fork-choice.md b/specs/phase0/fork-choice.md index 6854a8487..d082ede30 100644 --- a/specs/phase0/fork-choice.md +++ b/specs/phase0/fork-choice.md @@ -7,7 +7,9 @@ - [Introduction](#introduction) - [Fork choice](#fork-choice) + - [Constant](#constant) - [Preset](#preset) + - [Configuration](#configuration) - [Helpers](#helpers) - [`LatestMessage`](#latestmessage) - [`Store`](#store) @@ -56,12 +58,27 @@ Any of the above handlers that trigger an unhandled exception (e.g. a failed ass 4) **Manual forks**: Manual forks may arbitrarily change the fork choice rule but are expected to be enacted at epoch transitions, with the fork details reflected in `state.fork`. 5) **Implementation**: The implementation found in this specification is constructed for ease of understanding rather than for optimization in computation, space, or any other resource. A number of optimized alternatives can be found [here](https://github.com/protolambda/lmd-ghost). + +### Constant + +| Name | Value | +| - | - | +| `INTERVALS_PER_SLOT` | `uint64(3)` | + ### Preset | Name | Value | Unit | Duration | | - | - | :-: | :-: | | `SAFE_SLOTS_TO_UPDATE_JUSTIFIED` | `2**3` (= 8) | slots | 96 seconds | +### Configuration + +| Name | Value | +| - | - | +| `PROPOSER_SCORE_BOOST` | `uint64(70)` | + +- The proposer score boost is worth `PROPOSER_SCORE_BOOST` percentage of the committee's weight, i.e., for slot with committee weight `committee_weight` the boost weight is equal to `(committee_weight * PROPOSER_SCORE_BOOST) // 100`. + ### Helpers #### `LatestMessage` @@ -83,6 +100,7 @@ class Store(object): justified_checkpoint: Checkpoint finalized_checkpoint: Checkpoint best_justified_checkpoint: Checkpoint + proposer_boost_root: Root blocks: Dict[Root, BeaconBlock] = field(default_factory=dict) block_states: Dict[Root, BeaconState] = field(default_factory=dict) checkpoint_states: Dict[Checkpoint, BeaconState] = field(default_factory=dict) @@ -103,12 +121,14 @@ def get_forkchoice_store(anchor_state: BeaconState, anchor_block: BeaconBlock) - anchor_epoch = get_current_epoch(anchor_state) justified_checkpoint = Checkpoint(epoch=anchor_epoch, root=anchor_root) finalized_checkpoint = Checkpoint(epoch=anchor_epoch, root=anchor_root) + proposer_boost_root = Root() return Store( time=uint64(anchor_state.genesis_time + SECONDS_PER_SLOT * anchor_state.slot), genesis_time=anchor_state.genesis_time, justified_checkpoint=justified_checkpoint, finalized_checkpoint=finalized_checkpoint, best_justified_checkpoint=justified_checkpoint, + proposer_boost_root=proposer_boost_root, blocks={anchor_root: copy(anchor_block)}, block_states={anchor_root: copy(anchor_state)}, checkpoint_states={justified_checkpoint: copy(anchor_state)}, @@ -156,11 +176,22 @@ def get_ancestor(store: Store, root: Root, slot: Slot) -> Root: def get_latest_attesting_balance(store: Store, root: Root) -> Gwei: state = store.checkpoint_states[store.justified_checkpoint] active_indices = get_active_validator_indices(state, get_current_epoch(state)) - return Gwei(sum( + attestation_score = Gwei(sum( state.validators[i].effective_balance for i in active_indices if (i in store.latest_messages and get_ancestor(store, store.latest_messages[i].root, store.blocks[root].slot) == root) )) + proposer_score = Gwei(0) + if store.proposer_boost_root != Root(): + block = store.blocks[root] + if get_ancestor(store, root, block.slot) == store.proposer_boost_root: + num_validators = len(get_active_validator_indices(state, get_current_epoch(state))) + avg_balance = get_total_active_balance(state) // num_validators + committee_size = num_validators // SLOTS_PER_EPOCH + committee_weight = committee_size * avg_balance + proposer_score = (committee_weight * PROPOSER_SCORE_BOOST) // 100 + return attestation_score + proposer_score + ``` #### `filter_block_tree` @@ -339,6 +370,11 @@ def on_tick(store: Store, time: uint64) -> None: store.time = time current_slot = get_current_slot(store) + + # Reset store.proposer_boost_root if this is a new slot + if current_slot > previous_slot: + store.proposer_boost_root = Root() + # Not a new epoch, return if not (current_slot > previous_slot and compute_slots_since_epoch_start(current_slot) == 0): return @@ -377,6 +413,12 @@ def on_block(store: Store, signed_block: SignedBeaconBlock) -> None: # Add new state for this block to the store store.block_states[hash_tree_root(block)] = state + # Add proposer score boost if the block is timely + time_into_slot = (store.time - store.genesis_time) % SECONDS_PER_SLOT + is_before_attesting_interval = time_into_slot < SECONDS_PER_SLOT // INTERVALS_PER_SLOT + if get_current_slot(store) == block.slot and is_before_attesting_interval: + store.proposer_boost_root = hash_tree_root(block) + # Update justified checkpoint if state.current_justified_checkpoint.epoch > store.justified_checkpoint.epoch: if state.current_justified_checkpoint.epoch > store.best_justified_checkpoint.epoch: diff --git a/specs/phase0/validator.md b/specs/phase0/validator.md index cc5b7aeb5..e21ff980a 100644 --- a/specs/phase0/validator.md +++ b/specs/phase0/validator.md @@ -446,7 +446,7 @@ def get_block_signature(state: BeaconState, block: BeaconBlock, privkey: int) -> A validator is expected to create, sign, and broadcast an attestation during each epoch. The `committee`, assigned `index`, and assigned `slot` for which the validator performs this role during an epoch are defined by `get_committee_assignment(state, epoch, validator_index)`. -A validator should create and broadcast the `attestation` to the associated attestation subnet when either (a) the validator has received a valid block from the expected block proposer for the assigned `slot` or (b) one-third of the `slot` has transpired (`SECONDS_PER_SLOT / 3` seconds after the start of `slot`) -- whichever comes _first_. +A validator should create and broadcast the `attestation` to the associated attestation subnet when either (a) the validator has received a valid block from the expected block proposer for the assigned `slot` or (b) `1 / INTERVALS_PER_SLOT` of the `slot` has transpired (`SECONDS_PER_SLOT / INTERVALS_PER_SLOT` seconds after the start of `slot`) -- whichever comes _first_. *Note*: Although attestations during `GENESIS_EPOCH` do not count toward FFG finality, these initial attestations do give weight to the fork choice, are rewarded, and should be made. @@ -569,7 +569,7 @@ def get_aggregate_signature(attestations: Sequence[Attestation]) -> BLSSignature #### Broadcast aggregate -If the validator is selected to aggregate (`is_aggregator`), then they broadcast their best aggregate as a `SignedAggregateAndProof` to the global aggregate channel (`beacon_aggregate_and_proof`) two-thirds of the way through the `slot`-that is, `SECONDS_PER_SLOT * 2 / 3` seconds after the start of `slot`. +If the validator is selected to aggregate (`is_aggregator`), then they broadcast their best aggregate as a `SignedAggregateAndProof` to the global aggregate channel (`beacon_aggregate_and_proof`) `2 / INTERVALS_PER_SLOT` of the way through the `slot`-that is, `SECONDS_PER_SLOT * 2 / INTERVALS_PER_SLOT` seconds after the start of `slot`. Selection proofs are provided in `AggregateAndProof` to prove to the gossip channel that the validator has been selected as an aggregator. diff --git a/tests/core/pyspec/eth2spec/test/helpers/fork_choice.py b/tests/core/pyspec/eth2spec/test/helpers/fork_choice.py index 098c05bf9..2fe0de90d 100644 --- a/tests/core/pyspec/eth2spec/test/helpers/fork_choice.py +++ b/tests/core/pyspec/eth2spec/test/helpers/fork_choice.py @@ -157,6 +157,7 @@ def add_block(spec, 'epoch': int(store.best_justified_checkpoint.epoch), 'root': encode_hex(store.best_justified_checkpoint.root), }, + 'proposer_boost_root': encode_hex(store.proposer_boost_root), } }) diff --git a/tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_get_head.py b/tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_get_head.py index 12b261e4e..d2c84fce7 100644 --- a/tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_get_head.py +++ b/tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_get_head.py @@ -1,3 +1,4 @@ +import random from eth_utils import encode_hex from eth2spec.test.context import ( @@ -19,6 +20,7 @@ from eth2spec.test.helpers.fork_choice import ( add_block, ) from eth2spec.test.helpers.state import ( + next_slots, next_epoch, state_transition_and_sign_block, ) @@ -103,18 +105,23 @@ def test_split_tie_breaker_no_attestations(spec, state): } }) - # block at slot 1 + # Create block at slot 1 block_1_state = genesis_state.copy() block_1 = build_empty_block_for_next_slot(spec, block_1_state) signed_block_1 = state_transition_and_sign_block(spec, block_1_state, block_1) - yield from tick_and_add_block(spec, store, signed_block_1, test_steps) - # additional block at slot 1 + # Create additional block at slot 1 block_2_state = genesis_state.copy() block_2 = build_empty_block_for_next_slot(spec, block_2_state) block_2.body.graffiti = b'\x42' * 32 signed_block_2 = state_transition_and_sign_block(spec, block_2_state, block_2) - yield from tick_and_add_block(spec, store, signed_block_2, test_steps) + + # Tick time past slot 1 so proposer score boost does not apply + time = store.genesis_time + (block_2.slot + 1) * spec.config.SECONDS_PER_SLOT + on_tick_and_append_step(spec, store, time, test_steps) + + yield from add_block(spec, store, signed_block_1, test_steps) + yield from add_block(spec, store, signed_block_2, test_steps) highest_root = max(spec.hash_tree_root(block_1), spec.hash_tree_root(block_2)) assert spec.get_head(store) == highest_root @@ -261,3 +268,67 @@ def test_filtered_block_tree(spec, state): }) yield 'steps', test_steps + + +@with_all_phases +@spec_state_test +def test_proposer_boost_correct_head(spec, state): + test_steps = [] + genesis_state = state.copy() + + # Initialization + store, anchor_block = get_genesis_forkchoice_store_and_block(spec, state) + yield 'anchor_state', state + yield 'anchor_block', anchor_block + anchor_root = get_anchor_root(spec, state) + assert spec.get_head(store) == anchor_root + test_steps.append({ + 'checks': { + 'head': get_formatted_head_output(spec, store), + } + }) + + # Build block that serves as head ONLY on timely arrival, and ONLY in that slot + state_1 = genesis_state.copy() + next_slots(spec, state_1, 3) + block_1 = build_empty_block_for_next_slot(spec, state_1) + signed_block_1 = state_transition_and_sign_block(spec, state_1, block_1) + + # Build block that serves as current head, and remains the head after block_1.slot + state_2 = genesis_state.copy() + next_slots(spec, state_2, 2) + block_2 = build_empty_block_for_next_slot(spec, state_2) + signed_block_2 = state_transition_and_sign_block(spec, state_2.copy(), block_2) + while spec.hash_tree_root(block_1) >= spec.hash_tree_root(block_2): + block_2.body.graffiti = spec.Bytes32(hex(random.getrandbits(8 * 32))[2:].zfill(64)) + signed_block_2 = state_transition_and_sign_block(spec, state_2.copy(), block_2) + assert spec.hash_tree_root(block_1) < spec.hash_tree_root(block_2) + + # Tick to block_1 slot time + time = store.genesis_time + block_1.slot * spec.config.SECONDS_PER_SLOT + on_tick_and_append_step(spec, store, time, test_steps) + + # Process block_2 + yield from add_block(spec, store, signed_block_2, test_steps) + assert store.proposer_boost_root == spec.Root() + assert spec.get_head(store) == spec.hash_tree_root(block_2) + + # Process block_1 on timely arrival + # The head should temporarily change to block_1 + yield from add_block(spec, store, signed_block_1, test_steps) + assert store.proposer_boost_root == spec.hash_tree_root(block_1) + assert spec.get_head(store) == spec.hash_tree_root(block_1) + + # After block_1.slot, the head should revert to block_2 + time = store.genesis_time + (block_1.slot + 1) * spec.config.SECONDS_PER_SLOT + on_tick_and_append_step(spec, store, time, test_steps) + assert store.proposer_boost_root == spec.Root() + assert spec.get_head(store) == spec.hash_tree_root(block_2) + + test_steps.append({ + 'checks': { + 'head': get_formatted_head_output(spec, store), + } + }) + + yield 'steps', test_steps diff --git a/tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_on_block.py b/tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_on_block.py index 7194c6a20..f57522ad7 100644 --- a/tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_on_block.py +++ b/tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_on_block.py @@ -1,4 +1,5 @@ import random +from eth_utils import encode_hex from eth2spec.utils.ssz.ssz_impl import hash_tree_root from eth2spec.test.context import MINIMAL, spec_state_test, with_all_phases, with_presets @@ -703,3 +704,96 @@ def test_new_finalized_slot_is_justified_checkpoint_ancestor(spec, state): assert store.justified_checkpoint == another_state.current_justified_checkpoint yield 'steps', test_steps + + +@with_all_phases +@spec_state_test +def test_proposer_boost(spec, state): + test_steps = [] + genesis_state = state.copy() + + # Initialization + store, anchor_block = get_genesis_forkchoice_store_and_block(spec, state) + yield 'anchor_state', state + yield 'anchor_block', anchor_block + + # Build block that serves as head ONLY on timely arrival, and ONLY in that slot + state = genesis_state.copy() + next_slots(spec, state, 3) + block = build_empty_block_for_next_slot(spec, state) + signed_block = state_transition_and_sign_block(spec, state, block) + + # Process block on timely arrival just before end of boost interval + time = (store.genesis_time + block.slot * spec.config.SECONDS_PER_SLOT + + spec.config.SECONDS_PER_SLOT // spec.INTERVALS_PER_SLOT - 1) + on_tick_and_append_step(spec, store, time, test_steps) + yield from add_block(spec, store, signed_block, test_steps) + assert store.proposer_boost_root == spec.hash_tree_root(block) + assert spec.get_latest_attesting_balance(store, spec.hash_tree_root(block)) > 0 + + # Ensure that boost is removed after slot is over + time = (store.genesis_time + block.slot * spec.config.SECONDS_PER_SLOT + + spec.config.SECONDS_PER_SLOT) + on_tick_and_append_step(spec, store, time, test_steps) + assert store.proposer_boost_root == spec.Root() + assert spec.get_latest_attesting_balance(store, spec.hash_tree_root(block)) == 0 + + next_slots(spec, state, 3) + block = build_empty_block_for_next_slot(spec, state) + signed_block = state_transition_and_sign_block(spec, state, block) + + # Process block on timely arrival at start of boost interval + time = (store.genesis_time + block.slot * spec.config.SECONDS_PER_SLOT) + on_tick_and_append_step(spec, store, time, test_steps) + yield from add_block(spec, store, signed_block, test_steps) + assert store.proposer_boost_root == spec.hash_tree_root(block) + assert spec.get_latest_attesting_balance(store, spec.hash_tree_root(block)) > 0 + + # Ensure that boost is removed after slot is over + time = (store.genesis_time + block.slot * spec.config.SECONDS_PER_SLOT + + spec.config.SECONDS_PER_SLOT) + on_tick_and_append_step(spec, store, time, test_steps) + assert store.proposer_boost_root == spec.Root() + assert spec.get_latest_attesting_balance(store, spec.hash_tree_root(block)) == 0 + + test_steps.append({ + 'checks': { + 'proposer_boost_root': encode_hex(store.proposer_boost_root), + } + }) + + yield 'steps', test_steps + + +@with_all_phases +@spec_state_test +def test_proposer_boost_root_same_slot_untimely_block(spec, state): + test_steps = [] + genesis_state = state.copy() + + # Initialization + store, anchor_block = get_genesis_forkchoice_store_and_block(spec, state) + yield 'anchor_state', state + yield 'anchor_block', anchor_block + + # Build block that serves as head ONLY on timely arrival, and ONLY in that slot + state = genesis_state.copy() + next_slots(spec, state, 3) + block = build_empty_block_for_next_slot(spec, state) + signed_block = state_transition_and_sign_block(spec, state, block) + + # Process block on untimely arrival in the same slot + time = (store.genesis_time + block.slot * spec.config.SECONDS_PER_SLOT + + spec.config.SECONDS_PER_SLOT // spec.INTERVALS_PER_SLOT) + on_tick_and_append_step(spec, store, time, test_steps) + yield from add_block(spec, store, signed_block, test_steps) + + assert store.proposer_boost_root == spec.Root() + + test_steps.append({ + 'checks': { + 'proposer_boost_root': encode_hex(store.proposer_boost_root), + } + }) + + yield 'steps', test_steps diff --git a/tests/core/pyspec/eth2spec/test/phase0/unittests/test_config_invariants.py b/tests/core/pyspec/eth2spec/test/phase0/unittests/test_config_invariants.py index 3183904c8..8836d463e 100644 --- a/tests/core/pyspec/eth2spec/test/phase0/unittests/test_config_invariants.py +++ b/tests/core/pyspec/eth2spec/test/phase0/unittests/test_config_invariants.py @@ -74,3 +74,10 @@ def test_time(spec, state): @spec_state_test def test_networking(spec, state): assert spec.RANDOM_SUBNETS_PER_VALIDATOR <= spec.ATTESTATION_SUBNET_COUNT + + +@with_all_phases +@spec_state_test +def test_fork_choice(spec, state): + assert spec.INTERVALS_PER_SLOT < spec.config.SECONDS_PER_SLOT + assert spec.config.PROPOSER_SCORE_BOOST <= 100 diff --git a/tests/formats/fork_choice/README.md b/tests/formats/fork_choice/README.md index 48dde2fb1..e4da31a9b 100644 --- a/tests/formats/fork_choice/README.md +++ b/tests/formats/fork_choice/README.md @@ -110,6 +110,7 @@ best_justified_checkpoint: { epoch: int, -- Integer value from store.best_justified_checkpoint.epoch root: string, -- Encoded 32-byte value from store.best_justified_checkpoint.root } +proposer_boost_root: string -- Encoded 32-byte value from store.proposer_boost_root ``` For example: @@ -120,6 +121,7 @@ For example: justified_checkpoint: {epoch: 3, root: '0xc25faab4acab38d3560864ca01e4d5cc4dc2cd473da053fbc03c2669143a2de4'} finalized_checkpoint: {epoch: 2, root: '0x40d32d6283ec11c53317a46808bc88f55657d93b95a1af920403187accf48f4f'} best_justified_checkpoint: {epoch: 3, root: '0xc25faab4acab38d3560864ca01e4d5cc4dc2cd473da053fbc03c2669143a2de4'} + proposer_boost_root: '0xdaa1d49d57594ced0c35688a6da133abb086d191a2ebdfd736fad95299325aeb' ``` *Note*: Each `checks` step may include one or multiple items. Each item has to be checked against the current store.