Files
lighthouse/consensus/proto_array/src/proto_array.rs
2026-03-31 15:47:50 +11:00

2025 lines
79 KiB
Rust

use crate::error::InvalidBestNodeInfo;
use crate::proto_array_fork_choice::IndexedForkChoiceNode;
use crate::{
Block, ExecutionStatus, JustifiedBalances, LatestMessage, PayloadStatus, error::Error,
};
use fixed_bytes::FixedBytesExtended;
use serde::{Deserialize, Serialize};
use ssz::BitVector;
use ssz::Encode;
use ssz::four_byte_option_impl;
use ssz_derive::{Decode, Encode};
use std::collections::{HashMap, HashSet};
use std::time::Duration;
use superstruct::superstruct;
use typenum::U512;
use types::{
AttestationShufflingId, ChainSpec, Checkpoint, Epoch, EthSpec, ExecutionBlockHash, Hash256,
Slot,
};
// Define a "legacy" implementation of `Option<usize>` which uses four bytes for encoding the union
// selector.
four_byte_option_impl!(four_byte_option_usize, usize);
four_byte_option_impl!(four_byte_option_checkpoint, Checkpoint);
fn all_true_bitvector<N: typenum::Unsigned + Clone>() -> BitVector<N> {
let mut bv = BitVector::new();
for i in 0..bv.len() {
let _ = bv.set(i, true);
}
bv
}
/// Defines an operation which may invalidate the `execution_status` of some nodes.
#[derive(Clone, Debug)]
pub enum InvalidationOperation {
/// Invalidate only `block_root` and it's descendants. Don't invalidate any ancestors.
InvalidateOne { block_root: Hash256 },
/// Invalidate blocks between `head_block_root` and `latest_valid_ancestor`.
///
/// If the `latest_valid_ancestor` is known to fork choice, invalidate all blocks between
/// `head_block_root` and `latest_valid_ancestor`. The `head_block_root` will be invalidated,
/// whilst the `latest_valid_ancestor` will not.
///
/// If `latest_valid_ancestor` is *not* known to fork choice, only invalidate the
/// `head_block_root` if `always_invalidate_head == true`.
InvalidateMany {
head_block_root: Hash256,
always_invalidate_head: bool,
latest_valid_ancestor: ExecutionBlockHash,
},
}
impl InvalidationOperation {
pub fn block_root(&self) -> Hash256 {
match self {
InvalidationOperation::InvalidateOne { block_root } => *block_root,
InvalidationOperation::InvalidateMany {
head_block_root, ..
} => *head_block_root,
}
}
pub fn latest_valid_ancestor(&self) -> Option<ExecutionBlockHash> {
match self {
InvalidationOperation::InvalidateOne { .. } => None,
InvalidationOperation::InvalidateMany {
latest_valid_ancestor,
..
} => Some(*latest_valid_ancestor),
}
}
pub fn invalidate_block_root(&self) -> bool {
match self {
InvalidationOperation::InvalidateOne { .. } => true,
InvalidationOperation::InvalidateMany {
always_invalidate_head,
..
} => *always_invalidate_head,
}
}
}
#[superstruct(
variants(V17, V29),
variant_attributes(derive(Clone, PartialEq, Debug, Encode, Decode, Serialize, Deserialize))
)]
#[derive(PartialEq, Debug, Encode, Decode, Serialize, Deserialize, Clone)]
#[ssz(enum_behaviour = "union")]
pub struct ProtoNode {
/// The `slot` is not necessary for `ProtoArray`, it just exists so external components can
/// easily query the block slot. This is useful for upstream fork choice logic.
#[superstruct(getter(copy))]
pub slot: Slot,
/// The `state_root` is not necessary for `ProtoArray` either, it also just exists for upstream
/// components (namely attestation verification).
#[superstruct(getter(copy))]
pub state_root: Hash256,
/// The root that would be used for the `attestation.data.target.root` if a LMD vote was cast
/// for this block.
///
/// The `target_root` is not necessary for `ProtoArray` either, it also just exists for upstream
/// components (namely fork choice attestation verification).
#[superstruct(getter(copy))]
pub target_root: Hash256,
pub current_epoch_shuffling_id: AttestationShufflingId,
pub next_epoch_shuffling_id: AttestationShufflingId,
#[superstruct(getter(copy))]
pub root: Hash256,
#[superstruct(getter(copy))]
#[ssz(with = "four_byte_option_usize")]
pub parent: Option<usize>,
#[superstruct(only(V17, V29), partial_getter(copy))]
pub justified_checkpoint: Checkpoint,
#[superstruct(only(V17, V29), partial_getter(copy))]
pub finalized_checkpoint: Checkpoint,
#[superstruct(getter(copy))]
pub weight: u64,
#[superstruct(getter(copy))]
#[ssz(with = "four_byte_option_usize")]
pub best_child: Option<usize>,
#[superstruct(getter(copy))]
#[ssz(with = "four_byte_option_usize")]
pub best_descendant: Option<usize>,
/// Indicates if an execution node has marked this block as valid. Also contains the execution
/// block hash. This is only used pre-Gloas.
#[superstruct(only(V17), partial_getter(copy))]
pub execution_status: ExecutionStatus,
#[superstruct(getter(copy))]
#[ssz(with = "four_byte_option_checkpoint")]
pub unrealized_justified_checkpoint: Option<Checkpoint>,
#[superstruct(getter(copy))]
#[ssz(with = "four_byte_option_checkpoint")]
pub unrealized_finalized_checkpoint: Option<Checkpoint>,
/// We track the parent payload status from which the current node was extended.
#[superstruct(only(V29), partial_getter(copy))]
pub parent_payload_status: PayloadStatus,
#[superstruct(only(V29), partial_getter(copy))]
pub empty_payload_weight: u64,
#[superstruct(only(V29), partial_getter(copy))]
pub full_payload_weight: u64,
#[superstruct(only(V29), partial_getter(copy))]
pub execution_payload_block_hash: ExecutionBlockHash,
/// Equivalent to spec's `block_timeliness[root][ATTESTATION_TIMELINESS_INDEX]`.
#[superstruct(only(V29), partial_getter(copy))]
pub block_timeliness_attestation_threshold: bool,
/// Equivalent to spec's `block_timeliness[root][PTC_TIMELINESS_INDEX]`.
#[superstruct(only(V29), partial_getter(copy))]
pub block_timeliness_ptc_threshold: bool,
/// Equivalent to spec's `store.payload_timeliness_vote[root]`.
/// PTC timeliness vote bitfield, indexed by PTC committee position.
/// Bit i set means PTC member i voted `payload_present = true`.
/// Tiebreak derived as: `num_set_bits() > ptc_size / 2`.
#[superstruct(only(V29))]
pub payload_timeliness_votes: BitVector<U512>,
/// Equivalent to spec's `store.payload_data_availability_vote[root]`.
/// PTC data availability vote bitfield, indexed by PTC committee position.
/// Bit i set means PTC member i voted `blob_data_available = true`.
/// Tiebreak derived as: `num_set_bits() > ptc_size / 2`.
#[superstruct(only(V29))]
pub payload_data_availability_votes: BitVector<U512>,
/// Whether the execution payload for this block has been received and validated locally.
/// Maps to `root in store.payload_states` in the spec.
/// When true, `is_payload_timely` and `is_payload_data_available` return true
/// regardless of PTC vote counts.
#[superstruct(only(V29), partial_getter(copy))]
pub payload_received: bool,
/// The proposer index for this block, used by `should_apply_proposer_boost`
/// to detect equivocations at the parent's slot.
#[superstruct(only(V29), partial_getter(copy))]
pub proposer_index: u64,
/// Weight from equivocating validators that voted for this block.
/// Used by `is_head_weak` to match the spec's monotonicity guarantee:
/// more attestations can only increase head weight, never decrease it.
#[superstruct(only(V29), partial_getter(copy))]
pub equivocating_attestation_score: u64,
}
impl ProtoNode {
/// Generic version of spec's `parent_payload_status` that works for pre-Gloas nodes by
/// considering their parents Empty.
/// Pre-Gloas nodes have no ePBS, default to Empty.
pub fn get_parent_payload_status(&self) -> PayloadStatus {
self.parent_payload_status().unwrap_or(PayloadStatus::Empty)
}
pub fn is_parent_node_full(&self) -> bool {
self.get_parent_payload_status() == PayloadStatus::Full
}
pub fn attestation_score(&self, payload_status: PayloadStatus) -> u64 {
match payload_status {
PayloadStatus::Pending => self.weight(),
// Pre-Gloas (V17) nodes have no payload separation — all weight
// is in `weight()`. Post-Gloas (V29) nodes track per-status weights.
PayloadStatus::Empty => self
.empty_payload_weight()
.unwrap_or_else(|_| self.weight()),
PayloadStatus::Full => self.full_payload_weight().unwrap_or_else(|_| self.weight()),
}
}
pub fn is_payload_timely<E: EthSpec>(&self) -> bool {
let Ok(node) = self.as_v29() else {
return false;
};
// Equivalent to `if root not in store.payload_states` in the spec.
if !node.payload_received {
return false;
}
node.payload_timeliness_votes.num_set_bits() > E::ptc_size() / 2
}
pub fn is_payload_data_available<E: EthSpec>(&self) -> bool {
let Ok(node) = self.as_v29() else {
return false;
};
// Equivalent to `if root not in store.payload_states` in the spec.
if !node.payload_received {
return false;
}
// TODO(gloas): add function on EthSpec for DATA_AVAILABILITY_TIMELY_THRESHOLD
node.payload_data_availability_votes.num_set_bits() > E::ptc_size() / 2
}
}
#[derive(PartialEq, Debug, Encode, Decode, Serialize, Deserialize, Copy, Clone)]
pub struct ProposerBoost {
pub root: Hash256,
pub score: u64,
}
impl Default for ProposerBoost {
fn default() -> Self {
Self {
root: Hash256::zero(),
score: 0,
}
}
}
/// Accumulated score changes for a single proto-array node during a `find_head` pass.
///
/// `delta` tracks the ordinary LMD-GHOST balance change applied to the concrete block node.
/// This is the same notion of weight that pre-gloas fork choice used.
///
///
/// Under gloas we also need to track how votes contribute to the parent's virtual payload
/// branches:
///
/// - `empty_delta` is the balance change attributable to votes that support the `Empty` payload
/// interpretation of the node
/// - `full_delta` is the balance change attributable to votes that support the `Full` payload
/// interpretation of the node
///
/// Votes in `Pending` state only affect `delta`; they do not contribute to either payload bucket.
/// During score application these payload deltas are propagated independently up the tree so that
/// ancestors can compare children using payload-aware tie breaking.
#[derive(Clone, PartialEq, Debug, Copy)]
pub struct NodeDelta {
/// Total weight change for the node. All votes contribute regardless of payload status.
pub delta: i64,
/// Weight change from `PayloadStatus::Empty` votes.
pub empty_delta: i64,
/// Weight change from `PayloadStatus::Full` votes.
pub full_delta: i64,
/// Weight from equivocating validators that voted for this node.
pub equivocating_attestation_delta: u64,
}
impl NodeDelta {
/// Classify a vote into the payload bucket it contributes to for `block_slot`.
///
/// Per the gloas model:
///
/// - a same-slot vote is `Pending`
/// - a later vote with `payload_present = true` is `Full`
/// - a later vote with `payload_present = false` is `Empty`
///
/// This classification is used only for payload-aware accounting; all votes still contribute to
/// the aggregate `delta`.
pub fn payload_status(
vote_slot: Slot,
payload_present: bool,
block_slot: Slot,
) -> PayloadStatus {
if vote_slot == block_slot {
PayloadStatus::Pending
} else if payload_present {
PayloadStatus::Full
} else {
PayloadStatus::Empty
}
}
/// Add `balance` to the payload bucket selected by `status`.
///
/// `Pending` votes do not affect payload buckets, so this becomes a no-op for that case.
pub fn add_payload_delta(
&mut self,
status: PayloadStatus,
balance: u64,
index: usize,
) -> Result<(), Error> {
let field = match status {
PayloadStatus::Full => &mut self.full_delta,
PayloadStatus::Empty => &mut self.empty_delta,
PayloadStatus::Pending => return Ok(()),
};
*field = field
.checked_add(balance as i64)
.ok_or(Error::DeltaOverflow(index))?;
Ok(())
}
/// Create a delta that only affects the aggregate block weight.
///
/// This is useful for callers or tests that only care about ordinary LMD-GHOST weight changes
/// and do not need payload-aware accounting.
pub fn from_delta(delta: i64) -> Self {
Self {
delta,
empty_delta: 0,
full_delta: 0,
equivocating_attestation_delta: 0,
}
}
/// Subtract `balance` from the payload bucket selected by `status`.
///
/// `Pending` votes do not affect payload buckets, so this becomes a no-op for that case.
pub fn sub_payload_delta(
&mut self,
status: PayloadStatus,
balance: u64,
index: usize,
) -> Result<(), Error> {
let field = match status {
PayloadStatus::Full => &mut self.full_delta,
PayloadStatus::Empty => &mut self.empty_delta,
PayloadStatus::Pending => return Ok(()),
};
*field = field
.checked_sub(balance as i64)
.ok_or(Error::DeltaOverflow(index))?;
Ok(())
}
}
/// Compare NodeDelta with i64 by comparing the aggregate `delta` field.
/// This is used by tests that only care about the total weight delta.
impl PartialEq<i64> for NodeDelta {
fn eq(&self, other: &i64) -> bool {
self.delta == *other
}
}
#[derive(PartialEq, Debug, Serialize, Deserialize, Clone)]
pub struct ProtoArray {
/// Do not attempt to prune the tree unless it has at least this many nodes. Small prunes
/// simply waste time.
pub prune_threshold: usize,
pub nodes: Vec<ProtoNode>,
pub indices: HashMap<Hash256, usize>,
pub previous_proposer_boost: ProposerBoost,
}
impl ProtoArray {
/// Iterate backwards through the array, touching all nodes and their parents and potentially
/// the best-child of each parent.
///
/// The structure of the `self.nodes` array ensures that the child of each node is always
/// touched before its parent.
///
/// For each node, the following is done:
///
/// - Update the node's weight with the corresponding delta.
/// - Back-propagate each node's delta to its parents delta.
/// - Compare the current node with the parents best-child, updating it if the current node
/// should become the best child.
/// - If required, update the parents best-descendant with the current node or its best-descendant.
#[allow(clippy::too_many_arguments)]
pub fn apply_score_changes<E: EthSpec>(
&mut self,
mut deltas: Vec<NodeDelta>,
best_justified_checkpoint: Checkpoint,
best_finalized_checkpoint: Checkpoint,
current_slot: Slot,
) -> Result<(), Error> {
if deltas.len() != self.indices.len() {
return Err(Error::InvalidDeltaLen {
deltas: deltas.len(),
indices: self.indices.len(),
});
}
// Iterate backwards through all indices in `self.nodes`.
for node_index in (0..self.nodes.len()).rev() {
let node = self
.nodes
.get_mut(node_index)
.ok_or(Error::InvalidNodeIndex(node_index))?;
// There is no need to adjust the balances or manage parent of the zero hash since it
// is an alias to the genesis block. The weight applied to the genesis block is
// irrelevant as we _always_ choose it and it's impossible for it to have a parent.
if node.root() == Hash256::zero() {
continue;
}
let execution_status_is_invalid = if let Ok(proto_node) = node.as_v17()
&& proto_node.execution_status.is_invalid()
{
true
} else {
false
};
let node_delta = deltas
.get(node_index)
.copied()
.ok_or(Error::InvalidNodeDelta(node_index))?;
let delta = if execution_status_is_invalid {
// If the node has an invalid execution payload, reduce its weight to zero.
0_i64
.checked_sub(node.weight() as i64)
.ok_or(Error::InvalidExecutionDeltaOverflow(node_index))?
} else {
node_delta.delta
};
let (node_empty_delta, node_full_delta) = if node.as_v29().is_ok() {
(node_delta.empty_delta, node_delta.full_delta)
} else {
(0, 0)
};
// Proposer boost is NOT applied here. It is computed on-the-fly
// during the virtual tree walk in `get_weight`, matching the spec's
// `get_weight` which adds boost separately from `get_attestation_score`.
// Apply the delta to the node.
if execution_status_is_invalid {
// Invalid nodes always have a weight of 0.
*node.weight_mut() = 0;
} else {
*node.weight_mut() = apply_delta(node.weight(), delta, node_index)?;
}
// Apply post-Gloas score deltas.
if let Ok(node) = node.as_v29_mut() {
node.empty_payload_weight =
apply_delta(node.empty_payload_weight, node_empty_delta, node_index)?;
node.full_payload_weight =
apply_delta(node.full_payload_weight, node_full_delta, node_index)?;
node.equivocating_attestation_score = node
.equivocating_attestation_score
.saturating_add(node_delta.equivocating_attestation_delta);
}
// Update the parent delta (if any).
if let Some(parent_index) = node.parent() {
let parent_delta = deltas
.get_mut(parent_index)
.ok_or(Error::InvalidParentDelta(parent_index))?;
// Back-propagate the node's delta to its parent.
parent_delta.delta = parent_delta
.delta
.checked_add(delta)
.ok_or(Error::DeltaOverflow(parent_index))?;
// Route ALL child weight into the parent's FULL or EMPTY bucket
// based on the child's `parent_payload_status` (the ancestor path
// direction). If this child is on the FULL path from the parent,
// all weight supports the parent's FULL virtual node, and vice versa.
if let Ok(child_v29) = node.as_v29() {
if child_v29.parent_payload_status == PayloadStatus::Full {
parent_delta.full_delta = parent_delta
.full_delta
.checked_add(delta)
.ok_or(Error::DeltaOverflow(parent_index))?;
} else {
parent_delta.empty_delta = parent_delta
.empty_delta
.checked_add(delta)
.ok_or(Error::DeltaOverflow(parent_index))?;
}
} else {
// V17 child of a V29 parent (fork transition): treat as FULL
// since V17 nodes always have execution payloads inline.
parent_delta.full_delta = parent_delta
.full_delta
.checked_add(delta)
.ok_or(Error::DeltaOverflow(parent_index))?;
}
}
}
// Proposer boost is now applied on-the-fly in `get_weight` during the
// walk, so clear any stale boost from a prior call.
self.previous_proposer_boost = ProposerBoost::default();
// A second time, iterate backwards through all indices in `self.nodes`.
//
// We _must_ perform these functions separate from the weight-updating loop above to ensure
// that we have a fully coherent set of weights before updating parent
// best-child/descendant.
for node_index in (0..self.nodes.len()).rev() {
let node = self
.nodes
.get_mut(node_index)
.ok_or(Error::InvalidNodeIndex(node_index))?;
// If the node has a parent, try to update its best-child and best-descendant.
if let Some(parent_index) = node.parent() {
self.maybe_update_best_child_and_descendant::<E>(
parent_index,
node_index,
current_slot,
best_justified_checkpoint,
best_finalized_checkpoint,
)?;
}
}
Ok(())
}
/// Register a block with the fork choice.
///
/// It is only sane to supply a `None` parent for the genesis block.
pub fn on_block<E: EthSpec>(
&mut self,
block: Block,
current_slot: Slot,
best_justified_checkpoint: Checkpoint,
best_finalized_checkpoint: Checkpoint,
spec: &ChainSpec,
time_into_slot: Duration,
) -> Result<(), Error> {
// If the block is already known, simply ignore it.
if self.indices.contains_key(&block.root) {
return Ok(());
}
// We do not allow `proposer_index=None` for calls to `on_block`, it is only non-optional
// for backwards-compatibility with pre-Gloas V17 proto nodes.
let Some(proposer_index) = block.proposer_index else {
return Err(Error::OnBlockRequiresProposerIndex);
};
let node_index = self.nodes.len();
let parent_index = block
.parent_root
.and_then(|parent| self.indices.get(&parent).copied());
let node = if !spec.fork_name_at_slot::<E>(current_slot).gloas_enabled() {
ProtoNode::V17(ProtoNodeV17 {
slot: block.slot,
root: block.root,
target_root: block.target_root,
current_epoch_shuffling_id: block.current_epoch_shuffling_id,
next_epoch_shuffling_id: block.next_epoch_shuffling_id,
state_root: block.state_root,
parent: parent_index,
justified_checkpoint: block.justified_checkpoint,
finalized_checkpoint: block.finalized_checkpoint,
weight: 0,
best_child: None,
best_descendant: None,
execution_status: block.execution_status,
unrealized_justified_checkpoint: block.unrealized_justified_checkpoint,
unrealized_finalized_checkpoint: block.unrealized_finalized_checkpoint,
})
} else {
let is_current_slot = current_slot == block.slot;
let execution_payload_block_hash =
block
.execution_payload_block_hash
.ok_or(Error::BrokenBlock {
block_root: block.root,
})?;
let execution_payload_parent_hash =
block
.execution_payload_parent_hash
.ok_or(Error::BrokenBlock {
block_root: block.root,
})?;
let parent_payload_status: PayloadStatus = if let Some(parent_node) =
parent_index.and_then(|idx| self.nodes.get(idx))
{
// Get the parent's execution block hash, handling both V17 and V29 nodes.
// V17 parents occur during the Gloas fork transition.
// TODO(gloas): the spec's `get_parent_payload_status` assumes all blocks are
// post-Gloas with bids. Revisit once the spec clarifies fork-transition behavior.
let parent_el_block_hash = match parent_node {
ProtoNode::V29(v29) => Some(v29.execution_payload_block_hash),
ProtoNode::V17(v17) => v17.execution_status.block_hash(),
};
// Per spec's `is_parent_node_full`: if the child's EL parent hash
// matches the parent's EL block hash, the child extends the parent's
// payload chain, meaning the parent was Full.
if parent_el_block_hash.is_some_and(|hash| execution_payload_parent_hash == hash) {
PayloadStatus::Full
} else {
PayloadStatus::Empty
}
} else {
// Parent is missing (genesis or pruned due to finalization). Default to Full
// since this path should only be hit at Gloas genesis, and extending the payload
// chain is the safe default.
PayloadStatus::Full
};
// Per spec `get_forkchoice_store`: the anchor (genesis) block has
// its payload state initialized (`payload_states = {anchor_root: ...}`).
// Without `payload_received = true` on genesis, the FULL virtual
// child doesn't exist in the spec's `get_node_children`, making all
// Full concrete children of genesis unreachable in `get_head`.
let is_genesis = parent_index.is_none();
ProtoNode::V29(ProtoNodeV29 {
slot: block.slot,
root: block.root,
target_root: block.target_root,
current_epoch_shuffling_id: block.current_epoch_shuffling_id,
next_epoch_shuffling_id: block.next_epoch_shuffling_id,
state_root: block.state_root,
parent: parent_index,
justified_checkpoint: block.justified_checkpoint,
finalized_checkpoint: block.finalized_checkpoint,
weight: 0,
best_child: None,
best_descendant: None,
unrealized_justified_checkpoint: block.unrealized_justified_checkpoint,
unrealized_finalized_checkpoint: block.unrealized_finalized_checkpoint,
parent_payload_status,
empty_payload_weight: 0,
full_payload_weight: 0,
execution_payload_block_hash,
// Per spec `get_forkchoice_store`: the anchor block's PTC votes are
// initialized to all-True, ensuring `is_payload_timely` and
// `is_payload_data_available` return true for the anchor.
payload_timeliness_votes: if is_genesis {
all_true_bitvector()
} else {
BitVector::default()
},
payload_data_availability_votes: if is_genesis {
all_true_bitvector()
} else {
BitVector::default()
},
payload_received: is_genesis,
proposer_index,
// Spec: `record_block_timeliness` + `get_forkchoice_store`.
// Anchor gets [True, True]. Others computed from time_into_slot.
block_timeliness_attestation_threshold: is_genesis
|| (is_current_slot
&& time_into_slot < spec.get_unaggregated_attestation_due()),
// TODO(gloas): use GLOAS-specific PTC due threshold once
// `get_payload_attestation_due_ms` is on ChainSpec.
block_timeliness_ptc_threshold: is_genesis
|| (is_current_slot && time_into_slot < spec.get_slot_duration() / 2),
equivocating_attestation_score: 0,
})
};
// If the parent has an invalid execution status, return an error before adding the
// block to `self`. This applies only when the parent is a V17 node with execution tracking.
if let Some(parent_index) = node.parent() {
let parent = self
.nodes
.get(parent_index)
.ok_or(Error::InvalidNodeIndex(parent_index))?;
// Execution status tracking only exists on V17 (pre-Gloas) nodes.
if let Ok(v17) = parent.as_v17()
&& v17.execution_status.is_invalid()
{
return Err(Error::ParentExecutionStatusIsInvalid {
block_root: block.root,
parent_root: parent.root(),
});
}
}
self.indices.insert(node.root(), node_index);
self.nodes.push(node.clone());
if let Some(parent_index) = node.parent() {
self.maybe_update_best_child_and_descendant::<E>(
parent_index,
node_index,
current_slot,
best_justified_checkpoint,
best_finalized_checkpoint,
)?;
if matches!(block.execution_status, ExecutionStatus::Valid(_)) {
self.propagate_execution_payload_validation_by_index(parent_index)?;
}
}
Ok(())
}
/// Spec: `is_head_weak`.
///
/// The spec adds weight from equivocating validators in the head slot's
/// committees. We approximate this with `equivocating_attestation_score`
/// which tracks equivocating validators that voted for this block (close
/// but not identical to committee membership).
fn is_head_weak<E: EthSpec>(
&self,
head_node: &ProtoNode,
justified_balances: &JustifiedBalances,
spec: &ChainSpec,
) -> bool {
let reorg_threshold = calculate_committee_fraction::<E>(
justified_balances,
spec.reorg_head_weight_threshold.unwrap_or(20),
)
.unwrap_or(0);
let head_weight = head_node
.attestation_score(PayloadStatus::Pending)
.saturating_add(head_node.equivocating_attestation_score().unwrap_or(0));
head_weight < reorg_threshold
}
/// Spec's `should_apply_proposer_boost` for Gloas.
///
/// Returns `true` if the proposer boost should be kept. Returns `false` if the
/// boost should be subtracted (invalidated) because the parent is weak and there
/// are no equivocating blocks at the parent's slot.
fn should_apply_proposer_boost<E: EthSpec>(
&self,
proposer_boost_root: Hash256,
justified_balances: &JustifiedBalances,
spec: &ChainSpec,
) -> Result<bool, Error> {
if proposer_boost_root.is_zero() {
return Ok(false);
}
let block_index = *self
.indices
.get(&proposer_boost_root)
.ok_or(Error::NodeUnknown(proposer_boost_root))?;
let block = self
.nodes
.get(block_index)
.ok_or(Error::InvalidNodeIndex(block_index))?;
// TODO(gloas): handle parent unknown case?
let parent_index = block
.parent()
.ok_or(Error::NodeUnknown(proposer_boost_root))?;
let parent = self
.nodes
.get(parent_index)
.ok_or(Error::InvalidNodeIndex(parent_index))?;
let slot = block.slot();
// Apply proposer boost if `parent` is not from the previous slot
if parent.slot().saturating_add(1_u64) < slot {
return Ok(true);
}
// Apply proposer boost if `parent` is not weak
if !self.is_head_weak::<E>(parent, justified_balances, spec) {
return Ok(true);
}
// Parent is weak. Apply boost unless there's an equivocating block at
// the parent's slot from the same proposer.
let parent_slot = parent.slot();
let parent_root = parent.root();
// TODO(gloas): handle proposer index for pre-Gloas blocks?
let parent_proposer = parent.proposer_index();
let has_equivocation = self.nodes.iter().any(|node| {
if let Ok(timeliness) = node.block_timeliness_ptc_threshold()
&& let Ok(proposer_index) = node.proposer_index()
{
timeliness
&& Ok(proposer_index) == parent_proposer
&& node.slot() == parent_slot
&& node.root() != parent_root
} else {
// Pre-Gloas.
false
}
});
Ok(!has_equivocation)
}
/// Process an execution payload for a Gloas block.
///
/// Sets `payload_received` to true, which makes `is_payload_timely` and
/// `is_payload_data_available` return true regardless of PTC votes.
/// This maps to `store.payload_states[root] = state` in the spec.
pub fn on_valid_execution_payload(&mut self, block_root: Hash256) -> Result<(), Error> {
let index = *self
.indices
.get(&block_root)
.ok_or(Error::NodeUnknown(block_root))?;
let node = self
.nodes
.get_mut(index)
.ok_or(Error::InvalidNodeIndex(index))?;
let v29 = node
.as_v29_mut()
.map_err(|_| Error::InvalidNodeVariant { block_root })?;
v29.payload_received = true;
Ok(())
}
/// Updates the `block_root` and all ancestors to have validated execution payloads.
///
/// Returns an error if:
///
/// - The `block-root` is unknown.
/// - Any of the to-be-validated payloads are already invalid.
pub fn propagate_execution_payload_validation(
&mut self,
block_root: Hash256,
) -> Result<(), Error> {
let index = *self
.indices
.get(&block_root)
.ok_or(Error::NodeUnknown(block_root))?;
self.propagate_execution_payload_validation_by_index(index)
}
/// Updates the `verified_node_index` and all ancestors to have validated execution payloads.
///
/// Returns an error if:
///
/// - The `verified_node_index` is unknown.
/// - Any of the to-be-validated payloads are already invalid.
fn propagate_execution_payload_validation_by_index(
&mut self,
verified_node_index: usize,
) -> Result<(), Error> {
let mut index = verified_node_index;
loop {
let node = self
.nodes
.get_mut(index)
.ok_or(Error::InvalidNodeIndex(index))?;
let parent_index = match node {
ProtoNode::V17(node) => match node.execution_status {
// We have reached a node that we already know is valid. No need to iterate further
// since we assume an ancestors have already been set to valid.
ExecutionStatus::Valid(_) => return Ok(()),
// We have reached an irrelevant node, this node is prior to a terminal execution
// block. There's no need to iterate further, it's impossible for this block to have
// any relevant ancestors.
ExecutionStatus::Irrelevant(_) => return Ok(()),
// The block has an unknown status, set it to valid since any ancestor of a valid
// payload can be considered valid.
ExecutionStatus::Optimistic(payload_block_hash) => {
node.execution_status = ExecutionStatus::Valid(payload_block_hash);
if let Some(parent_index) = node.parent {
parent_index
} else {
// We have reached the root block, iteration complete.
return Ok(());
}
}
// An ancestor of the valid payload was invalid. This is a serious error which
// indicates a consensus failure in the execution node. This is unrecoverable.
ExecutionStatus::Invalid(ancestor_payload_block_hash) => {
return Err(Error::InvalidAncestorOfValidPayload {
ancestor_block_root: node.root,
ancestor_payload_block_hash,
});
}
},
// Gloas nodes don't carry `ExecutionStatus`. Mark the validated
// block as payload-received so that `is_payload_timely` /
// `is_payload_data_available` and `index == 1` attestations work.
ProtoNode::V29(node) => {
if index == verified_node_index {
node.payload_received = true;
}
if let Some(parent_index) = node.parent {
parent_index
} else {
return Ok(());
}
}
};
index = parent_index;
}
}
/// Invalidate zero or more blocks, as specified by the `InvalidationOperation`.
///
/// See the documentation of `InvalidationOperation` for usage.
pub fn propagate_execution_payload_invalidation<E: EthSpec>(
&mut self,
op: &InvalidationOperation,
best_finalized_checkpoint: Checkpoint,
) -> Result<(), Error> {
let mut invalidated_indices: HashSet<usize> = <_>::default();
let head_block_root = op.block_root();
/*
* Step 1:
*
* Find the `head_block_root` and maybe iterate backwards and invalidate ancestors. Record
* all invalidated block indices in `invalidated_indices`.
*/
let mut index = *self
.indices
.get(&head_block_root)
.ok_or(Error::NodeUnknown(head_block_root))?;
// Try to map the ancestor payload *hash* to an ancestor beacon block *root*.
let latest_valid_ancestor_root = op
.latest_valid_ancestor()
.and_then(|hash| self.execution_block_hash_to_beacon_block_root(&hash));
// Set to `true` if both conditions are satisfied:
//
// 1. The `head_block_root` is a descendant of `latest_valid_ancestor_hash`
// 2. The `latest_valid_ancestor_hash` is equal to or a descendant of the finalized block.
let latest_valid_ancestor_is_descendant =
latest_valid_ancestor_root.is_some_and(|ancestor_root| {
self.is_descendant(ancestor_root, head_block_root)
&& self.is_finalized_checkpoint_or_descendant::<E>(
ancestor_root,
best_finalized_checkpoint,
)
});
// Collect all *ancestors* which were declared invalid since they reside between the
// `head_block_root` and the `latest_valid_ancestor_root`.
loop {
let node = self
.nodes
.get_mut(index)
.ok_or(Error::InvalidNodeIndex(index))?;
let node_execution_status = node.execution_status();
match node_execution_status {
Ok(ExecutionStatus::Valid(hash))
| Ok(ExecutionStatus::Invalid(hash))
| Ok(ExecutionStatus::Optimistic(hash)) => {
// If we're no longer processing the `head_block_root` and the last valid
// ancestor is unknown, exit this loop and proceed to invalidate and
// descendants of `head_block_root`/`latest_valid_ancestor_root`.
//
// In effect, this means that if an unknown hash (junk or pre-finalization) is
// supplied, don't validate any ancestors. The alternative is to invalidate
// *all* ancestors, which would likely involve shutting down the client due to
// an invalid justified checkpoint.
if !latest_valid_ancestor_is_descendant && node.root() != head_block_root {
break;
} else if op.latest_valid_ancestor() == Some(hash) {
// If the `best_child` or `best_descendant` of the latest valid hash was
// invalidated, set those fields to `None`.
//
// In theory, an invalid `best_child` necessarily infers an invalid
// `best_descendant`. However, we check each variable independently to
// defend against errors which might result in an invalid block being set as
// head.
if node
.best_child()
.is_some_and(|i| invalidated_indices.contains(&i))
{
*node.best_child_mut() = None
}
if node
.best_descendant()
.is_some_and(|i| invalidated_indices.contains(&i))
{
*node.best_descendant_mut() = None
}
break;
}
}
Ok(ExecutionStatus::Irrelevant(_)) => break,
Err(_) => break,
}
// Only invalidate the head block if either:
//
// - The head block was specifically indicated to be invalidated.
// - The latest valid hash is a known ancestor.
if node.root() != head_block_root
|| op.invalidate_block_root()
|| latest_valid_ancestor_is_descendant
{
match node.execution_status() {
// It's illegal for an execution client to declare that some previously-valid block
// is now invalid. This is a consensus failure on their behalf.
Ok(ExecutionStatus::Valid(hash)) => {
return Err(Error::ValidExecutionStatusBecameInvalid {
block_root: node.root(),
payload_block_hash: hash,
});
}
Ok(ExecutionStatus::Optimistic(hash)) => {
invalidated_indices.insert(index);
if let ProtoNode::V17(node) = node {
node.execution_status = ExecutionStatus::Invalid(hash);
}
// It's impossible for an invalid block to lead to a "best" block, so set these
// fields to `None`.
//
// Failing to set these values will result in `Self::node_leads_to_viable_head`
// returning `false` for *valid* ancestors of invalid blocks.
*node.best_child_mut() = None;
*node.best_descendant_mut() = None;
}
// The block is already invalid, but keep going backwards to ensure all ancestors
// are updated.
Ok(ExecutionStatus::Invalid(_)) => (),
// This block is pre-merge, therefore it has no execution status. Nor do its
// ancestors.
Ok(ExecutionStatus::Irrelevant(_)) => break,
Err(_) => (),
}
}
if let Some(parent_index) = node.parent() {
index = parent_index
} else {
// The root of the block tree has been reached (aka the finalized block), without
// matching `latest_valid_ancestor_hash`. It's not possible or useful to go any
// further back: the finalized checkpoint is invalid so all is lost!
break;
}
}
/*
* Step 2:
*
* Start at either the `latest_valid_ancestor` or the `head_block_root` and iterate
* *forwards* to invalidate all descendants of all blocks in `invalidated_indices`.
*/
let starting_block_root = latest_valid_ancestor_root
.filter(|_| latest_valid_ancestor_is_descendant)
.unwrap_or(head_block_root);
let latest_valid_ancestor_index = *self
.indices
.get(&starting_block_root)
.ok_or(Error::NodeUnknown(starting_block_root))?;
let first_potential_descendant = latest_valid_ancestor_index + 1;
// Collect all *descendants* which have been declared invalid since they're the descendant of a block
// with an invalid execution payload.
for index in first_potential_descendant..self.nodes.len() {
let node = self
.nodes
.get_mut(index)
.ok_or(Error::InvalidNodeIndex(index))?;
if let Some(parent_index) = node.parent()
&& invalidated_indices.contains(&parent_index)
{
match node.execution_status() {
Ok(ExecutionStatus::Valid(hash)) => {
return Err(Error::ValidExecutionStatusBecameInvalid {
block_root: node.root(),
payload_block_hash: hash,
});
}
Ok(ExecutionStatus::Optimistic(hash)) | Ok(ExecutionStatus::Invalid(hash)) => {
if let ProtoNode::V17(node) = node {
node.execution_status = ExecutionStatus::Invalid(hash)
}
}
Ok(ExecutionStatus::Irrelevant(_)) => {
return Err(Error::IrrelevantDescendant {
block_root: node.root(),
});
}
Err(_) => (),
}
invalidated_indices.insert(index);
}
}
Ok(())
}
/// Follows the best-descendant links to find the best-block (i.e., head-block).
///
/// ## Notes
///
/// The result of this function is not guaranteed to be accurate if `Self::on_new_block` has
/// been called without a subsequent `Self::apply_score_changes` call. This is because
/// `on_new_block` does not attempt to walk backwards through the tree and update the
/// best-child/best-descendant links.
#[allow(clippy::too_many_arguments)]
pub fn find_head<E: EthSpec>(
&self,
justified_root: &Hash256,
current_slot: Slot,
best_justified_checkpoint: Checkpoint,
best_finalized_checkpoint: Checkpoint,
proposer_boost_root: Hash256,
justified_balances: &JustifiedBalances,
spec: &ChainSpec,
) -> Result<(Hash256, PayloadStatus), Error> {
let justified_index = self
.indices
.get(justified_root)
.copied()
.ok_or(Error::JustifiedNodeUnknown(*justified_root))?;
let justified_node = self
.nodes
.get(justified_index)
.ok_or(Error::InvalidJustifiedIndex(justified_index))?;
// Since there are no valid descendants of a justified block with an invalid execution
// payload, there would be no head to choose from.
// Execution status tracking only exists on V17 (pre-Gloas) nodes.
if let Ok(v17) = justified_node.as_v17()
&& v17.execution_status.is_invalid()
{
return Err(Error::InvalidJustifiedCheckpointExecutionStatus {
justified_root: *justified_root,
});
}
// In the post-Gloas world, always use a virtual tree walk.
//
// Best child/best descendant is dead.
let best_fc_node = self.find_head_walk::<E>(
justified_index,
current_slot,
best_justified_checkpoint,
best_finalized_checkpoint,
proposer_boost_root,
justified_balances,
spec,
)?;
// Perform a sanity check that the node is indeed valid to be the head.
let best_node = self
.nodes
.get(best_fc_node.proto_node_index)
.ok_or(Error::InvalidNodeIndex(best_fc_node.proto_node_index))?;
if !self.node_is_viable_for_head::<E>(
best_node,
current_slot,
best_justified_checkpoint,
best_finalized_checkpoint,
) {
return Err(Error::InvalidBestNode(Box::new(InvalidBestNodeInfo {
current_slot,
start_root: *justified_root,
justified_checkpoint: best_justified_checkpoint,
finalized_checkpoint: best_finalized_checkpoint,
head_root: best_node.root(),
head_justified_checkpoint: *best_node.justified_checkpoint(),
head_finalized_checkpoint: *best_node.finalized_checkpoint(),
})));
}
Ok((best_fc_node.root, best_fc_node.payload_status))
}
/// Spec: `get_filtered_block_tree`.
///
/// Returns the set of node indices on viable branches — those with at least
/// one leaf descendant with correct justified/finalized checkpoints.
fn get_filtered_block_tree<E: EthSpec>(
&self,
start_index: usize,
current_slot: Slot,
best_justified_checkpoint: Checkpoint,
best_finalized_checkpoint: Checkpoint,
) -> HashSet<usize> {
let mut viable = HashSet::new();
self.filter_block_tree::<E>(
start_index,
current_slot,
best_justified_checkpoint,
best_finalized_checkpoint,
&mut viable,
);
viable
}
/// Spec: `filter_block_tree`.
fn filter_block_tree<E: EthSpec>(
&self,
node_index: usize,
current_slot: Slot,
best_justified_checkpoint: Checkpoint,
best_finalized_checkpoint: Checkpoint,
viable: &mut HashSet<usize>,
) -> bool {
let Some(node) = self.nodes.get(node_index) else {
return false;
};
// Skip invalid children — they aren't in store.blocks in the spec.
let children: Vec<usize> = self
.nodes
.iter()
.enumerate()
.filter(|(_, child)| {
child.parent() == Some(node_index)
&& !child
.execution_status()
.is_ok_and(|status| status.is_invalid())
})
.map(|(i, _)| i)
.collect();
if !children.is_empty() {
// Evaluate ALL children (no short-circuit) to mark all viable branches.
let any_viable = children
.iter()
.map(|&child_index| {
self.filter_block_tree::<E>(
child_index,
current_slot,
best_justified_checkpoint,
best_finalized_checkpoint,
viable,
)
})
.collect::<Vec<_>>()
.into_iter()
.any(|v| v);
if any_viable {
viable.insert(node_index);
return true;
}
return false;
}
// Leaf node: check viability.
if self.node_is_viable_for_head::<E>(
node,
current_slot,
best_justified_checkpoint,
best_finalized_checkpoint,
) {
viable.insert(node_index);
return true;
}
false
}
/// Spec: `get_head`.
#[allow(clippy::too_many_arguments)]
fn find_head_walk<E: EthSpec>(
&self,
start_index: usize,
current_slot: Slot,
best_justified_checkpoint: Checkpoint,
best_finalized_checkpoint: Checkpoint,
proposer_boost_root: Hash256,
justified_balances: &JustifiedBalances,
spec: &ChainSpec,
) -> Result<IndexedForkChoiceNode, Error> {
let mut head = IndexedForkChoiceNode {
root: best_justified_checkpoint.root,
proto_node_index: start_index,
payload_status: PayloadStatus::Pending,
};
// Spec: `get_filtered_block_tree`.
let viable_nodes = self.get_filtered_block_tree::<E>(
start_index,
current_slot,
best_justified_checkpoint,
best_finalized_checkpoint,
);
// Compute once rather than per-child per-level.
let apply_proposer_boost =
self.should_apply_proposer_boost::<E>(proposer_boost_root, justified_balances, spec)?;
loop {
let children: Vec<_> = self
.get_node_children(&head)?
.into_iter()
.filter(|(fc_node, _)| viable_nodes.contains(&fc_node.proto_node_index))
.collect();
if children.is_empty() {
return Ok(head);
}
head = children
.into_iter()
.map(|(child, _)| -> Result<_, Error> {
let proto_node = self
.nodes
.get(child.proto_node_index)
.ok_or(Error::InvalidNodeIndex(child.proto_node_index))?;
let weight = self.get_weight::<E>(
&child,
proto_node,
apply_proposer_boost,
proposer_boost_root,
current_slot,
justified_balances,
spec,
)?;
let payload_status_tiebreaker = self.get_payload_status_tiebreaker::<E>(
&child,
proto_node,
current_slot,
proposer_boost_root,
)?;
Ok((child, weight, payload_status_tiebreaker))
})
.collect::<Result<Vec<_>, Error>>()?
.into_iter()
.max_by_key(|(child, weight, payload_status_tiebreaker)| {
(*weight, child.root, *payload_status_tiebreaker)
})
.map(|(child, _, _)| child)
.ok_or(Error::NoViableChildren)?;
}
}
/// Spec: `get_weight`.
#[allow(clippy::too_many_arguments)]
fn get_weight<E: EthSpec>(
&self,
fc_node: &IndexedForkChoiceNode,
proto_node: &ProtoNode,
apply_proposer_boost: bool,
proposer_boost_root: Hash256,
current_slot: Slot,
justified_balances: &JustifiedBalances,
spec: &ChainSpec,
) -> Result<u64, Error> {
if fc_node.payload_status == PayloadStatus::Pending
|| proto_node.slot().saturating_add(1_u64) != current_slot
{
let attestation_score = proto_node.attestation_score(fc_node.payload_status);
if !apply_proposer_boost {
return Ok(attestation_score);
}
// Spec: proposer boost is treated as a synthetic vote.
let message = LatestMessage {
slot: current_slot,
root: proposer_boost_root,
payload_present: false,
};
let proposer_score = if self.is_supporting_vote(fc_node, &message)? {
get_proposer_score::<E>(justified_balances, spec)?
} else {
0
};
Ok(attestation_score.saturating_add(proposer_score))
} else {
Ok(0)
}
}
/// Spec: `is_supporting_vote`.
fn is_supporting_vote(
&self,
node: &IndexedForkChoiceNode,
message: &LatestMessage,
) -> Result<bool, Error> {
let block = self
.nodes
.get(node.proto_node_index)
.ok_or(Error::InvalidNodeIndex(node.proto_node_index))?;
if node.root == message.root {
if node.payload_status == PayloadStatus::Pending {
return Ok(true);
}
// For the proposer boost case: message.slot == current_slot == block.slot,
// so this returns false — boost does not support EMPTY/FULL of the
// boosted block itself, only its ancestors.
if message.slot <= block.slot() {
return Ok(false);
}
if message.payload_present {
Ok(node.payload_status == PayloadStatus::Full)
} else {
Ok(node.payload_status == PayloadStatus::Empty)
}
} else {
let ancestor = self.get_ancestor_node(message.root, block.slot())?;
Ok(node.root == ancestor.root
&& (node.payload_status == PayloadStatus::Pending
|| node.payload_status == ancestor.payload_status))
}
}
/// Spec: `get_ancestor` (modified to return ForkChoiceNode with payload_status).
fn get_ancestor_node(&self, root: Hash256, slot: Slot) -> Result<IndexedForkChoiceNode, Error> {
let index = *self.indices.get(&root).ok_or(Error::NodeUnknown(root))?;
let block = self
.nodes
.get(index)
.ok_or(Error::InvalidNodeIndex(index))?;
if block.slot() <= slot {
return Ok(IndexedForkChoiceNode {
root,
proto_node_index: index,
payload_status: PayloadStatus::Pending,
});
}
// Walk up until we find the ancestor at `slot`.
let mut child_index = index;
let mut current_index = block.parent().ok_or(Error::NodeUnknown(block.root()))?;
loop {
let current = self
.nodes
.get(current_index)
.ok_or(Error::InvalidNodeIndex(current_index))?;
if current.slot() <= slot {
let child = self
.nodes
.get(child_index)
.ok_or(Error::InvalidNodeIndex(child_index))?;
return Ok(IndexedForkChoiceNode {
root: current.root(),
proto_node_index: current_index,
payload_status: child.get_parent_payload_status(),
});
}
child_index = current_index;
current_index = current.parent().ok_or(Error::NodeUnknown(current.root()))?;
}
}
/// Spec: `get_node_children`.
fn get_node_children(
&self,
node: &IndexedForkChoiceNode,
) -> Result<Vec<(IndexedForkChoiceNode, ProtoNode)>, Error> {
if node.payload_status == PayloadStatus::Pending {
let proto_node = self
.nodes
.get(node.proto_node_index)
.ok_or(Error::InvalidNodeIndex(node.proto_node_index))?;
let mut children = vec![(node.with_status(PayloadStatus::Empty), proto_node.clone())];
// The FULL virtual child only exists if the payload has been received.
if proto_node.payload_received().is_ok_and(|received| received) {
children.push((node.with_status(PayloadStatus::Full), proto_node.clone()));
}
Ok(children)
} else {
Ok(self
.nodes
.iter()
.enumerate()
.filter(|(_, child_node)| {
child_node.parent() == Some(node.proto_node_index)
&& child_node.get_parent_payload_status() == node.payload_status
})
.map(|(child_index, child_node)| {
(
IndexedForkChoiceNode {
root: child_node.root(),
proto_node_index: child_index,
payload_status: PayloadStatus::Pending,
},
child_node.clone(),
)
})
.collect())
}
}
fn get_payload_status_tiebreaker<E: EthSpec>(
&self,
fc_node: &IndexedForkChoiceNode,
proto_node: &ProtoNode,
current_slot: Slot,
proposer_boost_root: Hash256,
) -> Result<u8, Error> {
if fc_node.payload_status == PayloadStatus::Pending
|| proto_node.slot().saturating_add(1_u64) != current_slot
{
Ok(fc_node.payload_status as u8)
} else if fc_node.payload_status == PayloadStatus::Empty {
Ok(1)
} else if self.should_extend_payload::<E>(fc_node, proto_node, proposer_boost_root)? {
Ok(2)
} else {
Ok(0)
}
}
fn should_extend_payload<E: EthSpec>(
&self,
fc_node: &IndexedForkChoiceNode,
proto_node: &ProtoNode,
proposer_boost_root: Hash256,
) -> Result<bool, Error> {
// Per spec: `proposer_root == Root()` is one of the `or` conditions that
// makes `should_extend_payload` return True.
if proposer_boost_root.is_zero() {
return Ok(true);
}
let proposer_boost_node_index = *self
.indices
.get(&proposer_boost_root)
.ok_or(Error::NodeUnknown(proposer_boost_root))?;
let proposer_boost_node = self
.nodes
.get(proposer_boost_node_index)
.ok_or(Error::InvalidNodeIndex(proposer_boost_node_index))?;
let parent_index = proposer_boost_node
.parent()
.ok_or(Error::NodeUnknown(proposer_boost_root))?;
let proposer_boost_parent_root = self
.nodes
.get(parent_index)
.ok_or(Error::InvalidNodeIndex(parent_index))?
.root();
Ok(
(proto_node.is_payload_timely::<E>() && proto_node.is_payload_data_available::<E>())
|| proposer_boost_parent_root != fc_node.root
|| proposer_boost_node.is_parent_node_full(),
)
}
/// Update the tree with new finalization information. The tree is only actually pruned if both
/// of the two following criteria are met:
///
/// - The supplied finalized epoch and root are different to the current values.
/// - The number of nodes in `self` is at least `self.prune_threshold`.
///
/// # Errors
///
/// Returns errors if:
///
/// - The finalized epoch is less than the current one.
/// - The finalized epoch is equal to the current one, but the finalized root is different.
/// - There is some internal error relating to invalid indices inside `self`.
pub fn maybe_prune(&mut self, finalized_root: Hash256) -> Result<(), Error> {
let finalized_index = *self
.indices
.get(&finalized_root)
.ok_or(Error::FinalizedNodeUnknown(finalized_root))?;
if finalized_index < self.prune_threshold {
// Pruning at small numbers incurs more cost than benefit.
return Ok(());
}
// Remove the `self.indices` key/values for all the to-be-deleted nodes.
for node_index in 0..finalized_index {
let root = &self
.nodes
.get(node_index)
.ok_or(Error::InvalidNodeIndex(node_index))?
.root();
self.indices.remove(root);
}
// Drop all the nodes prior to finalization.
self.nodes = self.nodes.split_off(finalized_index);
// Adjust the indices map.
for (_root, index) in self.indices.iter_mut() {
*index = index
.checked_sub(finalized_index)
.ok_or(Error::IndexOverflow("indices"))?;
}
// Iterate through all the existing nodes and adjust their indices to match the new layout
// of `self.nodes`.
for node in self.nodes.iter_mut() {
if let Some(parent) = node.parent() {
// If `node.parent` is less than `finalized_index`, set it to `None`.
*node.parent_mut() = parent.checked_sub(finalized_index);
}
if let Some(best_child) = node.best_child() {
*node.best_child_mut() = Some(
best_child
.checked_sub(finalized_index)
.ok_or(Error::IndexOverflow("best_child"))?,
);
}
if let Some(best_descendant) = node.best_descendant() {
*node.best_descendant_mut() = Some(
best_descendant
.checked_sub(finalized_index)
.ok_or(Error::IndexOverflow("best_descendant"))?,
);
}
}
Ok(())
}
/// Observe the parent at `parent_index` with respect to the child at `child_index` and
/// potentially modify the `parent.best_child` and `parent.best_descendant` values.
///
/// ## Detail
///
/// There are four outcomes:
///
/// - The child is already the best child but it's now invalid due to a FFG change and should be removed.
/// - The child is already the best child and the parent is updated with the new
/// best-descendant.
/// - The child is not the best child but becomes the best child.
/// - The child is not the best child and does not become the best child.
fn maybe_update_best_child_and_descendant<E: EthSpec>(
&mut self,
parent_index: usize,
child_index: usize,
current_slot: Slot,
best_justified_checkpoint: Checkpoint,
best_finalized_checkpoint: Checkpoint,
) -> Result<(), Error> {
let child = self
.nodes
.get(child_index)
.ok_or(Error::InvalidNodeIndex(child_index))?;
let parent = self
.nodes
.get(parent_index)
.ok_or(Error::InvalidNodeIndex(parent_index))?;
let child_leads_to_viable_head = self.node_leads_to_viable_head::<E>(
child,
current_slot,
best_justified_checkpoint,
best_finalized_checkpoint,
)?;
// These three variables are aliases to the three options that we may set the
// `parent.best_child` and `parent.best_descendant` to.
let change_to_none = (None, None);
let change_to_child = (
Some(child_index),
child.best_descendant().or(Some(child_index)),
);
let no_change = (parent.best_child(), parent.best_descendant());
let (new_best_child, new_best_descendant) =
if let Some(best_child_index) = parent.best_child() {
if best_child_index == child_index && !child_leads_to_viable_head {
// If the child is already the best-child of the parent but it's not viable for
// the head, remove it.
change_to_none
} else if best_child_index == child_index {
// If the child is the best-child already, set it again to ensure that the
// best-descendant of the parent is updated.
change_to_child
} else {
let best_child = self
.nodes
.get(best_child_index)
.ok_or(Error::InvalidBestDescendant(best_child_index))?;
let best_child_leads_to_viable_head = self.node_leads_to_viable_head::<E>(
best_child,
current_slot,
best_justified_checkpoint,
best_finalized_checkpoint,
)?;
if child_leads_to_viable_head && !best_child_leads_to_viable_head {
change_to_child
} else if !child_leads_to_viable_head && best_child_leads_to_viable_head {
no_change
} else if child.weight() > best_child.weight() {
change_to_child
} else if child.weight() < best_child.weight() {
no_change
} else if *child.root() >= *best_child.root() {
change_to_child
} else {
no_change
}
}
} else if child_leads_to_viable_head {
change_to_child
} else {
no_change
};
let parent = self
.nodes
.get_mut(parent_index)
.ok_or(Error::InvalidNodeIndex(parent_index))?;
*parent.best_child_mut() = new_best_child;
*parent.best_descendant_mut() = new_best_descendant;
Ok(())
}
/// Indicates if the node itself is viable for the head, or if its best descendant is viable
/// for the head.
fn node_leads_to_viable_head<E: EthSpec>(
&self,
node: &ProtoNode,
current_slot: Slot,
best_justified_checkpoint: Checkpoint,
best_finalized_checkpoint: Checkpoint,
) -> Result<bool, Error> {
let best_descendant_is_viable_for_head =
if let Some(best_descendant_index) = node.best_descendant() {
let best_descendant = self
.nodes
.get(best_descendant_index)
.ok_or(Error::InvalidBestDescendant(best_descendant_index))?;
self.node_is_viable_for_head::<E>(
best_descendant,
current_slot,
best_justified_checkpoint,
best_finalized_checkpoint,
)
} else {
false
};
Ok(best_descendant_is_viable_for_head
|| self.node_is_viable_for_head::<E>(
node,
current_slot,
best_justified_checkpoint,
best_finalized_checkpoint,
))
}
/// This is the equivalent to the `filter_block_tree` function in the eth2 spec:
///
/// https://github.com/ethereum/eth2.0-specs/blob/v0.10.0/specs/phase0/fork-choice.md#filter_block_tree
///
/// Any node that has a different finalized or justified epoch should not be viable for the
/// head.
fn node_is_viable_for_head<E: EthSpec>(
&self,
node: &ProtoNode,
current_slot: Slot,
best_justified_checkpoint: Checkpoint,
best_finalized_checkpoint: Checkpoint,
) -> bool {
if let Ok(proto_node) = node.as_v17()
&& proto_node.execution_status.is_invalid()
{
return false;
}
let genesis_epoch = Epoch::new(0);
let current_epoch = current_slot.epoch(E::slots_per_epoch());
let node_epoch = node.slot().epoch(E::slots_per_epoch());
let node_justified_checkpoint = node.justified_checkpoint();
let voting_source = if current_epoch > node_epoch {
// The block is from a prior epoch, the voting source will be pulled-up.
node.unrealized_justified_checkpoint()
// Sometimes we don't track the unrealized justification. In
// that case, just use the fully-realized justified checkpoint.
.unwrap_or(*node_justified_checkpoint)
} else {
// The block is not from a prior epoch, therefore the voting source
// is not pulled up.
*node_justified_checkpoint
};
let correct_justified = best_justified_checkpoint.epoch == genesis_epoch
|| voting_source.epoch == best_justified_checkpoint.epoch
|| voting_source.epoch + 2 >= current_epoch;
let correct_finalized = best_finalized_checkpoint.epoch == genesis_epoch
|| self
.is_finalized_checkpoint_or_descendant::<E>(node.root(), best_finalized_checkpoint);
correct_justified && correct_finalized
}
/// Return a reverse iterator over the nodes which comprise the chain ending at `block_root`.
pub fn iter_nodes<'a>(&'a self, block_root: &Hash256) -> Iter<'a> {
let next_node_index = self.indices.get(block_root).copied();
Iter {
next_node_index,
proto_array: self,
}
}
/// Return a reverse iterator over the block roots of the chain ending at `block_root`.
///
/// Note that unlike many other iterators, this one WILL NOT yield anything at skipped slots.
pub fn iter_block_roots<'a>(
&'a self,
block_root: &Hash256,
) -> impl Iterator<Item = (Hash256, Slot)> + 'a {
self.iter_nodes(block_root)
.map(|node| (node.root(), node.slot()))
}
/// Returns `true` if the `descendant_root` has an ancestor with `ancestor_root`. Always
/// returns `false` if either input root is unknown.
///
/// ## Notes
///
/// Still returns `true` if `ancestor_root` is known and `ancestor_root == descendant_root`.
///
/// ## Warning
///
/// Do not use this function to check if a block is a descendant of the
/// finalized checkpoint. Use `Self::is_finalized_checkpoint_or_descendant`
/// instead.
pub fn is_descendant(&self, ancestor_root: Hash256, descendant_root: Hash256) -> bool {
self.indices
.get(&ancestor_root)
.and_then(|ancestor_index| self.nodes.get(*ancestor_index))
.and_then(|ancestor| {
self.iter_block_roots(&descendant_root)
.take_while(|(_root, slot)| *slot >= ancestor.slot())
.find(|(_root, slot)| *slot == ancestor.slot())
.map(|(root, _slot)| root == ancestor_root)
})
.unwrap_or(false)
}
/// Returns `true` if `root` is equal to or a descendant of
/// `self.finalized_checkpoint`.
///
/// Notably, this function is checking ancestory of the finalized
/// *checkpoint* not the finalized *block*.
pub fn is_finalized_checkpoint_or_descendant<E: EthSpec>(
&self,
root: Hash256,
best_finalized_checkpoint: Checkpoint,
) -> bool {
let finalized_root = best_finalized_checkpoint.root;
let finalized_slot = best_finalized_checkpoint
.epoch
.start_slot(E::slots_per_epoch());
let Some(mut node) = self
.indices
.get(&root)
.and_then(|index| self.nodes.get(*index))
else {
// An unknown root is not a finalized descendant. This line can only
// be reached if the user supplies a root that is not known to fork
// choice.
return false;
};
// The finalized and justified checkpoints represent a list of known
// ancestors of `node` that are likely to coincide with the store's
// finalized checkpoint.
//
// Run this check once, outside of the loop rather than inside the loop.
// If the conditions don't match for this node then they're unlikely to
// start matching for its ancestors.
for checkpoint in &[node.finalized_checkpoint(), node.justified_checkpoint()] {
if **checkpoint == best_finalized_checkpoint {
return true;
}
}
for checkpoint in &[
node.unrealized_finalized_checkpoint(),
node.unrealized_justified_checkpoint(),
] {
if checkpoint.is_some_and(|cp| cp == best_finalized_checkpoint) {
return true;
}
}
loop {
// If `node` is less than or equal to the finalized slot then `node`
// must be the finalized block.
if node.slot() <= finalized_slot {
return node.root() == finalized_root;
}
// Since `node` is from a higher slot that the finalized checkpoint,
// replace `node` with the parent of `node`.
if let Some(parent) = node.parent().and_then(|index| self.nodes.get(index)) {
node = parent
} else {
// If `node` is not the finalized block and its parent does not
// exist in fork choice, then the parent must have been pruned.
// Proto-array only prunes blocks prior to the finalized block,
// so this means the parent conflicts with finality.
return false;
};
}
}
/// Returns the first *beacon block root* which contains an execution payload with the given
/// `block_hash`, if any.
pub fn execution_block_hash_to_beacon_block_root(
&self,
block_hash: &ExecutionBlockHash,
) -> Option<Hash256> {
self.nodes
.iter()
.rev()
.find(|node| {
node.execution_status()
.ok()
.and_then(|execution_status| execution_status.block_hash())
.is_some_and(|node_block_hash| node_block_hash == *block_hash)
})
.map(|node| node.root())
}
/// Returns all nodes that have zero children and are descended from the finalized checkpoint.
///
/// For informational purposes like the beacon HTTP API, we use this as the list of known heads,
/// even though some of them might not be viable. We do this to maintain consistency between the
/// definition of "head" used by pruning (which does not consider viability) and fork choice.
pub fn heads_descended_from_finalization<E: EthSpec>(
&self,
best_finalized_checkpoint: Checkpoint,
) -> Vec<&ProtoNode> {
self.nodes
.iter()
.filter(|node| {
node.best_child().is_none()
&& self.is_finalized_checkpoint_or_descendant::<E>(
node.root(),
best_finalized_checkpoint,
)
})
.collect()
}
}
/// A helper method to calculate the proposer boost based on the given `justified_balances`.
///
/// https://github.com/ethereum/consensus-specs/blob/dev/specs/phase0/fork-choice.md#get_latest_attesting_balance
pub fn calculate_committee_fraction<E: EthSpec>(
justified_balances: &JustifiedBalances,
proposer_score_boost: u64,
) -> Option<u64> {
let committee_weight = justified_balances
.total_effective_balance
.checked_div(E::slots_per_epoch())?;
committee_weight
.checked_mul(proposer_score_boost)?
.checked_div(100)
}
/// Spec: `get_proposer_score`.
fn get_proposer_score<E: EthSpec>(
justified_balances: &JustifiedBalances,
spec: &ChainSpec,
) -> Result<u64, Error> {
let Some(proposer_score_boost) = spec.proposer_score_boost else {
return Ok(0);
};
calculate_committee_fraction::<E>(justified_balances, proposer_score_boost)
.ok_or(Error::ProposerBoostOverflow(0))
}
/// Apply a signed delta to an unsigned weight, returning an error on overflow.
fn apply_delta(weight: u64, delta: i64, index: usize) -> Result<u64, Error> {
if delta < 0 {
weight
.checked_sub(delta.unsigned_abs())
.ok_or(Error::DeltaOverflow(index))
} else {
weight
.checked_add(delta as u64)
.ok_or(Error::DeltaOverflow(index))
}
}
/// Reverse iterator over one path through a `ProtoArray`.
pub struct Iter<'a> {
next_node_index: Option<usize>,
proto_array: &'a ProtoArray,
}
impl<'a> Iterator for Iter<'a> {
type Item = &'a ProtoNode;
fn next(&mut self) -> Option<Self::Item> {
let next_node_index = self.next_node_index?;
let node = self.proto_array.nodes.get(next_node_index)?;
self.next_node_index = node.parent();
Some(node)
}
}