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state_processing: winning_root v0.6.1

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This commit is contained in:
Michael Sproul 2019-05-13 17:18:21 +10:00
parent ca73fb72da
commit fd56c8fa04
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2 changed files with 97 additions and 111 deletions
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45
eth2/state_processing/src/per_epoch_processing/validator_statuses.rs
View File

@ -1,4 +1,4 @@
use super::get_attestation_participants::get_attestation_participants;
use super::get_attesting_indices::get_attesting_indices_unsorted;
use super::WinningRootHashSet;
use types::*;
@ -29,7 +29,7 @@ pub struct InclusionInfo {
pub slot: Slot,
/// The distance between the attestation slot and the slot that attestation was included in a
/// block.
pub distance: Slot,
pub distance: u64,
/// The index of the proposer at the slot where the attestation was included.
pub proposer_index: usize,
}
@ -39,7 +39,7 @@ impl Default for InclusionInfo {
fn default() -> Self {
Self {
slot: Slot::max_value(),
distance: Slot::max_value(),
distance: u64::max_value(),
proposer_index: 0,
}
}
@ -199,7 +199,7 @@ impl ValidatorStatuses {
/// Process some attestations from the given `state` updating the `statuses` and
/// `total_balances` fields.
///
/// Spec v0.5.1
/// Spec v0.6.1
pub fn process_attestations(
&mut self,
state: &BeaconState,
@ -211,28 +211,30 @@ impl ValidatorStatuses {
.chain(state.current_epoch_attestations.iter())
{
let attesting_indices =
get_attestation_participants(state, &a.data, &a.aggregation_bitfield, spec)?;
get_attesting_indices_unsorted(state, &a.data, &a.aggregation_bitfield, spec)?;
let mut status = ValidatorStatus::default();
// Profile this attestation, updating the total balances and generating an
// `ValidatorStatus` object that applies to all participants in the attestation.
if is_from_epoch(a, state.current_epoch(spec), spec) {
if is_from_epoch(a, state.current_epoch(spec)) {
status.is_current_epoch_attester = true;
if target_matches_epoch_start_block(a, state, state.current_epoch(spec), spec)? {
status.is_current_epoch_target_attester = true;
}
} else if is_from_epoch(a, state.previous_epoch(spec), spec) {
} else if is_from_epoch(a, state.previous_epoch(spec)) {
status.is_previous_epoch_attester = true;
// The inclusion slot and distance are only required for previous epoch attesters.
let relative_epoch = RelativeEpoch::from_slot(state.slot, a.inclusion_slot, spec)?;
let attestation_slot = state.get_attestation_slot(&a.data, spec)?;
let inclusion_slot = attestation_slot + a.inclusion_delay;
let relative_epoch = RelativeEpoch::from_slot(state.slot, inclusion_slot, spec)?;
status.inclusion_info = Some(InclusionInfo {
slot: a.inclusion_slot,
distance: inclusion_distance(a),
slot: inclusion_slot,
distance: a.inclusion_delay,
proposer_index: state.get_beacon_proposer_index(
a.inclusion_slot,
attestation_slot,
relative_epoch,
spec,
)?,
@ -316,25 +318,17 @@ impl ValidatorStatuses {
}
}
/// Returns the distance between when the attestation was created and when it was included in a
/// block.
///
/// Spec v0.5.1
fn inclusion_distance(a: &PendingAttestation) -> Slot {
a.inclusion_slot - a.data.slot
}
/// Returns `true` if some `PendingAttestation` is from the supplied `epoch`.
///
/// Spec v0.5.1
fn is_from_epoch(a: &PendingAttestation, epoch: Epoch, spec: &ChainSpec) -> bool {
a.data.slot.epoch(spec.slots_per_epoch) == epoch
/// Spec v0.6.1
fn is_from_epoch(a: &PendingAttestation, epoch: Epoch) -> bool {
a.data.target_epoch == epoch
}
/// Returns `true` if the attestation's FFG target is equal to the hash of the `state`'s first
/// beacon block in the given `epoch`.
///
/// Spec v0.6.0
/// Spec v0.6.1
fn target_matches_epoch_start_block(
a: &PendingAttestation,
state: &BeaconState,
@ -350,13 +344,14 @@ fn target_matches_epoch_start_block(
/// Returns `true` if a `PendingAttestation` and `BeaconState` share the same beacon block hash for
/// the current slot of the `PendingAttestation`.
///
/// Spec v0.6.0
/// Spec v0.6.1
fn has_common_beacon_block_root(
a: &PendingAttestation,
state: &BeaconState,
spec: &ChainSpec,
) -> Result<bool, BeaconStateError> {
let state_block_root = *state.get_block_root(a.data.slot, spec)?;
let attestation_slot = state.get_attestation_slot(&a.data, spec)?;
let state_block_root = *state.get_block_root(attestation_slot, spec)?;
Ok(a.data.beacon_block_root == state_block_root)
}

163
eth2/state_processing/src/per_epoch_processing/winning_root.rs
View File

@ -1,11 +1,11 @@
use super::get_attestation_participants::get_attestation_participants;
use std::collections::HashSet;
use std::iter::FromIterator;
use super::get_attesting_indices::get_attesting_indices_unsorted;
use std::collections::{HashMap, HashSet};
use tree_hash::TreeHash;
use types::*;
#[derive(Clone)]
pub struct WinningRoot {
pub crosslink_data_root: Hash256,
pub crosslink: Crosslink,
pub attesting_validator_indices: Vec<usize>,
pub total_attesting_balance: u64,
}
@ -16,15 +16,15 @@ impl WinningRoot {
/// A winning root is "better" than another if it has a higher `total_attesting_balance`. Ties
/// are broken by favouring the higher `crosslink_data_root` value.
///
/// Spec v0.5.1
/// Spec v0.6.1
pub fn is_better_than(&self, other: &Self) -> bool {
if self.total_attesting_balance > other.total_attesting_balance {
true
} else if self.total_attesting_balance == other.total_attesting_balance {
self.crosslink_data_root > other.crosslink_data_root
} else {
false
}
(
self.total_attesting_balance,
self.crosslink.crosslink_data_root,
) > (
other.total_attesting_balance,
other.crosslink.crosslink_data_root,
)
}
}
@ -34,43 +34,55 @@ impl WinningRoot {
/// The `WinningRoot` object also contains additional fields that are useful in later stages of
/// per-epoch processing.
///
/// Spec v0.5.1
/// Spec v0.6.1
pub fn winning_root(
state: &BeaconState,
shard: u64,
epoch: Epoch,
spec: &ChainSpec,
) -> Result<Option<WinningRoot>, BeaconStateError> {
let mut winning_root: Option<WinningRoot> = None;
let shard_attestations: Vec<&PendingAttestation> = state
.get_matching_source_attestations(epoch, spec)?
.iter()
.filter(|a| a.data.shard == shard)
.collect();
let crosslink_data_roots: HashSet<Hash256> = HashSet::from_iter(
state
.previous_epoch_attestations
.iter()
.chain(state.current_epoch_attestations.iter())
.filter_map(|a| {
if is_eligible_for_winning_root(state, a, shard) {
Some(a.data.crosslink_data_root)
} else {
None
}
}),
);
let shard_crosslinks = shard_attestations.iter().map(|att| {
(
att,
state.get_crosslink_from_attestation_data(&att.data, spec),
)
});
for crosslink_data_root in crosslink_data_roots {
let current_shard_crosslink_root = state.current_crosslinks[shard as usize].tree_hash_root();
let candidate_crosslinks = shard_crosslinks.filter(|(_, c)| {
c.previous_crosslink_root.as_bytes() == &current_shard_crosslink_root[..]
|| c.tree_hash_root() == current_shard_crosslink_root
});
// Build a map from candidate crosslink to attestations that support that crosslink.
let mut candidate_crosslink_map: HashMap<Crosslink, Vec<&PendingAttestation>> = HashMap::new();
for (&attestation, crosslink) in candidate_crosslinks {
let supporting_attestations = candidate_crosslink_map
.entry(crosslink)
.or_insert_with(Vec::new);
supporting_attestations.push(attestation);
}
if candidate_crosslink_map.is_empty() {
return Ok(None);
}
let mut winning_root = None;
for (crosslink, attestations) in candidate_crosslink_map {
let attesting_validator_indices =
get_attesting_validator_indices(state, shard, &crosslink_data_root, spec)?;
let total_attesting_balance: u64 =
attesting_validator_indices
.iter()
.try_fold(0_u64, |acc, i| {
state
.get_effective_balance(*i, spec)
.and_then(|bal| Ok(acc + bal))
})?;
get_unslashed_attesting_indices_unsorted(state, &attestations, spec)?;
let total_attesting_balance =
state.get_total_balance(&attesting_validator_indices, spec)?;
let candidate = WinningRoot {
crosslink_data_root,
crosslink,
attesting_validator_indices,
total_attesting_balance,
};
@ -87,52 +99,29 @@ pub fn winning_root(
Ok(winning_root)
}
/// Returns `true` if pending attestation `a` is eligible to become a winning root.
///
/// Spec v0.5.1
fn is_eligible_for_winning_root(state: &BeaconState, a: &PendingAttestation, shard: Shard) -> bool {
if shard >= state.latest_crosslinks.len() as u64 {
return false;
}
a.data.previous_crosslink == state.latest_crosslinks[shard as usize]
}
/// Returns all indices which voted for a given crosslink. Does not contain duplicates.
///
/// Spec v0.5.1
fn get_attesting_validator_indices(
pub fn get_unslashed_attesting_indices_unsorted(
state: &BeaconState,
shard: u64,
crosslink_data_root: &Hash256,
attestations: &[&PendingAttestation],
spec: &ChainSpec,
) -> Result<Vec<usize>, BeaconStateError> {
let mut indices = vec![];
for a in state
.current_epoch_attestations
.iter()
.chain(state.previous_epoch_attestations.iter())
{
if (a.data.shard == shard) && (a.data.crosslink_data_root == *crosslink_data_root) {
indices.append(&mut get_attestation_participants(
state,
&a.data,
&a.aggregation_bitfield,
spec,
)?);
}
let mut output = HashSet::new();
for a in attestations {
output.extend(get_attesting_indices_unsorted(
state,
&a.data,
&a.aggregation_bitfield,
spec,
)?);
}
// Sort the list (required for dedup). "Unstable" means the sort may re-order equal elements,
// this causes no issue here.
//
// These sort + dedup ops are potentially good CPU time optimisation targets.
indices.sort_unstable();
// Remove all duplicate indices (requires a sorted list).
indices.dedup();
Ok(indices)
Ok(output
.into_iter()
.filter(|index| {
state
.validator_registry
.get(*index)
.map_or(false, |v| !v.slashed)
})
.collect())
}
#[cfg(test)]
@ -142,15 +131,17 @@ mod tests {
#[test]
fn is_better_than() {
let worse = WinningRoot {
crosslink_data_root: Hash256::from_slice(&[1; 32]),
crosslink: Crosslink {
epoch: Epoch::new(0),
previous_crosslink_root: Hash256::from_slice(&[0; 32]),
crosslink_data_root: Hash256::from_slice(&[1; 32]),
},
attesting_validator_indices: vec![],
total_attesting_balance: 42,
};
let better = WinningRoot {
crosslink_data_root: Hash256::from_slice(&[2; 32]),
..worse.clone()
};
let mut better = worse.clone();
better.crosslink.crosslink_data_root = Hash256::from_slice(&[2; 32]);
assert!(better.is_better_than(&worse));