508 lines
18 KiB
Rust
508 lines
18 KiB
Rust
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//! Provides an `ObservedAggregates` struct which allows us to reject aggregated attestations or
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//! sync committee contributions if we've already seen them.
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use std::collections::HashSet;
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use std::marker::PhantomData;
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use tree_hash::TreeHash;
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use types::consts::altair::{
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SYNC_COMMITTEE_SUBNET_COUNT, TARGET_AGGREGATORS_PER_SYNC_SUBCOMMITTEE,
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};
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use types::slot_data::SlotData;
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use types::{Attestation, EthSpec, Hash256, Slot, SyncCommitteeContribution};
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pub type ObservedSyncContributions<E> = ObservedAggregates<SyncCommitteeContribution<E>, E>;
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pub type ObservedAggregateAttestations<E> = ObservedAggregates<Attestation<E>, E>;
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/// A trait use to associate capacity constants with the type being stored in `ObservedAggregates`.
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pub trait Consts {
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/// The default capacity of items stored per slot, in a single `SlotHashSet`.
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const DEFAULT_PER_SLOT_CAPACITY: usize;
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/// The maximum number of slots
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fn max_slot_capacity() -> usize;
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/// The maximum number of items stored per slot, in a single `SlotHashSet`.
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fn max_per_slot_capacity() -> usize;
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}
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impl<T: EthSpec> Consts for Attestation<T> {
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/// Use 128 as it's the target committee size for the mainnet spec. This is perhaps a little
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/// wasteful for the minimal spec, but considering it's approx. 128 * 32 bytes we're not wasting
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/// much.
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const DEFAULT_PER_SLOT_CAPACITY: usize = 128;
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/// We need to keep attestations for each slot of the current epoch.
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fn max_slot_capacity() -> usize {
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T::slots_per_epoch() as usize
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}
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/// As a DoS protection measure, the maximum number of distinct `Attestations` or
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/// `SyncCommitteeContributions` that will be recorded for each slot.
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///
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/// Currently this is set to ~524k. If we say that each entry is 40 bytes (Hash256 (32 bytes) + an
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/// 8 byte hash) then this comes to about 20mb per slot. If we're storing 34 of these slots, then
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/// we're at 680mb. This is a lot of memory usage, but probably not a show-stopper for most
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/// reasonable hardware.
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///
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/// Upstream conditions should strongly restrict the amount of attestations that can show up in
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/// this pool. The maximum size with respect to upstream restrictions is more likely on the order
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/// of the number of validators.
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fn max_per_slot_capacity() -> usize {
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1 << 19 // 524,288
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}
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}
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impl<T: EthSpec> Consts for SyncCommitteeContribution<T> {
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/// Set to `TARGET_AGGREGATORS_PER_SYNC_SUBCOMMITTEE * SYNC_COMMITTEE_SUBNET_COUNT`. This is the
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/// expected number of aggregators per slot across all subcommittees.
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const DEFAULT_PER_SLOT_CAPACITY: usize =
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(SYNC_COMMITTEE_SUBNET_COUNT * TARGET_AGGREGATORS_PER_SYNC_SUBCOMMITTEE) as usize;
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/// We only need to keep contributions related to the current slot.
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fn max_slot_capacity() -> usize {
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1
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}
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/// We should never receive more aggregates than there are sync committee participants.
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fn max_per_slot_capacity() -> usize {
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T::sync_committee_size()
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}
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}
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#[derive(Debug, PartialEq)]
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pub enum ObserveOutcome {
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/// This item was already known.
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AlreadyKnown,
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/// This was the first time this item was observed.
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New,
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}
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#[derive(Debug, PartialEq)]
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pub enum Error {
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SlotTooLow {
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slot: Slot,
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lowest_permissible_slot: Slot,
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},
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/// The function to obtain a set index failed, this is an internal error.
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InvalidSetIndex(usize),
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/// We have reached the maximum number of unique items that can be observed in a slot.
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/// This is a DoS protection function.
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ReachedMaxObservationsPerSlot(usize),
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IncorrectSlot {
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expected: Slot,
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attestation: Slot,
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},
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}
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/// A `HashSet` that contains entries related to some `Slot`.
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struct SlotHashSet {
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set: HashSet<Hash256>,
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slot: Slot,
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max_capacity: usize,
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}
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impl SlotHashSet {
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pub fn new(slot: Slot, initial_capacity: usize, max_capacity: usize) -> Self {
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Self {
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slot,
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set: HashSet::with_capacity(initial_capacity),
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max_capacity,
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}
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}
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/// Store the items in self so future observations recognise its existence.
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pub fn observe_item<T: SlotData>(
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&mut self,
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item: &T,
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root: Hash256,
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) -> Result<ObserveOutcome, Error> {
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if item.get_slot() != self.slot {
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return Err(Error::IncorrectSlot {
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expected: self.slot,
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attestation: item.get_slot(),
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});
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}
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if self.set.contains(&root) {
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Ok(ObserveOutcome::AlreadyKnown)
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} else {
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// Here we check to see if this slot has reached the maximum observation count.
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//
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// The resulting behaviour is that we are no longer able to successfully observe new
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// items, however we will continue to return `is_known` values. We could also
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// disable `is_known`, however then we would stop forwarding items across the
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// gossip network and I think that this is a worse case than sending some invalid ones.
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// The underlying libp2p network is responsible for removing duplicate messages, so
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// this doesn't risk a broadcast loop.
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if self.set.len() >= self.max_capacity {
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return Err(Error::ReachedMaxObservationsPerSlot(self.max_capacity));
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}
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self.set.insert(root);
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Ok(ObserveOutcome::New)
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}
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}
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/// Indicates if `item` has been observed before.
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pub fn is_known<T: SlotData>(&self, item: &T, root: Hash256) -> Result<bool, Error> {
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if item.get_slot() != self.slot {
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return Err(Error::IncorrectSlot {
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expected: self.slot,
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attestation: item.get_slot(),
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});
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}
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Ok(self.set.contains(&root))
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}
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/// The number of observed items in `self`.
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pub fn len(&self) -> usize {
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self.set.len()
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}
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}
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/// Stores the roots of objects for some number of `Slots`, so we can determine if
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/// these have previously been seen on the network.
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pub struct ObservedAggregates<T: TreeHash + SlotData + Consts, E: EthSpec> {
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lowest_permissible_slot: Slot,
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sets: Vec<SlotHashSet>,
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_phantom_spec: PhantomData<E>,
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_phantom_tree_hash: PhantomData<T>,
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}
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impl<T: TreeHash + SlotData + Consts, E: EthSpec> Default for ObservedAggregates<T, E> {
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fn default() -> Self {
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Self {
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lowest_permissible_slot: Slot::new(0),
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sets: vec![],
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_phantom_spec: PhantomData,
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_phantom_tree_hash: PhantomData,
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}
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}
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}
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impl<T: TreeHash + SlotData + Consts, E: EthSpec> ObservedAggregates<T, E> {
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/// Store the root of `item` in `self`.
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///
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/// `root` must equal `item.tree_hash_root()`.
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pub fn observe_item(
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&mut self,
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item: &T,
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root_opt: Option<Hash256>,
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) -> Result<ObserveOutcome, Error> {
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let index = self.get_set_index(item.get_slot())?;
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let root = root_opt.unwrap_or_else(|| item.tree_hash_root());
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self.sets
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.get_mut(index)
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.ok_or(Error::InvalidSetIndex(index))
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.and_then(|set| set.observe_item(item, root))
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}
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/// Check to see if the `root` of `item` is in self.
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///
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/// `root` must equal `a.tree_hash_root()`.
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pub fn is_known(&mut self, item: &T, root: Hash256) -> Result<bool, Error> {
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let index = self.get_set_index(item.get_slot())?;
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self.sets
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.get(index)
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.ok_or(Error::InvalidSetIndex(index))
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.and_then(|set| set.is_known(item, root))
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}
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/// The maximum number of slots that items are stored for.
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fn max_capacity(&self) -> u64 {
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// We add `2` in order to account for one slot either side of the range due to
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// `MAXIMUM_GOSSIP_CLOCK_DISPARITY`.
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(T::max_slot_capacity() + 2) as u64
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}
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/// Removes any items with a slot lower than `current_slot` and bars any future
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/// item with a slot lower than `current_slot - SLOTS_RETAINED`.
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pub fn prune(&mut self, current_slot: Slot) {
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let lowest_permissible_slot = current_slot.saturating_sub(self.max_capacity() - 1);
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self.sets.retain(|set| set.slot >= lowest_permissible_slot);
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self.lowest_permissible_slot = lowest_permissible_slot;
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}
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/// Returns the index of `self.set` that matches `slot`.
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///
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/// If there is no existing set for this slot one will be created. If `self.sets.len() >=
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/// Self::max_capacity()`, the set with the lowest slot will be replaced.
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fn get_set_index(&mut self, slot: Slot) -> Result<usize, Error> {
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let lowest_permissible_slot = self.lowest_permissible_slot;
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if slot < lowest_permissible_slot {
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return Err(Error::SlotTooLow {
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slot,
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lowest_permissible_slot,
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});
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}
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// Prune the pool if this item indicates that the current slot has advanced.
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if lowest_permissible_slot + self.max_capacity() < slot + 1 {
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self.prune(slot)
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}
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if let Some(index) = self.sets.iter().position(|set| set.slot == slot) {
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return Ok(index);
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}
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// To avoid re-allocations, try and determine a rough initial capacity for the new set
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// by obtaining the mean size of all items in earlier epoch.
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let (count, sum) = self
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.sets
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.iter()
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// Only include slots that are less than the given slot in the average. This should
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// generally avoid including recent slots that are still "filling up".
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.filter(|set| set.slot < slot)
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.map(|set| set.len())
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.fold((0, 0), |(count, sum), len| (count + 1, sum + len));
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// If we are unable to determine an average, just use the `self.default_per_slot_capacity`.
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let initial_capacity = sum
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.checked_div(count)
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.unwrap_or(T::DEFAULT_PER_SLOT_CAPACITY);
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if self.sets.len() < self.max_capacity() as usize || self.sets.is_empty() {
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let index = self.sets.len();
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self.sets.push(SlotHashSet::new(
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slot,
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initial_capacity,
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T::max_per_slot_capacity(),
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));
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return Ok(index);
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}
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let index = self
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.sets
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.iter()
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.enumerate()
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.min_by_key(|(_i, set)| set.slot)
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.map(|(i, _set)| i)
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.expect("sets cannot be empty due to previous .is_empty() check");
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self.sets[index] = SlotHashSet::new(slot, initial_capacity, T::max_per_slot_capacity());
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Ok(index)
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}
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}
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#[cfg(test)]
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#[cfg(not(debug_assertions))]
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mod tests {
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use super::*;
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use tree_hash::TreeHash;
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use types::{test_utils::test_random_instance, Hash256};
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type E = types::MainnetEthSpec;
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fn get_attestation(slot: Slot, beacon_block_root: u64) -> Attestation<E> {
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let mut a: Attestation<E> = test_random_instance();
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a.data.slot = slot;
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a.data.beacon_block_root = Hash256::from_low_u64_be(beacon_block_root);
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a
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}
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fn get_sync_contribution(slot: Slot, beacon_block_root: u64) -> SyncCommitteeContribution<E> {
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let mut a: SyncCommitteeContribution<E> = test_random_instance();
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a.slot = slot;
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a.beacon_block_root = Hash256::from_low_u64_be(beacon_block_root);
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a
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}
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macro_rules! test_suite {
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($mod_name: ident, $type: ident, $method_name: ident) => {
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#[cfg(test)]
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mod $mod_name {
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use super::*;
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const NUM_ELEMENTS: usize = 8;
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fn single_slot_test(store: &mut $type<E>, slot: Slot) {
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let items = (0..NUM_ELEMENTS as u64)
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.map(|i| $method_name(slot, i))
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.collect::<Vec<_>>();
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for a in &items {
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assert_eq!(
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store.is_known(a, a.tree_hash_root()),
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Ok(false),
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"should indicate an unknown attestation is unknown"
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);
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assert_eq!(
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store.observe_item(a, None),
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Ok(ObserveOutcome::New),
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"should observe new attestation"
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);
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}
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for a in &items {
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assert_eq!(
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store.is_known(a, a.tree_hash_root()),
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Ok(true),
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"should indicate a known attestation is known"
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);
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assert_eq!(
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store.observe_item(a, Some(a.tree_hash_root())),
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Ok(ObserveOutcome::AlreadyKnown),
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"should acknowledge an existing attestation"
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);
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}
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}
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#[test]
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fn single_slot() {
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let mut store = $type::default();
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single_slot_test(&mut store, Slot::new(0));
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||
|
|
assert_eq!(store.sets.len(), 1, "should have a single set stored");
|
||
|
|
assert_eq!(
|
||
|
|
store.sets[0].len(),
|
||
|
|
NUM_ELEMENTS,
|
||
|
|
"set should have NUM_ELEMENTS elements"
|
||
|
|
);
|
||
|
|
}
|
||
|
|
|
||
|
|
#[test]
|
||
|
|
fn mulitple_contiguous_slots() {
|
||
|
|
let mut store = $type::default();
|
||
|
|
let max_cap = store.max_capacity();
|
||
|
|
|
||
|
|
for i in 0..max_cap * 3 {
|
||
|
|
let slot = Slot::new(i);
|
||
|
|
|
||
|
|
single_slot_test(&mut store, slot);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Ensure that the number of sets is correct.
|
||
|
|
*/
|
||
|
|
|
||
|
|
if i < max_cap {
|
||
|
|
assert_eq!(
|
||
|
|
store.sets.len(),
|
||
|
|
i as usize + 1,
|
||
|
|
"should have a {} sets stored",
|
||
|
|
i + 1
|
||
|
|
);
|
||
|
|
} else {
|
||
|
|
assert_eq!(
|
||
|
|
store.sets.len(),
|
||
|
|
max_cap as usize,
|
||
|
|
"should have max_capacity sets stored"
|
||
|
|
);
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Ensure that each set contains the correct number of elements.
|
||
|
|
*/
|
||
|
|
|
||
|
|
for set in &store.sets[..] {
|
||
|
|
assert_eq!(
|
||
|
|
set.len(),
|
||
|
|
NUM_ELEMENTS,
|
||
|
|
"each store should have NUM_ELEMENTS elements"
|
||
|
|
)
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Ensure that all the sets have the expected slots
|
||
|
|
*/
|
||
|
|
|
||
|
|
let mut store_slots =
|
||
|
|
store.sets.iter().map(|set| set.slot).collect::<Vec<_>>();
|
||
|
|
|
||
|
|
assert!(
|
||
|
|
store_slots.len() <= store.max_capacity() as usize,
|
||
|
|
"store size should not exceed max"
|
||
|
|
);
|
||
|
|
|
||
|
|
store_slots.sort_unstable();
|
||
|
|
|
||
|
|
let expected_slots = (i.saturating_sub(max_cap - 1)..=i)
|
||
|
|
.map(Slot::new)
|
||
|
|
.collect::<Vec<_>>();
|
||
|
|
|
||
|
|
assert_eq!(expected_slots, store_slots, "should have expected slots");
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
#[test]
|
||
|
|
fn mulitple_non_contiguous_slots() {
|
||
|
|
let mut store = $type::default();
|
||
|
|
let max_cap = store.max_capacity();
|
||
|
|
|
||
|
|
let to_skip = vec![1_u64, 2, 3, 5, 6, 29, 30, 31, 32, 64];
|
||
|
|
let slots = (0..max_cap * 3)
|
||
|
|
.into_iter()
|
||
|
|
.filter(|i| !to_skip.contains(i))
|
||
|
|
.collect::<Vec<_>>();
|
||
|
|
|
||
|
|
for &i in &slots {
|
||
|
|
if to_skip.contains(&i) {
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
|
||
|
|
let slot = Slot::from(i);
|
||
|
|
|
||
|
|
single_slot_test(&mut store, slot);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Ensure that each set contains the correct number of elements.
|
||
|
|
*/
|
||
|
|
|
||
|
|
for set in &store.sets[..] {
|
||
|
|
assert_eq!(
|
||
|
|
set.len(),
|
||
|
|
NUM_ELEMENTS,
|
||
|
|
"each store should have NUM_ELEMENTS elements"
|
||
|
|
)
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Ensure that all the sets have the expected slots
|
||
|
|
*/
|
||
|
|
|
||
|
|
let mut store_slots =
|
||
|
|
store.sets.iter().map(|set| set.slot).collect::<Vec<_>>();
|
||
|
|
|
||
|
|
store_slots.sort_unstable();
|
||
|
|
|
||
|
|
assert!(
|
||
|
|
store_slots.len() <= store.max_capacity() as usize,
|
||
|
|
"store size should not exceed max"
|
||
|
|
);
|
||
|
|
|
||
|
|
let lowest = store.lowest_permissible_slot.as_u64();
|
||
|
|
let highest = slot.as_u64();
|
||
|
|
let expected_slots = (lowest..=highest)
|
||
|
|
.filter(|i| !to_skip.contains(i))
|
||
|
|
.map(Slot::new)
|
||
|
|
.collect::<Vec<_>>();
|
||
|
|
|
||
|
|
assert_eq!(
|
||
|
|
expected_slots,
|
||
|
|
&store_slots[..],
|
||
|
|
"should have expected slots"
|
||
|
|
);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
};
|
||
|
|
}
|
||
|
|
test_suite!(
|
||
|
|
observed_sync_aggregates,
|
||
|
|
ObservedSyncContributions,
|
||
|
|
get_sync_contribution
|
||
|
|
);
|
||
|
|
test_suite!(
|
||
|
|
observed_aggregate_attestations,
|
||
|
|
ObservedAggregateAttestations,
|
||
|
|
get_attestation
|
||
|
|
);
|
||
|
|
}
|