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attestation_service.rs
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attestation_service.rs
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use crate::beacon_node_fallback::{BeaconNodeFallback, RequireSynced};
use crate::{
duties_service::{DutiesService, DutyAndProof},
http_metrics::metrics,
validator_store::{Error as ValidatorStoreError, ValidatorStore},
OfflineOnFailure,
};
use environment::RuntimeContext;
use futures::future::join_all;
use slog::{crit, debug, error, info, trace, warn};
use slot_clock::SlotClock;
use std::collections::HashMap;
use std::ops::Deref;
use std::sync::Arc;
use tokio::time::{sleep, sleep_until, Duration, Instant};
use tree_hash::TreeHash;
use types::{
AggregateSignature, Attestation, AttestationData, BitList, ChainSpec, CommitteeIndex, EthSpec,
Slot,
};
/// Builds an `AttestationService`.
pub struct AttestationServiceBuilder<T: SlotClock + 'static, E: EthSpec> {
duties_service: Option<Arc<DutiesService<T, E>>>,
validator_store: Option<Arc<ValidatorStore<T, E>>>,
slot_clock: Option<T>,
beacon_nodes: Option<Arc<BeaconNodeFallback<T, E>>>,
context: Option<RuntimeContext<E>>,
}
impl<T: SlotClock + 'static, E: EthSpec> AttestationServiceBuilder<T, E> {
pub fn new() -> Self {
Self {
duties_service: None,
validator_store: None,
slot_clock: None,
beacon_nodes: None,
context: None,
}
}
pub fn duties_service(mut self, service: Arc<DutiesService<T, E>>) -> Self {
self.duties_service = Some(service);
self
}
pub fn validator_store(mut self, store: Arc<ValidatorStore<T, E>>) -> Self {
self.validator_store = Some(store);
self
}
pub fn slot_clock(mut self, slot_clock: T) -> Self {
self.slot_clock = Some(slot_clock);
self
}
pub fn beacon_nodes(mut self, beacon_nodes: Arc<BeaconNodeFallback<T, E>>) -> Self {
self.beacon_nodes = Some(beacon_nodes);
self
}
pub fn runtime_context(mut self, context: RuntimeContext<E>) -> Self {
self.context = Some(context);
self
}
pub fn build(self) -> Result<AttestationService<T, E>, String> {
Ok(AttestationService {
inner: Arc::new(Inner {
duties_service: self
.duties_service
.ok_or("Cannot build AttestationService without duties_service")?,
validator_store: self
.validator_store
.ok_or("Cannot build AttestationService without validator_store")?,
slot_clock: self
.slot_clock
.ok_or("Cannot build AttestationService without slot_clock")?,
beacon_nodes: self
.beacon_nodes
.ok_or("Cannot build AttestationService without beacon_nodes")?,
context: self
.context
.ok_or("Cannot build AttestationService without runtime_context")?,
}),
})
}
}
/// Helper to minimise `Arc` usage.
pub struct Inner<T, E: EthSpec> {
duties_service: Arc<DutiesService<T, E>>,
validator_store: Arc<ValidatorStore<T, E>>,
slot_clock: T,
beacon_nodes: Arc<BeaconNodeFallback<T, E>>,
context: RuntimeContext<E>,
}
/// Attempts to produce attestations for all known validators 1/3rd of the way through each slot.
///
/// If any validators are on the same committee, a single attestation will be downloaded and
/// returned to the beacon node. This attestation will have a signature from each of the
/// validators.
pub struct AttestationService<T, E: EthSpec> {
inner: Arc<Inner<T, E>>,
}
impl<T, E: EthSpec> Clone for AttestationService<T, E> {
fn clone(&self) -> Self {
Self {
inner: self.inner.clone(),
}
}
}
impl<T, E: EthSpec> Deref for AttestationService<T, E> {
type Target = Inner<T, E>;
fn deref(&self) -> &Self::Target {
self.inner.deref()
}
}
impl<T: SlotClock + 'static, E: EthSpec> AttestationService<T, E> {
/// Starts the service which periodically produces attestations.
pub fn start_update_service(self, spec: &ChainSpec) -> Result<(), String> {
let log = self.context.log().clone();
let slot_duration = Duration::from_secs(spec.seconds_per_slot);
let duration_to_next_slot = self
.slot_clock
.duration_to_next_slot()
.ok_or("Unable to determine duration to next slot")?;
info!(
log,
"Attestation production service started";
"next_update_millis" => duration_to_next_slot.as_millis()
);
let executor = self.context.executor.clone();
let interval_fut = async move {
loop {
if let Some(duration_to_next_slot) = self.slot_clock.duration_to_next_slot() {
sleep(duration_to_next_slot + slot_duration / 3).await;
let log = self.context.log();
if let Err(e) = self.spawn_attestation_tasks(slot_duration) {
crit!(
log,
"Failed to spawn attestation tasks";
"error" => e
)
} else {
trace!(
log,
"Spawned attestation tasks";
)
}
} else {
error!(log, "Failed to read slot clock");
// If we can't read the slot clock, just wait another slot.
sleep(slot_duration).await;
continue;
}
}
};
executor.spawn(interval_fut, "attestation_service");
Ok(())
}
/// For each each required attestation, spawn a new task that downloads, signs and uploads the
/// attestation to the beacon node.
fn spawn_attestation_tasks(&self, slot_duration: Duration) -> Result<(), String> {
let slot = self.slot_clock.now().ok_or("Failed to read slot clock")?;
let duration_to_next_slot = self
.slot_clock
.duration_to_next_slot()
.ok_or("Unable to determine duration to next slot")?;
// If a validator needs to publish an aggregate attestation, they must do so at 2/3
// through the slot. This delay triggers at this time
let aggregate_production_instant = Instant::now()
+ duration_to_next_slot
.checked_sub(slot_duration / 3)
.unwrap_or_else(|| Duration::from_secs(0));
let duties_by_committee_index: HashMap<CommitteeIndex, Vec<DutyAndProof>> = self
.duties_service
.attesters(slot)
.into_iter()
.fold(HashMap::new(), |mut map, duty_and_proof| {
map.entry(duty_and_proof.duty.committee_index)
.or_insert_with(Vec::new)
.push(duty_and_proof);
map
});
// For each committee index for this slot:
//
// - Create and publish an `Attestation` for all required validators.
// - Create and publish `SignedAggregateAndProof` for all aggregating validators.
duties_by_committee_index
.into_iter()
.for_each(|(committee_index, validator_duties)| {
// Spawn a separate task for each attestation.
self.inner.context.executor.spawn_ignoring_error(
self.clone().publish_attestations_and_aggregates(
slot,
committee_index,
validator_duties,
aggregate_production_instant,
),
"attestation publish",
);
});
// Schedule pruning of the slashing protection database once all unaggregated
// attestations have (hopefully) been signed, i.e. at the same time as aggregate
// production.
self.spawn_slashing_protection_pruning_task(slot, aggregate_production_instant);
Ok(())
}
/// Performs the first step of the attesting process: downloading `Attestation` objects,
/// signing them and returning them to the validator.
///
/// https://github.com/ethereum/eth2.0-specs/blob/v0.12.1/specs/phase0/validator.md#attesting
///
/// ## Detail
///
/// The given `validator_duties` should already be filtered to only contain those that match
/// `slot` and `committee_index`. Critical errors will be logged if this is not the case.
async fn publish_attestations_and_aggregates(
self,
slot: Slot,
committee_index: CommitteeIndex,
validator_duties: Vec<DutyAndProof>,
aggregate_production_instant: Instant,
) -> Result<(), ()> {
let log = self.context.log();
let attestations_timer = metrics::start_timer_vec(
&metrics::ATTESTATION_SERVICE_TIMES,
&[metrics::ATTESTATIONS],
);
// There's not need to produce `Attestation` or `SignedAggregateAndProof` if we do not have
// any validators for the given `slot` and `committee_index`.
if validator_duties.is_empty() {
return Ok(());
}
// Step 1.
//
// Download, sign and publish an `Attestation` for each validator.
let attestation_opt = self
.produce_and_publish_attestations(slot, committee_index, &validator_duties)
.await
.map_err(move |e| {
crit!(
log,
"Error during attestation routine";
"error" => format!("{:?}", e),
"committee_index" => committee_index,
"slot" => slot.as_u64(),
)
})?;
drop(attestations_timer);
// Step 2.
//
// If an attestation was produced, make an aggregate.
if let Some(attestation_data) = attestation_opt {
// First, wait until the `aggregation_production_instant` (2/3rds
// of the way though the slot). As verified in the
// `delay_triggers_when_in_the_past` test, this code will still run
// even if the instant has already elapsed.
sleep_until(aggregate_production_instant).await;
// Start the metrics timer *after* we've done the delay.
let _aggregates_timer = metrics::start_timer_vec(
&metrics::ATTESTATION_SERVICE_TIMES,
&[metrics::AGGREGATES],
);
// Then download, sign and publish a `SignedAggregateAndProof` for each
// validator that is elected to aggregate for this `slot` and
// `committee_index`.
self.produce_and_publish_aggregates(&attestation_data, &validator_duties)
.await
.map_err(move |e| {
crit!(
log,
"Error during attestation routine";
"error" => format!("{:?}", e),
"committee_index" => committee_index,
"slot" => slot.as_u64(),
)
})?;
}
Ok(())
}
/// Performs the first step of the attesting process: downloading `Attestation` objects,
/// signing them and returning them to the validator.
///
/// https://github.com/ethereum/eth2.0-specs/blob/v0.12.1/specs/phase0/validator.md#attesting
///
/// ## Detail
///
/// The given `validator_duties` should already be filtered to only contain those that match
/// `slot` and `committee_index`. Critical errors will be logged if this is not the case.
///
/// Only one `Attestation` is downloaded from the BN. It is then cloned and signed by each
/// validator and the list of individually-signed `Attestation` objects is returned to the BN.
async fn produce_and_publish_attestations(
&self,
slot: Slot,
committee_index: CommitteeIndex,
validator_duties: &[DutyAndProof],
) -> Result<Option<AttestationData>, String> {
let log = self.context.log();
if validator_duties.is_empty() {
return Ok(None);
}
let current_epoch = self
.slot_clock
.now()
.ok_or("Unable to determine current slot from clock")?
.epoch(E::slots_per_epoch());
let attestation_data = self
.beacon_nodes
.first_success(
RequireSynced::No,
OfflineOnFailure::Yes,
|beacon_node| async move {
let _timer = metrics::start_timer_vec(
&metrics::ATTESTATION_SERVICE_TIMES,
&[metrics::ATTESTATIONS_HTTP_GET],
);
beacon_node
.get_validator_attestation_data(slot, committee_index)
.await
.map_err(|e| format!("Failed to produce attestation data: {:?}", e))
.map(|result| result.data)
},
)
.await
.map_err(|e| e.to_string())?;
// Create futures to produce signed `Attestation` objects.
let attestation_data_ref = &attestation_data;
let signing_futures = validator_duties.iter().map(|duty_and_proof| async move {
let duty = &duty_and_proof.duty;
let attestation_data = attestation_data_ref;
// Ensure that the attestation matches the duties.
#[allow(clippy::suspicious_operation_groupings)]
if duty.slot != attestation_data.slot || duty.committee_index != attestation_data.index
{
crit!(
log,
"Inconsistent validator duties during signing";
"validator" => ?duty.pubkey,
"duty_slot" => duty.slot,
"attestation_slot" => attestation_data.slot,
"duty_index" => duty.committee_index,
"attestation_index" => attestation_data.index,
);
return None;
}
let mut attestation = Attestation {
aggregation_bits: BitList::with_capacity(duty.committee_length as usize).unwrap(),
data: attestation_data.clone(),
signature: AggregateSignature::infinity(),
};
match self
.validator_store
.sign_attestation(
duty.pubkey,
duty.validator_committee_index as usize,
&mut attestation,
current_epoch,
)
.await
{
Ok(()) => Some((attestation, duty.validator_index)),
Err(ValidatorStoreError::UnknownPubkey(pubkey)) => {
// A pubkey can be missing when a validator was recently
// removed via the API.
warn!(
log,
"Missing pubkey for attestation";
"info" => "a validator may have recently been removed from this VC",
"pubkey" => ?pubkey,
"validator" => ?duty.pubkey,
"committee_index" => committee_index,
"slot" => slot.as_u64(),
);
None
}
Err(e) => {
crit!(
log,
"Failed to sign attestation";
"error" => ?e,
"validator" => ?duty.pubkey,
"committee_index" => committee_index,
"slot" => slot.as_u64(),
);
None
}
}
});
// Execute all the futures in parallel, collecting any successful results.
let (ref attestations, ref validator_indices): (Vec<_>, Vec<_>) = join_all(signing_futures)
.await
.into_iter()
.flatten()
.unzip();
// Post the attestations to the BN.
match self
.beacon_nodes
.first_success(
RequireSynced::No,
OfflineOnFailure::Yes,
|beacon_node| async move {
let _timer = metrics::start_timer_vec(
&metrics::ATTESTATION_SERVICE_TIMES,
&[metrics::ATTESTATIONS_HTTP_POST],
);
beacon_node
.post_beacon_pool_attestations(attestations)
.await
},
)
.await
{
Ok(()) => info!(
log,
"Successfully published attestations";
"count" => attestations.len(),
"validator_indices" => ?validator_indices,
"head_block" => ?attestation_data.beacon_block_root,
"committee_index" => attestation_data.index,
"slot" => attestation_data.slot.as_u64(),
"type" => "unaggregated",
),
Err(e) => error!(
log,
"Unable to publish attestations";
"error" => %e,
"committee_index" => attestation_data.index,
"slot" => slot.as_u64(),
"type" => "unaggregated",
),
}
Ok(Some(attestation_data))
}
/// Performs the second step of the attesting process: downloading an aggregated `Attestation`,
/// converting it into a `SignedAggregateAndProof` and returning it to the BN.
///
/// https://github.com/ethereum/eth2.0-specs/blob/v0.12.1/specs/phase0/validator.md#broadcast-aggregate
///
/// ## Detail
///
/// The given `validator_duties` should already be filtered to only contain those that match
/// `slot` and `committee_index`. Critical errors will be logged if this is not the case.
///
/// Only one aggregated `Attestation` is downloaded from the BN. It is then cloned and signed
/// by each validator and the list of individually-signed `SignedAggregateAndProof` objects is
/// returned to the BN.
async fn produce_and_publish_aggregates(
&self,
attestation_data: &AttestationData,
validator_duties: &[DutyAndProof],
) -> Result<(), String> {
let log = self.context.log();
let aggregated_attestation = &self
.beacon_nodes
.first_success(
RequireSynced::No,
OfflineOnFailure::Yes,
|beacon_node| async move {
let _timer = metrics::start_timer_vec(
&metrics::ATTESTATION_SERVICE_TIMES,
&[metrics::AGGREGATES_HTTP_GET],
);
beacon_node
.get_validator_aggregate_attestation(
attestation_data.slot,
attestation_data.tree_hash_root(),
)
.await
.map_err(|e| {
format!("Failed to produce an aggregate attestation: {:?}", e)
})?
.ok_or_else(|| format!("No aggregate available for {:?}", attestation_data))
.map(|result| result.data)
},
)
.await
.map_err(|e| e.to_string())?;
// Create futures to produce the signed aggregated attestations.
let signing_futures = validator_duties.iter().map(|duty_and_proof| async move {
let duty = &duty_and_proof.duty;
let selection_proof = duty_and_proof.selection_proof.as_ref()?;
let slot = attestation_data.slot;
let committee_index = attestation_data.index;
if duty.slot != slot || duty.committee_index != committee_index {
crit!(log, "Inconsistent validator duties during signing");
return None;
}
match self
.validator_store
.produce_signed_aggregate_and_proof(
duty.pubkey,
duty.validator_index,
aggregated_attestation.clone(),
selection_proof.clone(),
)
.await
{
Ok(aggregate) => Some(aggregate),
Err(ValidatorStoreError::UnknownPubkey(pubkey)) => {
// A pubkey can be missing when a validator was recently
// removed via the API.
debug!(
log,
"Missing pubkey for aggregate";
"pubkey" => ?pubkey,
);
None
}
Err(e) => {
crit!(
log,
"Failed to sign aggregate";
"error" => ?e,
"pubkey" => ?duty.pubkey,
);
None
}
}
});
// Execute all the futures in parallel, collecting any successful results.
let signed_aggregate_and_proofs = join_all(signing_futures)
.await
.into_iter()
.flatten()
.collect::<Vec<_>>();
if !signed_aggregate_and_proofs.is_empty() {
let signed_aggregate_and_proofs_slice = signed_aggregate_and_proofs.as_slice();
match self
.beacon_nodes
.first_success(
RequireSynced::No,
OfflineOnFailure::Yes,
|beacon_node| async move {
let _timer = metrics::start_timer_vec(
&metrics::ATTESTATION_SERVICE_TIMES,
&[metrics::AGGREGATES_HTTP_POST],
);
beacon_node
.post_validator_aggregate_and_proof(signed_aggregate_and_proofs_slice)
.await
},
)
.await
{
Ok(()) => {
for signed_aggregate_and_proof in signed_aggregate_and_proofs {
let attestation = &signed_aggregate_and_proof.message.aggregate;
info!(
log,
"Successfully published attestation";
"aggregator" => signed_aggregate_and_proof.message.aggregator_index,
"signatures" => attestation.aggregation_bits.num_set_bits(),
"head_block" => format!("{:?}", attestation.data.beacon_block_root),
"committee_index" => attestation.data.index,
"slot" => attestation.data.slot.as_u64(),
"type" => "aggregated",
);
}
}
Err(e) => {
for signed_aggregate_and_proof in signed_aggregate_and_proofs {
let attestation = &signed_aggregate_and_proof.message.aggregate;
crit!(
log,
"Failed to publish attestation";
"error" => %e,
"aggregator" => signed_aggregate_and_proof.message.aggregator_index,
"committee_index" => attestation.data.index,
"slot" => attestation.data.slot.as_u64(),
"type" => "aggregated",
);
}
}
}
}
Ok(())
}
/// Spawn a blocking task to run the slashing protection pruning process.
///
/// Start the task at `pruning_instant` to avoid interference with other tasks.
fn spawn_slashing_protection_pruning_task(&self, slot: Slot, pruning_instant: Instant) {
let attestation_service = self.clone();
let executor = self.inner.context.executor.clone();
let current_epoch = slot.epoch(E::slots_per_epoch());
// Wait for `pruning_instant` in a regular task, and then switch to a blocking one.
self.inner.context.executor.spawn(
async move {
sleep_until(pruning_instant).await;
executor.spawn_blocking(
move || {
attestation_service
.validator_store
.prune_slashing_protection_db(current_epoch, false)
},
"slashing_protection_pruning",
)
},
"slashing_protection_pre_pruning",
);
}
}
#[cfg(test)]
mod tests {
use super::*;
use futures::future::FutureExt;
use parking_lot::RwLock;
/// This test is to ensure that a `tokio_timer::Sleep` with an instant in the past will still
/// trigger.
#[tokio::test]
async fn delay_triggers_when_in_the_past() {
let in_the_past = Instant::now() - Duration::from_secs(2);
let state_1 = Arc::new(RwLock::new(in_the_past));
let state_2 = state_1.clone();
sleep_until(in_the_past)
.map(move |()| *state_1.write() = Instant::now())
.await;
assert!(
*state_2.read() > in_the_past,
"state should have been updated"
);
}
}