Use events API to eager send attestations (#7892)

Co-Authored-By: hopinheimer <knmanas6@gmail.com>

Co-Authored-By: hopinheimer <48147533+hopinheimer@users.noreply.github.com>

Co-Authored-By: Eitan Seri-Levi <eserilev@ucsc.edu>

Co-Authored-By: Michael Sproul <michael@sigmaprime.io>

Co-Authored-By: Michael Sproul <michaelsproul@users.noreply.github.com>

validator_client/src/cli.rs

@@ -476,6 +476,17 @@ pub struct ValidatorClient {
     )]
     pub beacon_nodes_sync_tolerances: Vec<u64>,
 
+    #[clap(
+        long,
+        help = "Disable the beacon head monitor which tries to attest as soon as any of the \
+                configured beacon nodes sends a head event. Leaving the service enabled is \
+                recommended, but disabling it can lead to reduced bandwidth and more predictable \
+                usage of the primary beacon node (rather than the fastest BN).",
+        display_order = 0,
+        help_heading = FLAG_HEADER
+    )]
+    pub disable_beacon_head_monitor: bool,
+
     #[clap(
         long,
         help = "Disable Lighthouse's slashing protection for all web3signer keys. This can \

validator_client/src/config.rs

@@ -82,6 +82,8 @@ pub struct Config {
     pub broadcast_topics: Vec<ApiTopic>,
     /// Enables a service which attempts to measure latency between the VC and BNs.
     pub enable_latency_measurement_service: bool,
+    /// Enables the beacon head monitor that reacts to head updates from connected beacon nodes.
+    pub enable_beacon_head_monitor: bool,
     /// Defines the number of validators per `validator/register_validator` request sent to the BN.
     pub validator_registration_batch_size: usize,
     /// Whether we are running with distributed network support.
@@ -132,6 +134,7 @@ impl Default for Config {
             builder_registration_timestamp_override: None,
             broadcast_topics: vec![ApiTopic::Subscriptions],
             enable_latency_measurement_service: true,
+            enable_beacon_head_monitor: true,
             validator_registration_batch_size: 500,
             distributed: false,
             initialized_validators: <_>::default(),
@@ -377,6 +380,7 @@ impl Config {
         config.validator_store.builder_boost_factor = validator_client_config.builder_boost_factor;
         config.enable_latency_measurement_service =
             !validator_client_config.disable_latency_measurement_service;
+        config.enable_beacon_head_monitor = !validator_client_config.disable_beacon_head_monitor;
 
         config.validator_registration_batch_size =
             validator_client_config.validator_registration_batch_size;

validator_client/src/lib.rs

@@ -9,10 +9,12 @@ use metrics::set_gauge;
 use monitoring_api::{MonitoringHttpClient, ProcessType};
 use sensitive_url::SensitiveUrl;
 use slashing_protection::{SLASHING_PROTECTION_FILENAME, SlashingDatabase};
+use tokio::sync::Mutex;
 
 use account_utils::validator_definitions::ValidatorDefinitions;
 use beacon_node_fallback::{
-    BeaconNodeFallback, CandidateBeaconNode, start_fallback_updater_service,
+    BeaconNodeFallback, CandidateBeaconNode, beacon_head_monitor::HeadEvent,
+    start_fallback_updater_service,
 };
 use clap::ArgMatches;
 use doppelganger_service::DoppelgangerService;
@@ -70,6 +72,8 @@ pub const AGGREGATION_PRE_COMPUTE_EPOCHS: u64 = 2;
 /// Number of slots in advance to compute sync selection proofs when in `distributed` mode.
 pub const AGGREGATION_PRE_COMPUTE_SLOTS_DISTRIBUTED: u64 = 1;
 
+const MAX_HEAD_EVENT_QUEUE_LEN: usize = 1_024;
+
 type ValidatorStore<E> = LighthouseValidatorStore<SystemTimeSlotClock, E>;
 
 #[derive(Clone)]
@@ -395,6 +399,17 @@ impl<E: EthSpec> ProductionValidatorClient<E> {
         beacon_nodes.set_slot_clock(slot_clock.clone());
         proposer_nodes.set_slot_clock(slot_clock.clone());
 
+        // Only the beacon_nodes are used for attestation duties and thus biconditionally
+        // proposer_nodes do not need head_send ref.
+        let head_monitor_rx = if config.enable_beacon_head_monitor {
+            let (head_monitor_tx, head_receiver) =
+                mpsc::channel::<HeadEvent>(MAX_HEAD_EVENT_QUEUE_LEN);
+            beacon_nodes.set_head_send(Arc::new(head_monitor_tx));
+            Some(Mutex::new(head_receiver))
+        } else {
+            None
+        };
+
         let beacon_nodes = Arc::new(beacon_nodes);
         start_fallback_updater_service::<_, E>(context.executor.clone(), beacon_nodes.clone())?;
 
@@ -505,15 +520,17 @@ impl<E: EthSpec> ProductionValidatorClient<E> {
 
         let block_service = block_service_builder.build()?;
 
-        let attestation_service = AttestationServiceBuilder::new()
+        let attestation_builder = AttestationServiceBuilder::new()
             .duties_service(duties_service.clone())
             .slot_clock(slot_clock.clone())
             .validator_store(validator_store.clone())
             .beacon_nodes(beacon_nodes.clone())
             .executor(context.executor.clone())
+            .head_monitor_rx(head_monitor_rx)
             .chain_spec(context.eth2_config.spec.clone())
-            .disable(config.disable_attesting)
-            .build()?;
+            .disable(config.disable_attesting);
+
+        let attestation_service = attestation_builder.build()?;
 
         let preparation_service = PreparationServiceBuilder::new()
             .slot_clock(slot_clock.clone())