Refactor attestation service (#1415)

## Issue Addressed

N/A

## Proposed Changes

Refactor attestation service to send out requests to find peers for subnets as soon as we get attestation duties. 
Earlier, we had much more involved logic to send the discovery requests to the discovery service only 6 slots before the attestation slot. Now that discovery is much smarter with grouped queries, the complexity in attestation service can be reduced considerably.



Co-authored-by: Age Manning <Age@AgeManning.com>

beacon_node/eth2_libp2p/src/behaviour/mod.rs

@@ -1,6 +1,6 @@
 use crate::peer_manager::{score::PeerAction, PeerManager, PeerManagerEvent};
 use crate::rpc::*;
-use crate::types::{EnrBitfield, GossipEncoding, GossipKind, GossipTopic};
+use crate::types::{EnrBitfield, GossipEncoding, GossipKind, GossipTopic, SubnetDiscovery};
 use crate::Eth2Enr;
 use crate::{error, metrics, Enr, NetworkConfig, NetworkGlobals, PubsubMessage, TopicHash};
 use futures::prelude::*;
@@ -29,7 +29,6 @@ use std::{
     marker::PhantomData,
     sync::Arc,
     task::{Context, Poll},
-    time::Instant,
 };
 use types::{EnrForkId, EthSpec, SignedBeaconBlock, SubnetId};
 
@@ -301,8 +300,9 @@ impl<TSpec: EthSpec> Behaviour<TSpec> {
 
     /// Attempts to discover new peers for a given subnet. The `min_ttl` gives the time at which we
     /// would like to retain the peers for.
-    pub fn discover_subnet_peers(&mut self, subnet_id: SubnetId, min_ttl: Option<Instant>) {
-        self.peer_manager.discover_subnet_peers(subnet_id, min_ttl)
+    pub fn discover_subnet_peers(&mut self, subnet_subscriptions: Vec<SubnetDiscovery>) {
+        self.peer_manager
+            .discover_subnet_peers(subnet_subscriptions)
     }
 
     /// Updates the local ENR's "eth2" field with the latest EnrForkId.

beacon_node/eth2_libp2p/src/discovery/mod.rs

@@ -8,7 +8,7 @@ pub use enr_ext::{CombinedKeyExt, EnrExt};
 pub use libp2p::core::identity::Keypair;
 
 use crate::metrics;
-use crate::{error, Enr, NetworkConfig, NetworkGlobals};
+use crate::{error, Enr, NetworkConfig, NetworkGlobals, SubnetDiscovery};
 use discv5::{enr::NodeId, Discv5, Discv5Event};
 use enr::{BITFIELD_ENR_KEY, ETH2_ENR_KEY};
 use futures::prelude::*;
@@ -305,12 +305,19 @@ impl<TSpec: EthSpec> Discovery<TSpec> {
     }
 
     /// Processes a request to search for more peers on a subnet.
-    pub fn discover_subnet_peers(&mut self, subnet_id: SubnetId, min_ttl: Option<Instant>) {
+    pub fn discover_subnet_peers(&mut self, subnets_to_discover: Vec<SubnetDiscovery>) {
         // If the discv5 service isn't running, ignore queries
         if !self.started {
             return;
         }
-        self.add_subnet_query(subnet_id, min_ttl, 0);
+        debug!(
+            self.log,
+            "Making discovery query for subnets";
+            "subnets" => format!("{:?}", subnets_to_discover.iter().map(|s| s.subnet_id).collect::<Vec<_>>())
+        );
+        for subnet in subnets_to_discover {
+            self.add_subnet_query(subnet.subnet_id, subnet.min_ttl, 0);
+        }
     }
 
     /// Add an ENR to the routing table of the discovery mechanism.
@@ -514,6 +521,11 @@ impl<TSpec: EthSpec> Discovery<TSpec> {
                         // This query is for searching for peers of a particular subnet
                         // Drain subnet_queries so we can re-use it as we continue to process the queue
                         let grouped_queries: Vec<SubnetQuery> = subnet_queries.drain(..).collect();
+                        debug!(
+                            self.log,
+                            "Starting grouped subnet query";
+                            "subnets" => format!("{:?}", grouped_queries.iter().map(|q| q.subnet_id).collect::<Vec<_>>()),
+                        );
                         self.start_subnet_query(grouped_queries);
                     }
                 }

beacon_node/eth2_libp2p/src/discovery/subnet_predicate.rs

@@ -1,5 +1,6 @@
 ///! The subnet predicate used for searching for a particular subnet.
 use super::*;
+use slog::{debug, trace};
 use std::ops::Deref;
 
 /// Returns the predicate for a given subnet.
@@ -30,7 +31,7 @@ where
                 .collect();
 
             if matches.is_empty() {
-                debug!(
+                trace!(
                     log_clone,
                     "Peer found but not on any of the desired subnets";
                     "peer_id" => format!("{}", enr.peer_id())

beacon_node/eth2_libp2p/src/lib.rs

@@ -14,7 +14,7 @@ pub mod rpc;
 mod service;
 pub mod types;
 
-pub use crate::types::{error, Enr, GossipTopic, NetworkGlobals, PubsubMessage};
+pub use crate::types::{error, Enr, GossipTopic, NetworkGlobals, PubsubMessage, SubnetDiscovery};
 pub use behaviour::{BehaviourEvent, PeerRequestId, Request, Response};
 pub use config::Config as NetworkConfig;
 pub use discovery::{CombinedKeyExt, EnrExt, Eth2Enr};

beacon_node/eth2_libp2p/src/peer_manager/mod.rs

@@ -4,7 +4,7 @@ pub use self::peerdb::*;
 use crate::discovery::{Discovery, DiscoveryEvent};
 use crate::rpc::{GoodbyeReason, MetaData, Protocol, RPCError, RPCResponseErrorCode};
 use crate::{error, metrics};
-use crate::{EnrExt, NetworkConfig, NetworkGlobals, PeerId};
+use crate::{EnrExt, NetworkConfig, NetworkGlobals, PeerId, SubnetDiscovery};
 use futures::prelude::*;
 use futures::Stream;
 use hashset_delay::HashSetDelay;
@@ -19,7 +19,7 @@ use std::{
     task::{Context, Poll},
     time::{Duration, Instant},
 };
-use types::{EthSpec, SubnetId};
+use types::EthSpec;
 
 pub use libp2p::core::{identity::Keypair, Multiaddr};
 
@@ -213,17 +213,19 @@ impl<TSpec: EthSpec> PeerManager<TSpec> {
     }
 
     /// A request to find peers on a given subnet.
-    pub fn discover_subnet_peers(&mut self, subnet_id: SubnetId, min_ttl: Option<Instant>) {
+    pub fn discover_subnet_peers(&mut self, subnets_to_discover: Vec<SubnetDiscovery>) {
         // Extend the time to maintain peers if required.
-        if let Some(min_ttl) = min_ttl {
-            self.network_globals
-                .peers
-                .write()
-                .extend_peers_on_subnet(subnet_id, min_ttl);
+        for s in subnets_to_discover.iter() {
+            if let Some(min_ttl) = s.min_ttl {
+                self.network_globals
+                    .peers
+                    .write()
+                    .extend_peers_on_subnet(s.subnet_id, min_ttl);
+            }
         }
 
         // request the subnet query from discovery
-        self.discovery.discover_subnet_peers(subnet_id, min_ttl);
+        self.discovery.discover_subnet_peers(subnets_to_discover);
     }
 
     /// A STATUS message has been received from a peer. This resets the status timer.

beacon_node/eth2_libp2p/src/types/mod.rs

@@ -1,6 +1,7 @@
 pub mod error;
 mod globals;
 mod pubsub;
+mod subnet;
 mod sync_state;
 mod topics;
 
@@ -13,5 +14,6 @@ pub type Enr = discv5::enr::Enr<discv5::enr::CombinedKey>;
 
 pub use globals::NetworkGlobals;
 pub use pubsub::PubsubMessage;
+pub use subnet::SubnetDiscovery;
 pub use sync_state::SyncState;
 pub use topics::{GossipEncoding, GossipKind, GossipTopic};

beacon_node/eth2_libp2p/src/types/subnet.rs

@@ -0,0 +1,28 @@
+use std::time::{Duration, Instant};
+use types::SubnetId;
+
+const DURATION_DIFFERENCE: Duration = Duration::from_millis(1);
+
+/// A subnet to discover peers on along with the instant after which it's no longer useful.
+#[derive(Debug, Clone)]
+pub struct SubnetDiscovery {
+    pub subnet_id: SubnetId,
+    pub min_ttl: Option<Instant>,
+}
+
+impl PartialEq for SubnetDiscovery {
+    fn eq(&self, other: &SubnetDiscovery) -> bool {
+        self.subnet_id == other.subnet_id
+            && match (self.min_ttl, other.min_ttl) {
+                (Some(min_ttl_instant), Some(other_min_ttl_instant)) => {
+                    min_ttl_instant.saturating_duration_since(other_min_ttl_instant)
+                        < DURATION_DIFFERENCE
+                        && other_min_ttl_instant.saturating_duration_since(min_ttl_instant)
+                            < DURATION_DIFFERENCE
+                }
+                (None, None) => true,
+                (None, Some(_)) => true,
+                (Some(_), None) => true,
+            }
+    }
+}