replace max_peers cli argument by target_peers and use excess peers above target_peers capped by a new constant PEER_EXCESS_FACTOR (relative to target_peers) (#1383)

beacon_node/eth2_libp2p/src/peer_manager/peerdb.rs

@@ -3,6 +3,7 @@ use super::peer_sync_status::PeerSyncStatus;
 use super::score::Score;
 use crate::rpc::methods::MetaData;
 use crate::PeerId;
+use rand::seq::SliceRandom;
 use slog::{crit, debug, trace, warn};
 use std::collections::HashMap;
 use std::time::Instant;
@@ -168,6 +169,20 @@ impl<TSpec: EthSpec> PeerDB<TSpec> {
             .map(|(peer_id, _)| peer_id)
     }
 
+    /// Returns a vector of all connected peers sorted by score beginning with the worst scores.
+    /// Ties get broken randomly.
+    pub fn worst_connected_peers(&self) -> Vec<(&PeerId, &PeerInfo<TSpec>)> {
+        let mut connected = self
+            .peers
+            .iter()
+            .filter(|(_, info)| info.connection_status.is_connected())
+            .collect::<Vec<_>>();
+
+        connected.shuffle(&mut rand::thread_rng());
+        connected.sort_by_key(|(_, info)| info.score);
+        connected
+    }
+
     /// Returns a vector containing peers (their ids and info), sorted by
     /// score from highest to lowest, and filtered using `is_status`
     pub fn best_peers_by_status<F>(&self, is_status: F) -> Vec<(&PeerId, &PeerInfo<TSpec>)>