refactor: Improve dialing after rendezvous discovery

Only dial when we are not at connected peer limit.
Only dial peers we are not already connected to.

homestar-runtime/src/event_handler/swarm_event.rs

@@ -28,7 +28,7 @@ use libp2p::{
  },
  mdns,
  multiaddr::Protocol,
- rendezvous::{self, Namespace},
+ rendezvous::{self, Namespace, Registration},
  request_response,
  swarm::{dial_opts::DialOpts, SwarmEvent},
  PeerId, StreamProtocol,
@@ -190,17 +190,34 @@ async fn handle_swarm_event<THandlerErr: fmt::Debug + Send, DB: Database>(
  registrations,
  cookie,
  } => {
- // save cookie for later (when we are hungry for snacks again. yummy.)
  if cookie.namespace() == Some(&Namespace::from_static(RENDEZVOUS_NAMESPACE)) {
+ // Store cookie
  event_handler
  .rendezvous_cookies
  .insert(rendezvous_node, cookie);
 
- // Dial discovered peers
- for (index, registration) in registrations.iter().enumerate() {
+ let connected_peers_count = event_handler.connected_peers.len();
+
+ // Skip dialing peers if at connected peers limit
+ if connected_peers_count >= event_handler.connected_peers_limit as usize {
+ return;
+ }
+
+ // Filter out already connected peers
+ let new_registrations: Vec<&Registration> = registrations
+ .iter()
+ .filter(|registration| {
+ !event_handler
+ .connected_peers
+ .contains_key(&registration.record.peer_id())
+ })
+ .collect();
+
+ // Dial newly discovered peers
+ for (index, registration) in new_registrations.iter().enumerate() {
  // Dial discovered peer if not us and not at connected peers limit
  if &registration.record.peer_id() != event_handler.swarm.local_peer_id()
- && event_handler.connected_peers.len() + index
+ && connected_peers_count + index
  < event_handler.connected_peers_limit as usize
  {
  // TODO: do anything with ttl here?
@@ -221,7 +238,7 @@ async fn handle_swarm_event<THandlerErr: fmt::Debug + Send, DB: Database>(
  }
  }
  } else {
- // don't add peers that aren't from our namespace
+ // Do not dial peers that are not using our namespace
  warn!(peer_id=rendezvous_node.to_string(), namespace=?cookie.namespace(), "rendezvous peer gave records from an unexpected namespace");
  }
  }