Speed up ENR update (#196)

* PING immediately if the connection direction is outgoing

* Add a comment

* suggested alternative that reduces cloning

* actually remove the extra clone

* only ping peers that manage to make it into the routing table

to get the added security measures, like bucket and table limits

* Fix borrow of moved value

* Fix E0502: self is already borrowed as immutable

https://github.com/sigp/discv5/actions/runs/5394916671/jobs/9796752728?pr=196#step:5:443

---------

Co-authored-by: Diva M <[email protected]>

Author: ackintosh

src/service.rs

@@ -1269,11 +1269,23 @@ impl Service {
                     state: ConnectionState::Connected,
                     direction,
                 };
-                match self.kbuckets.write().insert_or_update(&key, enr, status) {
+
+                let insert_result =
+                    self.kbuckets
+                        .write()
+                        .insert_or_update(&key, enr.clone(), status);
+                match insert_result {
                     InsertResult::Inserted => {
                         // We added this peer to the table
                         debug!("New connected node added to routing table: {}", node_id);
                         self.peers_to_ping.insert(node_id);
+
+                        // PING immediately if the direction is outgoing. This allows us to receive
+                        // a PONG without waiting for the ping_interval, making ENR updates faster.
+                        if direction == ConnectionDirection::Outgoing {
+                            self.send_ping(enr, None);
+                        }
+
                         let event = Discv5Event::NodeInserted {
                             node_id,
                             replaced: None,