feat/improve-automatic-bootstrap

protocols/kad/CHANGELOG.md

@@ -19,6 +19,10 @@
   See [PR 5317](https://github.com/libp2p/rust-libp2p/pull/5317).
 - Use `web-time` instead of `instant`.
   See [PR 5347](https://github.com/libp2p/rust-libp2p/pull/5347).
+- Improve automatic bootstrap triggering conditions:
+  trigger when the routing table is updated and we have less that `K_VALUE` peers in it,
+  trigger when a new listen address is discovered and we have no connected peers.
+  See [PR 5474](https://github.com/libp2p/rust-libp2p/pull/5474).
 
 ## 0.45.3
 

protocols/kad/src/behaviour.rs

@@ -606,7 +606,13 @@ where
                 };
                 match entry.insert(addresses.clone(), status) {
                     kbucket::InsertResult::Inserted => {
-                        self.bootstrap_status.on_new_peer_in_routing_table();
+                        if self.kbuckets().count() < K_VALUE.get() {
+                            // A new peer has been inserted in the routing table and the routing
+                            // table is currently small (less that `K_VALUE` peers are present).
+                            // We initiate a bootstrap to fill it up.
+                            self.bootstrap_status.trigger();
+                        }
+
                         self.queued_events.push_back(ToSwarm::GenerateEvent(
                             Event::RoutingUpdated {
                                 peer: *peer,
@@ -1334,7 +1340,13 @@ where
                         let addresses = Addresses::new(a);
                         match entry.insert(addresses.clone(), new_status) {
                             kbucket::InsertResult::Inserted => {
-                                self.bootstrap_status.on_new_peer_in_routing_table();
+                                if self.kbuckets().count() < K_VALUE.get() {
+                                    // A new peer has been inserted in the routing table and the routing
+                                    // table is currently small (less that `K_VALUE` peers are present).
+                                    // We initiate a bootstrap to fill it up.
+                                    self.bootstrap_status.trigger();
+                                }
+
                                 let event = Event::RoutingUpdated {
                                     peer,
                                     is_new_peer: true,
@@ -2628,6 +2640,12 @@ where
             }
             FromSwarm::DialFailure(dial_failure) => self.on_dial_failure(dial_failure),
             FromSwarm::AddressChange(address_change) => self.on_address_change(address_change),
+            FromSwarm::NewListenAddr(_) if self.connected_peers.is_empty() => {
+                // A new listen addr was just discovered and we have no connected peers,
+                // it can mean that our network interfaces were not up but they are now
+                // so it might be a good idea to trigger a bootstrap.
+                self.bootstrap_status.trigger();
+            }
             _ => {}
         }
     }

protocols/kad/src/bootstrap.rs

@@ -44,7 +44,8 @@ impl Status {
         }
     }
 
-    pub(crate) fn on_new_peer_in_routing_table(&mut self) {
+    /// Trigger a bootstrap now or after the configured `automatic_throttle` if configured.
+    pub(crate) fn trigger(&mut self) {
         // Registering `self.throttle_timer` means scheduling a bootstrap.
         // A bootstrap will be triggered when `self.throttle_timer` finishes.
         // A `throttle_timer` is useful to not trigger a batch of bootstraps when a
@@ -197,7 +198,7 @@ mod tests {
             "bootstrap to not be triggered immediately because periodic bootstrap is in ~1s"
         );
 
-        status.on_new_peer_in_routing_table(); // Connected to a new peer though!
+        status.trigger(); // Connected to a new peer though!
         assert!(
             status.next().now_or_never().is_some(),
             "bootstrap to be triggered immediately because we connected to a new peer"
@@ -222,7 +223,7 @@ mod tests {
             "bootstrap to not be triggered immediately because periodic bootstrap is in ~1s"
         );
 
-        status.on_new_peer_in_routing_table(); // Connected to a new peer though!
+        status.trigger(); // Connected to a new peer though!
         assert!(
             status.next().now_or_never().is_none(),
             "bootstrap to not be triggered immediately because throttle is 5ms"
@@ -243,7 +244,7 @@ mod tests {
         // User manually triggered a bootstrap
         do_bootstrap(&mut status);
 
-        status.on_new_peer_in_routing_table(); // Connected to a new peer though!
+        status.trigger(); // Connected to a new peer though!
 
         assert!(
             status.next().now_or_never().is_some(),
@@ -256,7 +257,7 @@ mod tests {
     ) {
         let mut status = Status::new(Some(MS_100), Some(MS_5));
 
-        status.on_new_peer_in_routing_table();
+        status.trigger();
 
         let start = Instant::now();
         await_and_do_bootstrap(&mut status).await;
@@ -276,7 +277,7 @@ mod tests {
     ) {
         let mut status = Status::new(None, Some(Duration::ZERO));
 
-        status.on_new_peer_in_routing_table();
+        status.trigger();
 
         status.next().await;
     }
@@ -300,10 +301,10 @@ mod tests {
     ) {
         let mut status = Status::new(None, Some(MS_100));
 
-        status.on_new_peer_in_routing_table();
+        status.trigger();
         for _ in 0..10 {
             Delay::new(MS_100 / 2).await;
-            status.on_new_peer_in_routing_table(); // should reset throttle_timer
+            status.trigger(); // should reset throttle_timer
         }
         assert!(
             status.next().now_or_never().is_none(),