validator_discovery: some logs to help identify authority discovery issues (#2533)

polkadot/node/network/bridge/src/validator_discovery.rs

@@ -264,6 +264,8 @@ impl<N: Network, AD: AuthorityDiscovery> Service<N, AD> {
 			if let Some(addresses) = result {
 				// We might have several `PeerId`s per `AuthorityId`
 				multiaddr_to_add.extend(addresses.into_iter().take(MAX_ADDR_PER_PEER));
+			} else {
+				tracing::debug!(target: LOG_TARGET, "Authority Discovery couldn't resolve {:?}", authority);
 			}
 		}
 
@@ -282,6 +284,9 @@ impl<N: Network, AD: AuthorityDiscovery> Service<N, AD> {
 		}
 
 		// clean up revoked requests states
+		//
+		// note that the `.rev()` here is important to guarantee `swap_remove`
+		// doesn't invalidate unprocessed `revoked_indices`
 		for to_revoke in revoked_indices.into_iter().rev() {
 			drop(state.non_revoked_discovery_requests.swap_remove(to_revoke));
 		}
@@ -289,9 +294,15 @@ impl<N: Network, AD: AuthorityDiscovery> Service<N, AD> {
 		// multiaddresses to remove
 		let mut multiaddr_to_remove = HashSet::new();
 		for id in revoked_validators.into_iter() {
-			let result = authority_discovery_service.get_addresses_by_authority_id(id).await;
+			let result = authority_discovery_service.get_addresses_by_authority_id(id.clone()).await;
 			if let Some(addresses) = result {
 				multiaddr_to_remove.extend(addresses.into_iter());
+			} else {
+				tracing::debug!(
+					target: LOG_TARGET,
+					"Authority Discovery couldn't resolve {:?} on cleanup, a leak is possible",
+					id,
+				);
 			}
 		}