client/network: Expose number of entries per Kademlia bucket (#7104)

Extend `sub_libp2p_kbuckets_num_nodes` Prometheus metric to expose the
number of nodes per bucket per Kademlia instance instead of only per
Kademlia instance.

client/network/src/behaviour.rs

@@ -211,9 +211,12 @@ impl<B: BlockT, H: ExHashT> Behaviour<B, H> {
  self.discovery.add_known_address(peer_id, addr)
  }
 
- /// Returns the number of nodes that are in the Kademlia k-buckets.
- pub fn num_kbuckets_entries(&mut self) -> impl ExactSizeIterator<Item = (&ProtocolId, usize)> {
- self.discovery.num_kbuckets_entries()
+ /// Returns the number of nodes in each Kademlia kbucket for each Kademlia instance.
+ ///
+ /// Identifies Kademlia instances by their [`ProtocolId`] and kbuckets by the base 2 logarithm
+ /// of their lower bound.
+ pub fn num_entries_per_kbucket(&mut self) -> impl ExactSizeIterator<Item = (&ProtocolId, Vec<(u32, usize)>)> {
+ self.discovery.num_entries_per_kbucket()
  }
 
  /// Returns the number of records in the Kademlia record stores.

client/network/src/discovery.rs

@@ -329,10 +329,18 @@ impl DiscoveryBehaviour {
  }
  }
 
- /// Returns the number of nodes that are in the Kademlia k-buckets.
- pub fn num_kbuckets_entries(&mut self) -> impl ExactSizeIterator<Item = (&ProtocolId, usize)> {
+ /// Returns the number of nodes in each Kademlia kbucket for each Kademlia instance.
+ ///
+ /// Identifies Kademlia instances by their [`ProtocolId`] and kbuckets by the base 2 logarithm
+ /// of their lower bound.
+ pub fn num_entries_per_kbucket(&mut self) -> impl ExactSizeIterator<Item = (&ProtocolId, Vec<(u32, usize)>)> {
  self.kademlias.iter_mut()
- .map(|(id, kad)| (id, kad.kbuckets().map(|bucket| bucket.iter().count()).sum()))
+ .map(|(id, kad)| {
+ let buckets = kad.kbuckets()
+ .map(|bucket| (bucket.range().0.ilog2().unwrap_or(0), bucket.iter().count()))
+ .collect();
+ (id, buckets)
+ })
  }
 
  /// Returns the number of records in the Kademlia record stores.

client/network/src/service.rs

@@ -1670,8 +1670,12 @@ impl<B: BlockT + 'static, H: ExHashT> Future for NetworkWorker<B, H> {
  this.is_major_syncing.store(is_major_syncing, Ordering::Relaxed);
 
  if let Some(metrics) = this.metrics.as_ref() {
- for (proto, num_entries) in this.network_service.num_kbuckets_entries() {
- metrics.kbuckets_num_nodes.with_label_values(&[&proto.as_ref()]).set(num_entries as u64);
+ for (proto, buckets) in this.network_service.num_entries_per_kbucket() {
+ for (lower_ilog2_bucket_bound, num_entries) in buckets {
+ metrics.kbuckets_num_nodes
+ .with_label_values(&[&proto.as_ref(), &lower_ilog2_bucket_bound.to_string()])
+ .set(num_entries as u64);
+ }
  }
  for (proto, num_entries) in this.network_service.num_kademlia_records() {
  metrics.kademlia_records_count.with_label_values(&[&proto.as_ref()]).set(num_entries as u64);

client/network/src/service/metrics.rs

@@ -171,9 +171,9 @@ impl Metrics {
  kbuckets_num_nodes: prometheus::register(GaugeVec::new(
  Opts::new(
  "sub_libp2p_kbuckets_num_nodes",
- "Number of nodes in the Kademlia k-buckets"
+ "Number of nodes per kbucket per Kademlia instance"
  ),
- &["protocol"]
+ &["protocol", "lower_ilog2_bucket_bound"]
  )?, registry)?,
  listeners_local_addresses: prometheus::register(Gauge::new(
  "sub_libp2p_listeners_local_addresses", "Number of local addresses we're listening on"
@@ -355,4 +355,3 @@ impl MetricSource for NumConnectedGauge {
  set(&[], self.0.load(Ordering::Relaxed) as u64);
  }
 }
-