adds metrics for number of nodes vs number of pubkeys (backport #20512) (#20524)

* adds metrics for number of nodes vs number of pubkeys (#20512)

(cherry picked from commit 0da661de62)

# Conflicts:
#	gossip/src/cluster_info_metrics.rs

* removes backport merge conflicts

Co-authored-by: behzad nouri <behzadnouri@gmail.com>

gossip/src/cluster_info_metrics.rs

@@ -163,11 +163,12 @@ pub(crate) fn submit_gossip_stats(
     gossip: &RwLock<CrdsGossip>,
     stakes: &HashMap<Pubkey, u64>,
 ) {
-    let (table_size, num_nodes, purged_values_size, failed_inserts_size) = {
+    let (table_size, num_nodes, num_pubkeys, purged_values_size, failed_inserts_size) = {
         let gossip = gossip.read().unwrap();
         (
             gossip.crds.len(),
             gossip.crds.num_nodes(),
+            gossip.crds.num_pubkeys(),
             gossip.crds.num_purged(),
             gossip.pull.failed_inserts.len(),
         )
@@ -192,6 +193,7 @@ pub(crate) fn submit_gossip_stats(
         ("failed_inserts_size", failed_inserts_size as i64, i64),
         ("num_nodes", num_nodes as i64, i64),
         ("num_nodes_staked", num_nodes_staked as i64, i64),
+        ("num_pubkeys", num_pubkeys, i64),
     );
     datapoint_info!(
         "cluster_info_stats2",

gossip/src/crds.rs

@@ -319,8 +319,13 @@ impl Crds {
             .map(move |i| self.table.index(*i))
     }
 
-    /// Returns number of known pubkeys (network size).
+    /// Returns number of known contact-infos (network size).
     pub(crate) fn num_nodes(&self) -> usize {
+        self.nodes.len()
+    }
+
+    /// Returns number of unique pubkeys.
+    pub(crate) fn num_pubkeys(&self) -> usize {
         self.records.len()
     }