[Narwhal] improve proposer metrics (#7738)

Addressing feedback from #7730

narwhal/primary/src/metrics.rs

@@ -5,10 +5,11 @@ use mysten_network::metrics::MetricsCallbackProvider;
 use network::metrics::{NetworkConnectionMetrics, NetworkMetrics};
 use prometheus::{
     core::{AtomicI64, GenericGauge},
-    default_registry, register_histogram_vec_with_registry, register_histogram_with_registry,
-    register_int_counter_vec_with_registry, register_int_counter_with_registry,
-    register_int_gauge_vec_with_registry, register_int_gauge_with_registry, Histogram,
-    HistogramVec, IntCounter, IntCounterVec, IntGauge, IntGaugeVec, Registry,
+    default_registry, linear_buckets, register_histogram_vec_with_registry,
+    register_histogram_with_registry, register_int_counter_vec_with_registry,
+    register_int_counter_with_registry, register_int_gauge_vec_with_registry,
+    register_int_gauge_with_registry, Histogram, HistogramVec, IntCounter, IntCounterVec, IntGauge,
+    IntGaugeVec, Registry,
 };
 use std::time::Duration;
 use tonic::Code;
@@ -272,10 +273,6 @@ impl PrimaryChannelMetrics {
                 "total received on channel signaling own committed headers.",
                 registry
             ).unwrap(),
-
-
-
-
         }
     }
 
@@ -316,7 +313,7 @@ pub struct PrimaryMetrics {
     pub headers_proposed: IntCounterVec,
     // total number of parents in all proposed headers, for calculating average number of parents
     // per header.
-    pub header_parents_total: IntCounter,
+    pub header_parents: Histogram,
     /// the current proposed header round
     pub proposed_header_round: IntGauge,
     /// The number of received votes for the proposed last round
@@ -362,6 +359,12 @@ pub struct PrimaryMetrics {
 
 impl PrimaryMetrics {
     pub fn new(registry: &Registry) -> Self {
+        let parents_buckets = [
+            linear_buckets(1.0, 1.0, 20).unwrap().as_slice(),
+            linear_buckets(21.0, 2.0, 20).unwrap().as_slice(),
+            linear_buckets(61.0, 3.0, 20).unwrap().as_slice(),
+        ]
+        .concat();
         Self {
             headers_proposed: register_int_counter_vec_with_registry!(
                 "headers_proposed",
@@ -370,9 +373,10 @@ impl PrimaryMetrics {
                 registry
             )
             .unwrap(),
-            header_parents_total: register_int_counter_with_registry!(
-                "header_parents_total",
+            header_parents: register_histogram_with_registry!(
+                "header_parents",
                 "Number of parents included in proposed headers",
+                parents_buckets,
                 registry
             )
             .unwrap(),

narwhal/primary/src/proposer.rs

@@ -228,23 +228,26 @@ impl Proposer {
         )
         .await;
 
-        let leader_support = if this_round % 2 == 0 {
-            "even_round"
+        let leader_and_support = if this_round % 2 == 0 {
+            let leader_name = self.committee.leader(this_round);
+            if self.name == leader_name {
+                "even_round_is_leader"
+            } else {
+                "even_round_not_leader"
+            }
         } else {
             let leader_name = self.committee.leader(this_round - 1);
             if parents.iter().any(|c| c.origin() == leader_name) {
-                "has_support"
+                "odd_round_gives_support"
             } else {
-                "no_support"
+                "odd_round_no_support"
             }
         };
         self.metrics
             .headers_proposed
-            .with_label_values(&[leader_support])
+            .with_label_values(&[leader_and_support])
             .inc();
-        self.metrics
-            .header_parents_total
-            .inc_by(parents.len() as u64);
+        self.metrics.header_parents.observe(parents.len() as f64);
 
         if enabled!(tracing::Level::DEBUG) {
             let mut msg = format!("Created header {header:?} with parent certificates:\n");