apollo_committer: add per-block commit latency histogram metric

crates/apollo_committer/Cargo.toml

@@ -22,8 +22,11 @@ starknet_patricia_storage = { workspace = true, features = ["rocksdb_storage"] }
 tracing.workspace = true
 
 [dev-dependencies]
+apollo_metrics = { workspace = true, features = ["testing"] }
 assert_matches.workspace = true
 indexmap.workspace = true
+metrics.workspace = true
+metrics-exporter-prometheus.workspace = true
 starknet_committer = { workspace = true, features = ["testing"] }
 starknet_patricia = { workspace = true, features = ["testing"] }
 tokio.workspace = true

crates/apollo_committer/src/committer.rs

@@ -76,6 +76,7 @@ use crate::metrics::{
     AVERAGE_READ_RATE,
     AVERAGE_WRITE_RATE,
     BLOCKS_COMMITTED,
+    COMMITTER_BLOCK_COMMIT_LATENCY,
     COMMITTER_OFFSET,
     COMPUTE_DURATION_PER_BLOCK,
     COUNT_CLASSES_TRIE_MODIFICATIONS_PER_BLOCK,
@@ -680,6 +681,7 @@ fn update_metrics(
 ) {
     BLOCKS_COMMITTED.increment(1);
     TOTAL_BLOCK_DURATION.increment((durations.block * 1000.0) as u64);
+    COMMITTER_BLOCK_COMMIT_LATENCY.record(durations.block);
     let n_modifications = modifications_counts.total();
     // Microseconds.
     let total_block_duration_per_modification = if n_modifications > 0 {

crates/apollo_committer/src/committer_test.rs

@@ -10,6 +10,7 @@ use apollo_committer_types::committer_types::{
 use apollo_committer_types::errors::CommitterError;
 use assert_matches::assert_matches;
 use indexmap::indexmap;
+use metrics_exporter_prometheus::PrometheusBuilder;
 use starknet_api::block::BlockNumber;
 use starknet_api::block_hash::state_diff_hash::calculate_state_diff_hash;
 use starknet_api::core::{ClassHash, CompiledClassHash, StateDiffCommitment};
@@ -21,6 +22,7 @@ use tracing_test::traced_test;
 
 use super::Committer;
 use crate::committer::StorageConstructor;
+use crate::metrics::{register_metrics, COMMITTER_BLOCK_COMMIT_LATENCY};
 
 #[cfg(feature = "os_input")]
 #[path = "request_paths_and_commit_block_tests.rs"]
@@ -339,3 +341,19 @@ async fn no_warn_when_block_commit_within_duration_threshold() {
     committer.commit_block(commit_block_request(1, Some(1), 0)).await.unwrap();
     assert!(!logs_contain("block commit duration above the"));
 }
+
+#[tokio::test]
+async fn block_commit_latency_histogram_records_commit_duration() {
+    let recorder = PrometheusBuilder::new().build_recorder();
+    let _recorder_guard = metrics::set_default_local_recorder(&recorder);
+    register_metrics(BlockNumber(0));
+
+    let mut committer = new_test_committer().await;
+    committer.commit_block(commit_block_request(1, Some(1), 0)).await.unwrap();
+
+    let recorded_metrics = recorder.handle().render();
+    let histogram_value =
+        COMMITTER_BLOCK_COMMIT_LATENCY.parse_histogram_metric(&recorded_metrics).unwrap();
+    assert_eq!(histogram_value.count, 1);
+    assert!(histogram_value.sum > 0.0);
+}

crates/apollo_committer/src/metrics.rs

@@ -96,6 +96,12 @@ define_metrics!(
             "Compute written entries per second average over a block (cumulative)",
             init = 0
         },
+        MetricHistogram {
+            COMMITTER_BLOCK_COMMIT_LATENCY,
+            "committer_block_commit_latency",
+            "Latency of committing a single block, in seconds (recorded for both commits and \
+             reverts)"
+        },
     },
 );
 
@@ -115,4 +121,5 @@ pub fn register_metrics(offset: BlockNumber) {
     AVERAGE_WRITE_RATE.register();
     COMPUTE_DURATION_PER_BLOCK.register();
     AVERAGE_COMPUTE_RATE.register();
+    COMMITTER_BLOCK_COMMIT_LATENCY.register();
 }