From cfb3ebcfe7dd497b3dd9a2b12871be17a9b639f4 Mon Sep 17 00:00:00 2001
From: Jimmy Chen <jchen.tc@gmail.com>
Date: Mon, 1 Jul 2024 12:49:03 +1000
Subject: [PATCH] Add metrics and update code comment.

---
 .../src/peer_manager/peerdb/peer_info.rs            |  4 +---
 beacon_node/lighthouse_network/src/types/globals.rs |  6 +++++-
 beacon_node/network/src/metrics.rs                  |  5 +++++
 beacon_node/network/src/sync/range_sync/chain.rs    | 13 +++++++++++--
 4 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/beacon_node/lighthouse_network/src/peer_manager/peerdb/peer_info.rs b/beacon_node/lighthouse_network/src/peer_manager/peerdb/peer_info.rs
index 2ce13e277a8..b0d28cc835e 100644
--- a/beacon_node/lighthouse_network/src/peer_manager/peerdb/peer_info.rs
+++ b/beacon_node/lighthouse_network/src/peer_manager/peerdb/peer_info.rs
@@ -95,9 +95,7 @@ impl<E: EthSpec> PeerInfo<E> {
                         .map_or(false, |s| s.get(**id as usize).unwrap_or(false))
                 }
                 Subnet::DataColumn(_) => {
-                    // There's no metadata field for data column subnets, we use the `csc` enr field
-                    // along with `node_id` to determine whether peer SHOULD be subscribed to a
-                    // given subnet.
+                    // TODO(das): Pending spec PR https://github.com/ethereum/consensus-specs/pull/3821
                     return true;
                 }
             }
diff --git a/beacon_node/lighthouse_network/src/types/globals.rs b/beacon_node/lighthouse_network/src/types/globals.rs
index 934ff276b6b..83ff9be5421 100644
--- a/beacon_node/lighthouse_network/src/types/globals.rs
+++ b/beacon_node/lighthouse_network/src/types/globals.rs
@@ -271,7 +271,11 @@ mod test {
         drop(peers_db_write_lock);
 
         let custody_subnets = (0..spec.data_column_sidecar_subnet_count)
-            .filter(|col_index| !globals.custody_peers_for_column(*col_index, &spec).is_empty())
+            .filter(|col_index| {
+                !globals
+                    .custody_peers_for_column(*col_index, &spec)
+                    .is_empty()
+            })
             .count();
 
         // The single peer's custody subnet should match custody_requirement.
diff --git a/beacon_node/network/src/metrics.rs b/beacon_node/network/src/metrics.rs
index 56af9833f1a..dd5e359af37 100644
--- a/beacon_node/network/src/metrics.rs
+++ b/beacon_node/network/src/metrics.rs
@@ -239,6 +239,11 @@ lazy_static! {
         "Number of connected peers per sync status type",
         &["sync_status"]
     );
+    pub static ref PEERS_PER_COLUMN_SUBNET: Result<IntGaugeVec> = try_create_int_gauge_vec(
+        "peers_per_column_subnet",
+        "Number of connected peers per column subnet",
+        &["subnet_id"]
+    );
     pub static ref SYNCING_CHAINS_COUNT: Result<IntGaugeVec> = try_create_int_gauge_vec(
         "sync_range_chains",
         "Number of Syncing chains in range, per range type",
diff --git a/beacon_node/network/src/sync/range_sync/chain.rs b/beacon_node/network/src/sync/range_sync/chain.rs
index 5ee0b16e029..071d634a39f 100644
--- a/beacon_node/network/src/sync/range_sync/chain.rs
+++ b/beacon_node/network/src/sync/range_sync/chain.rs
@@ -1,4 +1,5 @@
 use super::batch::{BatchInfo, BatchProcessingResult, BatchState};
+use crate::metrics::PEERS_PER_COLUMN_SUBNET;
 use crate::network_beacon_processor::ChainSegmentProcessId;
 use crate::sync::network_context::RangeRequestId;
 use crate::sync::{
@@ -7,6 +8,7 @@ use crate::sync::{
 use beacon_chain::block_verification_types::RpcBlock;
 use beacon_chain::BeaconChainTypes;
 use fnv::FnvHashMap;
+use lighthouse_metrics::set_int_gauge;
 use lighthouse_network::{PeerAction, PeerId, Subnet};
 use rand::seq::SliceRandom;
 use slog::{crit, debug, o, warn};
@@ -397,7 +399,9 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
                 }
             }
         } else if !self.good_peers_on_custody_subnets(self.processing_target, network) {
-            // If there's no good custody peers for this epoch, batch won't be created
+            // This is to handle the case where no batch was sent for the current processing
+            // target when there is no custody peers available. This is a valid state and should not
+            // return an error.
             return Ok(KeepChain);
         } else {
             return Err(RemoveChain::WrongChainState(format!(
@@ -1044,7 +1048,12 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
                         .read()
                         .good_peers_on_subnet(Subnet::DataColumn(subnet_id))
                         .count();
-                    debug!(self.log, "Peers found on custody subnet"; "subnet_id" => ?subnet_id, "peer_count" => peer_count);
+
+                    set_int_gauge(
+                        &PEERS_PER_COLUMN_SUBNET,
+                        &[&subnet_id.to_string()],
+                        peer_count as i64,
+                    );
                     peer_count > 0
                 });
             peers_on_all_custody_subnets