Use default registry over creating new registry

Author: njgheorghita

portalnet/src/metrics/overlay.rs

@@ -10,7 +10,10 @@ use prometheus_exporter::{
     },
 };
 
-/// TODO COMMENTS ON SETUP
+/// Contains metrics reporters for use in the overlay network
+/// (eg. `portalnet/src/overlay.rs` & `portalnet/src/overlay_service.rs`).
+/// Metric types reported here include protocol messages, utp transfers,
+/// and content validation.
 #[derive(Clone)]
 pub struct OverlayMetrics {
     pub message_count: IntCounterVec,

portalnet/src/metrics/portalnet.rs

@@ -1,15 +1,18 @@
 use crate::metrics::overlay::OverlayMetrics;
 use crate::metrics::storage::StorageMetrics;
 use lazy_static::lazy_static;
-use prometheus_exporter::prometheus::Registry;
+use prometheus_exporter::prometheus::{default_registry, Registry};
 
+// We use lazy_static to ensure that the metrics registry is initialized only once, for each
+// runtime. This is important because the registry is a global singleton, and if it is
+// initialized more than once, it will panic when trying to register the same metric for each
+// subnetwork.
 lazy_static! {
     pub static ref PORTALNET_METRICS: PortalnetMetrics = initialize_metrics_registry();
 }
 
 fn initialize_metrics_registry() -> PortalnetMetrics {
-    let registry = Registry::new();
-    PortalnetMetrics::new(registry).expect("failed to initialize metrics")
+    PortalnetMetrics::new().expect("failed to initialize metrics")
 }
 
 pub struct PortalnetMetrics {
@@ -18,7 +21,8 @@ pub struct PortalnetMetrics {
 }
 
 impl PortalnetMetrics {
-    pub fn new(registry: Registry) -> anyhow::Result<Self> {
+    pub fn new() -> anyhow::Result<Self> {
+        let registry = default_registry();
         let overlay = OverlayMetrics::new(&registry)?;
         let storage = StorageMetrics::new(&registry)?;
         Ok(Self { overlay, storage })

portalnet/src/metrics/storage.rs

@@ -7,6 +7,7 @@ use prometheus_exporter::{
     },
 };
 
+/// Contains metrics reporters for portalnet storage.
 #[derive(Clone, Debug)]
 pub struct StorageMetrics {
     pub content_storage_usage_bytes: GaugeVec,