Set xDS registry (#1162)

Author: Jake-Shadle

crates/xds/src/metrics.rs

@@ -14,7 +14,6 @@
  *  limitations under the License.
  */
 
-use arc_swap::ArcSwap;
 use once_cell::sync::Lazy;
 use prometheus::{IntCounterVec, IntGaugeVec, Registry};
 
@@ -23,20 +22,20 @@ pub(crate) const CONTROL_PLANE_LABEL: &str = "control_plane";
 pub(crate) const TYPE_LABEL: &str = "type";
 
 /// TODO: Remove and replace with a local registry.
-static REGISTRY: Lazy<ArcSwap<Registry>> = Lazy::new(|| {
-    ArcSwap::new(std::sync::Arc::new(
-        Registry::new_custom(Some("quilkin".into()), None).unwrap(),
-    ))
-});
+static REGISTRY_ONCE: parking_lot::Once = parking_lot::Once::new();
+static mut REGISTRY: Option<&'static Registry> = None;
 
 /// Sets the [`Registry`] containing all the metrics registered in xDS.
-pub fn set_registry(registry: std::sync::Arc<Registry>) {
-    REGISTRY.store(registry);
+pub fn set_registry(registry: &'static Registry) {
+    REGISTRY_ONCE.call_once(|| unsafe {
+        REGISTRY = Some(registry);
+    });
 }
 
 /// Returns the [`Registry`] containing all the metrics registered in xDS.
-pub fn registry() -> arc_swap::Guard<std::sync::Arc<Registry>> {
-    REGISTRY.load()
+#[inline]
+pub fn registry() -> &'static Registry {
+    unsafe { REGISTRY }.expect("set_registry must be called")
 }
 
 pub(crate) fn active_control_planes(control_plane: &str) -> prometheus::IntGauge {

src/cli/service.rs

@@ -246,6 +246,8 @@ impl Service {
         config: &Arc<Config>,
         shutdown_rx: &crate::signal::ShutdownRx,
     ) -> crate::Result<tokio::task::JoinHandle<crate::Result<()>>> {
+        quilkin_xds::metrics::set_registry(crate::metrics::registry());
+
         let mut shutdown_rx = shutdown_rx.clone();
         let mds_task = self.publish_mds(config)?;
         let (phoenix_task, phoenix_finalizer) = self.publish_phoenix(config)?;