prometheus

src/error.rs

@@ -5,6 +5,7 @@ use axum::{
 };
 use log::error;
 use thiserror::Error;
+use tokio::task::JoinError;
 
 #[derive(Debug, Error)]
 pub enum Error {
@@ -49,6 +50,9 @@ pub enum Error {
 
     #[error("Prometheus: {0:?}")]
     Prometheus(std::fmt::Error),
+
+    #[error("join error")]
+    Join(#[from] JoinError),
 }
 
 impl IntoResponse for Error {

src/main.rs

@@ -28,13 +28,13 @@ use garbage_collector::{start_gc, GarbageCollectorItem};
 use prometheus_client::{
     encoding::EncodeLabelSet,
     metrics::{counter::Counter, family::Family, gauge::Gauge},
-    registry::Registry,
+    registry::{self, Registry},
 };
 use question::{single_choice::SingleChoiceQuestion, Question};
 use sailfish::TemplateOnce;
 use serde::{Deserialize, Serialize};
 use stream::{PlayerBroadcastStream, ViewerBroadcastStream};
-use tokio::sync::RwLock;
+use tokio::{sync::RwLock, task::spawn_blocking};
 use tower::ServiceBuilder;
 use tower_http::services::ServeDir;
 use tower_sessions::{cookie::SameSite, MemoryStore, SessionManagerLayer};
@@ -313,9 +313,14 @@ pub async fn sse_player(
 }
 
 async fn metrics(State(app_state): State<AppState>) -> HandlerResult<impl IntoResponse> {
-    let mut buffer = String::new();
-    prometheus_client::encoding::text::encode(&mut buffer, &app_state.prometheus_registry)
-        .map_err(Error::Prometheus)?;
+    let registry = app_state.prometheus_registry.clone();
+    let buffer = spawn_blocking::<_, Result<String, Error>>(move || {
+        let mut buffer = String::new();
+        prometheus_client::encoding::text::encode(&mut buffer, &registry)
+            .map_err(Error::Prometheus)?;
+        Ok(buffer)
+    })
+    .await??;
 
     let mut headers = HeaderMap::new();
     headers.insert(