From 9ac3ef1e3d065c5dd4dbecce6796902e53c746c6 Mon Sep 17 00:00:00 2001
From: Bryan Stitt <bryan@llamanodes.com>
Date: Thu, 2 Feb 2023 13:58:04 -0800
Subject: [PATCH] cache /health and cache /status for longer

---
 web3_proxy/src/frontend/mod.rs    |  8 +++++++-
 web3_proxy/src/frontend/status.rs | 14 ++++++++++----
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/web3_proxy/src/frontend/mod.rs b/web3_proxy/src/frontend/mod.rs
index f4005963..e1a55e2f 100644
--- a/web3_proxy/src/frontend/mod.rs
+++ b/web3_proxy/src/frontend/mod.rs
@@ -30,6 +30,7 @@ pub enum FrontendResponseCaches {
 // TODO: what should this cache's value be?
 pub type FrontendResponseCache =
     Cache<FrontendResponseCaches, Arc<serde_json::Value>, hashbrown::hash_map::DefaultHashBuilder>;
+pub type FrontendHealthCache = Cache<(), bool, hashbrown::hash_map::DefaultHashBuilder>;
 
 /// Start the frontend server.
 pub async fn serve(port: u16, proxy_app: Arc<Web3ProxyApp>) -> anyhow::Result<()> {
@@ -37,7 +38,11 @@ pub async fn serve(port: u16, proxy_app: Arc<Web3ProxyApp>) -> anyhow::Result<()
     // TODO: a moka cache is probably way overkill for this.
     // no need for max items. only expire because of time to live
     let response_cache: FrontendResponseCache = Cache::builder()
-        .time_to_live(Duration::from_secs(1))
+        .time_to_live(Duration::from_secs(2))
+        .build_with_hasher(hashbrown::hash_map::DefaultHashBuilder::default());
+
+    let health_cache: FrontendHealthCache = Cache::builder()
+        .time_to_live(Duration::from_millis(100))
         .build_with_hasher(hashbrown::hash_map::DefaultHashBuilder::default());
 
     // TODO: read config for if fastest/versus should be available publicly. default off
@@ -173,6 +178,7 @@ pub async fn serve(port: u16, proxy_app: Arc<Web3ProxyApp>) -> anyhow::Result<()
         .layer(Extension(proxy_app.clone()))
         // frontend caches
         .layer(Extension(response_cache))
+        .layer(Extension(health_cache))
         // 404 for any unknown routes
         .fallback(errors::handler_404);
 
diff --git a/web3_proxy/src/frontend/status.rs b/web3_proxy/src/frontend/status.rs
index df7f8bc9..1199dc25 100644
--- a/web3_proxy/src/frontend/status.rs
+++ b/web3_proxy/src/frontend/status.rs
@@ -3,7 +3,7 @@
 //! For ease of development, users can currently access these endponts.
 //! They will eventually move to another port.
 
-use super::{FrontendResponseCache, FrontendResponseCaches};
+use super::{FrontendHealthCache, FrontendResponseCache, FrontendResponseCaches};
 use crate::app::{Web3ProxyApp, APP_USER_AGENT};
 use axum::{http::StatusCode, response::IntoResponse, Extension, Json};
 use axum_macros::debug_handler;
@@ -12,9 +12,15 @@ use std::sync::Arc;
 
 /// Health check page for load balancers to use.
 #[debug_handler]
-pub async fn health(Extension(app): Extension<Arc<Web3ProxyApp>>) -> impl IntoResponse {
-    // TODO: add a check that we aren't shutting down
-    if app.balanced_rpcs.synced() {
+pub async fn health(
+    Extension(app): Extension<Arc<Web3ProxyApp>>,
+    Extension(health_cache): Extension<FrontendHealthCache>,
+) -> impl IntoResponse {
+    let synced = health_cache
+        .get_with((), async { app.balanced_rpcs.synced() })
+        .await;
+
+    if synced {
         (StatusCode::OK, "OK")
     } else {
         (StatusCode::SERVICE_UNAVAILABLE, ":(")