From 5886db20dd9f8d0c65dce7aa794da85d6741463e Mon Sep 17 00:00:00 2001
From: Bryan Stitt <bryan@satoshiandkin.com>
Date: Wed, 16 Nov 2022 20:17:33 +0000
Subject: [PATCH] cache status page for 1 second

---
 web3_proxy/src/frontend/mod.rs    | 22 ++++++++++++++++++--
 web3_proxy/src/frontend/status.rs | 34 ++++++++++++++++++++-----------
 2 files changed, 42 insertions(+), 14 deletions(-)

diff --git a/web3_proxy/src/frontend/mod.rs b/web3_proxy/src/frontend/mod.rs
index da55808d..4faaaf58 100644
--- a/web3_proxy/src/frontend/mod.rs
+++ b/web3_proxy/src/frontend/mod.rs
@@ -16,15 +16,31 @@ use axum::{
 };
 use http::header::AUTHORIZATION;
 use log::info;
-use std::iter::once;
+use moka::future::Cache;
 use std::net::SocketAddr;
 use std::sync::Arc;
+use std::{iter::once, time::Duration};
 use tower_http::cors::CorsLayer;
 use tower_http::sensitive_headers::SetSensitiveRequestHeadersLayer;
 
-/// Start the frontend server.
+#[derive(Clone, Hash, PartialEq, Eq)]
+pub enum FrontendResponseCaches {
+    Status,
+}
 
+// TODO: what should this cache's value be?
+pub type FrontendResponseCache =
+    Cache<FrontendResponseCaches, Arc<serde_json::Value>, hashbrown::hash_map::DefaultHashBuilder>;
+
+/// Start the frontend server.
 pub async fn serve(port: u16, proxy_app: Arc<Web3ProxyApp>) -> anyhow::Result<()> {
+    // setup caches for whatever the frontend needs
+    // 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))
+        .build_with_hasher(hashbrown::hash_map::DefaultHashBuilder::default());
+
     // build our axum Router
     let app = Router::new()
         // routes should be ordered most to least common
@@ -70,6 +86,8 @@ pub async fn serve(port: u16, proxy_app: Arc<Web3ProxyApp>) -> anyhow::Result<()
         .layer(CorsLayer::very_permissive())
         // application state
         .layer(Extension(proxy_app.clone()))
+        // frontend caches
+        .layer(Extension(response_cache))
         // 404 for any unknown routes
         .fallback(errors::handler_404.into_service());
 
diff --git a/web3_proxy/src/frontend/status.rs b/web3_proxy/src/frontend/status.rs
index 5d1fb2e3..ceda6e95 100644
--- a/web3_proxy/src/frontend/status.rs
+++ b/web3_proxy/src/frontend/status.rs
@@ -3,6 +3,7 @@
 //! For ease of development, users can currently access these endponts.
 //! They will eventually move to another port.
 
+use super::{FrontendResponseCache, FrontendResponseCaches};
 use crate::app::Web3ProxyApp;
 use axum::{http::StatusCode, response::IntoResponse, Extension, Json};
 use axum_macros::debug_handler;
@@ -36,19 +37,28 @@ pub async fn prometheus(Extension(app): Extension<Arc<Web3ProxyApp>>) -> impl In
 /// TODO: replace this with proper stats and monitoring
 #[debug_handler]
 
-pub async fn status(Extension(app): Extension<Arc<Web3ProxyApp>>) -> impl IntoResponse {
-    app.pending_transactions.sync();
-    app.rpc_secret_key_cache.sync();
+pub async fn status(
+    Extension(app): Extension<Arc<Web3ProxyApp>>,
+    Extension(response_cache): Extension<FrontendResponseCache>,
+) -> impl IntoResponse {
+    let body = response_cache
+        .get_with(FrontendResponseCaches::Status, async {
+            app.pending_transactions.sync();
+            app.rpc_secret_key_cache.sync();
 
-    // TODO: what else should we include? uptime, cache hit rates, cpu load
-    let body = json!({
-        "pending_transactions_count": app.pending_transactions.entry_count(),
-        "pending_transactions_size": app.pending_transactions.weighted_size(),
-        "user_cache_count": app.rpc_secret_key_cache.entry_count(),
-        "user_cache_size": app.rpc_secret_key_cache.weighted_size(),
-        "balanced_rpcs": app.balanced_rpcs,
-        "private_rpcs": app.private_rpcs,
-    });
+            // TODO: what else should we include? uptime, cache hit rates, cpu load
+            let body = json!({
+                "pending_transactions_count": app.pending_transactions.entry_count(),
+                "pending_transactions_size": app.pending_transactions.weighted_size(),
+                "user_cache_count": app.rpc_secret_key_cache.entry_count(),
+                "user_cache_size": app.rpc_secret_key_cache.weighted_size(),
+                "balanced_rpcs": app.balanced_rpcs,
+                "private_rpcs": app.private_rpcs,
+            });
+
+            Arc::new(body)
+        })
+        .await;
 
     Json(body)
 }