refactor: Cache valid-session result

1 files changed, 29 insertions, 4 deletions

diff --git a/code/app/src/routes/(main)/+layout.server.ts b/code/app/src/routes/(main)/+layout.server.ts
index acb9c22..a4507e1 100644
--- a/code/app/src/routes/(main)/+layout.server.ts
+++ b/code/app/src/routes/(main)/+layout.server.ts
@@ -1,21 +1,22 @@
 import { api_base, CookieNames } from "$lib/configuration";
 import { log_debug, log_error } from "$lib/logger";
 import { error, redirect } from "@sveltejs/kit";
+import { Temporal } from "temporal-polyfill";
 import type { LayoutServerLoad } from "./$types";
 
 export const load: LayoutServerLoad = async ({ route, cookies, locals }) => {
     const isBaseRoute = route.id === "/(main)";
     const isPublicRoute = (route.id?.startsWith("/(main)/(public)") || isBaseRoute) ?? true;
-    const sessionIsValid = (await fetch(api_base("_/valid-session"), {
+    const sessionIsValid = (await cached_result<Response>("sessionCheck", 10, () => fetch(api_base("_/valid-session"), {
         headers: {
             Cookie: CookieNames.session + "=" + cookies.get(CookieNames.session)
         }
     }).catch((e) => {
         log_error(e);
         throw error(503, {
-            message: "We are experiencing a service distruption! Have patience while we resolve the issue."
+            message: "We are experiencing a service disruption! Have patience while we resolve the issue."
         })
-    })).ok;
+    }))).ok;
 
     log_debug("Base Layout loaded", {
         sessionIsValid,
@@ -32,4 +33,28 @@ export const load: LayoutServerLoad = async ({ route, cookies, locals }) => {
     return {
         locale: locals.locale
     }
-};
\ No newline at end of file
+}
+
+let resultCache = {};
+async function cached_result<T>(key: string, staleAfterSeconds: number, code: any) {
+    if (!resultCache[key]) {
+        resultCache[key] = {
+            l: 0,
+            c: undefined as T
+        }
+    }
+    const staleEpoch = ((resultCache[key]?.l ?? 0) + staleAfterSeconds);
+    const isStale = staleEpoch < Temporal.Now.instant().epochSeconds;
+    if (isStale || !resultCache[key]?.c) {
+        resultCache[key].c = await code();
+        resultCache[key].l = Temporal.Now.instant().epochSeconds;
+    }
+
+    console.log({
+        isStale,
+        cache: resultCache[key],
+        staleEpoch
+    });
+
+    return resultCache[key].c as T;
+}
\ No newline at end of file