From ab3c8982e2c33e5279bf1b167f523696078629e6 Mon Sep 17 00:00:00 2001
From: u80864958 <niklas.breitenstein@bit.admin.ch>
Date: Fri, 23 Jan 2026 14:32:51 +0100
Subject: [PATCH] feat: lru cache

---
 package.json                           |  1 +
 pnpm-lock.yaml                         |  9 +++++
 src/lib/server/cache.ts                | 50 +++++++++++++++++++++++---
 src/routes/assets/[...path]/+server.ts |  8 +++--
 4 files changed, 61 insertions(+), 7 deletions(-)

diff --git a/package.json b/package.json
index 865c971..432f744 100644
--- a/package.json
+++ b/package.json
@@ -30,6 +30,7 @@
 		"@inlang/paraglide-js": "^1.11.0",
 		"@inlang/paraglide-sveltekit": "^0.16.1",
 		"@ts-stack/markdown": "^1.5.0",
+		"lru-cache": "^11.2.4",
 		"mime-types": "^3.0.2",
 		"svelte-preprocess": "^6.0.2",
 		"webdav": "^5.8.0"
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index a30d4f9..2742813 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -20,6 +20,9 @@ importers:
       '@ts-stack/markdown':
         specifier: ^1.5.0
         version: 1.5.0
+      lru-cache:
+        specifier: ^11.2.4
+        version: 11.2.4
       mime-types:
         specifier: ^3.0.2
         version: 3.0.2
@@ -1269,6 +1272,10 @@ packages:
     resolution: {integrity: sha512-9hp3Vp2/hFQUiIwKo8XCeFVnrg8Pk3TYNPIR7tJADKi5YfcF7vEaK7avFHTlSy3kOKYaJQaalfEo6YuXdceBOQ==}
     engines: {node: 14 || >=16.14}
 
+  lru-cache@11.2.4:
+    resolution: {integrity: sha512-B5Y16Jr9LB9dHVkh6ZevG+vAbOsNOYCX+sXvFWFu7B3Iz5mijW3zdbMyhsh8ANd2mSWBYdJgnqi+mL7/LrOPYg==}
+    engines: {node: 20 || >=22}
+
   magic-string@0.30.10:
     resolution: {integrity: sha512-iIRwTIf0QKV3UAnYK4PU8uiEc4SRh5jX0mwpIwETPpHdhVM4f53RSwS/vXvN1JhGX+Cs7B8qIq3d6AH49O5fAQ==}
 
@@ -2988,6 +2995,8 @@ snapshots:
 
   lru-cache@10.2.2: {}
 
+  lru-cache@11.2.4: {}
+
   magic-string@0.30.10:
     dependencies:
       '@jridgewell/sourcemap-codec': 1.4.15
diff --git a/src/lib/server/cache.ts b/src/lib/server/cache.ts
index ec4c41d..11c4b69 100644
--- a/src/lib/server/cache.ts
+++ b/src/lib/server/cache.ts
@@ -1,5 +1,44 @@
-const cache = new Map<string, { timestamp: number; data: any }>();
+import { LRUCache } from "lru-cache";
+
+// const cache = new Map<string, { timestamp: number; data: any }>();
 const DEFAULT_TTL = 1000 * 60 * 15; // 15 minutes default TTL
+const MAX_CACHE_SIZE = 1000 * 1000 * 750; // 750 MB
+
+const cache = new LRUCache({
+  max: 100,
+  // Maximum allowed size (in bytes)
+  maxSize: MAX_CACHE_SIZE,
+
+  // IMPORTANT: We must teach the cache how to calculate the size of an item.
+  // We check for your specific image structure, generic buffers, or fallback to JSON length.
+  sizeCalculation: (value) => {
+    // 1. Check if it's our specific image object { buffer: ArrayBuffer, ... }
+    if (value && typeof value === "object") {
+      const obj = value as Record<string, any>;
+      if (obj.buffer instanceof ArrayBuffer) {
+        return obj.buffer.byteLength;
+      }
+    }
+
+    // 2. Handle raw ArrayBuffers or Node.js Buffers
+    if (value instanceof ArrayBuffer) {
+      return value.byteLength;
+    }
+
+    if (Buffer.isBuffer(value)) {
+      return value.length;
+    }
+
+    // 3. Fallback for strings or JSON metadata
+    try {
+      const str = JSON.stringify(value);
+      return str ? str.length : 1;
+    } catch {
+      return 1;
+    }
+  },
+  ttl: DEFAULT_TTL,
+});
 
 /**
  * Caches the result of a promise-returning function.
@@ -12,16 +51,17 @@ export async function withCache<T>(
   fetcher: () => Promise<T>,
   ttl = DEFAULT_TTL,
 ): Promise<T> {
-  const now = Date.now();
   const entry = cache.get(key);
 
-  if (entry && now - entry.timestamp < ttl) {
-    return entry.data as T;
+  if (entry) {
+    return entry as T;
   }
 
   try {
     const data = await fetcher();
-    cache.set(key, { timestamp: now, data });
+    if (data) {
+      cache.set(key, data, { ttl: ttl });
+    }
     return data;
   } catch (error) {
     console.error(`Error fetching data for key ${key}:`, error);
diff --git a/src/routes/assets/[...path]/+server.ts b/src/routes/assets/[...path]/+server.ts
index 446c199..c58be55 100644
--- a/src/routes/assets/[...path]/+server.ts
+++ b/src/routes/assets/[...path]/+server.ts
@@ -6,6 +6,9 @@ import mime from "mime-types";
 import { env } from "$env/dynamic/private";
 import { withCache } from "$lib/server/cache";
 
+const DEFAULT_TTL = 1000 * 60 * 15; // 15min
+const EXTENDED_TTL = 1000 * 60 * 60 * 24 * 7; // 1 week
+
 // Define what we are storing in the cache
 type CachedAsset = {
   buffer: ArrayBuffer;
@@ -24,6 +27,8 @@ export const GET: RequestHandler = async ({ params, url }) => {
   // 1. Create a unique cache key for this specific asset variation
   const cacheKey = `asset:${path}?w=${width ?? ""}&h=${height ?? ""}`;
 
+  const ttl = path.toString().includes("cover") ? DEFAULT_TTL : EXTENDED_TTL;
+
   try {
     // 2. Use withCache to wrap the fetching logic
     const cachedData = await withCache<CachedAsset>(
@@ -113,8 +118,7 @@ export const GET: RequestHandler = async ({ params, url }) => {
         throw lastError || new Error("Asset not found");
         // --- END OF FETCH LOGIC ---
       },
-      // Optional: Set a specific TTL for images (e.g., 1 hour instead of default 15m)
-      1000 * 60 * 60,
+      ttl,
     );
 
     // 3. Construct a fresh Response using the cached data