From 06b864055ceca066f046fdf3376f2f43395e6cb9 Mon Sep 17 00:00:00 2001
From: Khairul Hidayat <khai@rul.sh>
Date: Sat, 24 Feb 2024 04:56:53 +0000
Subject: [PATCH] feat: add caching to thumbnail creator

---
 server/api/thumbnail.ts  | 40 ++++++++++++++++++++++++++++++----------
 server/lib/screenshot.ts |  1 +
 2 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/server/api/thumbnail.ts b/server/api/thumbnail.ts
index 4320f3b..0444f59 100644
--- a/server/api/thumbnail.ts
+++ b/server/api/thumbnail.ts
@@ -1,24 +1,44 @@
 import { Request, Response } from "express";
 import { screenshot } from "../lib/screenshot";
 
-const cache = new Map<string, Buffer>();
+const cache = new Map<string, { data: Buffer; timestamp: number }>();
 
-export const thumbnail = async (req: Request, res: Response) => {
-  const { slug } = req.params;
-  const cacheData = cache.get(slug);
+const regenerateThumbnail = async (slug: string) => {
+  const curCache = cache.get(slug);
 
-  if (cacheData) {
-    res.contentType("image/jpeg");
-    return res.send(cacheData);
+  if (curCache?.data) {
+    cache.set(slug, {
+      data: curCache.data,
+      timestamp: Date.now(),
+    });
   }
 
   const result = await screenshot(slug);
   if (!result) {
-    return res.status(400).send("Cannot generate thumbnail!");
+    return curCache;
   }
 
-  cache.set(slug, result);
+  const data = {
+    data: result,
+    timestamp: Date.now(),
+  };
+
+  cache.set(slug, data);
+  return data;
+};
+
+export const thumbnail = async (req: Request, res: Response) => {
+  const { slug } = req.params;
+  let cacheData = cache.get(slug);
+
+  if (!cacheData) {
+    cacheData = await regenerateThumbnail(slug);
+  }
+
+  if (cacheData && Date.now() - cacheData.timestamp > 10000) {
+    regenerateThumbnail(slug);
+  }
 
   res.contentType("image/jpeg");
-  res.send(result);
+  res.send(cacheData?.data);
 };
diff --git a/server/lib/screenshot.ts b/server/lib/screenshot.ts
index a1569ca..b8d1e30 100644
--- a/server/lib/screenshot.ts
+++ b/server/lib/screenshot.ts
@@ -28,6 +28,7 @@ export const screenshot = async (slug: string) => {
 
     closeHandler = setTimeout(() => {
       browser?.close();
+      browser = null;
       closeHandler = null;
     }, 60000);