utilize etags

src/index.ts

@@ -1,26 +1,49 @@
-import { env, randomUUIDv7 } from 'bun';
 import homepage from '@routes/index.html';
+import auth from '@server/auth';
+import ptApi from '@server/pt-api';
+import favicon from '@static/favicon.png';
 import robotsTxt from '@static/robots.txt';
 import sitemapTxt from '@static/sitemap.txt';
-import favicon from '@static/favicon.png';
-import ptApi from '@server/pt-api';
-import auth from '@server/auth';
+import { env } from 'bun';
 
 const development = env.NODE_ENV !== 'production';
 
 const faviconInit = { headers: new Headers({ 'Content-Type': 'image/png' }) };
 
+let ptEntriesETag = '';
+let entriesETag = '';
 let entriesCache = '';
 let entriesCacheTime = 0;
-const entriesCacheTimeLimit = 1000 * 15;
+const entriesCacheMaxAge = 3;
+const entriesCacheTimeLimit = 1000 * entriesCacheMaxAge;
 
-async function getEntriesCached() {
-  if (entriesCacheTime + entriesCacheTimeLimit < Date.now()) {
-    const data = await ptApi.query();
-    entriesCache = JSON.stringify(data);
-    entriesCacheTime = Date.now();
+function getEtag(data: string) {
+  const sha = Bun.SHA256.hash(data);
+  return Buffer.from(sha.buffer).toString('base64url');
 }
-  return entriesCache;
+
+async function checkEntriesCache() {
+  if (entriesCacheTime + entriesCacheTimeLimit >= Date.now())
+    return;
+
+  try {
+    const [etag, data] = await ptApi.query(entriesETag);
+    if (etag === ptEntriesETag || !Array.isArray(data)) return; // No new data
+    if (etag !== null) ptEntriesETag = etag;
+
+    entriesCache = JSON.stringify(data);
+    entriesETag = getEtag(entriesCache);
+    entriesCacheTime = Date.now();
+  } catch (err) {
+    console.error('Failed to fetch entries:', err);
+  }
+}
+
+function etagResponse(etag: string, cacheControl?: string) {
+  const headers = new Headers();
+  headers.set('ETag', etag);
+  if (cacheControl) headers.set('Cache-Control', cacheControl);
+  return new Response('', { status: 304, headers });
 }
 
 Bun.serve({
@@ -41,14 +64,20 @@ Bun.serve({
           return auth.verifyFailResponse();
         }
 
-        return new Response(await getEntriesCached(), {
+        await checkEntriesCache();
+        if (req.headers.get('if-none-match') === entriesETag) {
+          return etagResponse(entriesETag, `max-age=${entriesCacheMaxAge}`);
+        }
+
+        return new Response(entriesCache, {
           headers: {
-            'Content-Type': 'application/json'
+            'Content-Type': 'application/json',
+            'Cache-Control': `max-age=${entriesCacheMaxAge}`,
+            'ETag': entriesETag,
           }
         });
       },
     },
-
     '/auth/logout': {
       async POST() {
         return auth.logoutResponse();

src/server/pt-api.ts

@@ -20,14 +20,28 @@ const bodyHeaders = new Headers({
   Authorization: `Bearer ${env.BEARER_TOKEN}`,
 });
 
-async function query(): Promise<Array<SelectEntry>> {
+async function query(etag?: string): Promise<[etag: string | null, data: Array<SelectEntry> | null]> {
   try {
+    const headers = new Headers({
+      Authorization: `Bearer ${env.BEARER_TOKEN}`,
+    });
+
+    if (etag) {
+      headers.set('if-none-match', etag);
+    }
+
     const response = await fetch(entriesUrl, {
       method: 'GET',
-      signal: AbortSignal.timeout(50000),
-      headers: noBodyHeaders,
+      signal: AbortSignal.timeout(5000),
+      headers,
     });
 
+    const respEtag = response.headers.get('etag');
+
+    if (response.status === 304) {
+      return [respEtag, null];
+    }
+
     if (!response.ok) {
       throw new Error('Failed to fetch entries');
     }
@@ -37,7 +51,7 @@ async function query(): Promise<Array<SelectEntry>> {
       throw new Error('Invalid entries data');
     }
 
-    return data;
+    return [respEtag, data];
   } catch (err) {
     console.error(err);
     throw new Error('Failed to fetch entries');