refactor: service worker

Author: jrasm91

web/src/service-worker/broadcast-channel.ts

@@ -1,4 +1,4 @@
-import { cancelLoad, getCachedOrFetch } from './fetch-event';
+import { cancelRequest, handleRequest } from './request';
 
 export const installBroadcastChannelListener = () => {
   const broadcast = new BroadcastChannel('immich');
@@ -7,12 +7,12 @@ export const installBroadcastChannelListener = () => {
     if (!event.data) {
       return;
     }
-    const urlstring = event.data.url;
-    const url = new URL(urlstring, event.origin);
+    const urlString = event.data.url;
+    const url = new URL(urlString, event.origin);
     if (event.data.type === 'cancel') {
-      cancelLoad(url.toString());
+      cancelRequest(url);
     } else if (event.data.type === 'preload') {
-      getCachedOrFetch(url);
+      handleRequest(url);
     }
   };
 };

web/src/service-worker/cache.ts

@@ -1,104 +1,42 @@
-import { build, files, version } from '$service-worker';
+import { version } from '$service-worker';
 
-const useCache = true;
 const CACHE = `cache-${version}`;
 
-export const APP_RESOURCES = [
-  ...build, // the app itself
-  ...files, // everything in `static`
-];
-
-let cache: Cache | undefined;
-export async function getCache() {
-  if (cache) {
-    return cache;
+let _cache: Cache | undefined;
+const getCache = async () => {
+  if (_cache) {
+    return _cache;
   }
-  cache = await caches.open(CACHE);
-  return cache;
-}
-
-export const isURL = (request: URL | RequestInfo): request is URL => (request as URL).href !== undefined;
-export const isRequest = (request: RequestInfo): request is Request => (request as Request).url !== undefined;
+  _cache = await caches.open(CACHE);
+  return _cache;
+};
 
-export async function deleteOldCaches() {
-  for (const key of await caches.keys()) {
-    if (key !== CACHE) {
-      await caches.delete(key);
-    }
-  }
-}
-
-const pendingRequests = new Map<string, AbortController>();
-const canceledRequests = new Set<string>();
-
-export async function cancelLoad(urlString: string) {
-  const pending = pendingRequests.get(urlString);
-  if (pending) {
-    canceledRequests.add(urlString);
-    pending.abort();
-    pendingRequests.delete(urlString);
-  }
-}
-
-export async function getCachedOrFetch(request: URL | Request | string) {
-  const response = await checkCache(request);
-  if (response) {
-    return response;
+export const get = async (key: string) => {
+  const cache = await getCache();
+  if (!cache) {
+    return;
   }
 
-  const urlString = getCacheKey(request);
-  const cancelToken = new AbortController();
+  return cache.match(key);
+};
 
-  try {
-    pendingRequests.set(urlString, cancelToken);
-    const response = await fetch(request, {
-      signal: cancelToken.signal,
-    });
-
-    checkResponse(response);
-    await setCached(response, urlString);
-    return response;
-  } catch (error) {
-    if (canceledRequests.has(urlString)) {
-      canceledRequests.delete(urlString);
-      return new Response(undefined, {
-        status: 499,
-        statusText: 'Request canceled: Instructions unclear, accidentally interrupted myself',
-      });
-    }
-    throw error;
-  } finally {
-    pendingRequests.delete(urlString);
-  }
-}
-
-export async function checkCache(url: URL | Request | string) {
-  if (!useCache) {
+export const put = async (key: string, response: Response) => {
+  if (response.status !== 200) {
     return;
   }
-  const cache = await getCache();
-  return await cache.match(url);
-}
 
-export async function setCached(response: Response, cacheKey: URL | Request | string) {
-  if (cache && response.status === 200) {
-    const cache = await getCache();
-    cache.put(cacheKey, response.clone());
+  const cache = await getCache();
+  if (!cache) {
+    return;
   }
-}
 
-function checkResponse(response: Response) {
-  if (!(response instanceof Response)) {
-    throw new TypeError('Fetch did not return a valid Response object');
-  }
-}
+  cache.put(key, response.clone());
+};
 
-export function getCacheKey(request: URL | Request | string) {
-  if (isURL(request)) {
-    return request.toString();
-  } else if (isRequest(request)) {
-    return request.url;
-  } else {
-    return request;
+export const prune = async () => {
+  for (const key of await caches.keys()) {
+    if (key !== CACHE) {
+      await caches.delete(key);
+    }
   }
-}
+};

web/src/service-worker/fetch-event.ts

@@ -3,22 +3,37 @@
 /// <reference lib="esnext" />
 /// <reference lib="webworker" />
 import { installBroadcastChannelListener } from './broadcast-channel';
-import { deleteOldCaches } from './cache';
-import { handleFetchEvent } from './fetch-event';
+import { prune } from './cache';
+import { handleRequest } from './request';
+
+const ASSET_REQUEST_REGEX = /^\/api\/assets\/[a-f0-9-]+\/(original|thumbnail)/;
 
 const sw = globalThis as unknown as ServiceWorkerGlobalScope;
 
 const handleActivate = (event: ExtendableEvent) => {
   event.waitUntil(sw.clients.claim());
-  event.waitUntil(deleteOldCaches());
+  event.waitUntil(prune());
 };
 
 const handleInstall = (event: ExtendableEvent) => {
   event.waitUntil(sw.skipWaiting());
   // do not preload app resources
 };
 
+const handleFetch = (event: FetchEvent): void => {
+  if (event.request.method !== 'GET') {
+    return;
+  }
+
+  // Cache requests for thumbnails
+  const url = new URL(event.request.url);
+  if (url.origin === self.location.origin && ASSET_REQUEST_REGEX.test(url.pathname)) {
+    event.respondWith(handleRequest(event.request));
+    return;
+  }
+};
+
 sw.addEventListener('install', handleInstall, { passive: true });
 sw.addEventListener('activate', handleActivate, { passive: true });
-sw.addEventListener('fetch', handleFetchEvent, { passive: true });
+sw.addEventListener('fetch', handleFetch, { passive: true });
 installBroadcastChannelListener();

web/src/service-worker/index.ts

@@ -0,0 +1,62 @@
+import { get, put } from './cache';
+
+const isURL = (request: URL | RequestInfo): request is URL => (request as URL).href !== undefined;
+const isRequest = (request: RequestInfo): request is Request => (request as Request).url !== undefined;
+
+const assertResponse = (response: Response) => {
+  if (!(response instanceof Response)) {
+    throw new TypeError('Fetch did not return a valid Response object');
+  }
+};
+
+const getCacheKey = (request: URL | Request) => {
+  if (isURL(request)) {
+    return request.toString();
+  }
+
+  if (isRequest(request)) {
+    return request.url;
+  }
+
+  throw new Error(`Invalid request: ${request}`);
+};
+
+const pendingRequests = new Map<string, AbortController>();
+
+export const handleRequest = async (request: URL | Request) => {
+  const cacheKey = getCacheKey(request);
+
+  const cachedResponse = await get(cacheKey);
+  if (cachedResponse) {
+    return cachedResponse;
+  }
+
+  try {
+    const cancelToken = new AbortController();
+    pendingRequests.set(cacheKey, cancelToken);
+    const response = await fetch(request, { signal: cancelToken.signal });
+
+    assertResponse(response);
+    put(cacheKey, response);
+
+    return response;
+  } catch {
+    return new Response(undefined, {
+      status: 499,
+      statusText: 'Request canceled: Instructions unclear, accidentally interrupted myself',
+    });
+  } finally {
+    pendingRequests.delete(cacheKey);
+  }
+};
+
+export const cancelRequest = (url: URL) => {
+  const cacheKey = getCacheKey(url);
+  const pending = pendingRequests.get(cacheKey);
+  if (!pending) {
+    return;
+  }
+
+  pending.abort();
+  pendingRequests.delete(cacheKey);
+};