remove sw response handling

perf - replace broadcast channel with direct postMessage

web/src/lib/utils/sw-messaging.ts

@@ -1,14 +1,15 @@
-const broadcast = new BroadcastChannel('immich');
+import { ServiceWorkerMessenger } from './sw-messenger';
+
+const messenger = new ServiceWorkerMessenger();
+const hasServiceWorker = globalThis.isSecureContext && 'serviceWorker' in navigator;
+
+const isValidSwContext = (url: string | undefined | null): url is string => {
+  return hasServiceWorker && !!url;
+};
 
 export function cancelImageUrl(url: string | undefined | null) {
-  if (!url) {
+  if (!isValidSwContext(url)) {
     return;
   }
-  broadcast.postMessage({ type: 'cancel', url });
-}
-export function preloadImageUrl(url: string | undefined | null) {
-  if (!url) {
-    return;
-  }
-  broadcast.postMessage({ type: 'preload', url });
+  void messenger.send('cancel', { url });
 }

web/src/lib/utils/sw-messenger.ts

@@ -0,0 +1,22 @@
+export class ServiceWorkerMessenger {
+  constructor() {}
+
+  #sendInternal(type: string, data: Record<string, unknown>) {
+    if (!('serviceWorker' in navigator)) {
+      throw new Error('Service Worker not enabled in this environment ');
+    }
+
+    // eslint-disable-next-line compat/compat
+    navigator.serviceWorker.controller?.postMessage({
+      type,
+      ...data,
+    });
+  }
+
+  /**
+   * Send a one-way message to the service worker.
+   */
+  send(type: string, data: Record<string, unknown>) {
+    return this.#sendInternal(type, data);
+  }
+}

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

@@ -1,25 +0,0 @@
-import { handleCancel, handlePreload } from './request';
-
-export const installBroadcastChannelListener = () => {
-  const broadcast = new BroadcastChannel('immich');
-  // eslint-disable-next-line  unicorn/prefer-add-event-listener
-  broadcast.onmessage = (event) => {
-    if (!event.data) {
-      return;
-    }
-
-    const url = new URL(event.data.url, event.origin);
-
-    switch (event.data.type) {
-      case 'preload': {
-        handlePreload(url);
-        break;
-      }
-
-      case 'cancel': {
-        handleCancel(url);
-        break;
-      }
-    }
-  };
-};

web/src/service-worker/cache.ts

@@ -1,42 +0,0 @@
-import { version } from '$service-worker';
-
-const CACHE = `cache-${version}`;
-
-let _cache: Cache | undefined;
-const getCache = async () => {
-  if (_cache) {
-    return _cache;
-  }
-  _cache = await caches.open(CACHE);
-  return _cache;
-};
-
-export const get = async (key: string) => {
-  const cache = await getCache();
-  if (!cache) {
-    return;
-  }
-
-  return cache.match(key);
-};
-
-export const put = async (key: string, response: Response) => {
-  if (response.status !== 200) {
-    return;
-  }
-
-  const cache = await getCache();
-  if (!cache) {
-    return;
-  }
-
-  cache.put(key, response.clone());
-};
-
-export const prune = async () => {
-  for (const key of await caches.keys()) {
-    if (key !== CACHE) {
-      await caches.delete(key);
-    }
-  }
-};

web/src/service-worker/index.ts

@@ -2,9 +2,9 @@
 /// <reference no-default-lib="true"/>
 /// <reference lib="esnext" />
 /// <reference lib="webworker" />
-import { installBroadcastChannelListener } from './broadcast-channel';
-import { prune } from './cache';
-import { handleRequest } from './request';
+
+import { installMessageListener } from './messaging';
+import { handleFetch as handleAssetFetch } from './request';
 
 const ASSET_REQUEST_REGEX = /^\/api\/assets\/[a-f0-9-]+\/(original|thumbnail)/;
 
@@ -12,12 +12,10 @@ const sw = globalThis as unknown as ServiceWorkerGlobalScope;
 
 const handleActivate = (event: ExtendableEvent) => {
   event.waitUntil(sw.clients.claim());
-  event.waitUntil(prune());
 };
 
 const handleInstall = (event: ExtendableEvent) => {
   event.waitUntil(sw.skipWaiting());
-  // do not preload app resources
 };
 
 const handleFetch = (event: FetchEvent): void => {
@@ -28,7 +26,7 @@ const handleFetch = (event: FetchEvent): void => {
   // 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));
+    event.respondWith(handleAssetFetch(event.request));
     return;
   }
 };
@@ -36,4 +34,4 @@ const handleFetch = (event: FetchEvent): void => {
 sw.addEventListener('install', handleInstall, { passive: true });
 sw.addEventListener('activate', handleActivate, { passive: true });
 sw.addEventListener('fetch', handleFetch, { passive: true });
-installBroadcastChannelListener();
+installMessageListener();

web/src/service-worker/messaging.ts

@@ -0,0 +1,53 @@
+/// <reference types="@sveltejs/kit" />
+/// <reference no-default-lib="true"/>
+/// <reference lib="esnext" />
+/// <reference lib="webworker" />
+
+import { handleCancel } from './request';
+
+const sw = globalThis as unknown as ServiceWorkerGlobalScope;
+
+/**
+ * Send acknowledgment for a request
+ */
+function sendAck(client: Client, requestId: string) {
+  client.postMessage({
+    type: 'ack',
+    requestId,
+  });
+}
+
+/**
+ * Handle 'cancel' request: cancel a pending request
+ */
+const handleCancelRequest = (client: Client, url: URL, requestId: string) => {
+  sendAck(client, requestId);
+  handleCancel(url);
+};
+
+export const installMessageListener = () => {
+  sw.addEventListener('message', (event) => {
+    if (!event.data?.requestId || !event.data?.type) {
+      return;
+    }
+
+    const requestId = event.data.requestId;
+
+    switch (event.data.type) {
+      case 'cancel': {
+        const url = event.data.url ? new URL(event.data.url, self.location.origin) : undefined;
+        if (!url) {
+          return;
+        }
+
+        const client = event.source;
+        if (!client) {
+          return;
+        }
+
+        handleCancelRequest(client, url, requestId);
+        break;
+      }
+    }
+  });
+};

web/src/service-worker/request.ts

@@ -1,73 +1,68 @@
-import { get, put } from './cache';
+/// <reference types="@sveltejs/kit" />
+/// <reference no-default-lib="true"/>
+/// <reference lib="esnext" />
+/// <reference lib="webworker" />
 
-const pendingRequests = new Map<string, AbortController>();
-
-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');
-  }
+type PendingRequest = {
+  controller: AbortController;
+  promise: Promise<Response>;
+  cleanupTimeout?: ReturnType<typeof setTimeout>;
 };
 
-const getCacheKey = (request: URL | Request) => {
-  if (isURL(request)) {
-    return request.toString();
+const pendingRequests = new Map<string, PendingRequest>();
+
+const getRequestKey = (request: URL | Request): string => (request instanceof URL ? request.href : request.url);
+
+const CANCELATION_MESSAGE = 'Request canceled by application';
+const CLEANUP_TIMEOUT_MS = 5 * 60 * 1000; // 5 minutes
+
+export const handleFetch = (request: URL | Request): Promise<Response> => {
+  const requestKey = getRequestKey(request);
+  const existing = pendingRequests.get(requestKey);
+
+  if (existing) {
+    // Clone the response since response bodies can only be read once
+    // Each caller gets an independent clone they can consume
+    return existing.promise.then((response) => response.clone());
   }
 
-  if (isRequest(request)) {
-    return request.url;
-  }
+  const pendingRequest: PendingRequest = {
+    controller: new AbortController(),
+    promise: undefined as unknown as Promise<Response>,
+  };
+  pendingRequests.set(requestKey, pendingRequest);
 
-  throw new Error(`Invalid request: ${request}`);
-};
+  // NOTE: fetch returns after headers received, not the body
+  pendingRequest.promise = fetch(request, { signal: pendingRequest.controller.signal })
+    .catch((error: unknown) => {
+      const standardError = error instanceof Error ? error : new Error(String(error));
+      if (standardError.name === 'AbortError' || standardError.message === CANCELATION_MESSAGE) {
+        // dummy response avoids network errors in the console for these requests
+        return new Response(undefined, { status: 204 });
+      }
+      throw standardError;
+    })
+    .finally(() => {
+      // Schedule cleanup after timeout to allow response body streaming to complete
+      const cleanupTimeout = setTimeout(() => {
+        pendingRequests.delete(requestKey);
+      }, CLEANUP_TIMEOUT_MS);
+      pendingRequest.cleanupTimeout = cleanupTimeout;
+    });
 
-export const handlePreload = async (request: URL | Request) => {
-  try {
-    return await handleRequest(request);
-  } catch (error) {
-    console.error(`Preload failed: ${error}`);
-  }
-};
-
-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 (error) {
-    if (error.name === 'AbortError') {
-      // dummy response avoids network errors in the console for these requests
-      return new Response(undefined, { status: 204 });
-    }
-
-    console.log('Not an abort error', error);
-
-    throw error;
-  } finally {
-    pendingRequests.delete(cacheKey);
-  }
+  // Clone for the first caller to keep the original response unconsumed for future callers
+  return pendingRequest.promise.then((response) => response.clone());
 };
 
 export const handleCancel = (url: URL) => {
-  const cacheKey = getCacheKey(url);
-  const pendingRequest = pendingRequests.get(cacheKey);
-  if (!pendingRequest) {
-    return;
-  }
+  const requestKey = getRequestKey(url);
 
-  pendingRequest.abort();
-  pendingRequests.delete(cacheKey);
+  const pendingRequest = pendingRequests.get(requestKey);
+  if (pendingRequest) {
+    pendingRequest.controller.abort(CANCELATION_MESSAGE);
+    if (pendingRequest.cleanupTimeout) {
+      clearTimeout(pendingRequest.cleanupTimeout);
+    }
+    pendingRequests.delete(requestKey);
+  }
 };