perf - replace broadcast channel with direct postMessage

web/src/lib/components/asset-viewer/asset-viewer.svelte

@@ -17,13 +17,12 @@
   import { alwaysLoadOriginalVideo } from '$lib/stores/preferences.store';
   import { SlideshowNavigation, SlideshowState, slideshowStore } from '$lib/stores/slideshow.store';
   import { user } from '$lib/stores/user.store';
-  import { getAssetJobMessage, getAssetUrl, getSharedLink, handlePromiseError } from '$lib/utils';
+  import { getAssetJobMessage, getSharedLink, handlePromiseError } from '$lib/utils';
   import type { OnUndoDelete } from '$lib/utils/actions';
   import { navigateToAsset } from '$lib/utils/asset-utils';
   import { handleError } from '$lib/utils/handle-error';
   import { InvocationTracker } from '$lib/utils/invocationTracker';
   import { SlideshowHistory } from '$lib/utils/slideshow-history';
-  import { preloadImageUrl } from '$lib/utils/sw-messaging';
   import { toTimelineAsset } from '$lib/utils/timeline-util';
   import {
     AssetJobName,
@@ -134,9 +133,7 @@
     }
 
     untrack(() => {
-      if (stack && stack?.assets.length > 1) {
-        preloadImageUrl(getAssetUrl({ asset: stack.assets[1] }));
-      }
+      preloadManager.preload(stack?.assets[1]);
     });
   };
 

web/src/lib/managers/PreloadManager.svelte.ts

@@ -1,13 +1,9 @@
 import { getAssetUrl } from '$lib/utils';
-import { cancelImageUrl, preloadImageUrl } from '$lib/utils/sw-messaging';
+import { cancelImageUrl } from '$lib/utils/sw-messaging';
 import { AssetTypeEnum, type AssetResponseDto } from '@immich/sdk';
 
 class PreloadManager {
   preload(asset: AssetResponseDto | undefined) {
-    if (globalThis.isSecureContext) {
-      preloadImageUrl(getAssetUrl({ asset }));
-      return;
-    }
     if (!asset || asset.type !== AssetTypeEnum.Image) {
       return;
     }

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

@@ -1,14 +1,24 @@
-const broadcast = new BroadcastChannel('immich');
+import { ServiceWorkerMessenger } from './sw-messenger';
+
+const messenger = new ServiceWorkerMessenger();
+
+let isServiceWorkerEnabled = true;
+
+messenger.onAckTimeout(() => {
+  if (!isServiceWorkerEnabled) {
+    return;
+  }
+  console.error('[ServiceWorker] No communication detected. Auto-disabled service worker.');
+  isServiceWorkerEnabled = false;
+});
+
+const isValidSwContext = (url: string | undefined | null): url is string => {
+  return globalThis.isSecureContext && isServiceWorkerEnabled && !!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 +1,157 @@
+/**
+ * Low-level protocol for communicating with the service worker via postMessage.
+ *
+ * Protocol:
+ * 1. Main thread sends request: { type: string, requestId: string, ...data }
+ * 2. SW sends ack: { type: 'ack', requestId: string }
+ * 3. SW sends response (optional): { type: 'response', requestId: string, result?: any, error?: string }
+ */
+
+interface PendingRequest {
+  resolveAck: () => void;
+  resolveResponse?: (result: unknown) => void;
+  rejectResponse?: (error: Error) => void;
+  ackTimeout: ReturnType<typeof setTimeout>;
+  ackReceived: boolean;
+}
+
+export class ServiceWorkerMessenger {
+  readonly #pendingRequests = new Map<string, PendingRequest>();
+  readonly #ackTimeoutMs: number;
+  #requestCounter = 0;
+  #onTimeout?: (type: string, data: Record<string, unknown>) => void;
+  #messageHandler?: (event: MessageEvent) => void;
+
+  constructor(ackTimeoutMs = 5000) {
+    this.#ackTimeoutMs = ackTimeoutMs;
+
+    // Listen for messages from the service worker
+    if ('serviceWorker' in navigator) {
+      this.#messageHandler = (event) => {
+        this.#handleMessage(event.data);
+      };
+      navigator.serviceWorker.addEventListener('message', this.#messageHandler);
+    }
+  }
+
+  #handleMessage(data: unknown) {
+    if (typeof data !== 'object' || data === null) {
+      return;
+    }
+
+    const message = data as { requestId?: string; type?: string; error?: string; result?: unknown };
+    const requestId = message.requestId;
+    if (!requestId) {
+      return;
+    }
+
+    const pending = this.#pendingRequests.get(requestId);
+    if (!pending) {
+      return;
+    }
+
+    if (message.type === 'ack') {
+      pending.ackReceived = true;
+      clearTimeout(pending.ackTimeout);
+      pending.resolveAck();
+      return;
+    }
+
+    if (message.type === 'response') {
+      clearTimeout(pending.ackTimeout);
+      this.#pendingRequests.delete(requestId);
+
+      if (message.error) {
+        pending.rejectResponse?.(new Error(message.error));
+        return;
+      }
+
+      pending.resolveResponse?.(message.result);
+    }
+  }
+
+  /**
+   * Set a callback to be invoked when an ack timeout occurs.
+   * This can be used to detect and disable faulty service workers.
+   */
+  onAckTimeout(callback: (type: string, data: Record<string, unknown>) => void): void {
+    this.#onTimeout = callback;
+  }
+
+  /**
+   * Send a message to the service worker.
+   * - send(): waits for ack, resolves when acknowledged
+   * - request(): waits for response, throws on error/timeout
+   */
+  #sendInternal<T>(type: string, data: Record<string, unknown>, waitForResponse: boolean): Promise<T> {
+    const requestId = `${type}-${++this.#requestCounter}-${Date.now()}`;
+
+    const promise = new Promise<T>((resolve, reject) => {
+      const ackTimeout = setTimeout(() => {
+        const pending = this.#pendingRequests.get(requestId);
+        if (pending && !pending.ackReceived) {
+          this.#pendingRequests.delete(requestId);
+          console.warn(`[ServiceWorker] ${type} request not acknowledged:`, data);
+          this.#onTimeout?.(type, data);
+          // Only reject if we're waiting for a response
+          if (waitForResponse) {
+            reject(new Error(`Service worker did not acknowledge ${type} request`));
+          } else {
+            resolve(undefined as T);
+          }
+        }
+      }, this.#ackTimeoutMs);
+
+      this.#pendingRequests.set(requestId, {
+        resolveAck: waitForResponse ? () => {} : () => resolve(undefined as T),
+        resolveResponse: waitForResponse ? (result: unknown) => resolve(result as T) : undefined,
+        rejectResponse: waitForResponse ? reject : undefined,
+        ackTimeout,
+        ackReceived: false,
+      });
+
+      // Send message to the active service worker
+      // Feature detection is done in constructor and at call sites (sw-messaging.ts:isValidSwContext)
+      // eslint-disable-next-line compat/compat
+      navigator.serviceWorker.controller?.postMessage({
+        type,
+        requestId,
+        ...data,
+      });
+    });
+
+    return promise;
+  }
+
+  /**
+   * Send a one-way message to the service worker.
+   * Returns a promise that resolves after the service worker acknowledges receipt.
+   * Resolves even if no ack is received within the timeout period.
+   */
+  send(type: string, data: Record<string, unknown>): Promise<void> {
+    return this.#sendInternal<void>(type, data, false);
+  }
+
+  /**
+   * Send a request and wait for ack + response.
+   * Returns a promise that resolves with the response data or rejects on error/timeout.
+   */
+  request<T = void>(type: string, data: Record<string, unknown>): Promise<T> {
+    return this.#sendInternal<T>(type, data, true);
+  }
+
+  /**
+   * Clean up pending requests and remove event listener
+   */
+  close(): void {
+    for (const pending of this.#pendingRequests.values()) {
+      clearTimeout(pending.ackTimeout);
+    }
+    this.#pendingRequests.clear();
+
+    if (this.#messageHandler && 'serviceWorker' in navigator) {
+      navigator.serviceWorker.removeEventListener('message', this.#messageHandler);
+      this.#messageHandler = undefined;
+    }
+  }
+}

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);
+  }
 };