split storage into indexeddeb storage and in-memory storage implementations

Author: Kevin Elko

packages/remote-config/src/api.ts

@@ -57,7 +57,8 @@ export function getRemoteConfig(app: FirebaseApp = getApp(), options: RemoteConf
   const rc = rcProvider.getImmediate() as RemoteConfigImpl;
 
   if (options.initialFetchResponse) {
-    // 
+    // We use these initial writes as the initialization promise since they will hydrate the same
+    // fields that storageCache.loadFromStorage would set.
     rc._initializePromise = Promise.all([
       rc._storage.setLastSuccessfulFetchResponse(options.initialFetchResponse),
       rc._storage.setActiveConfigEtag(options.initialFetchResponse?.eTag || ''),

packages/remote-config/src/register.ts

@@ -36,7 +36,7 @@ import { RetryingClient } from './client/retrying_client';
 import { RC_COMPONENT_NAME } from './constants';
 import { ErrorCode, ERROR_FACTORY } from './errors';
 import { RemoteConfig as RemoteConfigImpl } from './remote_config';
-import { Storage } from './storage/storage';
+import { IndexedDbStorage, InMemoryStorage, Storage } from './storage/storage';
 import { StorageCache } from './storage/storage_cache';
 // This needs to be in the same file that calls `getProvider()` on the component
 // or it will get tree-shaken out.
@@ -80,7 +80,7 @@ export function registerRemoteConfig(): void {
     }
     const namespace = options?.templateId || 'firebase';
 
-    const storage = new Storage(appId, app.name, namespace);
+    const storage = isIndexedDBAvailable() ? new IndexedDbStorage(appId, app.name, namespace) : new InMemoryStorage();
     const storageCache = new StorageCache(storage);
 
     const logger = new Logger(packageName);

packages/remote-config/src/storage/storage.ts

@@ -113,19 +113,7 @@ export function openDatabase(): Promise<IDBDatabase> {
 /**
  * Abstracts data persistence.
  */
-export class Storage {
-  /**
-   * @param appId enables storage segmentation by app (ID + name).
-   * @param appName enables storage segmentation by app (ID + name).
-   * @param namespace enables storage segmentation by namespace.
-   */
-  constructor(
-    private readonly appId: string,
-    private readonly appName: string,
-    private readonly namespace: string,
-    private readonly openDbPromise = openDatabase()
-  ) {}
-
+export abstract class Storage {
   getLastFetchStatus(): Promise<FetchStatus | undefined> {
     return this.get<FetchStatus>('last_fetch_status');
   }
@@ -187,6 +175,27 @@ export class Storage {
     return this.get<CustomSignals>('custom_signals');
   }
 
+  abstract setCustomSignals(customSignals: CustomSignals): Promise<CustomSignals>;
+  abstract get<T>(key: ProjectNamespaceKeyFieldValue): Promise<T | undefined>;
+  abstract set<T>(key: ProjectNamespaceKeyFieldValue, value: T): Promise<void>;
+  abstract delete(key: ProjectNamespaceKeyFieldValue): Promise<void>;
+}
+
+export class IndexedDbStorage extends Storage {
+  /**
+   * @param appId enables storage segmentation by app (ID + name).
+   * @param appName enables storage segmentation by app (ID + name).
+   * @param namespace enables storage segmentation by namespace.
+   */
+  constructor(
+    private readonly appId: string,
+    private readonly appName: string,
+    private readonly namespace: string,
+    private readonly openDbPromise = openDatabase()
+  ) {
+    super();
+  }
+
   async setCustomSignals(customSignals: CustomSignals): Promise<CustomSignals> {
     const db = await this.openDbPromise;
     const transaction = db.transaction([APP_NAMESPACE_STORE], 'readwrite');
@@ -344,3 +353,21 @@ export class Storage {
     return [this.appId, this.appName, this.namespace, key].join();
   }
 }
+
+export class InMemoryStorage extends Storage {
+  private db: { [key: string]: any } = {}
+
+  async get<T>(key: ProjectNamespaceKeyFieldValue): Promise<T> {
+    return Promise.resolve(this.db[key] as T);
+  }
+
+  async set<T>(key: ProjectNamespaceKeyFieldValue, value: T): Promise<void> {
+    this.db[key] = value;
+    return Promise.resolve(undefined);
+  }
+
+  async delete(key: ProjectNamespaceKeyFieldValue): Promise<void> {
+    this.db[key] = undefined;
+    return Promise.resolve();
+  }
+}