feat(core): implement generic CacheService and optimize setupUser (#21374)

packages/core/src/utils/cache.ts

@@ -0,0 +1,151 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+export interface CacheEntry<V> {
+  value: V;
+  timestamp: number;
+  ttl?: number;
+}
+
+export interface CacheOptions {
+  /**
+   * Default Time To Live in milliseconds.
+   */
+  defaultTtl?: number;
+
+  /**
+   * If true, and V is a Promise, the entry will be removed from the cache
+   * if the promise rejects.
+   */
+  deleteOnPromiseFailure?: boolean;
+
+  /**
+   * The underlying storage mechanism.
+   * Use 'weakmap' (default) for object keys to allow garbage collection.
+   * Use 'map' if you need to use strings as keys or need the clear() method.
+   */
+  storage?: 'map' | 'weakmap';
+}
+
+/**
+ * A generic caching service with TTL support.
+ */
+export class CacheService<K extends object | string | undefined, V> {
+  private readonly storage:
+    | Map<K, CacheEntry<V>>
+    | WeakMap<WeakKey, CacheEntry<V>>;
+  private readonly defaultTtl?: number;
+  private readonly deleteOnPromiseFailure: boolean;
+
+  constructor(options: CacheOptions = {}) {
+    // Default to map for safety unless weakmap is explicitly requested.
+    this.storage =
+      options.storage === 'weakmap'
+        ? new WeakMap<WeakKey, CacheEntry<V>>()
+        : new Map<K, CacheEntry<V>>();
+    this.defaultTtl = options.defaultTtl;
+    this.deleteOnPromiseFailure = options.deleteOnPromiseFailure ?? true;
+  }
+
+  /**
+   * Retrieves a value from the cache. Returns undefined if missing or expired.
+   */
+  get(key: K): V | undefined {
+    // We have to cast to Map or WeakMap specifically to call get()
+    // but since they have the same signature for object keys, we can
+    // safely cast to 'any' internally for the dispatch.
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-type-assertion
+    const entry = (this.storage as any).get(key) as CacheEntry<V> | undefined;
+    if (!entry) {
+      return undefined;
+    }
+
+    const ttl = entry.ttl ?? this.defaultTtl;
+    if (ttl !== undefined && Date.now() - entry.timestamp > ttl) {
+      this.delete(key);
+      return undefined;
+    }
+
+    return entry.value;
+  }
+
+  /**
+   * Stores a value in the cache.
+   */
+  set(key: K, value: V, ttl?: number): void {
+    const entry: CacheEntry<V> = {
+      value,
+      timestamp: Date.now(),
+      ttl,
+    };
+
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-type-assertion
+    (this.storage as any).set(key, entry);
+
+    if (this.deleteOnPromiseFailure && value instanceof Promise) {
+      value.catch(() => {
+        // Only delete if this exact entry is still in the cache
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-type-assertion
+        if ((this.storage as any).get(key) === entry) {
+          this.delete(key);
+        }
+      });
+    }
+  }
+
+  /**
+   * Helper to retrieve a value or create it if missing/expired.
+   */
+  getOrCreate(key: K, creator: () => V, ttl?: number): V {
+    let value = this.get(key);
+    if (value === undefined) {
+      value = creator();
+      this.set(key, value, ttl);
+    }
+    return value;
+  }
+
+  /**
+   * Removes an entry from the cache.
+   */
+  delete(key: K): void {
+    if (this.storage instanceof Map) {
+      this.storage.delete(key);
+    } else {
+      // WeakMap.delete returns a boolean, we can ignore it.
+      // Cast to any to bypass the WeakKey constraint since we've already
+      // confirmed the storage type.
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-type-assertion
+      (this.storage as any).delete(key);
+    }
+  }
+
+  /**
+   * Clears all entries. Only supported if using Map storage.
+   */
+  clear(): void {
+    if (this.storage instanceof Map) {
+      this.storage.clear();
+    } else {
+      throw new Error('clear() is not supported on WeakMap storage');
+    }
+  }
+}
+
+/**
+ * Factory function to create a new cache.
+ */
+export function createCache<K extends string | undefined, V>(
+  options: CacheOptions & { storage: 'map' },
+): CacheService<K, V>;
+export function createCache<K extends object, V>(
+  options?: CacheOptions,
+): CacheService<K, V>;
+export function createCache<K extends object | string | undefined, V>(
+  options: CacheOptions = {},
+): CacheService<K, V> {
+  return new CacheService<K, V>(options);
+}