jellyfin-expo/utils/CachingStorage.js

/**
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
import { AsyncStorage } from 'react-native';

/**
 * AsyncStorage wrapper with in memory caching
 * @deprecated
 */
export default class CachingStorage {
	static instance = null;

	cache = new Map();

	static getInstance() {
		if (this.instance === null) {
			console.debug('CachingStorage: Initializing new instance');
			this.instance = new CachingStorage();
		} else {
			console.debug('CachingStorage: Using existing instance');
		}
		return this.instance;
	}

	async getItem(key) {
		// Throw an error if no key is provided
		if (!key) {
			throw new Error('No key specified for `getItem()`');
		}

		// Return cached value if present
		if (this.cache.has(key)) {
			console.debug(`CachingStorage: Returning value from cache for ${key}`);
			return this.cache.get(key);
		}

		// Get the item from device storage
		console.debug(`CachingStorage: Loading value from device storage for ${key}`);
		let item = await AsyncStorage.getItem(key);
		if (item !== null) {
			item = JSON.parse(item);
			this.cache.set(key, item);
		}
		return item;
	}

	async setItem(key, item = '') {
		// Throw an error if no key is provided
		if (!key) {
			throw new Error('No key specified for `setItem()`');
		}

		console.debug(`CachingStorage: Saving value to device storage for ${key}`);
		await AsyncStorage.setItem(key, JSON.stringify(item));
		this.cache.set(key, item);
	}
}