ContentLayer Class — astro Architecture

Source Code

packages/astro/src/content/content-layer.ts lines 48–381

class ContentLayer {
	#logger: Logger;
	#store: MutableDataStore;
	#settings: AstroSettings;
	#watcher?: WrappedWatcher;
	#lastConfigDigest?: string;
	#unsubscribe?: () => void;
	#markdownProcessor?: MarkdownProcessor;
	#generateDigest?: (data: Record<string, unknown> | string) => string;

	#queue: PQueue;

	constructor({ settings, logger, store, watcher }: ContentLayerOptions) {
		// The default max listeners is 10, which can be exceeded when using a lot of loaders
		watcher?.setMaxListeners(50);

		this.#logger = logger;
		this.#store = store;
		this.#settings = settings;
		if (watcher) {
			this.#watcher = createWatcherWrapper(watcher);
		}
		this.#queue = new PQueue({ concurrency: 1 });
	}

	/**
	 * Whether the content layer is currently loading content
	 */
	get loading() {
		return this.#queue.size > 0 || this.#queue.pending > 0;
	}

	/**
	 * Watch for changes to the content config and trigger a sync when it changes.
	 */
	watchContentConfig() {
		this.#unsubscribe?.();
		this.#unsubscribe = globalContentConfigObserver.subscribe(async (ctx) => {
			if (ctx.status === 'loaded' && ctx.config.digest !== this.#lastConfigDigest) {
				this.sync();
			}
		});
	}

	unwatchContentConfig() {
		this.#unsubscribe?.();
	}

	dispose() {
		this.#queue.clear();
		this.#unsubscribe?.();
		this.#watcher?.removeAllTrackedListeners();
	}

	async #getGenerateDigest() {
		if (this.#generateDigest) {
			return this.#generateDigest;
		}
		// xxhash is a very fast non-cryptographic hash function that is used to generate a content digest
		// It uses wasm, so we need to load it asynchronously.
		const { h64ToString } = await xxhash();

		this.#generateDigest = (data: unknown) => {
			const dataString = typeof data === 'string' ? data : JSON.stringify(data);
			return h64ToString(dataString);
		};

		return this.#generateDigest;
	}

	async #getLoaderContext({
		collectionName,
		loaderName = 'content',
		parseData,
		refreshContextData,
	}: {
		collectionName: string;
		loaderName: string;
		parseData: LoaderContext['parseData'];
		refreshContextData?: Record<string, unknown>;
	}): Promise<LoaderContext> {