astro/dist/core/render-scope/collect.js

Astro is a modern site builder with web best practices, performance, and DX front-of-mind.

import { getInstalledRenderScope } from "./scope.js";
let warnedNoScope = false;
/**
* Runs `fn` inside a fresh per-render collectors store and returns its value
* together with a snapshot of everything recorded while it ran.
*
* When no render scope is installed, collection degrades to *not collecting*:
* warn once per process (when a `logger` is given), run `fn` bare, and return
* `metadata: undefined` ("not tracked") — never wrong attribution.
*
* Invariant: `fn` must not resolve until all recordable work is done — in
* practice, until the response body is fully buffered inside `fn`. The
* snapshot is taken by copy when `fn` resolves, so a late-arriving record (a
* floating promise carrying the async context past buffering) mutates only the
* abandoned store, never the returned metadata.
*/
export async function collectPrerenderMetadata(fn, logger, options = {}) {
	const scope = getInstalledRenderScope();
	if (!scope) {
		if (logger && !warnedNoScope) {
			warnedNoScope = true;
			logger.warn("build", "A prerenderer collected metadata but no render scope is installed; " + "install one with `installRenderScope` from `astro/app` — optimized images and " + "incremental metadata will not be collected for prerendered paths.");
		}
		return {
			value: await fn(),
			metadata: undefined
		};
	}
	const store = {
		contentEntries: new Set(),
		staticImages: options.staticImages === false ? undefined : [],
		referencedImages: new Set()
	};
	const value = await scope.run(store, fn);
	return {
		value,
		metadata: {
			contentEntryKeys: [...store.contentEntries],
			staticImages: [...new Map(store.staticImages?.map((image) => [`${image.originalPath}\0${image.hash}`, image])).values()],
			referencedImages: [...store.referencedImages]
		}
	};
}