iceshrimp/packages/backend/src/misc/fetch-meta.ts

import { db } from "@/db/postgre.js";
import { Meta } from "@/models/entities/meta.js";

let cache: Meta;

export async function fetchMeta(noCache = false): Promise<Meta> {
	if (!noCache && cache) return cache;

	return await db.transaction(async (transactionalEntityManager) => {
		// New IDs are prioritized because multiple records may have been created due to past bugs.
		const metas = await transactionalEntityManager.find(Meta, {
			order: {
				id: "DESC",
			},
		});

		const meta = metas[0];

		if (meta) {
			cache = meta;
			return meta;
		} else {
			// If fetchMeta is called at the same time when meta is empty, this part may be called at the same time, so use fail-safe upsert.
			const saved = await transactionalEntityManager
				.upsert(
					Meta,
					{
						id: "x",
					},
					["id"],
				)
				.then((x) =>
					transactionalEntityManager.findOneByOrFail(Meta, x.identifiers[0]),
				);

			cache = saved;
			return saved;
		}
	});
}

setInterval(() => {
	fetchMeta(true).then((meta) => {
		cache = meta;
	});
}, 1000 * 10);