filePath() — astro Function Reference

Source Code

packages/astro/src/content/mutable-data-store.ts lines 249–285

	async #writeFileAtomic(filePath: PathLike, data: string, depth = 0) {
		if (depth > MAX_DEPTH) {
			// If we hit the max depth, we skip a write to prevent the stack from growing too large
			// In theory this means we may miss the latest data, but in practice this will only happen when the file is being written to very frequently
			// so it will be saved on the next write. This is unlikely to ever happen in practice, as the writes are debounced. It requires lots of writes to very large files.
			return;
		}
		const fileKey = filePath.toString();
		// If we are already writing this file, instead of writing now, flag it as pending and write it when we're done.
		if (this.#writing.has(fileKey)) {
			this.#pending.add(fileKey);
			return;
		}
		// Prevent concurrent writes to this file by flagging it as being written
		this.#writing.add(fileKey);

		const tempFile = filePath instanceof URL ? new URL(`${filePath.href}.tmp`) : `${filePath}.tmp`;
		try {
			const oldData = await fs.readFile(filePath, 'utf-8').catch(() => '');
			if (oldData === data) {
				// If the data hasn't changed, we can skip the write
				return;
			}
			// Write it to a temporary file first and then move it to prevent partial reads.
			await fs.writeFile(tempFile, data);
			await fs.rename(tempFile, filePath);
		} finally {
			// We're done writing. Unflag the file and check if there are any pending writes for this file.
			this.#writing.delete(fileKey);
			// If there are pending writes, we need to write again to ensure we flush the latest data.
			if (this.#pending.has(fileKey)) {
				this.#pending.delete(fileKey);
				// Call ourself recursively to write the file again
				await this.#writeFileAtomic(filePath, data, depth + 1);
			}
		}
	}