@netlify/cache-utils/lib/hash.js

Utility for caching files in Netlify Build

import { createHash } from 'crypto';
import { createReadStream } from 'fs';
import getStream from 'get-stream';
import { locatePath } from 'locate-path';
// We need a hashing algorithm that's as fast as possible.
// Userland CRC32 implementations are actually slower than Node.js SHA1.
const HASH_ALGO = 'sha1';
// Caching a big directory like `node_modules` is slow. However, those can
// sometime be represented by a digest file such as `package-lock.json`. If this
// has not changed, we don't need to save cache again.
export const getHash = async function (digests, move) {
    // Moving files is faster than computing hashes
    if (move || digests.length === 0) {
        return;
    }
    const digestPath = await locatePath(digests);
    if (digestPath === undefined) {
        return;
    }
    const hash = await hashFile(digestPath);
    return hash;
};
// Hash a file's contents
const hashFile = async function (path) {
    const contentStream = createReadStream(path, 'utf8');
    const hashStream = createHash(HASH_ALGO, { encoding: 'hex' });
    contentStream.pipe(hashStream);
    const hash = await getStream(hashStream);
    return hash;
};