Function createBrotliHandle

lib/internal/streams/iter/transform.js:205–244

* Create a bare Brotli handle. * @returns {{ handle: object, writeState: Uint32Array, chunkSize: number }}

(mode, options, processCallback, onError)

 * @returns {{ handle: object, writeState: Uint32Array, chunkSize: number }}
 */
function createBrotliHandle(mode, options, processCallback, onError) {
  // Validate before creating native handle.
  const chunkSize = validateChunkSize(options);
  const dictionary = validateDictionary(options.dictionary);
  validateParams(options.params, kMaxBrotliParam, ERR_BROTLI_INVALID_PARAM);

  const handle = mode === BROTLI_ENCODE ?
    new binding.BrotliEncoder(mode) : new binding.BrotliDecoder(mode);
  const writeState = new Uint32Array(2);

  TypedArrayPrototypeFill(brotliInitParamsArray, -1);
  // Streaming-appropriate defaults: quality 6 (not 11) and lgwin 20 (1MB,
  // not 4MB). Quality 11 is intended for offline/build-time compression
  // and allocates ~400MB of internal state. Quality 6 is ~10x faster with
  // only ~10-15% worse compression ratio - the standard for dynamic HTTP
  // content-encoding (nginx, Caddy, Cloudflare all use 4-6).
  if (mode === BROTLI_ENCODE) {
    brotliInitParamsArray[constants.BROTLI_PARAM_QUALITY] = 6;
    brotliInitParamsArray[constants.BROTLI_PARAM_LGWIN] = 20;
  }
  if (options.params) {
    // User-supplied params override the defaults above.
    const params = options.params;
    const keys = ObjectKeys(params);
    for (let i = 0; i < keys.length; i++) {
      const key = +keys[i];
      brotliInitParamsArray[key] = params[keys[i]];
    }
  }

  handle.onerror = onError;
  handle.init(
    brotliInitParamsArray,
    writeState,
    processCallback,
    dictionary,
  );

  return { __proto__: null, handle, writeState, chunkSize };
}

/**
 * Create a bare Zstd handle.