import type { DuplexOptions } from 'node:stream';
/** The `highWaterMark` used by streams that do not specify one. */
export declare function getDefaultHighWaterMark(objectMode?: boolean): number;
/** Changes the process-wide default `highWaterMark` for object-mode or byte streams. */
export declare function setDefaultHighWaterMark(objectMode: boolean, value: number): void;
/**
 * Resolves the `highWaterMark` for one side of a stream.
 * `duplexKey` is only consulted when `isDuplex`, matching how a Duplex configures its sides separately.
 */
export declare function getHighWaterMark(objectMode: boolean, options: Pick<DuplexOptions, 'highWaterMark' | 'readableHighWaterMark' | 'writableHighWaterMark'>, duplexKey: 'readableHighWaterMark' | 'writableHighWaterMark', isDuplex: boolean): number;