import { Clock } from './clocks';
interface TimerOptions {
    isDummy?: boolean;
    clock: Clock<any>;
}
/**
 * Keeps track of timing data for events and turns that data into a `server-timing` header.
 */
export default class Timer {
    private _isDummy;
    private _clock;
    private _records;
    constructor(options: TimerOptions);
    /**
     * Start timing an event.
     * @param slug - The slug to use for timing.  The same slug must be supplied to `end(slug)` in order
     *   for this timing to show up in the final header.
     * @param [label] - Label to use in the server-timing header.
     */
    start(slug: string, label?: string): void;
    /**
     * Stop timing an event.
     * @param slug - The slug to supplied to `start()`.
     */
    end(slug: string): void;
    /**
     * Set the timing for an event.
     * @param slug - The slug to use for timing.
     * @param ms - Time, in milliseconds.  Can be a float.
     */
    setTime(slug: string, ms: number): void;
    /**
     * Set the timing for an event.
     * @param slug - The slug to use for timing.
     * @param label - Label to use in the server-timing header.
     * @param ms - Time, in milliseconds.  Can be a float.
     */
    setTime(slug: string, label: string, ms: number): void;
    /**
     * Time the duration of a promise.
     * @param slug - The slug to use for timing.
     * @param promise - The promise to time.
     * @return - Returns the passed in `promise`.
     */
    timePromise<T>(slug: string, promise: Promise<T>): Promise<T>;
    /**
     * Time the duration of a promise.
     * @param slug - The slug to use for timing.
     * @param label - Label to use in the server-timing header.
     * @param promise - The promise to time.
     * @return - Returns the passed in `promise`.
     */
    timePromise<T>(slug: string, label: string, promise: Promise<T>): Promise<T>;
    /**
     * Return the server-timing header.
     * @return {string} - The header.
     */
    getHeader(): string | null;
}
export {};