import Logger from '../logger/Logger';
export type PressureState = 'nominal' | 'fair' | 'serious' | 'critical';
/**
 * Wraps the browser Compute Pressure API to expose the latest CPU pressure
 * state. Returns `null` from {@link currentState} when the API is unavailable
 * or no sample has been received yet. Callers are responsible for any encoding
 * (e.g. into a metric value).
 */
export default class ComputePressureMonitor {
    private logger;
    private sampleIntervalMs;
    private static readonly DEFAULT_SAMPLE_INTERVAL_MS;
    private observer;
    private latestState;
    constructor(logger: Logger, sampleIntervalMs?: number);
    /**
     * Begins observing CPU pressure. Safe to call when the API is unavailable;
     * in that case it logs a debug message and does nothing.
     */
    start(): Promise<void>;
    stop(): void;
    /**
     * Returns the latest observed CPU pressure state, or `null` if no sample has
     * been observed yet.
     */
    currentState(): PressureState | null;
    private getPressureObserverCtor;
}