import { LeaderEvent } from '../types';
export declare type LeaderSettings = Readonly<{
    electionTimeoutMs: number;
    heartbeatIntervalMs: number;
    heartbeatTimeoutMs: number;
}>;
export declare const DEFAULT_LEADER_SETTINGS: LeaderSettings;
/**
 * This class takes a best-effort approach to picking a single leader amongst
 * multiple clients assuming a shared broadcast channel.
 *
 * Whenever a client comes online, it requests an election.
 *
 * 1. If there is already a leader, it will announce itself, cancelling the election.
 * 2. Otherwise, everyone announces themselves as available.
 *
 * After an election timeout, the client with the alphanumerically smallest
 * clientId announces itself as the leader to everyone.
 *
 * If a leader receives an announcement from another leader, a re-election will
 * occur, and all but one of them will be demoted back to non-leader.
 */
export declare class LeaderManager {
    /**
     * A unique identifier for each client. This can simply be a uuid
     */
    private readonly clientId;
    /**
     * A callback for when this client gains or loses leadership
     */
    private readonly onLeaderChange;
    /**
     * A callback for when this class needs to broadcast messages to other clients
     */
    private readonly broadcastEvent;
    private readonly settings;
    private closed;
    private currentLeaderId?;
    private isLeader;
    private potentialLeaders;
    private electionTimeout?;
    private leaderHeartbeat?;
    private heartbeatTimeout?;
    constructor(
    /**
     * A unique identifier for each client. This can simply be a uuid
     */
    clientId: string, 
    /**
     * A callback for when this client gains or loses leadership
     */
    onLeaderChange: (isLeader: boolean) => void, 
    /**
     * A callback for when this class needs to broadcast messages to other clients
     */
    broadcastEvent: (event: LeaderEvent) => void, settings?: LeaderSettings);
    private elect;
    private cancelElection;
    private finishElection;
    private setLeader;
    private onLeaderHeartbeat;
    private onHeartbeatTimeout;
    receiveEvent({ action, clientId: otherClientId }: LeaderEvent): void;
    shutdown(cleanShutdown?: boolean): void;
}