import RequestQueue from "./RequestQueue.js";
/**
 * An extension of `RequestQueue` that adds a concept of "subscribers," which may share references to a single request
 * or cancel their subscription without disrupting the request for other subscribers.
 */
export default class SubscribableRequestQueue {
    private queue;
    /** The next unused subscriber ID. Increments whenever a subscriber is added. */
    private nextSubscriberId;
    /**
     * Map of subscribers keyed by ID. Subscribers store a map to all their subscriptions by request key.
     * Subscribers are only useful as handles to cancel subscriptions early, so we only need to store rejecters here.
     */
    private subscribers;
    /** Map from "inner" request (managed by `queue`) to "outer" promises generated per-subscriber. */
    private requests;
    /**
     * Since `SubscribableRequestQueue` wraps `RequestQueue`, its constructor may either take the same arguments as the
     * `RequestQueue` constructor and create a new `RequestQueue`, or it may take an existing `RequestQueue` to wrap.
     */
    constructor(maxActiveRequests?: number, maxLowPriorityRequests?: number);
    constructor(inner: RequestQueue);
    /** Resolves all subscriptions to request `key` with `value` */
    private resolveAll;
    /** Rejects all subscriptions to request `key` with `reason` */
    private rejectAll;
    /** Adds a new request subscriber. Returns a unique ID to identify this subscriber. */
    addSubscriber(): number;
    /**
     * Queues a new request, or adds a subscription if the request is already queued/running.
     *
     * If `subscriberId` is already subscribed to the request, this rejects the existing promise and returns a new one.
     */
    addRequest<T>(key: string, subscriberId: number, requestAction: () => Promise<T>, lowPriority?: boolean, delayMs?: number): Promise<T>;
    /**
     * Rejects a subscription and removes it from the list of subscriptions for a request, then cancels the underlying
     * request if it is no longer subscribed and is not running already.
     */
    private rejectSubscription;
    /** Cancels a request subscription, and cancels the underlying request if it is no longer subscribed or running. */
    cancelRequest(key: string, subscriberId: number, cancelReason?: unknown): boolean;
    /** Removes a subscriber and cancels its remaining subscriptions. */
    removeSubscriber(subscriberId: number, cancelReason?: unknown): void;
    /** Returns whether a request with the given `key` is running or waiting in the queue */
    hasRequest(key: string): boolean;
    /** Returns whether a request with the given `key` is running */
    requestRunning(key: string): boolean;
    /** Returns whether a subscriber with the given `subscriberId` exists */
    hasSubscriber(subscriberId: number): boolean;
    /** Returns whether a subscriber with the given `subscriberId` is subscribed to the request with the given `key` */
    isSubscribed(subscriberId: number, key: string): boolean;
}