import type { SimEvent } from '../../types/events.ts';
import { ComponentType } from '../../types/components.ts';
import type { SimComponent, SimContext, ComponentConfig, ComponentMetrics } from '../../types/components.ts';
import type { ThrottleConfig } from '../../types/configs.ts';
/**
 * Throttle component: fast-rejects requests based on admission control.
 *
 * Two modes:
 * - **concurrency**: reject when in-flight count exceeds maxConcurrency
 * - **rps**: reject when EWMA of arrival rate exceeds maxRps
 *
 * Unlike a Queue, the throttle has no buffer — excess arrivals are immediately
 * returned as failures. Place between a load balancer and a server to enforce
 * admission control without queueing delay.
 */
export declare class Throttle implements SimComponent {
    readonly id: string;
    readonly type = ComponentType.THROTTLE;
    readonly config: ComponentConfig;
    private throttleConfig;
    private inFlightCount;
    private pendingOrigins;
    private ewmaRate;
    private lastArrivalTime;
    private totalAdmitted;
    private totalRejected;
    constructor(id: string, throttleConfig: ThrottleConfig);
    handleEvent(event: SimEvent, context: SimContext): SimEvent[];
    private shouldReject;
    /**
     * Compute the EWMA arrival rate. On each arrival, we update the estimate
     * using the time since the last arrival as an instantaneous rate sample.
     * The half-life controls how quickly old samples decay.
     */
    private getEwmaRate;
    private handleArrival;
    private handleDeparture;
    getMetrics(): ComponentMetrics;
    reset(): void;
}
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