/**
 * Semaphore: Concurrency Limiter
 *
 * Limits concurrent operations to prevent resource exhaustion.
 *
 * @module utils/semaphore
 */
import { VeryfrontError } from "../errors/types.js";
/**
 * Thrown when a semaphore acquire exceeds its configured timeout.
 *
 * Extends {@link VeryfrontError} so it carries registry slug/status/category
 * and RFC-9457 fields, while remaining `instanceof SemaphoreTimeoutError` for
 * existing catch sites.
 */
export declare class SemaphoreTimeoutError extends VeryfrontError {
    constructor(name: string, timeoutMs: number);
}
export declare class Semaphore {
    private permits;
    private readonly maxPermits;
    private readonly waiting;
    private readonly acquireTimeoutMs;
    private readonly semaphoreName;
    constructor(maxPermits: number, options?: {
        acquireTimeoutMs?: number;
        name?: string;
    });
    /** Acquire permit, execute operation, release automatically */
    acquire<T>(operation: () => Promise<T>): Promise<T>;
    private waitForPermit;
    private release;
    get active(): number;
    get waitingCount(): number;
}
export declare function getSemaphore(name: string, maxPermits: number, options?: {
    acquireTimeoutMs?: number;
}): Semaphore;
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