/**
 * Semaphore for Concurrency Control
 *
 * Controls maximum number of parallel processes.
 */
export declare class Semaphore {
    private maxPermits;
    private permits;
    private waiting;
    constructor(maxPermits: number);
    /**
     * Acquire a permit. Returns a release function.
     */
    acquire(): Promise<() => void>;
    /**
     * Try to acquire a permit without waiting.
     * Returns null if no permits available.
     */
    tryAcquire(): (() => void) | null;
    /**
     * Release a permit back to the pool.
     */
    private release;
    /**
     * Get number of available permits.
     */
    getAvailablePermits(): number;
    /**
     * Get maximum permits configured.
     */
    getMaxPermits(): number;
    /**
     * Get number of waiting requests.
     */
    getQueueLength(): number;
    /**
     * Check if any permits are available.
     */
    hasAvailablePermits(): boolean;
    /**
     * Update the maximum number of permits.
     * Can be used to dynamically adjust concurrency.
     */
    setMaxPermits(maxPermits: number): void;
    /**
     * Clear all waiting requests (e.g., during shutdown).
     */
    clearWaiting(): void;
}
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