import type { ExtraOptions, Querier, QuerierPool } from 'nukak/type';
export declare abstract class AbstractQuerierPool<Q extends Querier> implements QuerierPool<Q> {
    readonly extra?: ExtraOptions;
    constructor(extra?: ExtraOptions);
    /**
     * get a querier from the pool.
     */
    abstract getQuerier(): Promise<Q>;
    /**
     * end the pool.
     */
    abstract end(): Promise<void>;
}