import { BlockhashWithExpiryBlockHeight, Commitment, Connection } from '@solana/web3.js';
import { BlockhashFetcher } from './types';
/**
 * Fetches the latest blockhash and caches it for a configurable amount of time.
 *
 * - Prevents RPC spam by reusing cached values
 * - Retries on failure with exponential backoff
 * - Prevents concurrent requests for the same blockhash
 */
export declare class CachedBlockhashFetcher implements BlockhashFetcher {
    private connection;
    private blockhashCommitment;
    private retryCount;
    private retrySleepTimeMs;
    private staleCacheTimeMs;
    private recentBlockhashCache;
    private blockhashFetchingPromise;
    constructor(connection: Connection, blockhashCommitment: Commitment, retryCount: number, retrySleepTimeMs: number, staleCacheTimeMs: number);
    private fetchBlockhashWithRetry;
    private sleep;
    private updateBlockhashCache;
    getLatestBlockhash(): Promise<BlockhashWithExpiryBlockHeight | undefined>;
    private isCacheStale;
    /**
     * Refresh the blockhash cache, await a pending refresh if it exists
     */
    private refreshBlockhash;
}