import { BlockhashWithExpiryBlockHeight, Context } from '@solana/web3.js';
import { BlockhashSubscriberConfig } from './types';
export declare class BlockhashSubscriber {
    private connection;
    private isSubscribed;
    private latestBlockHeight;
    private latestBlockHeightContext;
    private blockhashes;
    private updateBlockhashIntervalId;
    private commitment;
    private updateIntervalMs;
    constructor(config: BlockhashSubscriberConfig);
    getBlockhashCacheSize(): number;
    getLatestBlockHeight(): number;
    getLatestBlockHeightContext(): Context | undefined;
    /**
     * Returns the latest cached blockhash, based on an offset from the latest obtained
     * @param offset Offset to use, defaulting to 0
     * @param offsetType If 'seconds', it will use calculate the actual element offset based on the update interval; otherwise it will return a fixed index
     * @returns Cached blockhash at the given offset, or undefined
     */
    getLatestBlockhash(offset?: number, offsetType?: 'index' | 'seconds'): BlockhashWithExpiryBlockHeight | undefined;
    pruneBlockhashes(): void;
    updateBlockhash(): Promise<void>;
    subscribe(): Promise<void>;
    unsubscribe(): void;
}