/**
 * @fileoverview Fetch Queue Interface
 *
 * Defines the fetch queue interface, configuration, and request types.
 * The queue manages block fetch requests with deduplication, priority ordering,
 * and configurable concurrency limits.
 *
 * @see cross-node-eventual-consistency design, Section 4
 */
import { PoolId } from '../storage/pooledBlockStore';
import { BlockFetchResult } from './blockFetcher';
/**
 * A single fetch request in the queue.
 * Tracks the block being fetched, its priority, and the promise callbacks
 * for resolving or rejecting the caller's await.
 */
export interface FetchRequest {
    /** The block checksum/ID to fetch */
    blockId: string;
    /** Optional pool scope for the fetch */
    poolId?: PoolId;
    /** Priority level — higher values are processed first */
    priority: number;
    /** Callback to resolve the caller's promise with the fetch result */
    resolve: (result: BlockFetchResult) => void;
    /** Callback to reject the caller's promise with an error */
    reject: (error: Error) => void;
    /** Timestamp (ms) when the request was enqueued */
    enqueuedAt: number;
}
/**
 * Configuration for the FetchQueue.
 */
export interface FetchQueueConfig {
    /** Maximum number of simultaneous remote fetches. Default: 5 */
    maxConcurrency: number;
    /** Maximum time in ms to wait for a single fetch before timeout. Default: 10000 */
    fetchTimeoutMs: number;
}
/** Default FetchQueue configuration values */
export declare const DEFAULT_FETCH_QUEUE_CONFIG: FetchQueueConfig;
/**
 * Fetch queue interface.
 * Manages block fetch requests with deduplication (concurrent requests for the
 * same block produce a single network fetch), priority ordering, and bounded
 * concurrency.
 */
export interface IFetchQueue {
    /**
     * Enqueue a block fetch request. If a fetch for the same blockId is already
     * pending or active, the caller's promise is coalesced with the existing request.
     * @param blockId - The block checksum/ID to fetch
     * @param poolId - Optional pool scope for the fetch
     * @returns The fetch result once the block is retrieved or an error occurs
     */
    enqueue(blockId: string, poolId?: PoolId): Promise<BlockFetchResult>;
    /** Get the number of requests waiting to be processed */
    getPendingCount(): number;
    /** Get the number of fetches currently in progress */
    getActiveCount(): number;
    /**
     * Cancel all pending and active fetch requests.
     * All waiting callers receive a rejection with the given reason.
     * @param reason - Description of why requests are being cancelled
     */
    cancelAll(reason: string): void;
    /** Get the current queue configuration */
    getConfig(): FetchQueueConfig;
}
//# sourceMappingURL=fetchQueue.d.ts.map