export interface Options {
    /**
     * Timeout for SQL operations (must take HTTP transfers into account)
     * @default 30000
     */
    timeout?: number;
    /**
     * Maximum supported page size
     * @default 4096
     */
    maxPageSize?: number;
    /**
     * Cache size in Kb
     * @default 4096
     */
    cacheSize?: number;
    /**
     * Optional custom headers to be used when requesting data
     */
    headers?: Record<string, string>;
    /**
     * Force the type of backend
     */
    backendType?: 'sync' | 'shared';
}
export declare const defaultOptions: {
    timeout: number;
    maxPageSize: number;
    cacheSize: number;
    headers: Record<string, string>;
};
export interface BackendChannel {
    port: MessagePort;
    shm: SharedArrayBuffer;
}
export interface Backend {
    /**
     * The backend type
     */
    type: 'shared' | 'sync';
    /**
     * @private
     */
    worker: Worker | null;
    /**
     * @private
     */
    createNewChannel: () => Promise<BackendChannel>;
    /**
     * Close the HTTP backend waiting for clean shutdown
     */
    close: () => Promise<void>;
    /**
     * Synchronously kill the HTTP backend
     */
    terminate: () => void;
    /**
     * The options object
     */
    options?: Options;
}
export type Operation = 'xOpen' | 'xAccess' | 'xRead' | 'xFilesize';
export interface Message {
    msg: Operation;
    url: string;
    offset?: bigint;
    n?: number;
    [key: string]: string | number | bigint | undefined;
}
export declare const debugSys: readonly ["threads", "vfs", "cache", "http"];
export declare const debug: Record<"http" | "threads" | "vfs" | "cache", (...args: unknown[]) => void>;