import { AgoraRteSequenceMessage, AgoraRteSequenceType } from '../type';
import { BaseSynchronizer } from './base-synchronizer';
/**
 * 主进程同步器观察者接口
 */
export interface FallbackSynchronizerObserver {
    onSequenceGapDetected: (data: {
        seq: number;
        count: number;
        queueHeadSeq: number;
    }) => void;
    onTaskReady: (data: {
        task: AgoraRteSequenceMessage;
    }) => void;
    onTaskQueueUpdate: (data: {
        queueSize: number;
        currentTask?: AgoraRteSequenceMessage;
        lastSeq: number;
    }) => void;
}
/**
 * 回退同步器实现
 * 当Worker创建失败时，使用此实现来保证功能正常运行
 */
export declare class FallbackSynchronizer extends BaseSynchronizer {
    private observable;
    constructor(sceneId: string, sequenceType: AgoraRteSequenceType, userId: string);
    /**
     * 添加观察者
     */
    addObserver(observer: FallbackSynchronizerObserver): void;
    /**
     * 移除观察者
     */
    removeObserver(observer: FallbackSynchronizerObserver): void;
    protected onTaskReady(task: AgoraRteSequenceMessage): void;
    protected onSequenceGapDetected(seq: number, count: number, queueHeadSeq: number): void;
}