ABP VNext + CRDT 打造实时协同编辑

️ ABP VNext + CRDT 打造实时协同编辑器

---

---

背景与挑战

• 多用户并发：无锁场景下自动合并冲突
• ⚡ 实时同步：毫秒级广播到所有客户端
• 缓存与持久化：重启后秒级恢复，支持版本回溯

基于 Yjs (CRDT) + ABP VNext + SignalR，打造企业级 Markdown 协作系统。

---

系统架构

️ 后端 (ABP VNext)

️ 客户端

delta

CollaborationHub

Redis (TTL=1h) ️

PostgreSQL (快照=10s)

BackgroundWorker ⏰

SignalR Hub

Monaco + Yjs + y-signalr

• Redis 缓存：key=doc:{docId}:state，TTL=1 小时
• PostgreSQL：二进制 CRDT 状态历史，定时快照（建议 10 秒一次）
• CRDT GC：定期合并状态、剪枝历史更新，避免状态膨胀

---

️ 端到端流程

Client Hub Redis ️ DB Client Hub Redis DB Send delta + JWT cache.Set(doc:{docId}:state) metrics.Counter("hub_messages_total").Inc() broadcast ReceiveDelta BackgroundWorker persist state ⏳ Client Hub Redis ️ DB Client Hub Redis DB

---

安全与鉴权

1. JWT 鉴权

   services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
     .AddJwtBearer(options => {
       options.Authority = "https://your-auth-server";
       options.Audience  = "collab-api";
     });
   
   [Authorize]
   public class CollaborationHub : Hub { … }
   

2. Rate Limiting

   builder.Services.AddRateLimiter(opts =>
     opts.AddFixedWindowLimiter("hubLimiter", o => {
       o.PermitLimit = 100;
       o.Window = TimeSpan.FromSeconds(1);
     }));
   app.UseRateLimiter();
   

3. 熔断与重试 ♻️

   Policy.Handle<Exception>()
         .CircuitBreaker(5, TimeSpan.FromSeconds(30))
         .WrapAsync(Policy.Handle<Exception>().RetryAsync(3));
   

---

✨ 后端核心代码 ️

CollaborationHub

[Authorize]
public class CollaborationHub : Hub
{
    private readonly ILogger<CollaborationHub> _logger;
    private readonly Counter _msgCounter = Metrics.CreateCounter(
        "hub_messages_total", "Total messages processed by Hub");

    public CollaborationHub(ILogger<CollaborationHub> logger) => _logger = logger;

    public override async Task OnConnectedAsync()
    {
        var docId = Context.GetHttpContext()?.Request.Query["docId"].ToString();
        if (string.IsNullOrWhiteSpace(docId))
            throw new HubException("docId required");
        await Groups.AddToGroupAsync(Context.ConnectionId, docId);
        await base.OnConnectedAsync();
    }

    public override async Task OnDisconnectedAsync(Exception? ex)
    {
        var docId = Context.GetHttpContext()?.Request.Query["docId"].ToString();
        if (!string.IsNullOrWhiteSpace(docId))
            await Groups.RemoveFromGroupAsync(Context.ConnectionId, docId);
        await base.OnDisconnectedAsync(ex);
    }

    public async Task SyncOperation(string docId, byte[] delta)
    {
        if (delta.Length > 1_000_000)
            throw new HubException("Delta too large");
        _msgCounter.Inc();
        try
        {
            await Clients.OthersInGroup(docId).SendAsync("ReceiveDelta", delta);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Sync failed for {DocId}", docId);
            throw;
        }
    }
}

DocumentStateManager

public class DocumentStateManager : ITransientDependency
{
    private readonly IDistributedCache _cache;
    private readonly IRepository<DocumentSnapshot, Guid> _repo;
    private readonly Histogram _persistHist = Metrics.CreateHistogram(
        "persist_duration_seconds", "DB persist duration");

    public DocumentStateManager(IDistributedCache cache,
        IRepository<DocumentSnapshot, Guid> repo)
    {
        _cache = cache;
        _repo  = repo;
    }

    public async Task SaveAsync(string docId, byte[] crdtState)
    {
        await _cache.SetAsync(
            $"doc:{docId}:state", crdtState,
            new DistributedCacheEntryOptions { AbsoluteExpirationRelativeToNow = TimeSpan.FromHours(1) });
        using var _ = _persistHist.NewTimer();
        await _repo.InsertAsync(new DocumentSnapshot {
            Id        = Guid.NewGuid(),
            DocId     = docId,
            CrdtState = crdtState,
            Timestamp = Clock.Now
        }, autoSave: true);
    }

    public async Task<byte[]?> LoadAsync(string docId)
    {
        var cache = await _cache.GetAsync($"doc:{docId}:state");
        if (cache is not null) return cache;
        var latest = await _repo
          .Where(x => x.DocId == docId)
          .OrderByDescending(x => x.Timestamp)
          .FirstOrDefaultAsync();
        return latest?.CrdtState;
    }
}

---

前端组件 (Yjs + y-signalr) ️

import * as Y from 'yjs';
import { MonacoBinding } from 'y-monaco';
import { SignalrProvider } from 'y-signalr';

const ydoc     = new Y.Doc();
const provider = new SignalrProvider(
  "wss://your-domain/hub?docId=mydoc",
  "markdown-room", ydoc);
const yText    = ydoc.getText("monaco");

const editor = monaco.editor.create(
  document.getElementById("editor"), { language: "markdown" });

new MonacoBinding(yText, editor.getModel(),
  new Set([editor]), provider.awareness);

---

⚙️ 环境搭建与快速启动 ‍♂️

# 指定版本
dotnet add package Volo.Abp.SignalR --version 7.4.0
dotnet add package Yjs.SignalR --version 1.2.3
npm install [email protected] [email protected] [email protected] [email protected]

title: docker-compose.yml
version: "3.8"
services:
  redis:
    image: redis:7.0
    ports: ["6379:6379"]
  postgres:
    image: postgres:15.2
    environment:
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: mypwd
    ports: ["5432:5432"]
  app:
    build: .
    environment:
      ConnectionStrings__Default: "Host=postgres;User=postgres;Password=mypwd;Database=collab"
    depends_on: ["redis","postgres"]
    ports: ["5000:80"]

启动后：

docker-compose up -d
dotnet run --project src/Collab.Api
npm run dev --prefix src/Collab.Web

---

性能测试与运维

• Artillery 压测：并发 500 用户测试 SyncOperation
• Prometheus & Grafana：
  • hub_messages_total ️
  • persist_duration_seconds ⏱️
  • redis_cache_hit_ratio
• CRDT GC：使用 ydoc.gc() 定期回收冗余状态
• 监控告警：缓存命中率 <80% 或持久化延迟 >500ms 时触发

---