在单独的线程问题中初始化存储库 [英] initializing repository in separated thread issue

问题描述

在MainForm.cs内部，我正在初始化几件事(IBookRepository和IDocumentStore).

Inside MainForm.cs I'm initializing couple of things (IBookRepository and IDocumentStore).

private IDocumentStore _store = new EmbeddableDocumentStore {RunInMemory = false };
private IBookRepository _repository;
public MainForm()
{
    InitializeComponent();
    _store.Initialize();
    _repository = new RavenDbBookRepository(_store);
}

因为可嵌入文档存储需要一段时间(5.6秒)才能启动，所以我想将其初始化移到单独的线程上

since embeddable document store takes a while (5,6 sec) to init I want to move it's initialization on separate thread

所以我尝试了

 private void InitOnNewThread()
    {
        _store.Initialize();
        _repository = new RavenDbBookRepository(_Store);            
    }

public MainForm()
{
    InitializeComponent();
    Thread t = new Thread(new ThreadStart(InitOnNewThread));
    t.Start();
}

但是在主线程中使用此_repository为空，原因是在单独的线程中填充的.

but using this _repository is null inside main thread, cause is populated in separate thread.

由于这是我第一次尝试使用线程，所以我看不出如何克服这个问题.\

Since this is first time I trying to work with thread I don't see how to overcome this.\

你会怎么做?

推荐答案

使用新的async和await关键字.

public class MainForm : Form
{
  private IDocumentStore _store = new EmbeddableDocumentStore {RunInMemory = false };
  private IBookRepository _repository;

  private async void MainForm_Load(object sender, EventArgs args)
  {
    // Do stuff here that does not depend on _store or _repository.
    await InitializeRepositoryAsync();
    // Now you can use _store and _repository here.
  }

  private Task InitializeRepositoryAsync()
  {
    return Task.Run(
      () =>
      {
        _store.Initialize();
        _repository = new RavenDbBookRepository(_store);
      };
  }
}

关于await工作方式的整洁之处在于，它将在任务在后台异步运行时抢占MainForm_Load的执行.任务完成后，MainForm_Load的其余部分将重新注入到UI线程的执行流中.这是非常聪明的，它是如何工作的，并提供了一个非常优雅的解决方案.

The neat thing about how await works is that it will preempt the execution of MainForm_Load while the task is running asynchronously in the background. After the task completes the remaining portion of MainForm_Load will be injected back into the execution stream of the UI thread. It is really quite clever how this works and makes for a really elegant solution.

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