Question

我有一个异步任务，需要比主线程更长的时间。主线程在异步任务之前完成，我没有看到Async任务的结果，例如我没有看到异步任务应该插入的DB记录。

这是我的代码

Framework 4.5

    public void Load(int id)
    {
        Task asynctask1;
        asynctask1 = CallWithAsync(id); // this is async task 
        task2(); // main thread
        task3(); // main thread

    }
    private async static Task CallWithAsync(int id)
    {
        string result = "";
        try
        {
            result = await InsertDataAsync(id);
        }
        catch (Exception ex)
        {
            //do some error logging
        }
        //return result;

    }
    static Task<string> InsertDataAsync(int id)
    {
        return Task.Run<string>(() =>
        {
            return InsertData(id);
        });
    }
    static string InsertData(int id)
    {

        try
        {

            System.Threading.Thread.Sleep(5000);//we have some code here which takes longer
            //code to insert DB record

        }
        catch (Exception ex)
        {
            //do some error logging
        }


        return "success";

    }


    public void task2()
    {
        //some thing
    }
    public void task3()
    {
        //some thing
    }

Answer 1

等待在方法结束时完成任务：

public void Load(int id)
{
    Task asynctask1;
    asynctask1 = CallWithAsync(id);
    task2();
    task3();
    asynctask1.Wait(); // wait for async task to complete
}

如果您将await关键字添加到async方法本身，也可以使用Load关键字。

Answer 2

加载异步并等待通话？您可以使用异步void方法，但如果它是异步任务会更好，并且您在调用链的后面等待它。

public async void Load(int id)
{
  await CallWithAsync(id); // this is async task 
  task2(); // main thread
  task3(); // main thread
}

Answer 3

在调用Load和async后等待asynctask1，task2()方法task3()。请注意，Load方法现在返回Task而不是void

public async Task Load(int id)
{
    Task asynctask1;
    asynctask1 = CallWithAsync(id); // this is async task 
    task2(); // main thread
    task3(); // main thread
    var result = await asynctask1;
    Console.Writeline(result); //verify returned value of asynctask1 task 
}

private async static Task<string> CallWithAsync(int id)
{
    string result = "";
    try
    {
        result = await InsertDataAsync(id);
    }
    catch (Exception ex)
    {
        //do some error logging
    }
    return result;

}

如何在C＃中完成异步任务之前等待主线程

3 个答案: