asp.net核心中的排队任务 [英] Queuing tasks in asp.net core

问题描述

例如功能的实现有20个用户，他们几乎一次单击了发送按钮，因此在队列中堆叠的方法和发送第一个用户消息并接收响应的方法，在第二个，第三个之后，依此类推.用户不会与其他人聊天，但会使用响应速度非常快的设备
因此，我试图将发送消息的Task排队.
我发现了使用Task排队的代码示例，如示例1 和示例2 所示.

E.g. of functionality There is 20 users and they clicked send button almost in one time, so methods stacking in queue and first user message is sent and response received, after second third and so on. Users wont chat with other people but with device which response is pretty fast
So I am trying to queue Task which sends Message.
I found code samples that uses Task queuing as shown in Example 1 and Example 2.

示例1

public class SerialQueue
{
    readonly object _locker = new object();
    WeakReference<Task> _lastTask;

    public Task Enqueue(Action action)
    {
        return Enqueue<object>(() => {
            action();
            return null;
        });
    }

    public Task<T> Enqueue<T>(Func<T> function)
    {
        lock (_locker)
        {
            Task lastTask = null;
            Task<T> resultTask = null;

            if (_lastTask != null && _lastTask.TryGetTarget(out lastTask))
            {
                resultTask = lastTask.ContinueWith(_ => function());
            }
            else
            {
                resultTask = Task.Run(function);
            }

            _lastTask = new WeakReference<Task>(resultTask);
            return resultTask;
        }
    }
}

示例2

 public class TaskQueue
{
    private readonly SemaphoreSlim _semaphoreSlim;

    public TaskQueue()
    {
        _semaphoreSlim = new SemaphoreSlim(1);
    }

    public async Task<T> Enqueue<T>(Func<Task<T>> taskGenerator)
    {
        await _semaphoreSlim.WaitAsync();

        try
        {
            return await taskGenerator();
        }
        finally
        {
            _semaphoreSlim.Release();
        }
    }

    public async Task Enqueue(Func<Task> taskGenerator)
    {
        await _semaphoreSlim.WaitAsync();
        try
        {
            await taskGenerator();
        }
        finally
        {
            _semaphoreSlim.Release();
        }
    }
}

问题是，当我每次按按钮传递要排队的任务(示例3 )时，任务仍然同时执行并且彼此中断.

Problem is that when I'm passing task which I want to queue (Example 3) each time I pressing button, tasks still are executed at the same time and interrupting each other.

示例3

 [HttpPost(Name = "add-message")]
        public async Task<IActionResult> PostMessage([FromBody] MessengerViewModel messengerViewModel)
        {
            TaskQueue taskQueue = new TaskQueue();
            SerialQueue serialQueue = new SerialQueue();

            await taskQueue.Enqueue(() => SendMessage(messengerViewModel.PhoneNr, messengerViewModel.MessageBody,
                messengerViewModel.ContactId, messengerViewModel.State));
//I'm not running tasks at same time, using one or other at time
            await serialQueue.Enqueue(() => SendMessage(messengerViewModel.PhoneNr, messengerViewModel.MessageBody,
                messengerViewModel.ContactId, messengerViewModel.State));

            return Ok();
        }

我该如何解决问题并通过每次单击将任务堆叠到队列中?

How could I solve problem and stack task to queue by each click?

推荐答案

您的问题是您每次都创建一个新的 TaskQueue 和 SerialQueue .因此，每次用户单击/调用 PostMessage 时，都会创建一个新队列，该任务是队列中的第一个任务，并直接执行.

Your problem is that you create a new TaskQueueand SerialQueue everytime. Thus each time a user clicks/invokes PostMessage a new queue is created, and the task is the first task in the queue and executed directly.

您应该使用静态/单个队列，以便每次单击/调用都可在同一队列对象上进行.

You should use a static/singleton queue so each click/invoke works on the same queue object.

但是，当您跨多个服务器扩展Web应用程序时，这会带来问题.为此，您应该结合使用Azure Queue Storage之类的东西(例如)与Azure Functions相结合.

But that would deliver problems when you scale your webapp across multiple servers. To that end you should use things like (for example) Azure Queue Storage in combination with Azure Functions.

public void ConfigureServices(IServiceCollection services)
{
    services.AddSingleton<TaskQueue>();
    services.AddSingleton<SerialQueue>();
    // the rest
}

SomeController.cs

[HttpPost(Name = "add-message")]
public async Task<IActionResult> PostMessage(
    [FromBody] MessengerViewModel messengerViewModel,
    [FromServices] TaskQueue taskQueue,
    [FromServices] SerialQueue serialQueue)
{
    await taskQueue.Enqueue(
        () => SendMessage(
                  messengerViewModel.PhoneNr, 
                  messengerViewModel.MessageBody,
                  messengerViewModel.ContactId, 
                  messengerViewModel.State));
    //I'm not running tasks at same time, using one or other at time
    await serialQueue.Enqueue(
        () => SendMessage(
                  messengerViewModel.PhoneNr, 
                  messengerViewModel.MessageBody,
                  messengerViewModel.ContactId, 
                  messengerViewModel.State));

    return Ok();
}

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