.NET 5.0 和 6.0，后台服务不会像来自 MS 的示例那样停止

Question

简而言之，我正在为一个简单的数据库进程构建一个 TCP 服务器。我查看了后台服务的 MS 样本，特别是 App.WorkerService.

到目前为止一切顺利，可以运行服务并且每个应用程序实例只启动一次 TCP 服务器。

现在我想在用户 window 命令运行ning 中按下键盘上的 [ESC]ape 键时停止服务。

这里是 Program.cs:

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace PostDataService
{
  public class Program
  {
    public static void Main(string[] args)
    {
      CreateHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureServices((hostContext, services) =>
            {
              services.AddHostedService<Worker>();
            });
  }
}

这是工人class:

using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using System;
using System.Threading;
using System.Threading.Tasks;
using WatsonTcp;

namespace PostDataService
{
  public class Worker : BackgroundService
  {
    private readonly ILogger<Worker> _logger;
    private int _serverPort = 1701;
    private static WatsonTcpServer _Server;

    public Worker(ILogger<Worker> logger)
    {
      _logger = logger;
      _Server = new(null, _serverPort);
      _Server.Events.ClientConnected += ClientConnected;
      _Server.Events.ClientDisconnected += ClientDisconnected;
      _Server.Events.MessageReceived += MsgReceived;
      _Server.Start();
    }

    private void MsgReceived(object sender, MessageReceivedEventArgs args)
    {
      Console.WriteLine("Got Msg");
    }

    private void ClientDisconnected(object sender, DisconnectionEventArgs args)
    {
      throw new NotImplementedException();
    }

    private void ClientConnected(object sender, ConnectionEventArgs args)
    {
      throw new NotImplementedException();
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
      while (!stoppingToken.IsCancellationRequested)
      {
        _logger.LogInformation("Worker running at: {time} {threadid}", DateTimeOffset.Now, Thread.CurrentThread.ManagedThreadId );

        await Task.Delay(500, stoppingToken);
      }
      _Server.Stop();
    }
  }
}

那么如何将 stoppingToken.IsCancellationRequested 设置为 true？

Answer 1

停止控制台应用程序的快捷方式是 Ctrl+C 而不是 Esc。如果您仍希望 Esc 正常工作，您可以这样做：

IHost host = Host.CreateDefaultBuilder(args)
    .ConfigureServices(services =>
    {
        services.AddHostedService<Worker>();
    })
    .Build();

var hostTask = host.RunAsync();

// listen for Esc 
_ = Task.Run(async () =>
{
    ConsoleKeyInfo key;
    do
    {
        key = Console.ReadKey();
    }
    while (key.Key != ConsoleKey.Escape);
    await host.StopAsync();
});

await hostTask;

我还建议在您的 Worker:

中添加类似的内容

public override Task StopAsync(CancellationToken cancellationToken)
{ 
    _logger.LogInformation("stopping server");
    _Server.Stop();
    return Task.CompletedTask;  
}

.NET 5.0 和 6.0，后台服务不会像来自 MS 的示例那样停止

.NET 5.0 and 6.0, background service not stopping like samples from MS

c#

.net-5

.net-6.0