是否可以在 ASP.NET Core 的 Timer 中注入服务？

Question

我目前正在使用 ASP.NET Core 开发带有计时器的多人网页游戏。对于实时通信，我使用 SignalR。到目前为止，一切都运行良好。 我实现计时器功能的方式如下：我创建了一个静态字典，其中键是游戏的 Id，值是与给定游戏对应的计时器。然后我公开了管理字典状态的公共方法：

public class TimerManager
{
    private static readonly Dictionary<string, GameTimer> gameTimersByGameIds = new();

    public void AttachTimerToGameState(GameTimer timer, string gameId)
    {
        if (!gameTimersByGameIds.ContainsKey(gameId))
        {
            gameTimersByGameIds.Add(gameId, timer);
            return;
        }

        gameTimersByGameIds[gameId] = timer;
    }

    public GameTimer? GetTimer(string gameId)
    {
        if (!gameTimersByGameIds.ContainsKey(gameId))
        {
            return null;
        }

        return gameTimersByGameIds[gameId];
    }

    public GameTimer CreateTimer(GameState gameState)
    {
        if (gameState.RemainingSecondsByUserNames.Count == 0)
        {
            return ActivatorUtilities.CreateInstance<StandardTimer>(_serviceProvider, gameState);
        }
        else
        {
            return ActivatorUtilities.CreateInstance<ChessTimer>(_serviceProvider, gameState, _gamesService);
        }
    }
}

我创建了自己的 GameTimer 基类，其中封装了 System.Timers.Timer：

public abstract class GameTimer
{
    protected readonly System.Timers.Timer _timer = new();

    public virtual void Reset()
    {
        _timer.AutoReset = true;
        _timer.Interval = 1_000;
    }

    public virtual void Start()
    {
        _timer.Start();
    }

    public virtual void Dispose()
    {
        _timer.Dispose();
    }
}

然后我从抽象 GameTimer 类继承来创建不同类型的计时器。

public class StandardTimer : GameTimer
public class ChessTimer : GameTimer

问题出在 ChessTimer 类内部：

public class ChessTimer : GameTimer
{
    private readonly GameState _gameState;
    private readonly IGameService _gameService;
    private readonly IHubContext<GameHub, IGameClient> _hubContext;
    private readonly IMatchmakingService _matchmakingService;
    private readonly IGamesService _gamesService;

    public ChessTimer(
        GameState gameState,
        IGamesService gamesService,
        IGameService gameService,
        IHubContext<GameHub, IGameClient> hubContext,
        IMatchmakingService matchmakingService)
    {
        _gameState = gameState;
        _gameService = gameService;
        _hubContext = hubContext;
        _matchmakingService = matchmakingService;
        _gamesService = gamesService;
        Reset();

        _timer.Elapsed += async (sender, args) => await OnTimedEvent(sender, args);
    }

    public int SecondsRemaining { get; private set; }

    public override void Reset()
    {
        string currentPlayerName = _gameState.CurrentTeam.CurrentPlayer.UserName;
        SecondsRemaining = _gameState.RemainingSecondsByUserNames[currentPlayerName];
        base.Reset();
    }

    private async Task OnTimedEvent(object? sender, ElapsedEventArgs args)
    {
        if (SecondsRemaining >= 0)
        {
            string currentPlayerUserName = _gameState.CurrentTeam.CurrentPlayer.UserName;
            _gameState.RemainingSecondsByUserNames[currentPlayerUserName] = SecondsRemaining;

            int minutes = SecondsRemaining / 60;
            int seconds = SecondsRemaining % 60;

            var viewModel = new UpdateGameTimerViewModel
            {
                Minutes = minutes,
                Seconds = seconds,
            };

            foreach (Player player in _gameState.Players)
            {
                if (player.ConnectionId == null)
                {
                    continue;
                }

                await _hubContext.Clients
                    .Client(player.ConnectionId)
                    .UpdateGameTimer(viewModel);
            }

            SecondsRemaining--;
            return;
        }

        if (_gameState.RemainingSecondsByUserNames.All(x => x.Value <= 0))
        {
            _gameState.EndGame();
        }
        else
        {
            _gameState.NextTeam();
        }

        foreach (Player player in _gameState.Players)
        {
            _gameService.FillPlayerTiles(_gameState, player);
        }

        foreach (Player player in _gameState.Players)
        {
            if (player.ConnectionId == null)
            {
                continue;
            }

            var viewModel = _gameService.MapFromGameState(_gameState, player.UserName);

            await _hubContext.Clients
                .Client(player.ConnectionId)
                .UpdateGameState(viewModel);

            if (_gameState.IsGameOver)
            {
                _matchmakingService.RemoveUserFromGame(player.UserName);

                await _hubContext.Groups
                    .RemoveFromGroupAsync(
                        player.ConnectionId, _gameState.GameId);
            }
        }

        if (_gameState.IsGameOver)
        {
            _matchmakingService.RemoveGameState(_gameState.GameId);

            await _gamesService!.SaveGameAsync(new SaveGameInputModel
            {
                GameId = _gameState.GameId,
                Players = _gameState.Players
            });

            Dispose();
        }

        Reset();
    }
}

基本上，我的 OnTimedEvent 方法的工作方式是每秒执行一次。然后检查所有玩家的时间是否已用完。如果没有，则更新游戏状态，否则结束游戏。完成其他所有操作后，我尝试将游戏保存在数据库中，以便用户能够看到有关他们所玩游戏的摘要。我正在使用一个名为 GamesService 的类来完成此任务。它在内部使用 UserManager 对数据库中的用户执行一些工作。

if (_gameState.IsGameOver)
{
    _matchmakingService.RemoveGameState(_gameState.GameId);

    await _gamesService!.SaveGameAsync(new SaveGameInputModel
    {
        GameId = _gameState.GameId,
        Players = _gameState.Players
    });

    Dispose();
}

Reset();

问题是，当游戏结束并执行上述代码时，会产生以下异常：

Unhandled exception. Unhandled exception. System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'UserManager`1'.
   at Microsoft.AspNetCore.Identity.UserManager`1.ThrowIfDisposed()
   at Microsoft.AspNetCore.Identity.UserManager`1.FindByNameAsync(String userName)
   at SuperScrabble.Services.Data.Users.UsersService.GetByUserNameAsync(String userName) in C:\Users\georg\Source\Github\SuperScrabble\src\Server\Services\SuperScrabble.Services.Data\Users\UsersService.cs:line 64
   at SuperScrabble.Services.Data.Games.GamesService.SaveGameAsync(SaveGameInputModel input) in C:\Users\georg\Source\Github\SuperScrabble\src\Server\Services\SuperScrabble.Services.Data\Games\GamesService.cs:line 52
   at SuperScrabble.WebApi.Timers.ChessTimer.OnTimedEvent(Object sender, ElapsedEventArgs args) in C:\Users\georg\Source\Github\SuperScrabble\src\Server\WebApi\SuperScrabble.WebApi\Timers\ChessTimer.cs:line 120
   at SuperScrabble.WebApi.Timers.ChessTimer.<.ctor>b__5_0(Object sender, ElapsedEventArgs args) in C:\Users\georg\Source\Github\SuperScrabble\src\Server\WebApi\SuperScrabble.WebApi\Timers\ChessTimer.cs:line 35
   at System.Threading.Tasks.Task.<>c.<ThrowAsync>b__128_1(Object state)
   at System.Threading.QueueUserWorkItemCallback.<>c.<.cctor>b__6_0(QueueUserWorkItemCallback quwi)
   at System.Threading.ExecutionContext.RunForThreadPoolUnsafe[TState](ExecutionContext executionContext, Action`1 callback, TState& state)
   at System.Threading.QueueUserWorkItemCallback.Execute()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()
   at System.Threading.PortableThreadPool.WorkerThread.WorkerThreadStart()
   at System.Threading.Thread.StartCallback()

在我看来，我传递给 TimerManager.CreateTimer() 方法内的 CreateInstance() 方法的 _gamesService 对象已经被释放，或者它内部使用的一些服务是。

public GameTimer CreateTimer(GameState gameState)
{
    if (gameState.RemainingSecondsByUserNames.Count == 0)
    {
        return ActivatorUtilities.CreateInstance<StandardTimer>(_serviceProvider, gameState);
    }
    else
    {
        return ActivatorUtilities.CreateInstance<ChessTimer>(_serviceProvider, gameState, _gamesService);
    }
}

我不确定我想做的是否正确。我需要在计时器类中使用服务类来在每次计时器计时时执行操作。但是，我无法使用依赖项注入，这就是我使用 ActivatorUtilities 类来实例化该对象的原因。

我从 SignalR hub 类中的方法创建所有计时器：

private async Task StartGameAsync()
{
    var gameState = _matchmakingService.GetGameState(UserName);
    string gameId = gameState.GameId;

    foreach (Player player in gameState.Players)
    {
        await Groups.AddToGroupAsync(player.ConnectionId!, gameId);
    }

    var timer = _timerManager.CreateTimer(gameState);
    Console.WriteLine(timer.GetType().Name);
    _timerManager.AttachTimerToGameState(timer, gameId);

    await Clients.Group(gameId).StartGame(gameId);
    await UpdateGameStateAsync(gameState);

    timer.Start();
}

所以我的问题是：是否有可能找到解决该问题的方法？ 如果您需要更多说明，请随时向我询问。任何帮助将不胜感激！谢谢