c# - 使用依赖注入(inject)在工作线程中实例化对象

Question

我的目标是在并行线程中运行一个永无止境的进程。问题是，我不能只在新线程中实例化我的辅助服务，因为我在我的应用程序中使用 DI。

根据我对 SO 的研究，我注意到很多人建议需要将抽象工厂注入(inject)到线程中，以在并行线程中动态实例化线程安全对象。 1 , 2

/// <summary>
/// Responsible for starting parallel long running worker threads
/// </summary>
public class ParallelWorkerStarter
{
    private readonly IQueueProcessorFactory _queueProcessorFactory;

    public ParallelWorkerStarter(IQueueProcessorFactory queueProcessorFactory)
    {
        _queueProcessorFactory = queueProcessorFactory;
    }

    public void StartQueueProcessorThread()
    {    
        queueProcessor = new Thread(
        () =>
        {
            _queueProcessorFactory.Create().ProcessQueue();
        })
        { Name = "QueueProcessor" };
        queueProcessor.Start();
    }
}

IQueueProcessorFactory 的抽象工厂如下所示:

/// <summary>
/// Abstract factory responsible for producing an <see cref="IQueueProcessor"/>
/// </summary>
/// <remarks>
///  This abstract factory is used to generate an <see cref="IQueueProcessor"/> In a seperate thread. 
///  Therefore, all of its dependencies also need to be dynamically generated
/// </remarks>
public interface IQueueProcessorFactory
{
    /// <summary>
    /// Dynamically creates ab <see cref="IQueueProcessor"/>
    /// </summary>
    /// <returns>
    /// The <see cref="IQueueProcessor"/>.
    /// </returns>
    IQueueProcessor Create();
}

现在，我的主要问题是，实现 IQueueProcessor 的具体 QueueProcessor 有 11 个依赖项(我知道 SRP 代码味道)，每个依赖项有 5 个-6 依赖本身。

/// <inheritdoc />
public class QueueProcessorFactory : IQueueProcessorFactory
{
    private readonly IEventTriggerQueuedEventServiceFactory _qeueuedEventServiceFactory;

    private readonly ILoggerFactory _loggerFactory;

    private readonly IEventTriggerActionGroupLogServiceFactory _eventTriggerActionGroupLogServiceFactory;

    private readonly IExceptionLogServiceFactory _exceptionLogServiceFactory;

    private readonly IEventTriggerServiceFactory _eventTriggerServiceFactory;

    private readonly IConditionServiceFactory _conditionServiceFactory;

    private readonly IEventTriggerActionServiceFactory _eventTriggerActionServiceFactory;

    private readonly IEngineEnabledCheckerFactory _engineEnabledCheckerFactory;

    private readonly IEventTriggerScheduleSetServiceFactory _eventTriggerScheduleSetServiceFactory;

    private readonly IEventTriggerActionResultServiceFactory _eventTriggerActionResultServiceFactory;

    private readonly IWorkflowExceptionHandlerFactory _workflowExceptionHandlerFactory;

    public QueueProcessorFactory(
        IEventTriggerQueuedEventServiceFactory qeueuedEventServiceFactory,
        ILoggerFactory loggerFactory,
        IEventTriggerActionGroupLogServiceFactory eventTriggerActionGroupLogServiceFactory,
        IExceptionLogServiceFactory exceptionLogServiceFactory,
        IEventTriggerServiceFactory eventTriggerServiceFactory,
        IConditionServiceFactory conditionServiceFactory,
        IEventTriggerActionServiceFactory eventTriggerActionServiceFactory,
        IEngineEnabledCheckerFactory engineEnabledCheckerFactory,
        IEventTriggerScheduleSetServiceFactory eventTriggerScheduleSetServiceFactory,
        IEventTriggerActionResultServiceFactory eventTriggerActionResultServiceFactory,
        IWorkflowExceptionHandlerFactory workflowExceptionHandlerFactory)
    {
        _qeueuedEventServiceFactory = qeueuedEventServiceFactory;
        _loggerFactory = loggerFactory;
        _eventTriggerActionGroupLogServiceFactory = eventTriggerActionGroupLogServiceFactory;
        _exceptionLogServiceFactory = exceptionLogServiceFactory;
        _eventTriggerServiceFactory = eventTriggerServiceFactory;
        _conditionServiceFactory = conditionServiceFactory;
        _eventTriggerActionServiceFactory = eventTriggerActionServiceFactory;
        _engineEnabledCheckerFactory = engineEnabledCheckerFactory;
        _eventTriggerScheduleSetServiceFactory = eventTriggerScheduleSetServiceFactory;
        _eventTriggerActionResultServiceFactory = eventTriggerActionResultServiceFactory;
        _workflowExceptionHandlerFactory = workflowExceptionHandlerFactory;
    }

    /// <inheritdoc />
    public IQueueProcessor Create()
    {
        return new QueueProcessor(
            _qeueuedEventServiceFactory.Create(),
            _loggerFactory.Create(),
            _eventTriggerActionGroupLogServiceFactory.Create(),
            _exceptionLogServiceFactory.Create(),
            _eventTriggerServiceFactory.Create(),
            _conditionServiceFactory.Create(),
            _eventTriggerActionServiceFactory.Create(),
            _engineEnabledCheckerFactory.Create(),
            _eventTriggerScheduleSetServiceFactory.Create(),
            _eventTriggerActionResultServiceFactory.Create(),
            _workflowExceptionHandlerFactory.Create());
    }
}

这是否意味着我需要 ~60 多个抽象工厂才能在工作线程中实例化我的 IQueueProcessor？这听起来像一场噩梦!有没有更好或更有效的方法来实现这一点？

Answer 1

Does this mean I need ~60+ abstract factories in order to instantiate my IQueueProcessor in a worker thread?

在最坏的情况下，可能需要这样做。当所有依赖项都必须具有 Transient 生命周期时，就会发生这种情况 - 例如，当它们不是线程安全的时。

然而，在最佳情况中，所有这些依赖项都可以具有单例生命周期，这可能适用于线程安全的依赖项。在那种情况下，不需要内部工厂:

public class QueueProcessorFactory : IQueueProcessorFactory
{
    private readonly IEventTriggerQueuedEventService _qeueuedEventService;    
    private readonly ILogger _logger;    
    private readonly IEventTriggerActionGroupLogService _eventTriggerActionGroupLogService;
    // etc...

    public QueueProcessorFactory(
        IEventTriggerQueuedEventService qeueuedEventService,
        ILogger logger,
        IEventTriggerActionGroupLogService eventTriggerActionGroupLogService,
        /* etc... */)
    {
        _qeueuedEventService = qeueuedEventService;
        _logger = logger;
        _eventTriggerActionGroupLogService = eventTriggerActionGroupLogService;
        // etc...
    }

    public IQueueProcessor Create()
    {
        return new QueueProcessor(
            _qeueuedEventService,
            _logger,
            _eventTriggerActionGroupLogService,
            /* etc... */);
    }
}

实际上，您可能需要混合一些 transient 依赖项(这需要工厂)和一些单例依赖项。

如果您最终需要数十个工厂，您可以考虑使用 DI 容器。其中一些可以自动生成工厂接口(interface)的实现 - 您只需提供它们必须实现的接口(interface)。

此外，您不必为每个依赖项定义接口(interface)，但可以考虑使用通用接口(interface)，例如:

public interface IFactory<T>
{
    T Create();
}

同样，一些 DI 容器支持这样的工厂。您也可以考虑完全放弃接口(interface)，只使用像 Func<T> 这样的委托(delegate)。 .

除非情况特殊，否则我不推荐DI Container，而是赞同Pure DI .当您使用 DI 容器时，您会失去编译时安全性，我倾向于认为这是不值得的权衡；毕竟，编程的瓶颈很少是你的打字速度。