Question

尝试使用Autofac构建以下内容时出现循环依赖项异常：

        builder.RegisterType<Session>().As<ISession>();
        builder.RegisterType<SFEventStore>().As<IEventStore>();
        builder.RegisterType<MemoryCache>().As<ICache>();
        builder.Register(c =>
        {
            return new CacheRepository(new Repository(c.Resolve<IEventStore>()), c.Resolve<IEventStore>(), c.Resolve<ICache>());

        })
        .As<IRepository>();

问题是IRepository，它解析为CacheRepository，而CacheRepository依赖于IRepository：

public CacheRepository(IRepository repository, IEventStore eventStore, ICache cache);

Repository在其构造函数中使用IEventStore：

    public class Repository : IRepository
    {
        private readonly IEventStore _eventStore;

        public Repository(IEventStore eventStore)
        {
            _eventStore = eventStore ?? throw new ArgumentNullException(nameof(eventStore));
        }
    }

CacheRepository遵循装饰器模式并向存储库添加功能：

public class CacheRepository : IRepository
    {
        private readonly IRepository _repository;
        private readonly IEventStore _eventStore;
        private readonly ICache _cache;

        public CacheRepository(IRepository repository, IEventStore eventStore, ICache cache)
        {
            _repository = repository ?? throw new ArgumentNullException(nameof(repository));
            _eventStore = eventStore ?? throw new ArgumentNullException(nameof(eventStore));
            _cache = cache ?? throw new ArgumentNullException(nameof(cache));

        }

因此，尽管我在Autofac构建器方法中新建了一个Repository，但Autofac仍然会尝试解析CacheRepository构造函数中的IRepository，该构造函数解析为CacheRepository。因此循环依赖。

尝试使用Autofac装饰器解决此问题，如下所示：

        builder.RegisterType<Session>().As<ISession>();
        builder.RegisterType<SFEventStore>().As<IEventStore>();
        builder.RegisterType<MemoryCache>().As<ICache>();
        builder.Register(c =>
        {
            return new Repository(c.Resolve<IEventStore>());
        })
        .Named<IRepository>("implementor");

        builder.RegisterDecorator<IRepository>(
            (c, inner) => new CacheRepository(inner, c.Resolve<IEventStore>(), c.Resolve<ICache>()),
            fromKey: "implementor");

但没有运气。仍然给出循环依赖！

该链从解析会话开始，该会话具有以下ctor：

public Session(IRepository repository);

所以我应该得到以下组件依赖树：

Session --> CacheRepository --> Repository --> SFEventStore

但它转而解决：

Session --> CacheRepository --> CacheRepository

这是堆栈跟踪：

Autofac.Core.DependencyResolutionException：检测到循环组件依赖关系：AnswersBC.Command.Handlers.AddAnswerCmdHandler - ＆gt; CQRSlite.Domain.Session - ＆gt; CQRSlite.Cache.CacheRepository - ＆gt; CQRSlite.Cache.CacheRepository。在Autofac.Core.Resolving.CircularDependencyDetector.CheckForCircularDependency（IComponentRegistration注册，堆栈1 activationStack, Int32 callDepth) in C:\BuildAgent\work\3206e2123f54fce4\src\NServiceBus.Core\Licensing\LogErrorOnInvalidLicenseBehavior.cs:line 0 at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable 1个参数）在C：\ BuildAgent \工作\ 3206e2123f54fce4 \ SRC \ NServiceBus.Core \许可\ LogErrorOnInvalidLicenseBehavior.cs：在Autofac线0。 Core.Activators.Reflection.ConstructorParameterBinding.Instantiate（）位于C：\ BuildAgent \ work \ 3206e2123f54fce4 \ src \ NServiceBus.Core \ Licensing \ LogErrorOnInvalidLicenseBehavior.cs：第0行，位于Autofac.Core.Activators.Reflection.ReflectionActivator.ActivateInstance（IComponentContext context），IEnumerable的1 parameters) in C:\BuildAgent\work\3206e2123f54fce4\src\NServiceBus.Core\Licensing\LogErrorOnInvalidLicenseBehavior.cs:line 0 at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable 1个参数）在C：\ BuildAgent \工作\ 3206e2123f54fce4 \ SRC \ NServiceBus.Core \许可\ LogErrorOnInvalidLicenseBehavior.cs：行0在Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare（GUID ID，Func键{ {1}} 1个参数）在C：\ BuildAgent \ work \ 3206e2123f54fce4 \ src \ NServiceBus.Core \ Licensing \ LogErrorOnInvalidLicenseBehavior.cs：第0行，位于C：\ BuildA中的Autofac.Core.Activators.Reflection.ConstructorParameterBinding.Instantiate（）绅士\工作\ 3206e2123f54fce4 \ SRC \ NServiceBus.Core \许可\ LogErrorOnInvalidLicenseBehavior.cs：行0在Autofac.Core.Activators.Reflection.ReflectionActivator.ActivateInstance（IComponentContext上下文，IEnumerable的1 creator) in C:\BuildAgent\work\3206e2123f54fce4\src\NServiceBus.Core\Licensing\LogErrorOnInvalidLicenseBehavior.cs:line 0 at Autofac.Core.Resolving.InstanceLookup.Execute() in C:\BuildAgent\work\3206e2123f54fce4\src\NServiceBus.Core\Licensing\LogErrorOnInvalidLicenseBehavior.cs:line 0 at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable 1个参数）在C：\ BuildAgent \ work \ 3206e2123f54fce4 \ src \ NServiceBus.Core \ Licensing \ LogErrorOnInvalidLicenseBehavior.cs：在C：\ BuildAgent \ work \中的Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare（Guid id，Func 1 parameters) in C:\BuildAgent\work\3206e2123f54fce4\src\NServiceBus.Core\Licensing\LogErrorOnInvalidLicenseBehavior.cs:line 0 at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable 1个参数）的第0行3206e2123f54fce4 \ src \ NServiceBus.Core \ Licensing \ LogErrorOnInvalidLicenseBehavior.cs：第0行，位于C：\ BuildAgent \ work \ 3206e2123f54fce4 \ src \ NServiceBus.Core \ Licensing \ LogErrorOnInvalidLicenseBehavior中的Autofac.Core.Activators.Reflection.ConstructorParameterBinding.Instantiate（）。 CS：线0在Autofac.Core.Activators.Reflection.ReflectionActivator.ActivateInstance（IComponentContext上下文，IEnumerable的1 creator) in C:\BuildAgent\work\3206e2123f54fce4\src\NServiceBus.Core\Licensing\LogErrorOnInvalidLicenseBehavior.cs:line 0 at Autofac.Core.Resolving.InstanceLookup.Execute() in C:\BuildAgent\work\3206e2123f54fce4\src\NServiceBus.Core\Licensing\LogErrorOnInvalidLicenseBehavior.cs:line 0 at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable 1个参数）在C：\ BuildAgent \工作\ 3206e2123f54fce4 \ SRC \ NServiceBus.Core \许可\ LogErrorOnInvalidLicenseBehavior.cs ：第0行在Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare（GUID标识，函数功能1 parameters) in C:\BuildAgent\work\3206e2123f54fce4\src\NServiceBus.Core\Licensing\LogErrorOnInvalidLicenseBehavior.cs:line 0 at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable 1个参数）在C：\ BuildAgent \工作\ 3206e2123f54fce4 \ SRC \ NServiceBus.Core \许可\ LogErrorOnInvalidLicenseBehavior.cs：在Autofac线0。 Core.Resolving.ResolveOperation.Execute（IComponentRegistration注册，IEnumerable 1 creator) in C:\BuildAgent\work\3206e2123f54fce4\src\NServiceBus.Core\Licensing\LogErrorOnInvalidLicenseBehavior.cs:line 0 at Autofac.Core.Resolving.InstanceLookup.Execute() in C:\BuildAgent\work\3206e2123f54fce4\src\NServiceBus.Core\Licensing\LogErrorOnInvalidLicenseBehavior.cs:line 0 at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable 1个参数，Object＆amp;在C：\ BuildAgent \ work \ 3206e2123f54fce4 \ src \ NServiceBus.Core \ Licensing \ LogErrorOnInvalidLicenseBehavior.cs中：在C：\ BuildAgent \中的Autofac.ResolutionExtensions.ResolveService（IComponentContext上下文，服务服务，IEnumerable`1参数）中的第0行work \ 3206e2123f54fce4 \ src \ NServiceBus.Core \ Licensing \ LogErrorOnInvalidLicenseBehavior.cs：位于C：\ BuildAgent \ work \ 3206e2123f54fce4 \ src \ NServiceBus.Core \ ObjectBuilder \ Autofac \ AutofacObjectBuilder中的NServiceBus.AutofacObjectBuilder.Build（Type typeToBuild）的第0行。 cs：位于C：\ BuildAgent \ work \ 3206e2123f54fce4 \ src \ NServiceBus.Core \ Pipeline \ Incoming \ LoadHandlersConnector.cs：第37行的NServiceBus.LoadHandlersConnector.d__1.MoveNext（）第39行

Answer 1

您描述的内容与Decorator模式完全相同。你有两个IRepository实现，一个包装另一个。 Autofac使用.RegisterDecorator（）

本地支持此功能

请参阅此处的文档， http://docs.autofac.org/en/latest/advanced/adapters-decorators.html

我相信你的新问题就是问题，见下面的例子

不要使用它：

builder.Register(c =>
{
    return new Repository(c.Resolve<IEventStore>());
})
.Named<IRepository>("implementor");

而是使用它：

builder.RegisterType<Repository>().Named<IRepository>("implementor");
builder.RegisterDecorator<IRepository>(
        (c, inner) => new CacheRepository(inner, c.Resolve<IEventStore>(), c.Resolve<ICache>()),
        fromKey: "implementor");

Answer 2

似乎必须对NServiceBus中组件的配置做一些事情：

        nsbEndpointConfig.RegisterComponents(registration: configureComponents =>
        {
            configureComponents.ConfigureComponent<Session>(DependencyLifecycle.InstancePerUnitOfWork);
            configureComponents.ConfigureComponent<SFEventStore>(DependencyLifecycle.InstancePerUnitOfWork);
            configureComponents.ConfigureComponent<MemoryCache>(DependencyLifecycle.InstancePerUnitOfWork);
            configureComponents.ConfigureComponent<Repository>(DependencyLifecycle.InstancePerUnitOfWork);
            configureComponents.ConfigureComponent<CacheRepository>(DependencyLifecycle.InstancePerUnitOfWork);
        });

当我省略此配置时，未检测到循环依赖性。我所做的就是设置生命望远镜。

Autofac循环依赖

2 个答案: