是否可以使Unity始终不抛出SynchronizationLockException?

我确信有很多方法代码可以调用SynchronizedLifetimeManager,或者像ContainerControlledLifetimeManager这样的子代,但是有两种特别的场景给我带来了问题。

第一个是我自己的错误-我使用构造函数注入来提供对容器的引用,在该构造函数中,我还将类的新实例添加到容器中以供将来使用。这种向后的方法的效果是将生存期管理器从Transient更改为ContainerControlled,从而使名为GetValue on的对象统一性与名为SetValue on的对象不同。吸取的教训是

第二种情况是,每次调用RegisterInstance时,UnityDefaultBehaviorExtension都会调用SetValue,而不首先调用GetValue。幸运的是,团结是可以扩展的,只要有足够的血性思维,你就可以解决这个问题。

从以下新的行为扩展开始:

/// <summary>
/// Replaces <see cref="UnityDefaultBehaviorExtension"/> to eliminate 
/// <see cref="SynchronizationLockException"/> exceptions that would otherwise occur
/// when using <c>RegisterInstance</c>.
/// </summary>
public class UnitySafeBehaviorExtension : UnityDefaultBehaviorExtension
{
    /// <summary>
    /// Adds this extension's behavior to the container.
    /// </summary>
    protected override void Initialize()
    {
        Context.RegisteringInstance += PreRegisteringInstance;

        base.Initialize();
    }

    /// <summary>
    /// Handles the <see cref="ExtensionContext.RegisteringInstance"/> event by
    /// ensuring that, if the lifetime manager is a 
    /// <see cref="SynchronizedLifetimeManager"/> that its 
    /// <see cref="SynchronizedLifetimeManager.GetValue"/> method has been called.
    /// </summary>
    /// <param name="sender">The object responsible for raising the event.</param>
    /// <param name="e">A <see cref="RegisterInstanceEventArgs"/> containing the
    /// event's data.</param>
    private void PreRegisteringInstance(object sender, RegisterInstanceEventArgs e)
    {
        if (e.LifetimeManager is SynchronizedLifetimeManager)
        {
            e.LifetimeManager.GetValue();
        }
    }
}

然后需要一种方法来替换默认行为。Unity没有删除特定扩展的方法,因此您必须删除所有内容,然后重新放入其他扩展:

public static IUnityContainer InstallCoreExtensions(this IUnityContainer container)
{
    container.RemoveAllExtensions();
    container.AddExtension(new UnityClearBuildPlanStrategies());
    container.AddExtension(new UnitySafeBehaviorExtension());

#pragma warning disable 612,618 // Marked as obsolete, but Unity still uses it internally.
    container.AddExtension(new InjectedMembers());
#pragma warning restore 612,618

    container.AddExtension(new UnityDefaultStrategiesExtension());

    return container;
}

UnityClearBuildPlanStrategies ? RemoveAllExtensions清除了容器中所有策略和策略的内部列表(除了一个),因此我必须使用另一个扩展来避免在还原默认扩展时插入重复的扩展:

/// <summary>
/// Implements a <see cref="UnityContainerExtension"/> that clears the list of 
/// build plan strategies held by the container.
/// </summary>
public class UnityClearBuildPlanStrategies : UnityContainerExtension
{
    protected override void Initialize()
    {
        Context.BuildPlanStrategies.Clear();
    }
}

现在,您可以安全地使用RegisterInstance,而不用担心被推向疯狂的边缘。当然,这里有一些测试:

[TestClass]
public class UnitySafeBehaviorExtensionTests : ITest
{
    private IUnityContainer Container;
    private List<Exception> FirstChanceExceptions;

    [TestInitialize]
    public void TestInitialize()
    {
        Container = new UnityContainer();
        FirstChanceExceptions = new List<Exception>();
        AppDomain.CurrentDomain.FirstChanceException += FirstChanceExceptionRaised;
    }

    [TestCleanup]
    public void TestCleanup()
    {
        AppDomain.CurrentDomain.FirstChanceException -= FirstChanceExceptionRaised;
    }

    private void FirstChanceExceptionRaised(object sender, FirstChanceExceptionEventArgs e)
    {
        FirstChanceExceptions.Add(e.Exception);
    }

    /// <summary>
    /// Tests that the default behavior of <c>UnityContainer</c> leads to a <c>SynchronizationLockException</c>
    /// being throw on <c>RegisterInstance</c>.
    /// </summary>
    [TestMethod]
    public void UnityDefaultBehaviorRaisesExceptionOnRegisterInstance()
    {
        Container.RegisterInstance<ITest>(this);

        Assert.AreEqual(1, FirstChanceExceptions.Count);
        Assert.IsInstanceOfType(FirstChanceExceptions[0], typeof(SynchronizationLockException));
    }

    /// <summary>
    /// Tests that <c>UnitySafeBehaviorExtension</c> protects against <c>SynchronizationLockException</c>s being
    /// thrown during calls to <c>RegisterInstance</c>.
    /// </summary>
    [TestMethod]
    public void SafeBehaviorPreventsExceptionOnRegisterInstance()
    {
        Container.RemoveAllExtensions();
        Container.AddExtension(new UnitySafeBehaviorExtension());
        Container.AddExtension(new InjectedMembers());
        Container.AddExtension(new UnityDefaultStrategiesExtension());

        Container.RegisterInstance<ITest>(this);

        Assert.AreEqual(0, FirstChanceExceptions.Count);
    }
}

public interface ITest { }

Fixed 在Unity的最新版本(2.1.505.2)中。通过NuGet获取。

很遗憾,您的问题的答案是否定的。我在Microsoft patterns&实践小组(直到最近我还是那里的开发负责人),我们把它作为一个bug考虑到entlib5.0中。我们做了一些调查,得出的结论是,这是由我们的代码和调试器之间的一些意外交互造成的。我们确实考虑过修复,但结果证明这比现有代码更复杂。最后,这被排在了其他事情之后,并没有成为5的标准。

我使用这个简短的解决方案:

/// <summary>
/// KVV 20110502
/// Fix for bug in Unity throwing a synchronizedlockexception at each register
/// </summary>
class LifeTimeManager : ContainerControlledLifetimeManager
{
    protected override void SynchronizedSetValue(object newValue)
    {
        base.SynchronizedGetValue();
        base.SynchronizedSetValue(newValue);
    }
}

像这样使用:

private UnityContainer _container;
...
_container.RegisterInstance(instance, new LifeTimeManager());

当做, 科恩

罗里的解决方案很好-谢谢。解决了每天困扰我的问题! 我对Rory的解决方案做了一些小的调整,这样它就可以处理注册的任何扩展(在我的例子中,我有一个wpfprism/复合扩展)。。

    public static void ReplaceBehaviourExtensionsWithSafeExtension(IUnityContainer container)
    {
        var extensionsField = container.GetType().GetField("extensions", BindingFlags.Instance | BindingFlags.NonPublic);
        var extensionsList = (List<UnityContainerExtension>)extensionsField.GetValue(container);
        var existingExtensions = extensionsList.ToArray();
        container.RemoveAllExtensions();
        container.AddExtension(new UnitySafeBehaviorExtension());
        foreach (var extension in existingExtensions)
        {
            if (!(extension is UnityDefaultBehaviorExtension))
            {
                container.AddExtension(extension);
            }
        }
    }

注意祖宾阿波的回答中的一个错误:有 UnityClearBuildPlanStrategies公司

正确的代码段是:

FieldInfo extensionsField = container.GetType().GetField("extensions", BindingFlags.Instance | BindingFlags.NonPublic);
List<UnityContainerExtension> extensionsList = (List<UnityContainerExtension>)extensionsField.GetValue(container);
UnityContainerExtension[] existingExtensions = extensionsList.ToArray();
container.RemoveAllExtensions();
container.AddExtension(new UnityClearBuildPlanStrategiesExtension());
container.AddExtension(new UnitySafeBehaviorExtension());

foreach (UnityContainerExtension extension in existingExtensions)
{
   if (!(extension is UnityDefaultBehaviorExtension))
   {
       container.AddExtension(extension);
   }
}

Unity 2.1 - August 2012 update fix the bug

1. 解决线程安全问题: http://unity.codeplex.com/discussions/328841

2. https://entlib.uservoice.com/forums/89245-general/suggestions/2377307-fix-the-system-threading-synchronizationlockexcep

3. 在无法加载类型时,通过更好的错误消息传递改进调试体验: http://unity.codeplex.com/workitem/9223

4. 支持在没有公共构造函数的类的现有实例上执行building()的场景: http://unity.codeplex.com/workitem/9460

这可能会帮助您:

• 转到调试->例外。。。
• 找出真正让你不安的异常,比如SynchronizationLockException