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Deadlock in Interceptor #47

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asmus opened this Issue · 9 comments

5 participants

@asmus

When calling Method1 on the mock, and Method one is executing Method2 asynchronously and then waiting for Method2 to complete Moq will cause a deadlock due to the interceptor implementation.

public void Intercept(ICallContext invocation)
{

    lock (Mock) // this solves issue #249
    {
        var interceptionContext = new InterceptStrategyContext(Mock
                                                            , targetType
                                                            , invocationLists
                                                            , actualInvocations
                                                            , behavior
                                                            , orderedCalls
                                                            );
        foreach (var strategy in InterceptionStrategies())
        {
            if (InterceptionAction.Stop == strategy.HandleIntercept(invocation, interceptionContext))
            {
                break;
            }
        }
    }
}

The actual method of the Mock will be called unter lock condition. This will cause a deadlock in some cases. Simple TestCase to reproduce the behavior:

public class ClassToMock
{
    AutoResetEvent reset = new AutoResetEvent(false);
    public virtual void M1()
    {
        var task = new TaskFactory().StartNew(M2);
        Thread.Sleep(500);
        reset.Set();
        task.Wait();
    }

    public virtual void M2()
    {
        reset.WaitOne();
    }
}

[TestMethod]
public void TestMock()
{
    var testMock = new Mock<ClassToMock>{CallBase = true};
    testMock.Object.M1(); // <-- This will never return!
    testMock.Verify(x => x.M1());
    testMock.Verify(x => x.M2());
}
@kzu
Owner

Could this be related to the fix @yonahw contributed in pull #36 ?

@asmus

I don´t think so. The InvokeBase Interception strategy is still called under lock conditions and the lock is still made on "Mock". I believe executing the InvokeBase strategy under lock conditions is causing the deadlock. Unfortunately I do not have the time to verify that right now. Maybe I can can try to fix it on the weekend.

@yonahw

I didn't have time to run test myself but doesn't seem related on the surface.

@kzu
Owner
@asmus

In my opinion this behavior was introduced when fixing issue #3. As far as I can tell (I´m still not so familiar with github) the lock was introduced to resolve the threading issue when calling methods on a mock from different threads in parallel. The lock is just covering to much. It is calling "foreign" code under lock conditions, what always is dangerous. But on the other hand it could very well be that I´m missing something here and I´m completely wrong .... that happens from time to time :)

@kzu
Owner

@FelicePollano did you have a chance to look at this?

@FelicePollano
@asmus

I thought I have a look at the code and try to fix it. Got the code from gitHub and build the whole thing (VS 2012). But somehow almost all UnitTest are failing with:

System.TypeInitializationException
The type initializer for 'Moq.Mock1' threw an exception.
at Moq.Mock
1.b__0() in Mock.Generic.cs: line 138
at Moq.PexProtector.Invoke(Action action) in PexProtector.cs: line 56
at Moq.Mock1.InitializeInstance() in Mock.Generic.cs: line 136
at Moq.Mock
1.OnGetObject() in Mock.Generic.cs: line 153
at Moq.Mock.GetObject() in Mock.cs: line 152
at Moq.Mock.get_Object() in Mock.cs: line 147
at Moq.Mock1.get_Object() in Mock.Generic.cs: line 131
at Moq.Tests.AsInterfaceFixture.GetMockFromNonAddedInterfaceThrows() in AsInterfaceFixture.cs: line 120
System.TypeInitializationException
The type initializer for 'Moq.Proxy.CastleProxyFactory' threw an exception.
at Moq.Proxy.CastleProxyFactory..ctor()
at Moq.Mock
1..cctor() in Mock.Generic.cs: line 54
System.IO.FileLoadException
Could not load file or assembly 'Castle.Core, Version=2.5.0.0, Culture=neutral, PublicKeyToken=407dd0808d44fbdc' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
at Moq.Proxy.CastleProxyFactory..cctor()

Obviously I miss something here ... any hints?

@MatKubicki

I've added pull request #68 that fixes this problem, i've used the code asmus attached as test for the fix.

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