Check Value of .NET Handle ^

Question

Here's my situation:

I have .NET wrapper-objects in a C++/CLI layer that hold pointers to unmanaged C++ objects. I've implemented the finalizer so that it deletes the unmanaged memory pointed to by the wrapper-object on garbage-collection and sets the pointer to null.

Here's the problem:

I'm watching the finalizer for the .NET wrapper-object and it gets called twice and tries to delete the same memory twice, indicating that I have somehow created 2 .NET wrapper objects that go out-of-scope, and are garbage collected while I'm still expecting the wrapper object to be in scope (these wrapper objects are getting passed to a VB.NET application).

Here's my question:

Is there anyway for me to check the handle value so that I can confirm where the wrapper objects are getting created (copied or whatever)? Currently I'm looking at the handle values (EG - 0x0014fe80), but I see 3 different values for when the object is created, added to a collection, and deleted. So I'm not sure if the GC is just moving stuff around and this is the same object, or if I'm actually seeing 3 different objects that reference the same unmanaged memory. I would like to resolve the duplicate object copies if possible, but I understand that I will probably want to implement some sort of smart pointer so that this doesn't happen.

Thanks, Ian

Answer 1

Take a look at this question
Here is an implementation of a scoped_ptr that is noncopyable and has an auto-release mechanism for unmanaged objects, by @Ben Voigt

Answer 2

Yeah, I ended up modifying an auto_ptr class to be a shared pointer to ensure that the unmanaged memory is only deleted once through the smart pointer finalizer. I'm assuming I did something similar to all the other implementations; I created a static dictionary in the auto_ptr template class, using the native pointer value as the key, that is checked every time the finalizer is called to update the count of each item, or delete the memory.