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[.net] Finalize() and Dispose()

Started by iliak May 2, 2010 at 3:25 AM 3 replies 1.6k views

Original Post

May 2, 2010 at 3:25 AM

I my framework, to be sure to call Dispose() on my classes, I do the following :

public class Foo : IDisposable
{
	public Foo()
	{
		GL.GenBuffers(1, out Handle);
	}

	public ~Foo()
	{
		if (Handle != -1)
			throw new Exception("Handle != -1, Call Dispose() !!");
	}
	
	public void Dispose()
	{
		GL.DeleteBuffers(1, ref Handle);
		Handle = -1;

		GC.SuppressFinalize(this);
	}
	
	int Handle;
}

Am I right using this method (be sure Dispose() is called) ?

Rattenhirn

May 2, 2010 at 5:11 AM

"GC.SuppressFinalize(this);" prevents the GC from calling the finalizer, so the "if" shouldn't even be needed. However, I'm not sure how useful throwing an exception in the finalizer is...

The better way to handle this is to simply call "Dispose" in the finalizer, as suggested in the docs of IDisposable.

Calling "Dispose" manually should never be mandatory, just an optimization.

iliak

May 2, 2010 at 6:23 AM

Not in my case (OpenGL) as the GL context is invalid when calling Finalize()/Destructor.

Rattenhirn

May 2, 2010 at 7:39 AM

Quote:
Original post by iliak
Not in my case (OpenGL) as the GL context is invalid when calling Finalize()/Destructor.

I see. In that case I suggest the following:
Since those GL buffers are created and destroyed via the GL class, it knows how many of them exist. As soon as the GL context is about to be invalidated, check if there are any leftover buffers and throw an exception in this case.

As an extension, you could also save the callstack of each GL.GenBuffers with the created buffer (at least in debug mode), in order to provide the user very useful info where the resource leaks have originated.

Again, do not use the .net finalizers for error reporting, or really, for anything. Here's an article about that topic, I'm sure there are many more.

vermilion_wizard

May 3, 2010 at 12:04 AM

In your finalizer, you should store the handle ID in an external list and then check that list periodically and release the buffers in that list. Or if you want to throw an exception for an unreleased resource, you should do it there instead of the finalizer thread.

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