Prevent memory from being changed while it's in use

[Frinavale]

I have a problem and I don't know why I'm having such a hard time solving it.

The problem comes from a VB6 COM object that raises an event periodically. The call back method for the event (the method that handles the event) has a strange signature. It looks like this:

onTheEvent(ByRef x As AStructureType, ByRef y As Boolean)

I need to retrieve the information stored in "x" but sometimes the next event is raised before I can retrieve this information. Since it's being passed in ByRef the underlying memory for the structure is changed and ...well...things get really messed up.

How do I prevent the memory from being changed by the COM object (lock it) while I am using that memory?

(PS...if you haven't already gathered, it's a Structure, not an Object that I'm working with)

Thanks,

-Frinny

[Frinavale]

I've been trying to find information on how to copy the structure so that I'm not always pointing to the same memory location.......I am not having any luck with this though.

The data is changed if I try a member-by-member copy in my .NET code....which means the copy will not work.

*Frustrated!*

-Frinny

[Plater]

Yeah generally I would say the first thing you should do is copy the struct data to a local variable.
However you go about doing that. (Is it as simple as declaring a new var and using the = operator?)

[Frinavale]

It would be as simple as declaring a new assignment operator except that I don't have access to the code where it should be implemented (the VB6 code).

[Plater]

Ok so the event and its handler are all raised INSIDE the COM object then?

[Frinavale]

The event is raised by the COM object.

My code handles the event that is raised but it is passed a variable ByRef. This means that the next time the event happens the memory is changed even though I'm in the midst of using it.

I tried using reflection to copy the Structure but I found it was too slow, the next event was raised before it could complete (when you first start receiving events a Whole bunch of them are sent to you extremely quickly).

I changed my code so that it didn't use reflection and things have been working without incident so far (on my development machine)...not sure how it will fair on a faster, better machine.

-Frinny

[Plater]

Right, thats what i thought the handler is in your managed code.
So couldn't you copy the value in the handler?
Just like when working with threads, make a local copy imediately?