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(ByRe f 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...thing s 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?