Re: Threading

[Richard Frith-Macdonald]

On Sunday, July 1, 2001, at 06:10 AM, Philip Knodle wrote:

> Is it possible to mix C/pthreads and objc/NSThread code in a project?  
> I've
> been looking at the code, and it looks like it is not possible.  I 
> guess my
> real question is *should* it be possible?

It is possible...

> Let me be a bit clearer.  It is possible to have C/pthread all by 
> itself in
> a project.  However, when the C code calls objective C code, the program
> will seg fault.  The objective C code has a some thread private 
> variables that
> are not initialized
>
> Does OPENStep say anything about this?  My main concern is that if the
> threading semantics of GNUStep change, then programs that work on 
> GNUStep
> won't work on other implementation.  This may be a a bad thing.

I doubt that the OpenStep spec says anything about it, but my 
recollection
is that answers from NeXT used to be that it was a bad idea to try to mix
threads.
The standard API does not provide any mechanism for mixing thread models
safely.

The GNUstep base library adds two functions to the API -
GSRegisterCurrentThread() and GSUnregisterCurrentThread()

You can use these from your pthread code before and after
running GNUstep code, and they will set up the appropriate thread
variables for you.

I don't know of any equivalent in MacOS-X, but there is probably a
private API that does the same sort of job - unless it's built in to
their Java bridge directly, and not accessible from anywhere else
(you have to do something of this sort to lets Java threads work
with ObjC threads in GNUstep).