[Mono-list] pthreads in mono

[Chris Howie]

On Fri, Mar 28, 2008 at 8:10 AM, Paolo Molaro <lupus at ximian.com> wrote:
>  The pointer is the one you got with gps_set_callback, so you can just
>  ignore the fact that it is a pthread_t pointer and all this thread that
>  went ballistic on that:
>
>         [DllImport("gps")]
>         static extern int gps_set_callback (IntPtr gps_data, GpsCallback cb, out IntPtr handler);
>
>  ...
>
>         IntPtr handler;
>         IntPtr gps = gps_open ("localhost", "2947");
>         gps_set_callback (gps, mycb, out handler);
>         ...
>
>  lupus

Ah, it *creates* a thread.  That is a detail I missed when reading the manpage.

Note that it's not that simple though.  The signature specifies a
pthread_t*, not a pthead_t**.  It wants a pointer to a structure that
will be filled in, not a pointer to a pointer (as is IntPtr&).  The
code as writted above will certainly corrupt the memory next to the
location that the "handler" local is stored in, unless
sizeof(pthread_t) is <= IntPtr.Size.

So there are a basically two options: declare a struct matching the
pthread_t struct, or create a new byte[] of some size reasonably large
enough to contain a pthread_t and pass that off to the function.

-- 
Chris Howie
http://www.chrishowie.com
http://en.wikipedia.org/wiki/User:Crazycomputers