[Mono-list] pthreads in mono
jestin.stoffel at gmail.com
Fri Mar 28 12:15:46 EDT 2008
On Fri, 2008-03-28 at 11:42 -0400, Chris Howie wrote:
> 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.
The only code I found that uses the gps_set_callback function is in
libgpsmm.cpp, which is part of the gpsd source. Here's how it's used:
handler = new pthread_t;
where handler is declared
Unless I am mistaken, it is the caller's responsibility to create the
pthread_t structure before setting the callback.
Anyways, I went ahead and worked around this issue, and I think my new
solution is better for a few other reasons. Thanks to everyone who
looked into this for me.
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