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c++ -> guile threading

(YES, I read the FAQ, YES, I read the mailing list archives)

I'm writing an application in c++ and I want to use guile as a scripting
language, however, I have a problem.

The server part of this apps is going to serve many users at once.  Users
will be able to upload bits of their own scheme to automate server tasks.
So far so good, but the problem is, what if someone uploads a bit of
infinitly recursive code?  If the server is single threaded, then the
whole thing grinds to a halt.

So my thought is, what if I were to write the server multithreaded, and
start an new thread for each new user?  Scheme code for a user is executed
in his/her own thread, so if they screw up they don't affect other people.

What I would *like* to do is, from my C++ code, create a new thread and be
able to arbitrarily move between guile and C++ (guile calling C functions,
C running guile on various expressions) in that thread, whilst other
threads are ALSO using guile for stuff.

From what I've been able to gather, if I recompile guile with
--enable-threads, then I can use QuickThreads in guile.  Does this mean I
can start quickthread threads in C++ and guile will reconignize them as
such?  However, QT are app-level instead of OS-level threads...  I'm on an
SMP system and would much prefer OS-level threads (i.e. pthreads).  What
is the status on pthreads?  The current stable release (1.3) has some code
hanging around for mit-pthreads but from what I can tell it doesn't
work...  At any rate you can't easily enable it in the makefile.

The other option would be to write a single-threaded app and somehow limit
the amount of time that a user's code can spend in the guile system, but I
don't know how I would go about interrupting and canceling execution like
so...  Perhaps setting and alarm and catching the signal, but is there a
scm_??? function that cause guile to drop everything and return that would
be callable from a signal handler?

           ------------------ Peter Amstutz --------------------
           -------------- -------------
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