Re: [q-lang-users] OpenBSD, threading

[<Dr....@t-...>]

Julian Fondren wrote:
> ;; OpenBSD [...]
> 
> Everything compiles fine expect for
> modules/clib/clib.c
> -- there I had to add an "#include <unistd.h>", since
> something
> apparently failed to define HAVE_UNISTD_H

That's *really* strange. Could you please check the generated config.h 
(in the toplevel directory of the sources), to see if it defines 
HAVE_UNISTD_H?

> (I also get many complaints about including malloc.h
> instead of stdlib.h,
> but nothing seems hurt by this.)

Yes, I noticed this on older (4.x) FreeBSD systems, too. I actually 
think that it's OpenBSD's fault, and since it's harmless I probably 
won't do anything about it.

> ;; threading
> [original source snipped]
> I've already uglified it a bit, trying to figure out
> the problem.  On my
> machine I get the "Got connection from: ..." message
> on a connection,
> and on subsequent connections, but the (thread
> (echo_loop C)) never seems
> to happen.  I know that everything but the threading
> works, because I
> had this server running in exactly this form before I
> started trying to
> make it multithreaded.

Hmm, I tried to run your example, but somehow I can't get it to work, 
the accept call in the server always fails with EINVAL for me. Here's 
the call sequence I used for initializing the server and the client, I 
guess that's correct so far? Maybe I'm missing something obvious?

def S = server 5001
def C = socket AF_INET SOCK_STREAM 0
connect C ("localhost",5001)

Anyway, the problem with your code is that you don't keep the handle for 
the echo_loop thread. You see, the thread will be canceled automatically 
as soon as the thread handle T is garbage collected. Here this happens 
when server_loop FD tail-reduces to itself (the local T variable is not 
used anymore and its value is therefore thrown away). The solution is to 
keep track of the thread handles, either in the server_loop function or 
in echo_loop itself. The latter solution would be something like the 
following:

server_loop FD = printf "Got connection from: %s:%d\n" (H,P) || 
server_loop FD
		   where (C:Int,(H,P)) = accept FD,
		     _ = thread (echo_loop this_thread C);
	       = perror "server(accept)" || server_loop FD otherwise;

echo_loop T FD = printf "(loop %d)\n" FD || echo_loop T FD
		   where MSG = recv FD 0 4096,
		     () = echo FD MSG (bcmp MSG (bytestr ""));
	       = closesocket FD otherwise;

(As you'll notice I changed the second server_loop rule to track down 
the cause of the mysterious accept failures I encountered. Also note 
that you don't have to explicitly cancel this_thread on exit from 
echo_loop, in the second rule for echo_loop, as the thread will be 
terminated anyway when the loop ends.)

Can you try whether this works for you?

Cheers,
Albert

-- 
Dr. Albert Gr"af
Email:  Dr....@t-..., ag...@mu...
WWW:    http://www.musikwissenschaft.uni-mainz.de/~ag