On Tue, Oct 21, 2008 at 1:24 PM, Chun Tian (binghe) binghe.lisp@gmail.com wrote:

...

Hi, usocket-devel

(testing 0.4 branch)

In LispWorks Professional and Enterprise Edition, user can save a image without thread support. When such a lispworks image started, all function in MP package is there but no thread running:

  binghe@binghe-debian:~$ lispworks-cli
  LispWorks(R): The Common Lisp Programming Environment
  Copyright (C) 1987-2008 LispWorks Ltd.  All rights reserved.
  Version 5.1.1
  Saved by binghe as lispworks-5-1-1-64-bit-cli, at 12 Jun 2008  

14:50 User binghe on binghe-debian.local

  CL-USER 1 > (mp:list-all-processes)
  NIL

  CL-USER 3 > mp:*current-process*
  NIL

When there's no thread support in LispWorks, USOCKET:WAIT-FOR-INPUT cannot be used (on non-win32 platform) because it calls MP:PROCESS- WAIT on current thread, that will cause a UNKNOWN-ERROR:

Nice catch!

...

USOCKET 9 > (wait-for-input x)

Error: The condition #<UNKNOWN-ERROR 405008A5B0> occurred 1 (abort) Return to level 0. 2 Restart top-level loop.

Type :b for backtrace, :c <option number> to proceed, or :? for other options

USOCKET 10 : 1 > :b Call to ERROR Call to RAISE-USOCK-ERR Call to SIGNAL Call to ERROR Call to MP::WITHOUT-PREEMPTION-ERROR Call to MP:PROCESS-WAIT Call to WAIT-FOR-INPUT-INTERNAL Call to WAIT-FOR-INPUT Call to WAIT-FOR-INPUT Call to EVAL

I think may be there're some way not use MP-related function to achieve the same effect, i.e. direct call select() or turn to use LispWorks' SYS:WAIT-FOR-INPUT-STREAMS [1] instead (which works on all platform include win32 but just for stream usocket).

Well, that would severely limit the usability of WAIT-FOR-INPUT, because it wouldn't be usable with listening sockets or udp sockets.

Could we just error out when someone tries to use WAIT-FOR-INPUT without MP support? I mean... Are there any problems with requiring the apps be built with mp support? (licensing from LW, for example)

Yes, I think just limit the use of WAIT-FOR-INPUT on "LispWorks with MP enabled" is OK, but following things should be done:

* When usocket is loading on LispWorks without MP enabled, a warn should be output. I found a piece of code in GBBopen's portable- threads.lisp, may help:

;;; --------------------------------------------------------------------------- ;;; Warn if multiprocessing is not running on Lispworks

#+lispworks (defun check-for-multiprocessing-started (&optional errorp) (unless mp:*current-process* (funcall (if errorp 'error 'warn) "You must start multiprocessing on Lispworks by calling~ ~%~3t(~s)~ ~%for ~s, locks, and other thread operations to function ~ properly." 'initialize-multiprocessing 'with-timeout)))

#+lispworks (check-for-multiprocessing-started)

* When WAIT-FOR-INPUT is called on LispWorks without MP enabled, a better error should be signaled to tell user the MP should be enabled.

If you agree, I'll try to commit some code according to above two points.

--binghe