From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Ken Raeburn <raeburn@raeburn.org>
Cc: Tom Tromey <tromey@redhat.com>,
Emacs development discussions <emacs-devel@gnu.org>
Subject: Re: advice needed for multi-threading patch
Date: Wed, 26 Aug 2009 23:12:55 -0400 [thread overview]
Message-ID: <jwvr5uy551b.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <9DE0B828-815B-45DA-BD2B-0AB4DAD59CE2@raeburn.org> (Ken Raeburn's message of "Wed, 26 Aug 2009 14:50:36 -0400")
> Oh, right... I meant to ask you at some point if there was a reason for that
> other than streamlining performance a little.
It has nothing to do with performance, and everything to do with code
cleanliness and robustness. Using Lisp_Symbol* rather than Lisp_Object
makes it clear (both to the reader and to the type-checker) that the
object received (or returned) can only be a symbol.
> Now, with the GC work in progress, it's possible that during conservative
> stack scanning, the pointer to the big structure might be enough to cause
> it to not get freed up; I'm not that familiar with the new code. But the
> conservative approach seems to be to keep the SCM (Lisp_Object) values live
> as long as the pointed-to data is needed.
Emacs's stack scanning already has to check both Lisp_Object values
(i.e. tagged pointers) and plain direct untagged pointers. This was
needed IIRC because even if the C code appears to hold on to
a Lisp_Object value, the optimizer may get rid of it and only keep the
untagged pointer.
So, I think Guile's stack scanning will have to do that as well, I think
(regardless of Emacs integration).
> However, there's also the little matter that eventually I want to make Emacs
> use Guile symbols for its own symbols, for better interaction between the
> languages. That means that "struct Lisp_Symbol" would go away. If it's
> part of the internal function interfaces, that means the Guile work has to
> have greater divergence from the upstream code.
We'll cross that bridge when we get there. I think we'll find that the
particular interface used by the function will be a very minor issue
(the whole function will probably need to be rewritten).
Stefan
next prev parent reply other threads:[~2009-08-27 3:12 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-26 4:38 advice needed for multi-threading patch Tom Tromey
2009-08-26 7:06 ` Ken Raeburn
2009-08-26 14:52 ` Stefan Monnier
2009-08-26 18:50 ` Ken Raeburn
2009-08-27 3:12 ` Stefan Monnier [this message]
2009-08-27 6:28 ` Ken Raeburn
2009-08-27 17:02 ` Stefan Monnier
2009-08-26 16:08 ` Tom Tromey
2009-08-26 18:50 ` Ken Raeburn
2009-08-27 5:07 ` Miles Bader
2009-08-27 6:39 ` Ken Raeburn
2009-08-27 6:50 ` Miles Bader
2009-08-28 20:48 ` Juri Linkov
2009-08-28 22:15 ` Miles Bader
2009-08-28 23:27 ` Juri Linkov
2009-08-28 23:54 ` Miles Bader
2009-08-29 20:21 ` Richard Stallman
2009-08-26 15:02 ` Stefan Monnier
2009-08-26 15:31 ` Tom Tromey
2009-08-26 19:18 ` Stefan Monnier
2009-09-18 22:59 ` Tom Tromey
2009-09-19 0:09 ` Stephen J. Turnbull
2009-09-19 0:32 ` Chong Yidong
2009-09-21 21:19 ` Stefan Monnier
2009-09-21 21:50 ` Tom Tromey
2009-09-22 14:24 ` Stefan Monnier
2009-09-22 23:59 ` Ken Raeburn
2009-09-23 3:11 ` Stefan Monnier
2009-09-23 15:53 ` Chong Yidong
2009-09-23 3:16 ` Tom Tromey
2009-09-24 17:25 ` Stefan Monnier
2009-09-24 17:57 ` Tom Tromey
2009-09-27 20:59 ` Tom Tromey
2009-09-27 23:05 ` Stefan Monnier
2009-09-28 4:27 ` Tom Tromey
2009-09-29 0:27 ` Stefan Monnier
2009-09-29 2:26 ` Ken Raeburn
2009-09-29 3:20 ` Stefan Monnier
2009-09-29 3:57 ` Ken Raeburn
2009-09-29 3:33 ` Tom Tromey
2009-09-29 4:07 ` Ken Raeburn
2009-09-29 2:30 ` Tom Tromey
2009-09-23 18:43 ` Giuseppe Scrivano
2009-09-24 17:29 ` Stefan Monnier
2009-09-24 18:53 ` Giuseppe Scrivano
2009-09-24 20:04 ` Tom Tromey
2009-09-24 21:59 ` Stefan Monnier
2009-09-24 22:23 ` Giuseppe Scrivano
2009-09-24 22:47 ` Ken Raeburn
2009-09-28 14:52 ` Ted Zlatanov
2009-10-05 6:02 ` joakim
2009-09-28 7:44 ` Lynbech Christian
2009-08-29 0:28 ` Giuseppe Scrivano
2009-08-29 4:57 ` Tom Tromey
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