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Re: GH replacement proposal (includes a bit of Unicode)
From: |
Rob Browning |
Subject: |
Re: GH replacement proposal (includes a bit of Unicode) |
Date: |
Wed, 21 Apr 2004 23:39:00 -0500 |
User-agent: |
Gnus/5.1006 (Gnus v5.10.6) Emacs/21.3 (gnu/linux) |
Marius Vollmer <address@hidden> writes:
> Hi,
>
> I have a partial proposal for making type conversions between Scheme
> and C easier.
Overall, I like it, and most of the comments I thought of have already
been covered by Paul, Dirk, and others.
> These two functions lock and unlock all SCM objects (the heap). The
> heap should not be locked for long periods of time and no calls to
> 'normal' libguile functions are allowed while it is locked. A
> function is 'normal' unless it is specifically documented to be
> useable with a locked heap. (Indeed, most 'unnormal' functions can
> _only_ be used while the heap is locked.)
>
> You can not lock the heap twice. Calling scm_lock_heap while the
> heap is already locked results in undefined behavior. Likewise,
> calling scm_unlock_heap when the heap is not locked is verboten.
>
> - const unsigned char *scm_l_get_utf8_string_mem (SCM str);
I'm a little wary of the locking, especially global locking, but I
suppose it may well be necessary. I don't have a strong feeling
either way offhand, but presuming for the moment that it is necessary,
then is there any way to lock down a particular value rather than the
entire heap? Also, could and should we make it easy to install a
frame unwind handler that unlocks the heap when acquiring the lock?
Finally, what's the argument against allowing recursive locking by the
same thread, too expensive?
On a related note, in many cases, I suspect all the user may really
need is a cheap way to copy some offset + size chunk of the data into
their own buffer, especially when dealing with homogeneous uint8
arrays. If so, then it might make sense to provide a set of functions
that can do that, handling whatever locking and memcpying is needed.
--
Rob Browning
rlb @defaultvalue.org and @debian.org; previously @cs.utexas.edu
GPG starting 2002-11-03 = 14DD 432F AE39 534D B592 F9A0 25C8 D377 8C7E 73A4
- Re: GH replacement proposal (includes a bit of Unicode), (continued)
- Re: GH replacement proposal (includes a bit of Unicode), Dirk Herrmann, 2004/04/22
- Re: GH replacement proposal (includes a bit of Unicode), Dirk Herrmann, 2004/04/24
- Re: GH replacement proposal (includes a bit of Unicode), Marius Vollmer, 2004/04/24
- Re: GH replacement proposal (includes a bit of Unicode), Dirk Herrmann, 2004/04/25
- Re: GH replacement proposal (includes a bit of Unicode), Paul Jarc, 2004/04/25
Re: GH replacement proposal (includes a bit of Unicode), Dirk Herrmann, 2004/04/17
Re: GH replacement proposal (includes a bit of Unicode),
Rob Browning <=