unofficial mirror of guile-user@gnu.org 
 help / color / mirror / Atom feed
From: Olivier Dion via General Guile related discussions <guile-user@gnu.org>
To: Chris Vine <vine24683579@gmail.com>, guile-user@gnu.org
Subject: Re: Question about an error with ports
Date: Fri, 11 Mar 2022 09:58:59 -0500	[thread overview]
Message-ID: <87czisbkng.fsf@laura> (raw)
In-Reply-To: <20220311120500.ad94ea6ad79068dc1f8ff85d@gmail.com>

On Fri, 11 Mar 2022, Chris Vine <vine24683579@gmail.com> wrote:
> On Thu, 10 Mar 2022 18:46:34 -0500
> Olivier Dion via General Guile related discussions <guile-user@gnu.org>
> wrote:
>> On Thu, 10 Mar 2022, Zelphir Kaltstahl <zelphirkaltstahl@posteo.de> wrote:
>> 
>> > Just one question: Why is get-bytevector-some better than
>> > get-bytevector-n and specifying a number of bytes?
>> 
>> I haven't check the implementation details, but I think it's just a
>> question of buffering.  `get-bytevector-n` will block just like
>> `get-bytevector-some` when the port is empty.  The former will return up
>> to N bytes and the latter might return more than N bytes.  The former
>> probably also lead to less memory allocation since N is known in
>> advanced, a singled allocation can be made, while the latter might do
>> multiple allocations.  This can be useful depending on your usage of the
>> port.  For example, you could make a web server that only accepts HTTP
>> body up to 4096 bytes (1 system page).  This is what some web server
>> does I think.
>> 
>> There's also `get-bytevector-all`, but this would lead to more memory
>> usage and multiple allocations.  Again, it depends on the usage.
>
> Avoid using get-bytevector-n!, get-bytevector-some and
> get-bytevector-all if you are going to use something like fibers or
> some other asynchronous i/o, as those procedures are not suspendable
> (they can block).  get-bytevector-n (note the difference from
> get-bytevector-n!) and get-string-all are suspendable and should
> generally be preferred where suspension is required.

I'm not sure this is related to the functions themself but instead the
underlying filedescriptor opened iwth ON_NONBLOCK?

-- 
Olivier Dion
Polymtl



  reply	other threads:[~2022-03-11 14:58 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-10  1:26 Question about an error with ports Zelphir Kaltstahl
2022-03-10 15:05 ` Olivier Dion via General Guile related discussions
2022-03-10 22:32   ` Zelphir Kaltstahl
2022-03-10 23:46     ` Olivier Dion via General Guile related discussions
2022-03-11 12:05       ` Chris Vine
2022-03-11 14:58         ` Olivier Dion via General Guile related discussions [this message]
2022-03-11 17:26           ` Chris Vine
2022-03-11 17:47             ` Olivier Dion via General Guile related discussions
2022-03-11 18:13             ` Chris Vine
2022-03-11 19:48               ` Maxime Devos
2022-03-11 19:49               ` Maxime Devos
2022-03-12  0:10                 ` Chris Vine
2022-03-12  0:27                   ` Chris Vine
2022-03-11 12:11       ` Maxime Devos
2022-03-11 15:06         ` Olivier Dion via General Guile related discussions

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: https://www.gnu.org/software/guile/

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87czisbkng.fsf@laura \
    --to=guile-user@gnu.org \
    --cc=olivier.dion@polymtl.ca \
    --cc=vine24683579@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).