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From: ludovic.courtes@inria.fr (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: RPC performance
Date: Fri, 23 Jun 2017 11:24:50 +0200
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In-Reply-To: <cuc7f03kr3w.fsf@igalia.com> (Andy Wingo's message of "Fri, 23
	Jun 2017 11:09:23 +0200")
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To: Andy Wingo <wingo@igalia.com>
Cc: guix-devel@gnu.org

Hi Andy,

Andy Wingo <wingo@igalia.com> skribis:

> On Thu 22 Jun 2017 18:05, ludovic.courtes@inria.fr (Ludovic Court=C3=A8s)=
 writes:
>
>> Andy Wingo <wingo@igalia.com> skribis:
>>
>>> Why not just set to _IOFBF and let Guile 2.2's buffering handle it?
>>
>> Because we want controlled buffering when writing (we need to flush
>> pending output when we=E2=80=99re done writing the RPC request), and no
>> buffering at all when reading.
>
> For controlling output buffering, there is the setvbuf buffer size, and
> "force-output".  In Guile 2.2 the CBOP's "write" function is really a
> "flush" function -- it only gets called when the internal buffer is
> filled, or when flush-output is called, or (for line-buffered ports)
> when a newline is written.
>
> Why do you not want buffering when reading?  Do you need to hand off
> this FD to some other process?

With the current protocol, often we=E2=80=99re just reading a handful of by=
tes.
Full buffering would mean that Guile would block on an 8K read or so
that will never be fulfilled.

Ludo=E2=80=99.