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From: Junio C Hamano <gitster@pobox.com>
To: Eric Sunshine <sunshine@sunshineco.com>
Cc: Fabian Stelzer <fs@gigacodes.de>,
	git@vger.kernel.org, Pedro Martelletto <pedro@yubico.com>,
	Jeff King <peff@peff.net>,
	Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: Re: [PATCH v3] gpg-interface: trim CR from ssh-keygen
Date: Mon, 10 Jan 2022 09:03:20 -0800	[thread overview]
Message-ID: <xmqq8rvn34mf.fsf@gitster.g> (raw)
In-Reply-To: <YdtVrT4gBvnXfNr6@flurp.local> (Eric Sunshine's message of "Sun, 9 Jan 2022 16:37:49 -0500")

Eric Sunshine <sunshine@sunshineco.com> writes:

> of the existing string-splitting functions. For instance, something
> like this:
>
>     struct strbuf **line, **to_free;
>     line = to_free = strbuf_split(&ssh_principals_out, '\n');
>     for (; *line; line++) {
>         strbuf_trim_trailing_newline(*line);
>         if (!(*line)->len)
>             continue;
>         principal = (*line)->buf;
>
> keeping in mind that strbuf_trim_trailing_newline() takes care of
> CR/LF, and with appropriate cleanup at the end of the loop:
>
>         strbuf_list_free(to_free);
>
> (and removal of `FREE_AND_NULL(principal)` which is no longer needed).
>
> Something similar can be done with string_list_split(), as well.

Unless you are writing an interactive text editor, an array of
lines, each of which can individually be manupulated cheaply when
inserting or deleting a span of chars, is a way too ugly and overly
expensive data structure to keep your data in the long haul.  In
short, strbuf_split() was a mistaken piece of API that does not
belong to this project ;-)

The cycles spent by crypto before getting to this point in the code
is expensive enough that the extra cycles to separately scan to
split them into lines and another scan from the end of the each line
to trim may not matter, so I'd stop at saying "I'd rather not to see
the above code" instead of my usual "Please don't", from performance
perspective in this case.

But from code cleanliness perspective, well, let me just say that
this is not Python or Java but a C project.



      parent reply	other threads:[~2022-01-10 17:03 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-03 13:31 [PATCH] gpg-interface: trim CR from ssh-keygen -Y find-principals Johannes Schindelin via GitGitGadget
2021-12-03 14:18 ` Fabian Stelzer
2021-12-03 15:58 ` Jeff King
2021-12-04 13:11   ` Fabian Stelzer
2021-12-05  5:50     ` Junio C Hamano
     [not found]       ` <CABPYr=y+sDDko9zPxQTOM6Tz4E7CafH7hJc6oB1zv7XYA9KH1A@mail.gmail.com>
2021-12-09 16:33         ` Fabian Stelzer
     [not found]           ` <CABPYr=xfotWvTQK9k1eKHa0kP4SsB=TKKuM0d8cpMb5BtuUZLA@mail.gmail.com>
2021-12-09 17:20             ` Fabian Stelzer
2021-12-30 10:25             ` Fabian Stelzer
2021-12-05 23:06     ` Damien Miller
2021-12-06  8:39       ` Fabian Stelzer
2022-01-03  9:53 ` [PATCH v2] gpg-interface: trim CR from ssh-keygen Fabian Stelzer
2022-01-03 17:17   ` Eric Sunshine
2022-01-03 23:34     ` Junio C Hamano
2022-01-04  0:41       ` Eric Sunshine
2022-01-04  1:19         ` Junio C Hamano
2022-01-04  3:06           ` Eric Sunshine
2022-01-04 12:55             ` Fabian Stelzer
2022-01-04 19:33               ` Junio C Hamano
2022-01-05  7:09                 ` Eric Sunshine
2022-01-05 10:36                   ` Fabian Stelzer
2022-01-05 20:40                     ` Junio C Hamano
2022-01-06 10:26                       ` Fabian Stelzer
2022-01-06 17:50                         ` Junio C Hamano
2022-01-09 20:49                     ` Eric Sunshine
2022-01-10 12:28                       ` Fabian Stelzer
2022-01-07  9:07   ` [PATCH v3] " Fabian Stelzer
2022-01-09 21:37     ` Eric Sunshine
2022-01-10 12:59       ` Fabian Stelzer
2022-01-10 17:51         ` Junio C Hamano
2022-01-10 17:03       ` Junio C Hamano [this message]

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