Re: [PATCH v3] set-head: no update without change and better output for --auto

["Bence Ferdinandy" <bence@ferdinandy.com>]

On Mon Sep 16, 2024 at 20:36, Junio C Hamano <gitster@pobox.com> wrote:

[snip]

>  - This is inherently racy, isn't it?  We read the _current_ value.
>    After we do so, but before we write _our_ value, another process
>    may update it, so we'd end up overwriting the value they wrote.

So I've been thinking my first patch need not be so ambitious. The current
behaviour is to indiscriminately overwrite remote/HEAD. So what if we dial this
back a bit, leave the indiscriminate overwrite in place (the added benefit of
that is pretty small anyway) and only improve the printed output, which was the
main goal anyway? 

This is still slightly racy, since between the read and the write the status of
remote/HEAD could still change potentially, so the information received by the
user may be _slightly_ off, as we may be printing that the command just created
remote/HEAD when it was actually created a split millisecond earlier by another
command, but the printed end result will be always correct. And since the
output is aimed at humans really, I'd say even if some other process did create
that remote/HEAD between read and write, it's still actually true that before
running set-head it did not exist and now it does and is set to X.

In short: any raciness left should not have practical implications if we always
actually write remote/HEAD.

What do you think?

Best,
Bence

-- 
bence.ferdinandy.com