Re: [PATCH v3 2/3] refs: add option core.logAllRefUpdates = always

From: Cornelius Weig <cornelius.weig@tngtech.com>
Date: Jan 31, 2017, 14:00 UTC
Message-ID: <1e341485-6fb6-243a-0b27-4035789a6f2a@tngtech.com>
In-Reply-To: <20170130233702.o6naszpz32juf5gt@sigill.intra.peff.net>

On 01/31/2017 12:37 AM, Jeff King wrote:

Show 15 quoted lines

> On Mon, Jan 30, 2017 at 01:58:10PM -0800, Junio C Hamano wrote:
> 
>>>     When writing the test for git-tag, I realized that the option
>>>     --no-create-reflog to git-tag does not take precedence over
>>>     logAllRefUpdate=always. IOW the setting cannot be overridden on the command
>>>     line. Do you think this is a defect or would it not be desirable to have this
>>>     feature anyway?
>>
>> "--no-create-reflog" should override the configuration set to "true"
>> or "always".  Also "--create-reflog" should override the
>> configuration set to "false".
>>
>> If the problem was inherited from the original code before your
>> change (e.g. you set logAllRefUpdates to true and then did
>> "update-ref --no-create-reflog refs/heads/foo".

I was actually not referring to update-ref, for which the --no-create-reflog option works fine. I was referring to git-tag which also has the --create-reflog option. For git-tag, the current code does not allow to override logAllRefUpdates=always with --no-create-reflog. On the other hand logAllRefUpdates=false is overridden by "git tag --create-reflog". The reason is that the file-backend does allow to force reflog creation, but it does not allow to force reflog non-creation. I have a patch that amends this, but it's not pretty and I don't think it will be useful (see last paragraph).

> I hadn't thought about that. I think "git branch --no-create-reflog" has
> the same problem in the existing code.

You are right, git-branch also ignores --no-create-reflog.

Show 10 quoted lines

> I suspect nobody cares much in practice. Even if you say "don't create a
> reflog now", if you have core.logAllRefUpdates turned on, then it's
> likely that some _other_ operation will create the reflog later
> accidentally (e.g., as soon as you "git checkout foo && git commit",
> you'll get a reflog). I think you're fighting an uphill battle to turn
> logAllRefUpdates on and then try to disable some reflogs selectively.
> 
> So I agree the current behavior is quietly broken, which is not good.
> But I wonder if "--no-create-reflog" is really sane in the first place,
> and whether we might be better off to simply disallow it.

Concerning branches, I fully agree. For git-branch, the "--no-create-reflog" option does not make sense at all and should produce an error.

On the other hand, for tags it may make sense to override logAllRefUpdates=always. As tag updates come exclusively from force-creating the same tag on another revision, a reflog will actually not be created by accident.

Nevertheless, I don't think it is very useful to have the "--no-create-reflog" argument to any of git-branch or git-tag. It only takes effect if a user has configured logAllRefUpdates=always, and he probably has done that for a reason. Given that the overhead from a reflog is minuscule, IMHO no-one will ever bother about "--no-create-reflog".