Re: [RFC] bisect: Introduce skip-when to automatically skip commits

From: Phillip Wood <phillip.wood123@gmail.com>
Date: Apr 6, 2024, 13:50 UTC
Message-ID: <4bedcad2-218a-4b16-88a7-cc70cc126af3@gmail.com>
In-Reply-To: <b194ba7c-454b-494f-bef2-e9eac7ca87f1@schinagl.nl>

Hi Olliver

On 06/04/2024 11:06, Olliver Schinagl wrote:

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> On 06-04-2024 03:08, Junio C Hamano wrote:
>> Olliver Schinagl <oliver@schinagl.nl> writes:
>>
>>> Hey all,
>>>
>>> I've also got my work on a branch in my repo, if that helps to look at
>>> things, https://gitlab.com/olliver/git/-/tree/skip_bisect
>>>
>>> Also included is a script to be used as an example. I opted to use
>>> `git show`, which is nice because it works both on commits, but also
>>> on notes.
>>>
>>> Anyway, any thoughts on the bellow before I send the full series?
>>>
>>> Olliver
>>
>> I would not write get_skip_when() before studying the same file to
>> see if there already is a helper to read the whole file used in the
>> vicinity (like strbuf_read_file(), perhaps).
> 
> Fair enough. I'm a little worried about optimization vs readability. I 
> think it makes it mre clear what the code does in its current form; but 
> I'll investigate. Bisecting shouldn't be a computational often happening 
> thing, so I'm not to worried about performance. But I'm not too familiar 
> with the git code base, so I don't know either :p

If you search builtin/bisect.c you'll see some existing callers of strbuf_read_file() that read other files like BISECT_START. Those callers should give you an idea of how to use it.

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>>
>> I do not have enough concentration to follow changes to
>> bisect_auto_next() is reasonable.  Especially I do not know why
>> "bisect-skip_when" wants to exist and what it is trying to do,
>> besides the fact that its name looks horrible ;-).
>>
> naming things, sure. I can look into this absolutly :)

For me it's not just the name but the whole hook thing - do we really need that rather than just the command line option?

The other thing I wondered about is the exit code handling for the "--skip-when" script. In Junio's example in an earlier message he used a successful exit to mean "skip this commit" and an unsuccessful exit to mean "test this commit". To me that matches the name of the option - we skip when the script given to "--skip-when" is successful. Copying the mechanism used by "git bisect run" seems a bit cumbersome as we only need to know whether to skip or not, we don't need a special way of distinguishing "skip this commit" from "this commit is good" and "this commit is bad"

Best Wishes

Phillip

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> But in short, bisect_auto_next was returning just after checkout It 
> seemed. So after checkout, running the script seemed sensible. But I 
> look at it as a normal git user. So you checkout, test your commit, skip 
> to the next one if applicable.
> 
> 
> I'll think of your two comments, and see if I can address them as you 
> regain your concentration :p
> 
> But seeing that these are your main concerns, I'm more confident I'm not 
> completly on the wrong path here.
> 
> Olliver
>