[Users] [GSOC][Gerrit] add potential reviewers - questions

[David Caro]

On Tue 11 Mar 2014 04:14:26 PM CET, Eyal Edri wrote:
>
>
> ----- Original Message -----
>> From: "Itamar Heim" <iheim at redhat.com>
>> To: "Eyal Edri" <eedri at redhat.com>, "Tomasz Kołek" <tomasz-kolek at o2.pl>, users at ovirt.org, "infra" <infra at ovirt.org>
>> Sent: Tuesday, March 11, 2014 5:10:54 PM
>> Subject: Re: [Users] [GSOC][Gerrit] add potential reviewers - questions
>>
>> On 03/11/2014 05:06 PM, Ewoud Kohl van Wijngaarden wrote:
>>> On Tue, Mar 11, 2014 at 10:37:22AM -0400, Eyal Edri wrote:
>>>>> Tomasz Kołek wrote:
>>>>>
>>>>> I've got a few questions about project description.
>>>>> Please tell me if my problem's understanding is good or not.
>>>>> We need to add a few flags/methods to git review module. This flags
>>>>> should
>>>>> allow to add potential reviewers in gerrit.
>>>>> So:
>>>>> Let's assume that we've got special flags for this operations. What's
>>>>> next?
>>>>> 1. In gerrit system we need to add special place for potential reviewers?
>>>>> 2. Potential reviewers should agree that they want to review?
>>>>> 3. We can have more than one accepted reviewer?
>>>>
>>>> I'm not sure i understood exactly what you mean by 'potential
>>>> reviewers'.  do want gerrit (hook?) to automatically add reviewers to
>>>> a patch according to the code sent?  so in fact you'll have a place
>>>> somewhere for mapping code & specific developers?
>>>
>>> I really like this idea. Gerrit currently requires new users to know who
>>> to add as reviewers, IMHO impeding new contributors.
>>>
>>> One relative simple solution would be to look at who recently touched
>>> the files that are being modified and add them as reviewers. This can be
>>> done by looking at the git log for a file. Some pseudo python code
>>> solution:
>>>
>>> reviewers = set()
>>>
>>> for modified_file in commit.files:
>>>      reviewers += set(commit.author for commit in git.log(modified_file))
>>>
>>> return reviewers
>>>
>>> This gives a system that those who touche a file, become the maintainer
>>> for that file. A more complex solution could improve on that and limit
>>> the reviewers added per patch. One can think of limiting to only
>>> contributions in the last X months, weigh contributions so common
>>> committers are prefered. It could also combine several methods.
>>>
>>> For example to limit to the 5 authors who touched the most files:
>>>
>>> reviewers = collections.Counter()  # New in python 2.7
>>>
>>> for modified_file in commit.files:
>>>      reviewers += collections.Counter(commit.author for commit in
>>>      git.log(modified_file))
>>>
>>> return [author for author, count in reviewers.most_common(5)]
>>>
>>> Since Counter also accepts a dictionary, one could also weigh the
>>> touched lines per file. Downside there is big whitespace/formatting
>>> patches can skew the line count.
>>>
>>> In short, I think an entire thesis could be written on the optimal way
>>> to determine reviewers but a simple algorithm could do to show the
>>> method works.
>>>
>>> Does this help?
>>> _______________________________________________
>>> Users mailing list
>>> Users at ovirt.org
>>> http://lists.ovirt.org/mailman/listinfo/users
>>>
>>
>> I think if we do this, we want to make sure we cover per file who is
>> required to +2 it before we consider it acked.
>>
>
> won't it require maintaining static lists of people per file/path/project?
> _______________________________________________
> Infra mailing list
> Infra at ovirt.org
> http://lists.ovirt.org/mailman/listinfo/infra

We already discussed that, in the project, and one of the solutions 
proposed was to add metadata on each file/directory about the 
maintainers for that file/directory. For what I've seen in other 
projects (mainly openstack), they do that per repository, and not per 
file, that simplifies the maintainers selection greatly (having it on 
gerrit config so you don't have to check the code to decide who has 
merge rights).

But that might be another subject.

About dynamically adding reviewers, it should be fairly easy to do 
using a small gerrit hook to run on patch-submitted. But gerrit will 
fail if the user is not already created in gerrit so not really 
allowing non-registered users to get in. But I'm not sure if it's 
'polite' to add someone as a reviewer if he did not previously agreed 
to it, specially when emails will be sent to him.

And as Ewoud says, selecting which commiters are considered possible 
reviewers gives enough talk for a thesis by itself.

--
David Caro

Red Hat S.L.
Continuous Integration Engineer - EMEA ENG Virtualization R&D

Email: dcaro at redhat.com
Web: www.redhat.com
RHT Global #: 82-62605

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