On 03/12/2014 04:57 PM, Eli Mesika wrote:

----- Original Message -----
From: "David Caro" <dcaro...@redhat.com>
To: "Itamar Heim" <ih...@redhat.com>
Cc: "Maor Lipchuk" <mlipc...@redhat.com>, users@ovirt.org, "Tomasz Kołek" 
<tomasz-ko...@o2.pl>, "infra"
Sent: Wednesday, March 12, 2014 11:01:21 AM
Subject: Re: [Users] [GSOC][Gerrit] add potential reviewers - questions

On Wed 12 Mar 2014 08:16:02 AM CET, Itamar Heim wrote:
On 03/11/2014 10:08 PM, Maor Lipchuk wrote:
On 03/11/2014 05:20 PM, Itamar Heim wrote:
On 03/11/2014 05:14 PM, Eyal Edri wrote:

----- Original Message -----
From: "Itamar Heim" <ih...@redhat.com>
To: "Eyal Edri" <ee...@redhat.com>, "Tomasz Kołek"
<tomasz-ko...@o2.pl>, users@ovirt.org, "infra" <in...@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
allow to add potential reviewers in gerrit.
Let's assume that we've got special flags for this operations.
1. In gerrit system we need to add special place for potential
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
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

reviewers = set()

for modified_file in commit.files:
        reviewers += set(commit.author for commit in

return reviewers

This gives a system that those who touche a file, become the
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

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?

Maybe it will be worth to use the information we have in Bugzilla here:

We can browse the BZ that were closed/verified in the last XXX days
Per BZ , we know which patches are involved, who reviewed the patches, which 
files were changed, when files were changed and the rank of the change (number 
of lines changed)
I believe that from this information we can compose a simple ranking algorithm 
that its output will be a list of N potential reviewers for the patch.
Since we can aggregate the above information for all files related to the patch 
we want to add reviewers, we can have this set for the whole patch.
This information should be processed and stored each N days and gerrit will be 
able to use it.

why are we trying to invent hueristics, instead of declaring clear ownership?

Users mailing list

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

yes, but considering our project layout, i don't see an alternative.
(some of the layout could be improved to be path based, rather than file
I think it could be done automatically by analysing the file and see who
mostly changed it recently, since the "owner" of the file might be
dynamic, who ever changed most of it few days ago might be more familiar
with it today

IMO the algorithm of adding the reviewers should be flexible.
For example, using a folder which will contain files, where each file
implement an algorithm to add the reviewers.

for instance we can have two files:
1. Add a reviewers by blame - the contributor which changed recently the
code lines
2. Add a reviewers by file - the contributor who changed most of the
file recently.

Each file will implement the functional operation and will output the
reviewers emails.

The user can then add a new algorithm or change it to be more specific
to its project.
for example the user can add also the maintainers which acked the patch
that was blamed.
Users mailing list

this shouldn't be automatic. we need to clearly define ownership. we can't
this per repo for the engine/vdsm. we can do this per repo for the other
repo's probably (though solving the folder/file approach would cover the
simpler repos as a private case).

yes, it will require some work, maybe some moving around of files to make
easier by folders (topics) which should be relevant anyway.

I think it would easier to maintain if we just have one file at the
root, instead of having the ownership information distributed
throughout the files/directories. That way you'll know where to look at
to check/modify the ownership as opposed to having to walk all the
files and upper directories.

Also, adding all that ownership logic to gerrit might not be easy, as
it's not meant to go checking the source of the repositories looking
for configuration. We might want to take a look (again) to zuul, the
tool that openstack uses as gateway to trigger jenkins jobs and merge

Infra mailing list

David Caro

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

Email: dc...@redhat.com
Web: www.redhat.com
RHT Global #: 82-62605

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