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

[Ewoud Kohl van Wijngaarden]

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?