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Re: Improving CHANGES (or at least making it easier to produce)

From: Johan Corveleyn <jcorvel_at_gmail.com>
Date: Fri, 20 Sep 2013 01:09:34 +0200

On Wed, Sep 11, 2013 at 9:38 PM, Ben Reser <ben_at_reser.org> wrote:
> On 9/1/13 2:42 AM, Johan Corveleyn wrote:
>> That's not really an argument, because that's true whether you do it
>> at commit time or afterwards. You don't save any time (quite the
>> contrary) by postponing it until CHANGES needs to be produced, or
>> until the revision needs to be backported. Except perhaps by having
>> better understanding of which changes matter to users and why, but I'd
>> say that's true for perhaps 5% of CHANGES.
>> Unless you're saying you don't want to put this burden on the
>> committer (right at the point of committing), because that would
>> hinder commits? Then I'd argue that this is just a habit, and once you
>> get used to it, it doesn't really slow you down much (just like we are
>> all used to writing good, concise, high-information-density log
>> messages for our fellow developers). And for those really hard ones,
>> you can always come back to the log message later, and massage the
>> user-facing text (or add it if it's not there).
>> So that would leave the argument of "that's not what we are used to
>> do", and I can accept that (habits matter, and can be hard to change).
>> It's an important argument, but not a technical one.
>> So far, I haven't read a really rational argument against my
>> suggestion. "That's not what log message are for"? Why not?
> I think I already replied giving those reasons which you reply to further on down.
> It essentially comes down to whatever we put in commit messages on trunk won't
> necessarily be accurate when we go to produce a new minor release (as in
> major.minor.patch)
>> Fair enough. I understand you're currently only trying to solve the
>> CHANGES-for-backports problem for the RM, and that's okay.
>> I just want to put this in the larger context of producing user-facing
>> messages for our changes for *all* our releases, minor or major. Think
>> back to all the time spent by several developers while preparing for
>> the 1.8.0 release, sifting through all the log messages since the last
>> release (in batches of 500 commits), trying to extract user-facing
>> information [1]. That's a huge waste of valuable developer-time, IMO.
> If there really is a better solution I'm open to it, I'm just not convinced
> that there is a good solution for trunk -> minor release.
> There are so many problems with automating it that I think it'll take a lot of
> time to sort them all out and for all pracitcal purposes minor releases are
> relatively rare.
> If we start doing them more often then a lot of the problems with automating it
> go away because there's less likelihood that the Changes: line in the commit is
> out of date by the time we do the minor release.
>> I agree, making concurrent commits to CHANGES is a bad idea. Much
>> better to put it in the log message :-).
> Realize I'm not opposed to putting better information in our commit messages to
> help produce the CHANGES later, I just don't think we can automate the
> production in a very useful way.
> I do think we can put a Change: line in, but I still think someone is going to
> have to review all of them for reasons I'll get into below.
>> Ah, but that can be solved perfectly automatically (we do this at my
>> workplace too): it's the perfect use case for 'svn mergeinfo
>> --show-revs eligible'.
>> When you're about to produce CHANGES for 1.9.0, and 1.8.6 is currently
>> the latest 1.8 release, you'll want to process all the revisions
>> produced by
>> svn mergeinfo --show-revs eligible ^/branches/1.9.x ^/tags/1.8.6
> This doesn't completely work, sometimes we make changes that only apply to a
> given branch due to trunk having a completely different fix that can't be
> backported.

Actually, it works perfectly. Note that I requested the eligibles
between the "to-be-released-branch" and the

If you apply rN to ^/branches/1.9.x, that revision will show up in the
above query.

I don't have our script handy, but with some simple operations, it
works fine for collecting the commit messages of:
- revisions applied directly to the new branch
- revisions backported to the branch (and not to the previous tag)
- revisions from the natural history of the branch (and not part of
the previous tag)

>> Okay, but usually the developer who makes such a change knows he's
>> fixing something (on trunk or whatever) that's never been in the hands
>> of users. In that case, of course he doesn't write such a user-facing
>> note in the log message. The entire idea hinges on the fact that a
>> developer usually knows what his change means to users.
> My concern here is that people will forget to put them in when they should. If
> we automate it then there's no chance to catch this.

Okay, but then I say: this can be caught by regular post-commit
review. Similar to how we catch other omissions to the log message.

Occasionally something will be missed, but with good post-commit
review this will be rare. With the current process, with one single
person scanning hundreds of commit messages, there will also be
occasional mistakes / omissions.

>> Also, when working with feature branches, it's clear that commits to
>> the branch are usually not interesting to users. In this case you
>> usually end up with one summary "change", when the branch gets
>> reintegrate (e.g. "Change: add new FSX repository back-end
>> (experimental)", as a result of integrating the fsx branch).
>>> If you look at the 411 Content-Length issue I think any attempt to put the
>>> CHANGES entry in the log files would have been a mess.
>> You'll have to refresh my memory here. But there can be exceptions of
>> course, where it's better to wait a bit for the dust to settle on a
>> particular issue, and then come up with what it means to users. But
>> those are exceptions.
> We went back and forth between several different implementations of the fix.
> With entirely different default behavior.
> The other issue here is how do you remove a CHANGES entry that's no longer
> important? The only way I can see if you put it in commit logs is to go back
> and edit the commit log to remove the Changes: line. But I'm not convinced
> that we will actually do that.

Hm, you may have a point there. With the weekly release cycle at our
company such situations are quite rare. Still, sometimes we end up
with conflicting or overlapping notes (not often, but it happens).

- (issue #1234) Change color of SomeForm to have more contrast.
- (issue #1234) Rollback color change to SomeForm. Testers pointed out
potential problems for color-blind people.

- (issue #1234) Change color of SomeForm to yellow.
- (issue #1234) Change color of SomeForm to green.
- (issue #1234) Make color of SomeForm user-configurable.

>> Also, most commits won't end up with a "Change:" note, just like not
>> every commit has a "Review by:" note. Only when you have something
>> interesting to say to users.
> Sure I understand that. But that's exactly the problem that complicates this.
> Those attribution tags get missed all the time as well. The difference though
> is that the person who should have been attributed can say something or fix it
> themselves.
> If it was something we needed on every commit it's much easier to review for
> that. But when it may be appropriate to ommit it then it's unlikely someone is
> going to point out they are missing because then they'd have to go through the
> process of figuring out if it was necessary.
> Maybe the alternative is to require some sort of Change line in every commit
> and to specify why one isn't necessary somehow when that's the case. But I
> suspect people will object to that because it's just more tedious work to put
> into a commit.

Indeed, it's not intended to be added to every commit, that would be
tedious. Like I said, I think post-commit review would have to ensure
that no things are missed.

But I agree that "evolving changes" and "changes being rolled back",
without going back to edit the outdated "change lines", could be a
significant problem (especially with long release cycles). So I won't
push this any further :-), and leave it at that.

Received on 2013-09-20 01:10:28 CEST

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