I was also thinking about the possibility of wanting to revert
individual commits from a merge commit. The solution you propose works,
but only if you want to revert everything.
On 19.09.18 22:12, Charles Chen wrote:
What I mean is that if you get the first-parent commit using "git log
--first-parent", it will incorporate any and all fix up commits so we
don't need to worry about missing any.
On Wed, Sep 19, 2018, 1:07 PM Maximilian Michels <m...@apache.org
<mailto:m...@apache.org>> wrote:
Generally, +1 for isolated commits which are easy to revert.
> I don't think it's actually harder to roll back a set of commits
that are merged together.
I think Thomas was mainly concerned about "fixup" commits to land in
master (as part of a merge). These indeed make reverting commits more
difficult because you have to check whether you missed a "fixup".
> Ideally every commit should compile and pass tests though, right?
That is definitely what we should strive for when doing a merge against
master.
> Perhaps the bigger issue is that we need better documentation and
a playbook on how to do this these common tasks in git.
We do actually have basic documentation about this but most people
don't
read it. For example, the commit message of a Merge commit should be:
Merge pull request #xxxx: [BEAM-yyyy] Issue title
But most merge commits don't comply with this rule :) See
https://beam.apache.org/contribute/committer-guide/#merging-it
On 19.09.18 21:34, Reuven Lax wrote:
> Ideally every commit should compile and pass tests though, right?
>
> On Wed, Sep 19, 2018 at 12:15 PM Ankur Goenka <goe...@google.com
<mailto:goe...@google.com>
> <mailto:goe...@google.com <mailto:goe...@google.com>>> wrote:
>
> I agree with the cleanliness of the Commit history.
> "Fixup!", "Address comments", "Address even more comments"
type of
> comments does not convey meaningful information and are not very
> useful. Its a good idea to squash them.
> However, I think its ok to keep separate commits for different
> logical pieces of the code which make reviewing and
revisiting code
> easier.
> Example PR: Support X in the pipeline
> Commit 1: Restructuring a bunch of code without any logical
change.
> Commit 2: Changing validation logic for pipeline.
> Commit 3: Supporting new field "X" for pipeline.
>
> On Wed, Sep 19, 2018 at 11:27 AM Charles Chen <c...@google.com
<mailto:c...@google.com>
> <mailto:c...@google.com <mailto:c...@google.com>>> wrote:
>
> To be concrete, it is very easy to revert a commit in any
case:
>
> 1. First, use "git log --first-parent" to find the
first-parent
> commit corresponding to a PR merge (this is a one-to-one
> correspondence).
> 2. Use "git revert -m 1 <commitid>" to revert the
commit; this
> selects the first parent as the base for a merge
commit (in
> the case where a single commit needs to be reverted, just
> use "git revert <commitid>" without the "-m 1" flag).
>
> In any case, as a general good engineering practice, I do
agree
> that it is highly desirable to have small independent PRs
> instead of large jumbo PRs whenever possible.
>
> On Wed, Sep 19, 2018 at 11:20 AM Charles Chen
<c...@google.com <mailto:c...@google.com>
> <mailto:c...@google.com <mailto:c...@google.com>>> wrote:
>
> I don't think it's actually harder to roll back a set of
> commits that are merged together. Git has the notion of
> first-parent commits (you can see, for example, "git log
> --first-parent", which filters out the intermediate
> commits). In this sense, PRs still get merged as one
unit
> and this is preserved even if intermediate commits are
> kept. Perhaps the bigger issue is that we need better
> documentation and a playbook on how to do this these
common
> tasks in git.
>
> On Wed, Sep 19, 2018 at 9:27 AM Thomas Weise
<t...@apache.org <mailto:t...@apache.org>
> <mailto:t...@apache.org <mailto:t...@apache.org>>> wrote:
>
> Wanted to bring this up as reminder as well as
> opportunity to discuss potential changes to our
> committer guide. It has been a while since last
related
> discussion and we welcomed several new committers
since
> then.
>
> Finishing up pull requests pre-merge:
>
> https://beam.apache.org/contribute/committer-guide/#finishing-touches
>
> PRs are worked on over time and may accumulate many
> commits. Sometimes because scope expands,
sometimes just
> to separate independent changes but most of the
time the
> commits are just fixups that are added as review
progresses.
> It is important that the latter get squashed
prior to PR
> merge, as otherwise we lost the ability to roll back
> changes by reverting a single commit and also
generally
> cause a lot of noise in the commit history that
does not
> help other contributors. To be clear, I refer to the
> "Fixup!", "Address comments", "Address even more
> comments" type of entries :)
>
> I would also propose that every commit gets
tagged with
> a JIRA (except those fixups that will be squashed).
> Having the JIRA and possibly other tags makes it
easier
> for others not involved in the PR to identify changes
> after they were merged, for example when looking
at the
> revision history or annotated source.
>
> As for other scenarios of jumbo PRs with many
commits,
> there are probably situations where work needs to be
> broken down into smaller units, making life
better for
> both, contributor and reviewer(s). Ideally, every PR
> would have only one commit, but that may be a bit
much
> to mandate? Is the general expectation something
we need
> to document more clearly?
>
> Thanks,
> Thomas
>
