[infinispan-dev] Branching proposal

[Dan Berindei]

I use something like this to check what tags contain a particular fix:

git tag --contains $(git log --grep <JIRA> -1 --format="%h" master)

True, it's a bit longer, but it stays in the bash/zsh history :)

Cheers
Dan


On Mon, Mar 27, 2017 at 1:33 PM, Radim Vansa <rvansa at redhat.com> wrote:
> If you can't merge a commit (based on 9.0.x) to master clearly, do you
> need to file another PR anyway? Then the lag to get some code to master
> increases a lot. I am not sure how useful is git tag --contains <sha1>
> if you cannot be sure that you'll find all occurrences due to this kind
> of issues.
>
> R.
>
> On 03/27/2017 11:33 AM, Sebastian Laskawiec wrote:
>> Hey!
>>
>> We are about to start working on 9.1.x and 9.2.y branches so I would
>> like to propose alternative merging strategy.
>>
>> Our current workflow looks like this:
>>
>> X - new commit
>> X` - cherry pick to maintenance branch
>> --+-------------------+-------X----- master
>>   |                    \------X`---- 9.2.x
>>   \---------------------------X``--- 9.1.x
>>
>> Each commit needs to be reviewed in master branch and backported to
>> the maintenance branches. From maintenance perspective this is a bit
>> painful, since in above example we need to get 3 times through PR
>> queue. Also it's worth to mention that X is not X` nor X``.
>> Cherry-picking creates a copy of a commit. This makes some useful
>> tricks (like git tag --contains <sha1>) a bit harder to use. Finally,
>> this approach allows the codebase to diverge from maintenance branches
>> very fast (someone might just forget to backport some of the
>> refactoring stuff).
>>
>> The proposal:
>>
>> X, Y - new commits
>> / - merge commits
>> --+---------+------/----/--- master
>>   |          \----/---Y/---- 9.2.x
>>   \-------------X/---------- 9.1.x
>>
>> With the proposal, a developer should always implement a given feature
>> in the lowest possible maintenance branch. Then we will run a set of
>> merges from 9.1.x into 9.2.x and finally into master. The biggest
>> advantage of this approach is that given functionality (identified by
>> a commit) will have the same SHA1 for all branches. This will allow
>> all tools like (mentioned before) `git tag --contains <sha1>` to work.
>> There are also some further implications of this approach:
>>
>>   * Merging commits should be performed very often (even automatically
>>     in the night (if merged without any problems)).
>>   * After releasing each maintenance release, someone will need to do
>>     a merge with strategy `ours` (`git merge -s ours upstream/9.2.x`).
>>     This way we will not have to solve version conflicts in poms.
>>   * Since there is no nice way to rebase a merge commit, they should
>>     be pushed directly into the master branch (without review, without
>>     CI). After the merge, HEAD will change and CI will
>>     automatically pick the build. Remember, merges should be done very
>>     often. So I assume there won't be any problems most of the times.
>>   * Finally, with this approach the code diverges slight slower (at
>>     least from my experience). Mainly because we don't need to
>>     remember to cherry-pick individual commits. They are automatically
>>     "taken" by a merge.
>>
>> From my past experience, this strategy works pretty nice and can be
>> almost fully automated. It significantly lowers the maintenance pain
>> around cherry-picks. However there is nothing for free, and we would
>> need to get used to pushing merged directly into master (which is fine
>> to me but some of you might not like it).
>>
>> Thanks,
>> Sebastian
>>
>>
>> _______________________________________________
>> infinispan-dev mailing list
>> infinispan-dev at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
>
>
> --
> Radim Vansa <rvansa at redhat.com>
> JBoss Performance Team
>
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