Re: [edk2-devel] [edk2-rfc] GitHub Pull Request based Code Review Process

["Laszlo Ersek" <lersek@redhat.com>]

On 05/10/20 23:43, Rebecca Cran wrote:
> Mike,
> 
> On 5/10/20 3:29 PM, Michael D Kinney wrote:
> 
>> There is no difference between CI checks run during code review
>> and the final CI checks before merge.  I think it is an interesting
>> conversation to decide how many times those CI checks should be
>> run and if they should run automatically on every change during
>> review or on demand.
> 
> I'd suggest following what other Github projects do, which I think is to
> run the CI checks automatically on every change that's made in a pull
> request - I don't know if it might also be necessary to run them during
> the merge, if master has changed in the meantime. That gives the
> _submitter_ feedback about any changes they need to make, instead of
> having to wait until the maintainer tells them their change has broken
> something: it speeds up the development process.

Build-testing at every stage through a patch series is important for
ensuring bisectability.

But there's a critical ingredient to that: based on the assumption that
our build system / build rules are good, the builds mentioned above
should be *incremental*.

That is, if we have a patch set with 10 patches, then then the first
patch in the series should trigger a complete build, and the 9 later
patches should trigger only incremental builds.

(During a bisection, the same commits wouldn't be visited in that same
order of course, but that's where the sanity of the build system / build
rules comes in! Basically, if your builds succeed with a linear
progression through the series, then the build system / build rules
ought to *guarantee* that the same "tree states" will build
incrementally just fine when visited in any particular order. "git
checkout" updates the relevant files, and the build system should be
able to derive the minimum set of necessary actions.

Anyway, digression ends.)

The incremental nature of builds is important for saving energy, and
also for saving developer time. The above 10-part example series should
not take 10 times as long to build as 10 independent patches, submitted
in isolation. Patches#2 through #10 should only rebuild a few modules
each (unless lib class headers, protocol headers and such are modified).


> 
>> Mergify is more flexible.  We want to make sure the git history
>> is linear with not git merges and supports both single patches
>> and patch series without squashing.  GitHub merge button by
>> default squashes all commits into a single commit.
> 
> Wouldn't disabling all but "Allow rebase merging" do the same thing
> without the additional potential failure point? Though it sounds like
> we've resolved the problems with Mergify, so it's not important.
> 
> https://help.github.com/en/github/administering-a-repository/configuring-commit-squashing-for-pull-requests

mergify has been pretty stable for me!

Thanks,
Laszlo