[Lldb-commits] [PATCH] D22463: [RFC] Moving to GitHub Proposal: NOT DECISION!

[Robinson, Paul via lldb-commits]

> > I think we could emulate any pre-commit hook we like via GitHub
> > WebHooks by having two repositories: llvm and llvm-staging (say).
> >
> > People push to llvm-staging, which notifies some LLVM server we own.
> > That does basic sanity checks and pushes to llvm proper if passed.
> 
> I think that would be terrible in practice, for instance how do you handle
> situations like:
> 
> 1) Dev A push commit A
> 2) Dev B push commit B that changes some lines close to the one changed by
> commit A
> 3) sanity check fails on commit A, but llvm-staging contains A and B and
> can’t get rid of A easily because B would not apply without A.
> 
> At this point Dev B gets an email (or other mechanism, I don’t know what
> you imagined) telling that his changed are rejected for no good reason.
> 
> Also reverting to a state "before A” on llvm-staging would mean that that
> the history would be rewritten and everyone that pulled/fetched in the
> meantime would suffer .
> 
> If we want to go towards pre-check using staging, I believe we should work
> with pull-request (we’d still have the issue of conflicting PR, but I
> don’t believe it’d be that bad in practice).
> That’d be welcome, but that’d also be a whole other story to setup and
> maintain!
> 
> —
> Mehdi

Hear hear.  The schemes to handle this that I'm aware of do look more like
pull requests.  You submit your change to the pre-qualification queue.
If it rebases cleanly and passes pre-qual, your change becomes the new HEAD.
If it doesn't rebase cleanly or fails pre-qual, your change gets bounced.

A pull-request-like model also helps avoid the rebase-build-test-push(fail)
loop that you can get into with a very active git-based project.  This is
a mechanical task best suited to automation rather than wasting valuable
developer time on it.  But I suspect GitHub does not have anything like
this OOB so it would be an enhancement for a later time.
--paulr

P.S. At Sony we are building a system with a "staging" step but it's not
for our own work... more of a "flood control" dam.  :-)