The goal is to reduce maintenance and odd disk interactions &
concurrency issues, by not creating concurrent clones, not having to
push forks back in the repository, etc... it also removes the need to
cleanup "scratch" working copies though that looks not to have been an
issue in a while.
The work is done on isolated objects without using or mutating refs,
so even concurrent work should not be a problem.
This turns out to not be any more verbose (less so if anything) than
using `cherry-pick`, as that is not really designed for scripted /
non-interactive use, or for squashing commits thereafter. Working
directly with trees and commits is quite a bit cleaner even without a
ton of helpers.
Much of the credit goes to Julia Evans for [their investigation of
3-way merges as the underpinnings of cherry-picking][3-way merge],
this would have been a lot more difficult if I'd had to rediscover the
merge-base trick independently.
A few things have been changed by this:
- The old trace/stderr from cherrypick has disappeared as it's
generated by cherrypick, but for a non-interactive use it's kinda
useless anyway so I probably should have looked into removing it
earlier (I think the main use was investigation of the inflateinit
issue).
- Error on emptied commits has to be hand-rolled as `merge-tree`
couldn't care less, this is not hard but is a bit annoying.
- `merge-tree`'s conflict information only references raw commits,
which makes sense, but requires updating a bunch of tests. Then
again so does the fact that it *usually* doesn't send anything to
stderr, so that's usually disappearing.
Conveniently `merge-tree` merges the conflict marker directly in the
files / tree so we don't have to mess about moving them back out of
the repository and into the working copy as I assume cherry-pick does,
which means we don't have to try and commit them back in ether. That
is a huge part of the gain over faffing about with the working copy.
Fixes#847
[3-way merge]: https://jvns.ca/blog/2023/11/10/how-cherry-pick-and-revert-work/
Using a regex as the pattern is quite frustrating due to all the
escaping necessary, which in this refactoring I found out I'd missed,
multiple times.
Convert the pattern to something bespoke but not too complicated, we
may want to add anchoring support and a bit more finesse and the
future but for now straightforward "holes" seem to work well. I've
added support for capturing and even named groups even if this as yet
unnecessary and unused.
Fixes#861
[^1]: https://docs.pytest.org/en/stable/reference.html#pytest.hookspec.pytest_assertrepr_compare
Initially wanted to skip this only for FW PRs, but after some thinking
I feel this info could still be valuable even for non-fw PRs which
were never merged in the first place.
Requires a few adjustments to not break *everything*: `batch.prs`
excludes closed PRs by default as most processes only expect to be
faced by a closed PR inside a batch, and we *especially* want to avoid
that before the batch is merged (as we'd risk staging a closed PR).
However since PRs don't get removed from batches anymore (and batches
don't get deleted when they have no PRs) we now may have a bunch of
batches whose PRs (usually a single one) are all closed, this has two
major side-effects:
- a new PR may get attached to an old batch full of closed PRs (as
batches are filtered out on being *merged*), which is weird
- the eventual list of batches gets polluted with a bunch of
irrelevant batches which are hard to filter out
The solution is to reintroduce an `active` field, as a stored compute
field based on the state of batch PRs. This way if all PRs of a batch
are closed it switches to inactive, and is automatically filtered out
by search which solves both issues.
Given a batch which has been merged, and been forward-ported, to
multiple branches (because skipci was set or ci passed on the repos
the batch covers).
There might come the need to add a PR for one of the uncovered
repos. This raises the question of what to do with it, since the
forward-ports for the batch already exist it's not going to get
forwardported normally, nor may we want to, possibly?
Options are:
- don't do anything, such additions don't get ported, this is
incongruous and unexpected as by default PRs are forward-ported, and
if the batch wasn't an intermediate (but e.g. a conflict) it
probably would be ported forward
- port on merge, this allows configuring the PR properly (as it might
need its own limit) but it means further batches may get
unexpectedly merged (or at least retied) without the additional PR
even though we likely want it in
- immediately port the additional PR on creation, this makes the limit
harder or impossible to configure but it makes the *batch sequence*
more consistent
We ended up selecting the latter, it feels closer to the updates
system, and it creates more consistent batches through the
sequence. It's also technically easier to ad-hoc port a PR through a
bunch of branches than it is to update the "normal" forward-port
process to handle partial fixups.
This tests that the new setup *does* allow both removing PRs from a
forward-ported batch (something which may have worked previously
already, anyway) and importantly *adding* PRs to a forward ported
batch.
The updated batch behaves somewhat like a new batch, but it should
retain the history via linking through the batch, and it allows
cross-repo fixes which were not necessary earlier (e.g. because we're
touching an API of repo A which was not used in repo B in earlier
branches, but now is), something which was not really possible before
the refactoring of batches & co.
Because github materialises every labels change in the
timeline (interspersed with comments), the increasing labels churn
contributes to PRs being difficult to read and review.
This change removes the update of labels on PRs, instead the mergebot
will automatically send a comment to created PRs serving as a
notification that the PR was noticed & providing a link to the
mergebot's dashboard for that PR where users should be able to see the
PR state in detail in case they wonder what's what.
Lots of tests had to be edited to:
- remove any check on the labels of the PR
- add checks on the PR dashboard (to ensure that they're at least on
the correct "view")
- add a helper to handle the comment now added to every PR by the 'bot
- since that helper is needed by both mergebot and forwardbot, the
utils modules were unified and moved out of the odoo modules
Probably relevant note: no test was added for the dashboard
ACL, though since I had to explicitly unset the group on the repo used
for tests for things to work it looks to me like it at least excludes
people just fine.
Fixes#419
In the case where we have a co-dependent forward port (co-dependent
PRs got forward-ported, which they should be together) where *one* of
the PRs got explicitly updated, the batch would "fall into a hole"
being handled as neither "this is part of a forward-port sequence" nor
"this is a new merge to forward-port" (the latter being the proper
one).
Modify & remove guards which checked that either no or all PRs in a
batch have parents: should be either all or not all.
Fixes#231
