Test and refine the handling of batch forward ports around branch
deactivation, especially with differential. Notably, fix an error in
the conversion of the FW process to batches: individual PR limit was
not correctly taken in account during forward port unless *all* PRs
were done, even though that is a primary motivation for the
change.
Partial forward porting should now work correctly, and the detection
and handling of differential next target should be better handled to
boot.
Significantly rework the interplay between batches and PRs being
closed in order to maintain sequencing / consistency of forward port
sequences: previously a batch would get deleted if all its PRs are
closed, but that is an issue when it is part of a forward port
sequence as we now lose information.
Instead, detach the PRs from the batch as before but have the batch
skip unlinking if it has historical value (parent or child
batch). Currently the batch's state is a bit weird as it doesn't get
merged, but...
While at it, significantly simplify `_try_closing` as it turns out to
have a ton of incidental / historical complexity from old attempts at
fixing concurrency issues, which should not be necessary anymore and
in fact actively interfere with the new and more compute-heavy state
of things.
Thank god I have a bunch of tests because once again I forgot / missed
a bunch of edge cases in doing the conversion, which the tests
caught (sadly that means I almost certainly broke a few untested edge
cases).
Important notes:
Handling of parent links
------------------------
Unlike PRs, batches don't lose their parent info ever, the link is
permanent, which is convenient to trawl through a forward port
(currently implemented very inefficiently, maybe we'll optimise that
in the future).
However this means the batch having a parent and the batch's PRs
having parents are slightly different informations, one of the edge
cases I missed is that of conflicting PRs, which are deparented and
have to be merged by hand before being forward ported further, I had
originally replaced the checks on a pr and its sibling having parents
by just the batch.
Batches & targets
-----------------
Batches were originally concepted as being fixed to a target and PRs
having that target, a PR being retargeted would move it from one batch
to an other.
As it turns out this does not work in the case where people retarget
forward-port PRs, which I know they do because #551
(2337bd8518). I could not think of a
good way to handle this issue as is, so scrapped the moving PRs thing,
instead one of the coherence checks of a batch being ready is that all
its PRs have the same target, and a batch only has a target if all its
PRs have the same target.
It's possible for somewhat odd effects to arise, notably if a PR is
closed (removed from batch), the other PRs are retargeted, and the new
PR is reopened, it will now be on a separate batch even if it also
gets retargeted. This is weird. I don't quite know how I should handle
it, maybe batches could merge if they have the same target and label?
however batches don't currently have a label so...
Improve limits
--------------
Keep limits on the PRs rather than lift them on the batchL if we can
add/remove PRs of batches having different limits on different PRs of
the same batch is reasonable.
Also leave limit unset by default: previously, the limit was eagerly
set to the tip (accessible) branch. That doesn't really seem
necessary, so stop doing that.
Also remove completely unnecessary `max` when trying to find a PR's
next target: `root` is either `self` or `self.source_id`, so it should
not be possible for that to have a later target.
And for now ensure the limits are consistent per batch: a PR defaults
to the limit of their batch-mate if they don't have one, and if a
limit is set via command it's set on all PRs of a batch.
This commit does not allow differential limits via commands, they are
allowed via the backend but not really tested. The issue is mostly
that it's not clear what the UX should look like to have clear and not
super error prone interactions. So punt on it for now, and hopefully
there's no hole I missed which will create inconsistent batches.
In case of PRs not being ready, don't just say the PRs are waiting for
CI even though they might be unreviewed, and make a difference
between *waiting* for CI (pending) and having failed CI.
It's a bit weird and inconsistent to have a PR being staged while
unreviewed or unapproved or w/e. If we compute the state based on
skipchecks then everything is consistent.
Also remove the implicit override of all statuses when explicitly
marking the pr as `ready`, it risks creating difficult to understand
states, and it's unnecessary since `skipchecks` gets set.
Also as with setting skipchecks, sets the current user as reviewer on
all PRs of the batch without a reviewer.
Move staging cancellation to the batch, remove its (complicated)
handling from the PRs.
This loses some precision in the cancellation message, but that could
likely be recovered (in part) by adding more precise checks &
diagnostic extractions in the compute.
Simplifies the `ready_prs` query a bit and allows it to be converted
to an ORM search, by moving the priority check outside. This also
allows the caller to not need to post-process the records list
anywhere near the previous state of affairs.
`ready_prs` now returns *either* the "alone" batches, or the non-alone
batches, rather than mixing both into a single sequence. This requires
correctly applying the search filters to not retrieve priority of
batches in error or targeting other branches.
Staging readiness is a batch-level concerns, and many of the markers
are already there though a few need to be aggregated from the PRs. As
such, staging has no reason to be performed in terms of PRs anymore,
it should be performed via batches directly.
There is a bit of a mess in order not to completely fuck up when
retargeting PRs (implicitly via freeze wizard, or explicitely) as for
now we're moving PRs between batches in order to keep the
batches *mostly* target-bound.
Some of the side-effects in managing the coherence of the targeting
and moving PRs between batches is... not great. This might need to be
revisited and cleaned up with those scenarios better considered.
- `merge_date` should be common to an entire batch, so move it there
- remove `Batch.active` which should probably have been removed when
batches were made persistent (can eventually re-add as a proxy for
`merge_date` being set maybe, but for now removing it seems a better
way to catch mistakes)
- update various sites to use `Batch.merge_date` instead of
`Batch.active`
This probably has latent bugs, and is only the start of the road to v2
(#789): PR batches are now created up-front (alongside the PR), with
PRs attached and detached as needed, hopefully such that things are
not broken (tests pass but...), this required a fair number of
ajustments to code not taking batches into account, or creating
batches on the fly.
`PullRequests.blocked` has also been updated to rely on the batch to
get its batch-mates, such that it can now be a stored field with the
right dependencies.
The next step is to better leverage this change:
- move cross-PR state up to the batch (e.g. skipchecks, priority, ...)
- add fw info to the batch, perform forward-ports batchwise in order
to avoid redundant batch-selection work, and allow altering batches
during fw (e.g. adding or removing PRs)
- use batches to select stagings
- maybe expose staging history of a batch?
