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Earl Warren
adc273e3a8 fix: do not ignore automerge while a PR is checking for conflicts (#8189)
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Automerge can be ignored when the following race happens:

* Conflict check is happening on a repository and
  `pr.Status = issues_model.PullRequestStatusChecking` for all open pull
  requests (this happens every time a pull request is merged).
* While the conflict check is ongoing, an event (Forgejo Actions being
  successful for instance) happens and and `StartPRCheckAndAutoMerge*` is called.
* Because `pr.CanAutoMerge()` is false, the pull request is not
  selected and not added to the automerge queue.
* When the conflict check completes and `pr.CanAutoMerge()` becomes
  true, there no longer is a task in the auto merge queue and the
  auto merge does not happen.

This is fixed by adding a task to the auto merge queue when the conflict check for a pull request completes. This is done when the mutx protecting the conflict check task is released to prevent a deadlock when a synchronous queues are used in the following situation:

* the conflict check task finds the pull request is mergeable
* it schedules the auto merge tasks that finds it must be merged
* merging concludes with scheduling a conflict check task

Avoid an extra loop where a conflict check task queues an auto merge task that will schedule a conflict check task if the pull request can be merged. The auto merge row is removed from the database before merging. It would otherwise be removed after the merge commit is received via the git hook which happens asynchronously and can lead to a race.

StartPRCheckAndAutoMerge is modified to re-use HeadCommitID when available, such as when called after a pull request conflict check.

---

A note on tests: they cover the new behavior, i.e. automerge being triggered by a successful conflict check. This is also on the critical paths for every test that involve creating, merging or updating a pull request.

- `tests/integration/git_test.go`
- `tests/integration/actions_commit_status_test.go`
- `tests/integration/api_helper_for_declarative_test.go`
- `tests/integration/patch_status_test.go`
- `tests/integration/pull_merge_test.go`

The [missing fixture file](https://codeberg.org/forgejo/forgejo/pulls/8189/files#diff-b86fdd79108b3ba3cb2e56ffcfd1be2a7b32f46c) for the auto merge table can be verified to be necessary simply by removing it an observing that the integration tests fail.

The [scheduling of the auto merge task](https://codeberg.org/forgejo/forgejo/pulls/8189/files#diff-9489262e93967f6bb2db41837f37c06f4e70d978) in `testPR` can be verified to be required by moving it in the `testPRProtected` function and observing that the tests hang forever because of the deadlock.

## Checklist

The [contributor guide](https://forgejo.org/docs/next/contributor/) contains information that will be helpful to first time contributors. There also are a few [conditions for merging Pull Requests in Forgejo repositories](https://codeberg.org/forgejo/governance/src/branch/main/PullRequestsAgreement.md). You are also welcome to join the [Forgejo development chatroom](https://matrix.to/#/#forgejo-development:matrix.org).

### Tests

- I added test coverage for Go changes...
  - [ ] in their respective `*_test.go` for unit tests.
  - [x] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I added test coverage for JavaScript changes...
  - [ ] in `web_src/js/*.test.js` if it can be unit tested.
  - [ ] in `tests/e2e/*.test.e2e.js` if it requires interactions with a live Forgejo server (see also the [developer guide for JavaScript testing](https://codeberg.org/forgejo/forgejo/src/branch/forgejo/tests/e2e/README.md#end-to-end-tests)).

### Documentation

- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [ ] I do not want this change to show in the release notes.
- [x] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.

<!--start release-notes-assistant-->

## Release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Bug fixes
  - [PR](https://codeberg.org/forgejo/forgejo/pulls/8189): <!--number 8189 --><!--line 0 --><!--description ZG8gbm90IGlnbm9yZSBhdXRvbWVyZ2Ugd2hpbGUgYSBQUiBpcyBjaGVja2luZyBmb3IgY29uZmxpY3Rz-->do not ignore automerge while a PR is checking for conflicts<!--description-->
<!--end release-notes-assistant-->

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8189
Reviewed-by: Michael Kriese <michael.kriese@gmx.de>
Reviewed-by: Lucas <sclu1034@noreply.codeberg.org>
Co-authored-by: Earl Warren <contact@earl-warren.org>
Co-committed-by: Earl Warren <contact@earl-warren.org>
2025-06-17 10:58:07 +02:00
Gusted
90f8239448 fix: make test suite run on older git version (#8188)
Ref: forgejo/forgejo#8140, forgejo/forgejo#8144
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8188
Reviewed-by: Michael Kriese <michael.kriese@gmx.de>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-committed-by: Gusted <postmaster@gusted.xyz>
2025-06-14 19:50:58 +02:00
Gusted
7c150be23d feat: improved performances when checking for conflicts on pull requests (#7727)
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- `testPatch` is a function that is called to test a pull request and determine the state of the pull request. Checking for merge conflicts, check if the diff is empty and if the pull request modifies any protected files.
- The checking for merge conflict and if the diff is empty used git commands that relied on a working tree to correctly functions. Forgejo store repositories in a bare format which do not contain a working tree. This means that a temporary copy was created every time a pull request had to be re-checked and for large repositories involving quite some I/O interaction.
- This patch adjusts those codepaths to instead use newer Git plumbing commands that work without requiring a work tree and can thus be used directly on the bare repository. The merge conflict is now done via [`git-merge-tree(1)`](https://git-scm.com/docs/git-merge-tree/) and checking if the diff is empty is done via [`git-diff-tree(1)`](https://git-scm.com/docs/git-diff-tree).
- If the function is called to test a patch where the head and base repository are not the same, then [Git alternate](https://git-scm.com/docs/gitglossary#Documentation/gitglossary.txt-aiddefalternateobjectdatabaseaalternateobjectdatabase) is used to make the head commit available in the base repository, this done on a per git command basis via the `GIT_ALTERNATE_OBJECT_DIRECTORIES` environment.
- As far as I can understand the documentation and the existing code, there's no edge case that the new code cannot handle. It also results in a cleaner codepath, as the existing code did a lot of checking and merging in a more traditional approach that required a lot of (parsing) code, while the new code offloads this to git and has a trivial parser of the output.
- Resolves forgejo/forgejo#7701
- Added exhaustive integration testing.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7727
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Reviewed-by: Otto <otto@codeberg.org>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-committed-by: Gusted <postmaster@gusted.xyz>
2025-05-16 12:40:38 +00:00