This could only be possible for users that can create merge requests
within a project.
So they need to be a allowed to create a branch and create a merge request.
This ensures that we have more visibility in the number of SQL queries
that are executed in web requests. The current threshold is hardcoded to
100 as we will rarely (maybe once or twice) change it.
In production and development we use Sentry if enabled, in the test
environment we raise an error. This feature is also only enabled in
production/staging when running on GitLab.com as it's not very useful to
other users.
Compared to the merge_request_diff association:
1. It's simpler to query. The query uses a foreign key to the
merge_request_diffs table, so no ordering is necessary.
2. It's faster for preloading. The merge_request_diff association has to load
every diff for the MRs in the set, then discard all but the most recent for
each. This association means that Rails can just query for N diffs from N
MRs.
3. It's more complicated to update. This is a bidirectional foreign key, so we
need to update two tables when adding a diff record. This also means we need
to handle this as a special case when importing a GitLab project.
There is some juggling with this association in the merge request model:
* `MergeRequest#latest_merge_request_diff` is _always_ the latest diff.
* `MergeRequest#merge_request_diff` reuses
`MergeRequest#latest_merge_request_diff` unless:
* Arguments are passed. These are typically to force-reload the association.
* It doesn't exist. That means we might be trying to implicitly create a
diff. This only seems to happen in specs.
* The association is already loaded. This is important for the reasons
explained in the comment, which I'll reiterate here: if we a) load a
non-latest diff, then b) get its `merge_request`, then c) get that MR's
`merge_request_diff`, we should get the diff we loaded in c), even though
that's not the latest diff.
Basically, `MergeRequest#merge_request_diff` is the latest diff in most cases,
but not quite all.
And add support for additional query parameters:
- `author_id`: Returns merge requests created by the given user `id`
- `assignee_id`: Returns merge requests assigned to the given user `id`
- `scope`: Return merge requests for the given scope: `created-by-me`, `assigned-to-me` or `all`
New version of the gem returns 200 status code on delete with content
instead of 204 so we explicitly set status code to keep existing
behavior
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>