Previously, we called the `peek_enabled?` method like so:
prepend_before_action :set_peek_request_id, if: :peek_enabled?
Now we don't have a `set_peek_request_id` method, so we don't need that
line. However, the `peek_enabled?` part had a side-effect: it would also
populate the request store cache for whether the performance bar was
enabled for the current request or not.
This commit makes that side-effect explicit, and replaces all uses of
`peek_enabled?` with the more explicit
`Gitlab::PerformanceBar.enabled_for_request?`. There is one spec that
still sets `SafeRequestStore[:peek_enabled]` directly, because it is
contrasting behaviour with and without a request store enabled.
The upshot is:
1. We still set the value in one place. We make it more explicit that
that's what we're doing.
2. Reading that value uses a consistent method so it's easier to find in
future.
Peek's `Peek.request_id` method doesn't work well with a multi-threaded
server and concurrent requests, because requests can 'steal' another
request's ID, or unset it before it was due.
The upstream change resolves this; the commit here is just to ensure
that GitLab works with that upstream change, mostly by not using
`Peek.request_id` any more (as the method doesn't exist).
1. The output isn't great. It can be hard to find hotspots and, even
when you do find them, to find why those are hotspots.
2. It uses some jQuery-specific frontend code which we can remove now
that we don't have this any more.
3. It's only possible to profile the initial request, not any subsequent
AJAX requests.
A `performance_team` Flipper group has been created. By default this
group is nil but this can be customized in `gitlab.yml` via the
performance_bar.allowed_group setting.
Signed-off-by: Rémy Coutable <remy@rymai.me>
