When moving a project, it's possible that some users who had
access to the project in old path can not access the project
in the new path.
Because `project_authorizations` records are updated asynchronously,
when we send the notification about moved project the list of project
team members contains old project members, we want to notify all these
members except the old users who can not access the new location.
When getting the max member access for a group of users, we stored the results
in RequestStore. However, this will only return results for project members, so
anyone who wasn't a member of the project would be checked once at the start,
and then once for each comment they made. These queries are generally quite
fast, but no query is faster!
This commit introduces the usage of Common Table Expressions (CTEs) to
efficiently retrieve nested group hierarchies, without having to rely on
the "routes" table (which is an _incredibly_ inefficient way of getting
the data). This requires a patch to ActiveRecord (found in the added
initializer) to work properly as ActiveRecord doesn't support WITH
statements properly out of the box.
Unfortunately MySQL provides no efficient way of getting nested groups.
For example, the old routes setup could easily take 5-10 seconds
depending on the amount of "routes" in a database. Providing vastly
different logic for both MySQL and PostgreSQL will negatively impact the
development process. Because of this the various nested groups related
methods return empty relations when used in combination with MySQL.
For project authorizations the logic is split up into two classes:
* Gitlab::ProjectAuthorizations::WithNestedGroups
* Gitlab::ProjectAuthorizations::WithoutNestedGroups
Both classes get the fresh project authorizations (= as they should be
in the "project_authorizations" table), including nested groups if
PostgreSQL is used. The logic of these two classes is quite different
apart from their public interface. This complicates development a bit,
but unfortunately there is no way around this.
This commit also introduces Gitlab::GroupHierarchy. This class can be
used to get the ancestors and descendants of a base relation, or both by
using a UNION. This in turn is used by methods such as:
* Namespace#ancestors
* Namespace#descendants
* User#all_expanded_groups
Again this class relies on CTEs and thus only works on PostgreSQL. The
Namespace methods will return an empty relation when MySQL is used,
while User#all_expanded_groups will return only the groups a user is a
direct member of.
Performance wise the impact is quite large. For example, on GitLab.com
Namespace#descendants used to take around 580 ms to retrieve data for a
particular user. Using CTEs we are able to reduce this down to roughly 1
millisecond, returning the exact same data.
== On The Fly Refreshing
Refreshing of authorizations on the fly (= when
users.authorized_projects_populated was not set) is removed with this
commit. This simplifies the code, and ensures any queries used for
authorizations are not mutated because they are executed in a Rails
scope (e.g. Project.visible_to_user).
This commit includes a migration to schedule refreshing authorizations
for all users, ensuring all of them have their authorizations in place.
Said migration schedules users in batches of 5000, with 5 minutes
between every batch to smear the load around a bit.
== Spec Changes
This commit also introduces some changes to various specs. For example,
some specs for ProjectTeam assumed that creating a personal project
would _not_ lead to the owner having access, which is incorrect. Because
we also no longer refresh authorizations on the fly for new users some
code had to be added to the "empty_project" factory. This chunk of code
ensures that the owner's permissions are refreshed after creating the
project, something that is normally done in Projects::CreateService.
This also updates _some_ specs to use these new methods, just to serve
as an example for others going forward, but by no means is this
exhaustive.
Original implementations at !5992 and !6012.
Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/20944
We were calling `.where` and `.send` on the relation, but never doing
anything with the return value, resulting in proper access-level
filtering never being of any consequence.
GitLab Bot
Rémy Coutable
Thong Kuah
Jan Provaznik
Mark Chao
blackst0ne
Robert Speicher
Grzegorz Bizon
Oswaldo Ferreira
Sean McGivern
Yorick Peterse
Ahmad Sherif
Nick Thomas
Stan Hu