RUN AS-IF-FOSS Fix group search users scope times out

changelogs/unreleased/31092-user-search-filtered-to-group-times-out.yml

+---
+title: Improve group search users scope performance
+merge_request: 38701
+author:
+type: performance

lib/gitlab/group_search_results.rb

@@ -12,20 +12,24 @@ module Gitlab
 
     # rubocop:disable CodeReuse/ActiveRecord
     def users
-      # 1: get all groups the current user has access to
-      groups = GroupsFinder.new(current_user).execute.joins(:users)
+      # get all groups the current user has access to
+      # ignore order inherited from GroupsFinder to improve performance
+      current_user_groups = GroupsFinder.new(current_user).execute.unscope(:order)
 
-      # 2: Get the group's whole hierarchy
-      group_users = @group.direct_and_indirect_users
+      # the hierarchy of the current group
+      group_groups = @group.self_and_hierarchy.unscope(:order)
 
-      # 3: get all users the current user has access to (->
-      # `SearchResults#users`), which also applies the query.
+      # the groups where the above hierarchies intersect
+      intersect_groups = group_groups.where(id: current_user_groups)
+
+      # members of @group hierarchy where the user has access to the groups
+      members = GroupMember.where(group: intersect_groups).non_invite
+
+      # get all users the current user has access to (-> `SearchResults#users`), which also applies the query
       users = super
 
-      # 4: filter for users that belong to the previously selected groups
-      users
-        .where(id: group_users.select('id'))
-        .where(id: groups.select('members.user_id'))
+      #  filter users that belong to the previously selected groups
+      users.where(id: members.select(:user_id))
     end
     # rubocop:enable CodeReuse/ActiveRecord
 

spec/lib/gitlab/group_search_results_spec.rb

@@ -3,8 +3,10 @@
 require 'spec_helper'
 
 RSpec.describe Gitlab::GroupSearchResults do
+  # group creation calls GroupFinder, so need to create the group
+  # before so expect(GroupsFinder) check works
+  let_it_be(:group) { create(:group) }
   let(:user) { create(:user) }
-  let(:group) { create(:group) }
 
   subject(:results) { described_class.new(user, 'gob', anything, group: group) }
 
@@ -60,6 +62,19 @@ RSpec.describe Gitlab::GroupSearchResults do
 
       is_expected.to be_empty
     end
+
+    it 'does not return the user invited to the group' do
+      user = create(:user, username: 'gob_bluth')
+      create(:group_member, :invited, :developer, user: user, group: group)
+
+      is_expected.to be_empty
+    end
+
+    it 'calls GroupFinder during execution' do
+      expect(GroupsFinder).to receive(:new).with(user).and_call_original
+
+      subject
+    end
   end
 
   describe "#issuable_params" do