Fix three N+1s in Releases API entity generation

Author and links count queries happened per release, added them
to includes to preload this and remove the N+1.

The links are exposed as links.sorted in the API entity, in order
to preload it, a scope that includes the sort had to be created,
and that included in the preloaded scope to prevent sorting links
for every release as an N+1.

Changelog: performance

app/graphql/types/release_assets_type.rb

@@ -13,7 +13,7 @@ module Types
 
     field :count, GraphQL::INT_TYPE, null: true, method: :assets_count,
           description: 'Number of assets of the release.'
-    field :links, Types::ReleaseAssetLinkType.connection_type, null: true,
+    field :links, Types::ReleaseAssetLinkType.connection_type, null: true, method: :sorted_links,
           description: 'Asset links of the release.'
     field :sources, Types::ReleaseSourceType.connection_type, null: true,
           description: 'Sources of the release.'

app/models/release.rb

@@ -13,6 +13,7 @@ class Release < ApplicationRecord
   belongs_to :author, class_name: 'User'
 
   has_many :links, class_name: 'Releases::Link'
+  has_many :sorted_links, -> { sorted }, class_name: 'Releases::Link'
 
   has_many :milestone_releases
   has_many :milestones, through: :milestone_releases
@@ -27,7 +28,10 @@ class Release < ApplicationRecord
   validates :links, nested_attributes_duplicates: { scope: :release, child_attributes: %i[name url filepath] }
 
   scope :sorted, -> { order(released_at: :desc) }
-  scope :preloaded, -> { includes(:evidences, :milestones, project: [:project_feature, :route, { namespace: :route }]) }
+  scope :preloaded, -> {
+    includes(:author, :evidences, :milestones, :links, :sorted_links,
+             project: [:project_feature, :route, { namespace: :route }])
+  }
   scope :with_project_and_namespace, -> { includes(project: :namespace) }
   scope :recent, -> { sorted.limit(MAX_NUMBER_TO_DISPLAY) }
   scope :without_evidence, -> { left_joins(:evidences).where(::Releases::Evidence.arel_table[:id].eq(nil)) }
@@ -58,8 +62,8 @@ class Release < ApplicationRecord
   end
 
   def assets_count(except: [])
-    links_count = links.count
-    sources_count = except.include?(:sources) ? 0 : sources.count
+    links_count = links.size
+    sources_count = except.include?(:sources) ? 0 : sources.size
 
     links_count + sources_count
   end

changelogs/unreleased/cat-releases-api-perf-nplusone.yml

+---
+title: Fix three N+1s in Releases API entity generation
+merge_request: 60189
+author:
+type: performance

lib/api/entities/release.rb

@@ -28,9 +28,7 @@ module API
       expose :assets do
         expose :assets_count, as: :count
         expose :sources, using: Entities::Releases::Source, if: ->(_, _) { can_download_code? }
-        expose :links, using: Entities::Releases::Link do |release, options|
-          release.links.sorted
-        end
+        expose :sorted_links, as: :links, using: Entities::Releases::Link
       end
       expose :evidences, using: Entities::Releases::Evidence, expose_nil: false, if: ->(_, _) { can_download_code? }
       expose :_links do

spec/lib/gitlab/import_export/all_models.yml

@@ -113,6 +113,7 @@ releases:
 - author
 - project
 - links
+- sorted_links
 - milestone_releases
 - milestones
 - evidences

spec/models/release_spec.rb

@@ -54,7 +54,7 @@ RSpec.describe Release do
   end
 
   describe '#assets_count' do
-    subject { release.assets_count }
+    subject { Release.find(release.id).assets_count }
 
     it 'returns the number of sources' do
       is_expected.to eq(Gitlab::Workhorse::ARCHIVE_FORMATS.count)
@@ -68,7 +68,7 @@ RSpec.describe Release do
       end
 
       it "excludes sources count when asked" do
-        assets_count = release.assets_count(except: [:sources])
+        assets_count = Release.find(release.id).assets_count(except: [:sources])
         expect(assets_count).to eq(1)
       end
     end

spec/requests/api/releases_spec.rb

@@ -136,8 +136,8 @@ RSpec.describe API::Releases do
         get api("/projects/#{project.id}/releases", maintainer)
       end.count
 
-      create(:release, :with_evidence, project: project, tag: 'v0.1', author: maintainer)
-      create(:release, :with_evidence, project: project, tag: 'v0.1', author: maintainer)
+      create_list(:release, 2, :with_evidence, project: project, tag: 'v0.1', author: maintainer)
+      create_list(:release, 2, project: project)
 
       expect do
         get api("/projects/#{project.id}/releases", maintainer)