Revert "Merge branch '21801-remigrate-epic-user-mentions' into 'master'"

This reverts commit c34a4b6b, reversing
changes made to 54cd52b6.

db/post_migrate/20191115115043_migrate_epic_mentions_to_db.rb

 # frozen_string_literal: true
 
 class MigrateEpicMentionsToDb < ActiveRecord::Migration[5.2]
-  include Gitlab::Database::MigrationHelpers
-
   DOWNTIME = false
 
   disable_ddl_transaction!
@@ -28,7 +26,7 @@ class MigrateEpicMentionsToDb < ActiveRecord::Migration[5.2]
       .where(QUERY_CONDITIONS)
       .each_batch(of: BATCH_SIZE) do |batch, index|
       range = batch.pluck(Arel.sql('MIN(epics.id)'), Arel.sql('MAX(epics.id)')).first
-      migrate_in(index * DELAY, MIGRATION, ['Epic', JOIN, QUERY_CONDITIONS, false, *range])
+      BackgroundMigrationWorker.perform_in(index * DELAY, MIGRATION, ['Epic', JOIN, QUERY_CONDITIONS, false, *range])
     end
   end
 

db/post_migrate/20200214173000_cleanup_empty_epic_user_mentions.rb

-# frozen_string_literal: true
-
-class CleanupEmptyEpicUserMentions < ActiveRecord::Migration[5.2]
-  DOWNTIME = false
-  BATCH_SIZE = 10000
-
-  class EpicUserMention < ActiveRecord::Base
-    include EachBatch
-
-    self.table_name = 'epic_user_mentions'
-  end
-
-  def up
-    return unless Gitlab.ee?
-
-    # cleanup epic user mentions with no actual mentions,
-    # re https://gitlab.com/gitlab-org/gitlab/-/merge_requests/24586#note_285982468
-    EpicUserMention
-      .where(mentioned_users_ids: nil)
-      .where(mentioned_groups_ids: nil)
-      .where(mentioned_projects_ids: nil)
-      .each_batch(of: BATCH_SIZE) do |batch|
-      batch.delete_all
-    end
-  end
-
-  def down
-    # no-op
-  end
-end

db/post_migrate/20200214174519_remigrate_epic_mentions_to_db.rb

-# frozen_string_literal: true
-
-class RemigrateEpicMentionsToDb < ActiveRecord::Migration[5.2]
-  include Gitlab::Database::MigrationHelpers
-
-  DOWNTIME = false
-
-  disable_ddl_transaction!
-
-  DELAY = 2.minutes.to_i
-  BATCH_SIZE = 10000
-  MIGRATION = 'UserMentions::CreateResourceUserMention'
-
-  JOIN = "LEFT JOIN epic_user_mentions on epics.id = epic_user_mentions.epic_id"
-  QUERY_CONDITIONS = "(description like '%@%' OR title like '%@%') AND epic_user_mentions.epic_id is null"
-
-  class Epic < ActiveRecord::Base
-    include EachBatch
-
-    self.table_name = 'epics'
-  end
-
-  def up
-    return unless Gitlab.ee?
-
-    Epic
-      .joins(JOIN)
-      .where(QUERY_CONDITIONS)
-      .each_batch(of: BATCH_SIZE) do |batch, index|
-      range = batch.pluck(Arel.sql('MIN(epics.id)'), Arel.sql('MAX(epics.id)')).first
-      migrate_in(index * DELAY, MIGRATION, ['Epic', JOIN, QUERY_CONDITIONS, false, *range])
-    end
-  end
-
-  def down
-    # no-op
-  end
-end

db/post_migrate/20200214174607_remigrate_epic_notes_mentions_to_db.rb

-# frozen_string_literal: true
-
-class RemigrateEpicNotesMentionsToDb < ActiveRecord::Migration[5.2]
-  include Gitlab::Database::MigrationHelpers
-
-  DOWNTIME = false
-
-  disable_ddl_transaction!
-
-  DELAY = 2.minutes.to_i
-  BATCH_SIZE = 10000
-  MIGRATION = 'UserMentions::CreateResourceUserMention'
-
-  INDEX_NAME = 'epic_mentions_temp_index'
-  INDEX_CONDITION = "note LIKE '%@%'::text AND notes.noteable_type = 'Epic'"
-  QUERY_CONDITIONS = "#{INDEX_CONDITION} AND epic_user_mentions.epic_id IS NULL"
-  JOIN = 'INNER JOIN epics ON epics.id = notes.noteable_id LEFT JOIN epic_user_mentions ON notes.id = epic_user_mentions.note_id'
-
-  class Note < ActiveRecord::Base
-    include EachBatch
-
-    self.table_name = 'notes'
-  end
-
-  def up
-    return unless Gitlab.ee?
-
-    # create temporary index for notes with mentions, may take well over 1h
-    add_concurrent_index(:notes, :id, where: INDEX_CONDITION, name: INDEX_NAME)
-
-    Note
-      .joins(JOIN)
-      .where(QUERY_CONDITIONS)
-      .each_batch(of: BATCH_SIZE) do |batch, index|
-      range = batch.pluck(Arel.sql('MIN(notes.id)'), Arel.sql('MAX(notes.id)')).first
-      migrate_in(index * DELAY, MIGRATION, ['Epic', JOIN, QUERY_CONDITIONS, true, *range])
-    end
-  end
-
-  def down
-    # no-op
-    # temporary index is to be dropped in a different migration in an upcoming release:
-    # https://gitlab.com/gitlab-org/gitlab/issues/196842
-  end
-end

ee/spec/lib/gitlab/background_migration/user_mentions/create_resource_user_mention_spec.rb

@@ -3,8 +3,6 @@
 require 'spec_helper'
 require './db/post_migrate/20191115115043_migrate_epic_mentions_to_db'
 require './db/post_migrate/20191115115522_migrate_epic_notes_mentions_to_db'
-require './db/post_migrate/20200214174519_remigrate_epic_mentions_to_db'
-require './db/post_migrate/20200214174607_remigrate_epic_notes_mentions_to_db'
 require './db/post_migrate/20200124110831_migrate_design_notes_mentions_to_db'
 
 describe Gitlab::BackgroundMigration::UserMentions::CreateResourceUserMention, schema: :latest do
@@ -67,7 +65,6 @@ describe Gitlab::BackgroundMigration::UserMentions::CreateResourceUserMention, s
         let(:resource) { epic }
 
         it_behaves_like 'resource mentions migration', MigrateEpicMentionsToDb, Epic
-        it_behaves_like 'resource mentions migration', RemigrateEpicMentionsToDb, Epic
 
         context 'mentions in epic notes' do
           let!(:note1) { notes.create!(noteable_id: epic.id, noteable_type: 'Epic', author_id: author.id, note: description_mentions) }
@@ -79,7 +76,6 @@ describe Gitlab::BackgroundMigration::UserMentions::CreateResourceUserMention, s
           let!(:note5) { notes.create!(noteable_id: epics.maximum(:id) + 10, noteable_type: 'Epic', author_id: author.id, note: description_mentions, project_id: project.id) }
 
           it_behaves_like 'resource notes mentions migration', MigrateEpicNotesMentionsToDb, Epic
-          it_behaves_like 'resource notes mentions migration', RemigrateEpicNotesMentionsToDb, Epic
         end
       end
     end

ee/spec/migrations/cleanup_empty_epic_user_mentions_spec.rb

-# frozen_string_literal: true
-
-require 'spec_helper'
-require Rails.root.join('db', 'post_migrate', '20200214173000_cleanup_empty_epic_user_mentions')
-
-describe CleanupEmptyEpicUserMentions, :sidekiq do
-  let(:users) { table(:users) }
-  let(:namespaces) { table(:namespaces) }
-  let(:epics) { table(:epics) }
-  let(:notes) { table(:notes) }
-  let(:epic_user_mentions) { table(:epic_user_mentions) }
-
-  let(:user) { users.create!(name: 'root', email: 'root@example.com', username: 'root', projects_limit: 0) }
-  let(:group) { namespaces.create!(name: 'group1', path: 'group1', owner_id: user.id, type: 'Group') }
-  let(:epic) { epics.create!(iid: 1, title: "title", title_html: 'title', description: 'epic description', group_id: group.id, author_id: user.id) }
-
-  # migrateable resources
-  let!(:resource1) { notes.create!(note: 'note1 for @root to check', noteable_id: epic.id, noteable_type: 'Epic') }
-  let!(:resource2) { notes.create!(note: 'note2 for @root to check', noteable_id: epic.id, noteable_type: 'Epic', system: true) }
-  let!(:resource3) { notes.create!(note: 'note3 for @root to check', noteable_id: epic.id, noteable_type: 'Epic') }
-
-  # non-migrateable resources
-  # this note is already migrated, as it has a record in the epic_user_mentions table
-  let!(:resource4) { notes.create!(note: 'note3 for @root to check', noteable_id: epic.id, noteable_type: 'Epic') }
-  let!(:user_mention) { epic_user_mentions.create!(epic_id: epic.id, note_id: resource4.id, mentioned_users_ids: [1]) }
-
-  # these should get cleanup, by the migration
-  let!(:blank_epic_user_mention1) { epic_user_mentions.create!(epic_id: epic.id, note_id: resource1.id)}
-  let!(:blank_epic_user_mention2) { epic_user_mentions.create!(epic_id: epic.id, note_id: resource2.id)}
-  let!(:blank_epic_user_mention3) { epic_user_mentions.create!(epic_id: epic.id, note_id: resource3.id)}
-
-  it 'cleans blank user mentions' do
-    expect(epic_user_mentions.count).to eq 4
-
-    migrate!
-
-    expect(epic_user_mentions.count).to eq 1
-  end
-end

ee/spec/migrations/migrate_design_notes_mentions_to_db_spec.rb

@@ -27,5 +27,9 @@ describe MigrateDesignNotesMentionsToDb, :sidekiq do
   # this note points to an innexistent noteable record
   let!(:resource5) { notes.create!(note: 'note3 for @root to check', noteable_id: designs.maximum(:id) + 10, noteable_type: 'DesignManagement::Design') }
 
+  before do
+    stub_const("#{described_class.name}::BATCH_SIZE", 1)
+  end
+
   it_behaves_like 'schedules resource mentions migration', DesignManagement::Design, true
 end

ee/spec/migrations/migrate_epic_mentions_to_db_spec.rb

@@ -2,9 +2,8 @@
 
 require 'spec_helper'
 require Rails.root.join('db', 'post_migrate', '20191115115043_migrate_epic_mentions_to_db')
-require Rails.root.join('db', 'post_migrate', '20200214174519_remigrate_epic_mentions_to_db')
 
-describe 'epic mentions migration', migration: false do
+describe MigrateEpicMentionsToDb, :migration do
   let(:users) { table(:users) }
   let(:namespaces) { table(:namespaces) }
   let(:epics) { table(:epics) }
@@ -25,11 +24,5 @@ describe 'epic mentions migration', migration: false do
   # this epic has no mentions so should be filtered out
   let!(:resource5) { epics.create!(iid: 5, title: "title5", title_html: 'title5', description: 'epic description with no mention', group_id: group.id, author_id: user.id) }
 
-  describe MigrateEpicMentionsToDb, :migration do
   it_behaves_like 'schedules resource mentions migration', Epic, false
-  end
-
-  describe RemigrateEpicMentionsToDb, :migration do
-    it_behaves_like 'schedules resource mentions migration', Epic, false
-  end
 end

ee/spec/migrations/migrate_epic_notes_mentions_to_db_spec.rb

@@ -2,9 +2,8 @@
 
 require 'spec_helper'
 require Rails.root.join('db', 'post_migrate', '20191115115522_migrate_epic_notes_mentions_to_db')
-require Rails.root.join('db', 'post_migrate', '20200214174607_remigrate_epic_notes_mentions_to_db')
 
-describe 'epic notes mentions migration', migration: false do
+describe MigrateEpicNotesMentionsToDb, :migration do
   let(:users) { table(:users) }
   let(:namespaces) { table(:namespaces) }
   let(:epics) { table(:epics) }
@@ -27,11 +26,5 @@ describe 'epic notes mentions migration', migration: false do
   # this note points to an inexistent noteable record
   let!(:resource5) { notes.create!(note: 'note3 for @root to check', noteable_id: epics.maximum(:id) + 10, noteable_type: 'Epic') }
 
-  describe MigrateEpicNotesMentionsToDb, :migration do
   it_behaves_like 'schedules resource mentions migration', Epic, true
-  end
-
-  describe RemigrateEpicNotesMentionsToDb, :migration do
-    it_behaves_like 'schedules resource mentions migration', Epic, true
-  end
 end

lib/gitlab/background_migration/user_mentions/models/epic.rb

@@ -18,6 +18,7 @@ module Gitlab
           self.table_name = 'epics'
 
           belongs_to :author, class_name: "User"
+          belongs_to :project
           belongs_to :group
 
           def self.user_mention_model