Merge remote-tracking branch 'upstream/master' into 27377-preload-pipeline-entity27377-preload-pipeline-entity

* upstream/master: (2534 commits)
  Update VERSION to 9.3.0-pre
  Update CHANGELOG.md for 9.2.0
  removes unnecessary redundacy in usage ping doc
  Respect the typo as rubocop said
  Add a test to ensure this works on MySQL
  Change pipelines schedules help page path
  change domain to hostname in usage ping doc
  Fixes broken MySQL migration for retried
  Show password field mask while editing service settings
  Add notes for supported schedulers and cloud providers
  Move environment monitoring to environments doc
  Add docs for change of Cache/Artifact restore order"
  Avoid resource intensive login checks if password is not provided
  Change translation for 'coding' by 'desarrollo' for Spanish
  Add to docs: issues multiple assignees
  rename "Add emoji" and "Award emoji" to "Add reaction" where appropriate
  Add project and group notification settings info
  32570 Fix border-bottom for project activity tab
  Add users endpoint to frontend API class
  Rename users on mysql
  ...

1 files changed, 71 insertions, 0 deletions

diff --git a/app/services/users/migrate_to_ghost_user_service.rb b/app/services/users/migrate_to_ghost_user_service.rb
new file mode 100644
index 00000000000..4628c4c6f6e
--- /dev/null
+++ b/app/services/users/migrate_to_ghost_user_service.rb
@@ -0,0 +1,71 @@
+# When a user is destroyed, some of their associated records are
+# moved to a "Ghost User", to prevent these associated records from
+# being destroyed.
+#
+# For example, all the issues/MRs a user has created are _not_ destroyed
+# when the user is destroyed.
+module Users
+  class MigrateToGhostUserService
+    extend ActiveSupport::Concern
+
+    attr_reader :ghost_user, :user
+
+    def initialize(user)
+      @user = user
+    end
+
+    def execute
+      transition = user.block_transition
+
+      user.transaction do
+        # Block the user before moving records to prevent a data race.
+        # For example, if the user creates an issue after `migrate_issues`
+        # runs and before the user is destroyed, the destroy will fail with
+        # an exception.
+        user.block
+
+        # Reverse the user block if record migration fails
+        if !migrate_records && transition
+          transition.rollback
+          user.save!
+        end
+      end
+
+      user.reload
+    end
+
+    private
+
+    def migrate_records
+      user.transaction(requires_new: true) do
+        @ghost_user = User.ghost
+
+        migrate_issues
+        migrate_merge_requests
+        migrate_notes
+        migrate_abuse_reports
+        migrate_award_emojis
+      end
+    end
+
+    def migrate_issues
+      user.issues.update_all(author_id: ghost_user.id)
+    end
+
+    def migrate_merge_requests
+      user.merge_requests.update_all(author_id: ghost_user.id)
+    end
+
+    def migrate_notes
+      user.notes.update_all(author_id: ghost_user.id)
+    end
+
+    def migrate_abuse_reports
+      user.reported_abuse_reports.update_all(reporter_id: ghost_user.id)
+    end
+
+    def migrate_award_emojis
+      user.award_emoji.update_all(user_id: ghost_user.id)
+    end
+  end
+end