diff options
Diffstat (limited to 'app/models/concerns/loose_foreign_key.rb')
-rw-r--r-- | app/models/concerns/loose_foreign_key.rb | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/app/models/concerns/loose_foreign_key.rb b/app/models/concerns/loose_foreign_key.rb new file mode 100644 index 00000000000..4e822a04869 --- /dev/null +++ b/app/models/concerns/loose_foreign_key.rb @@ -0,0 +1,95 @@ +# frozen_string_literal: true + +module LooseForeignKey + extend ActiveSupport::Concern + + # This concern adds loose foreign key support to ActiveRecord models. + # Loose foreign keys allow delayed processing of associated database records + # with similar guarantees than a database foreign key. + # + # TODO: finalize this later once the async job is in place + # + # Prerequisites: + # + # To start using the concern, you'll need to install a database trigger to the parent + # table in a standard DB migration (not post-migration). + # + # > add_loose_foreign_key_support(:projects, :gitlab_main) + # + # Usage: + # + # > class Ci::Build < ApplicationRecord + # > + # > loose_foreign_key :security_scans, :build_id, on_delete: :async_delete, gitlab_schema: :gitlab_main + # > + # > # associations can be still defined, the dependent options is no longer necessary: + # > has_many :security_scans, class_name: 'Security::Scan' + # > + # > end + # + # Options for on_delete: + # + # - :async_delete - deletes the children rows via an asynchronous process. + # - :async_nullify - sets the foreign key column to null via an asynchronous process. + # + # Options for gitlab_schema: + # + # - :gitlab_ci + # - :gitlab_main + # + # The value can be determined by calling `Model.gitlab_schema` where the Model represents + # the model for the child table. + # + # How it works: + # + # When adding loose foreign key support to the table, a DELETE trigger is installed + # which tracks the record deletions (stores primary key value of the deleted row) in + # a database table. + # + # These deletion records are processed asynchronously and records are cleaned up + # according to the loose foreign key definitions described in the model. + # + # The cleanup happens in batches, which reduces the likelyhood of statement timeouts. + # + # When all associations related to the deleted record are cleaned up, the record itself + # is deleted. + included do + class_attribute :loose_foreign_key_definitions, default: [] + end + + class_methods do + def loose_foreign_key(to_table, column, options) + symbolized_options = options.symbolize_keys + + unless base_class? + raise <<~MSG + loose_foreign_key can be only used on base classes, inherited classes are not supported. + Please define the loose_foreign_key on the #{base_class.name} class. + MSG + end + + on_delete_options = %i[async_delete async_nullify] + gitlab_schema_options = [ApplicationRecord.gitlab_schema, Ci::ApplicationRecord.gitlab_schema] + + unless on_delete_options.include?(symbolized_options[:on_delete]&.to_sym) + raise "Invalid on_delete option given: #{symbolized_options[:on_delete]}. Valid options: #{on_delete_options.join(', ')}" + end + + unless gitlab_schema_options.include?(symbolized_options[:gitlab_schema]&.to_sym) + raise "Invalid gitlab_schema option given: #{symbolized_options[:gitlab_schema]}. Valid options: #{gitlab_schema_options.join(', ')}" + end + + definition = ActiveRecord::ConnectionAdapters::ForeignKeyDefinition.new( + table_name.to_s, + to_table.to_s, + { + column: column.to_s, + on_delete: symbolized_options[:on_delete].to_sym, + gitlab_schema: symbolized_options[:gitlab_schema].to_sym + } + ) + + self.loose_foreign_key_definitions += [definition] + end + end +end |