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# frozen_string_literal: true
module Backup
class DatabaseConnection
attr_reader :database_configuration, :snapshot_id
delegate :connection_name, to: :database_configuration
delegate :connection, to: :@backup_model
# Initializes a database connection
#
# @param [String] connection_name the key from `database.yml` for multi-database connection configuration
def initialize(connection_name)
@database_configuration = Backup::DatabaseConfiguration.new(connection_name)
@backup_model = backup_model
@snapshot_id = nil
configure_backup_model
end
# Start a new transaction and run pg_export_snapshot()
# Returns the snapshot identifier
#
# @return [String] snapshot identifier
def export_snapshot!
disable_timeouts!
connection.begin_transaction(isolation: :repeatable_read)
@snapshot_id = connection.select_value("SELECT pg_export_snapshot()")
end
# Rollback the transaction to release the effects of pg_export_snapshot()
def release_snapshot!
return unless snapshot_id
connection.rollback_transaction
@snapshot_id = nil
end
def disable_timeouts!
transaction_timeout_settings.disable_timeouts
end
def restore_timeouts!
transaction_timeout_settings.restore_timeouts
end
private
delegate :activerecord_configuration, to: :database_configuration, private: true
def configure_backup_model
@backup_model.establish_connection(activerecord_configuration)
Gitlab::Database::LoadBalancing::Setup.new(@backup_model).setup
end
# Creates a disposable model to be used to host the Backup connection only
def backup_model
klass_name = connection_name.camelize
return "#{self.class.name}::#{klass_name}".constantize if self.class.const_defined?(klass_name.to_sym, false)
self.class.const_set(klass_name, Class.new(ApplicationRecord))
end
def transaction_timeout_settings
Gitlab::Database::TransactionTimeoutSettings.new(connection)
end
end
end
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