with_pool_transaction_isolation_level

# File activerecord/lib/active_record/transactions.rb, line 240
      def with_pool_transaction_isolation_level(isolation_level, &block)
        if current_transaction.open?
          raise ActiveRecord::TransactionIsolationError, "cannot set default isolation level while transaction is open"
        end

        old_level = connection_pool.pool_transaction_isolation_level
        connection_pool.pool_transaction_isolation_level = isolation_level
        yield
      ensure
        connection_pool.pool_transaction_isolation_level = old_level
      end