# File lib/cgikit.rb, line 4320
        def add( level, message = nil, &block )
                if message.nil? and block_given? then
                        message = yield
                end

                message = _format_message( level, @name, message )

                if @file then
                        if _max_file_size? message then
                                raise FileSizeError, "#@file: Can't write log. The file size is limit."
                        else
                                CKFileLock.exclusive_lock(@file, 'a') do |f|
                                        f.write message
                                end
                        end
                else
                        @out.write message
                end
        end