class Net::BufferedIO

def write0(*strs)
  @debug_output << strs.map(&:dump).join if @debug_output
  orig_written_bytes = @written_bytes
  strs.each_with_index do |str, i|
    need_retry = true
    case len = @io.write_nonblock(str, exception: false)
    when Integer
      @written_bytes += len
      len -= str.bytesize
      if len == 0
        if strs.size == i+1
          return @written_bytes - orig_written_bytes
        else
          need_retry = false
          # next string
        end
      elsif len < 0
        str = str.byteslice(len, -len)
      else # len > 0
        need_retry = false
        # next string
      end
      # continue looping
    when :wait_writable
      (io = @io.to_io).wait_writable(@write_timeout) or raise Net::WriteTimeout.new(io)
      # continue looping
    end while need_retry
  end
end