Parse diskstats (/proc/diskstats) [Ruby]

diskstats.rb

EXAMPLE = <<-EOE
   1       0 ram0 0 0 0 0 0 0 0 0 0 0 0
   1       1 ram1 0 0 0 0 0 0 0 0 0 0 0
   1       2 ram2 0 0 0 0 0 0 0 0 0 0 0
   1       3 ram3 0 0 0 0 0 0 0 0 0 0 0
   1       4 ram4 0 0 0 0 0 0 0 0 0 0 0
   1       5 ram5 0 0 0 0 0 0 0 0 0 0 0
   1       6 ram6 0 0 0 0 0 0 0 0 0 0 0
   1       7 ram7 0 0 0 0 0 0 0 0 0 0 0
   1       8 ram8 0 0 0 0 0 0 0 0 0 0 0
   1       9 ram9 0 0 0 0 0 0 0 0 0 0 0
   1      10 ram10 0 0 0 0 0 0 0 0 0 0 0
   1      11 ram11 0 0 0 0 0 0 0 0 0 0 0
   1      12 ram12 0 0 0 0 0 0 0 0 0 0 0
   1      13 ram13 0 0 0 0 0 0 0 0 0 0 0
   1      14 ram14 0 0 0 0 0 0 0 0 0 0 0
   1      15 ram15 0 0 0 0 0 0 0 0 0 0 0
   7       0 loop0 0 0 0 0 0 0 0 0 0 0 0
   7       1 loop1 0 0 0 0 0 0 0 0 0 0 0
   7       2 loop2 0 0 0 0 0 0 0 0 0 0 0
   7       3 loop3 0 0 0 0 0 0 0 0 0 0 0
   7       4 loop4 0 0 0 0 0 0 0 0 0 0 0
   7       5 loop5 0 0 0 0 0 0 0 0 0 0 0
   7       6 loop6 0 0 0 0 0 0 0 0 0 0 0
   7       7 loop7 0 0 0 0 0 0 0 0 0 0 0
  11       0 sr0 0 0 0 0 0 0 0 0 0 0 0
   2       0 fd0 0 0 0 0 0 0 0 0 0 0 0
   8      16 sdb 89058036 3036 2038861338 27561368 177255631 250783894 114648810520 2204478124 0 55806380 2232046128
   8       0 sda 5943640 4656869 132155940 1335728 16665008 20784171 491671830 4545148 0 2107472 5873036
   8       1 sda1 324397 254 780862 23896 155 10246 80646 796 0 23844 24604
   8       2 sda2 2 0 4 0 0 0 0 0 0 0 0
   8       5 sda5 5554333 4656615 130855810 1297336 16664853 20773925 491591184 4544352 0 2069228 5833996
 252       0 dm-0 88209700 0 2031956178 27528932 428058600 0 114648810520 2374520096 0 56357652 2403020116
 252       1 dm-1 1891510 0 64292354 620312 29186278 0 425470448 4285744 0 1015860 4906752
 252       2 dm-2 7662265 0 61298120 1729304 8265092 0 66120736 34455500 0 1021008 36186260
EOE

require 'ostruct'

class Diskstats
  COLUMNS = %i(
    major
    minor
    device_name
    reads_success
    reads_merged
    sectors_read
    read_time_ms
    writes_success
    writes_merged
    sectors_written
    write_time_ms
    current_ios
    io_time_ms
    weightd_io_time_ms
  )

  attr_reader :raw_stats
   
  def initialize(stats)
    @raw_stats = stats
  end

  def rows
    @rows ||= raw_stats.lines.map do |line|
      OpenStruct.new(Hash[COLUMNS.zip(line.strip.split)])
    end
  end

  def self.from_proc
    new(File.read('/proc/diskstats'))
  end
end

puts Diskstats.new(EXAMPLE).rows.map(&:device_name)