A benchmark for printing bytes

bm-4.rb

#!/usr/bin/env ruby

require 'benchmark'

PREFIX = %W(TiB GiB MiB KiB B).freeze
UNITS = %W(B KiB MiB GiB TiB).freeze

def as_size1( s )
  s = s.to_f
  i = PREFIX.length - 1
  while s > 512 && i > 0
    s /= 1024
    i -= 1
  end
  ((s > 9 || s.modulo(1) < 0.1 ? '%d' : '%.1f') % s) + ' ' + PREFIX[i]
end

def as_size2(s)
  s, unit = UNITS.reduce(s.to_f) do |(fsize, _), utype|
    fsize > 512 ? [fsize / 1024, utype] : (break [fsize, utype])
  end
  ((s > 9 || s.modulo(1) < 0.1 ? '%d' : '%.1f') % s) + ' ' + unit
end

def as_size3 s
  s = s.to_f
  if s < 512
    i = 0
  else
    max_exp  = UNITS.size - 1
    i = ( Math.log( s ) / Math.log( 1024 ) ).round
    i = max_exp  if i > max_exp
    s /= 1024 ** i
  end
  ((s > 9 || s.modulo(1) < 0.1 ? '%d' : '%.1f') % s) + ' ' + UNITS[i]
end

ITERATIONS = 1000000

[200, 300, 400, 500, 600, 700, 800].each do |n|
  p "#{as_size1(n)} / #{as_size2(n)} / #{as_size3(n)}"
end

Benchmark.bmbm do |bench|

	heading = "split"

	bench.report( 'while' ) do
		ITERATIONS.times do
		    sz = rand(500000000000000)
		    as_size1(sz)
		end
	end

	bench.report( 'reduce' ) do
		ITERATIONS.times do
		    sz = rand(500000000000000)
		    as_size2(sz)
		end
	end

	bench.report( 'log' ) do
		ITERATIONS.times do
		    sz = rand(500000000000000)
		    as_size3(sz)
		end
	end

end