compares several ways to calculate the number of days passed since epoch

days_since_epoch_bench.rb

require 'date'
require 'benchmark/ips'

Benchmark.ips do |x|
  # Configure the number of seconds used during
  # the warmup phase (default 2) and calculation phase (default 5)
  x.config(:time => 5, :warmup => 2)

  # These parameters can also be configured this way
  x.time = 5
  x.warmup = 2

  # Typical mode, runs the block as many times as it can
  x.report(1) { Date.today.to_time.to_i / (60 * 60 * 24) }
  x.report(2) { Date.today.to_time.to_i / 86400 }
  x.report(3) { (Date.today.to_time.to_f / 86400.0).to_i }
  x.report(4) { (Time.now.to_f / 86400.0).to_i }
end


shito> bundle exec ruby test/days_since_epoch_bench.rb
Warming up --------------------------------------
                   1    37.304k i/100ms
                   2    31.911k i/100ms
                   3    31.645k i/100ms
                   4   235.326k i/100ms
Calculating -------------------------------------
                   1    355.753k (± 2.8%) i/s -      1.791M in   5.037189s
                   2    357.397k (± 3.6%) i/s -      1.787M in   5.006714s
                   3    332.356k (± 4.1%) i/s -      1.677M in   5.054967s
                   4      2.352M (± 3.9%) i/s -     11.766M in   5.011465s
shito> bundle exec ruby test/days_since_epoch_bench.rb
Warming up --------------------------------------
                   1    37.145k i/100ms
                   2    35.933k i/100ms
                   3    34.502k i/100ms
                   4   238.409k i/100ms
Calculating -------------------------------------
                   1    374.085k (± 2.1%) i/s -      1.894M in   5.066361s
                   2    373.731k (± 2.7%) i/s -      1.869M in   5.003710s
                   3    362.250k (± 2.5%) i/s -      1.829M in   5.051346s
                   4      2.424M (± 2.0%) i/s -     12.159M in   5.018387s