Benchmarck Hash#[] vs Hash#fetch

bench_hash_key_vs_fetch.rb

require 'benchmark'

TIMES = 100000
HASH = { as: :fuu }

Benchmark.bm(25) do |x|
  x.report('[:as] (existing)') do
    TIMES.times do
      HASH[:as] || :default
    end
  end

  x.report('[:as] (non existing)') do
    TIMES.times do
      HASH[:ax] || :default
    end
  end

  x.report('fetch(:as) (existing)') do
    TIMES.times do
      HASH.fetch(:as, :default)
    end
  end

  x.report('fetch(:as) (non existing)') do
    TIMES.times do
      HASH.fetch(:ax, :default)
    end
  end

  x.report('fetch(:as) {} (existing)') do
    TIMES.times do
      HASH.fetch(:as) { :default }
    end
  end

  x.report('fetch(:as) {} (non existing)') do
    TIMES.times do
      HASH.fetch(:ax) { :default }
    end
  end
end

require 'benchmark/ips'

Benchmark.ips do |x|
  x.report('[:as] (existing)') do
    HASH[:as] || :default
  end

  x.report('[:as] (non existing)') do
    HASH[:ax] || :default
  end

  x.report('fetch(:as) (existing)') do
    HASH.fetch(:as, :default)
  end

  x.report('fetch(:as) (non existing)') do
    HASH.fetch(:ax, :default)
  end

  x.report('fetch(:as) {} (existing)') do
    HASH.fetch(:as) { :default }
  end

  x.report('fetch(:as) {} (non existing)') do
    HASH.fetch(:ax) { :default }
  end
end

=begin
# BM
                                user     system      total        real
[:as] (existing)            0.000000   0.000000   0.000000 (  0.008880)
[:as] (non existing)        0.020000   0.000000   0.020000 (  0.012835)
fetch(:as) (existing)       0.020000   0.000000   0.020000 (  0.020105)
fetch(:as) (non existing)   0.010000   0.000000   0.010000 (  0.014273)
fetch(:as) {} (existing)    0.020000   0.000000   0.020000 (  0.016462)
fetch(:as) {} (non existing)  0.030000   0.000000   0.030000 (  0.028847)

# IPS

Calculating -------------------------------------
    [:as] (existing)          86313 i/100ms
[:as] (non existing)          85304 i/100ms
fetch(:as) (existing)         76593 i/100ms
fetch(:as) (non existing)     62863 i/100ms
fetch(:as) {} (existing)      74604 i/100ms
fetch(:as) {} (non existing)  71734 i/100ms
-------------------------------------------------
    [:as] (existing)          5604410.9 (±8.7%) i/s -   27792786 in   5.009524s
[:as] (non existing)          4877521.6 (±9.8%) i/s -   24141032 in   5.008405s
fetch(:as) (existing)         3729943.1 (±5.2%) i/s -   18612099 in   5.005361s
fetch(:as) (non existing)     3708001.5 (±7.5%) i/s -   18418859 in   5.001811s
fetch(:as) {} (existing)      3721445.4 (±7.2%) i/s -   18501792 in   5.001294s
fetch(:as) {} (non existing)  2900120.0 (±5.5%) i/s -   14490268 in   5.014043s

=end