Some small benchmarks used during the creation of kramdown

small_benchmarks.rb

# -*- coding: utf-8 -*-
require 'benchmark'
class Test

  CONST = 5
  N = 1_000_000

  def test_const
    Benchmark.bm 20 do |results|
      results.report 'one' do
        N.times { CONST }
      end
      results.report "two" do
        N.times { self.class::CONST}
      end
    end
  end

  def test_string_insert
    Benchmark.bm 20 do |results|
      x = 'my'
      results.report 'one' do
        N.times { s = "data"; s.insert(0, x) }
      end
      results.report "two" do
        N.times { s = "data"; s = "#{x}#{s}" }
      end
    end
  end

  # one/two simliar, three slower
  def test_string_concat
    Benchmark.bm 20 do |results|
      x = 'my' * 100
      results.report 'one' do
        N.times { "data#{x}" }
      end
      results.report "two" do
        N.times { "data" << x }
      end
      results.report 'three' do
        N.times { "data" + x }
      end
    end
  end

  # similar performance
  def test_assignment
    Benchmark.bm 20 do |results|
      results.report 'one' do
        N.times { x = {}; x[5] = 6; x[7] = 8 }
      end
      results.report "two" do
        N.times { (x ||= {})[5] = 6; (x ||= {})[7] = 8 }
      end
    end
  end

  # getch about 35% faster
  def test_strscan_getch
    require 'strscan'
    y = StringScanner.new("hallöchen")
    Benchmark.bm 20 do |results|
      results.report 'one' do
        N.times { y.reset; 8.times {y.scan(/./)} }
      end
      results.report "two" do
        N.times { y.reset; 8.times {y.getch} }
      end
    end
  end

  # rest about 55% (47%) faster (with setting position to eos)
  def test_strscan_rest
    require 'strscan'
    y = StringScanner.new("hallöchen\nsome\nother data")
    Benchmark.bm 20 do |results|
      results.report 'one' do
        N.times { y.pos = 4; y.scan(/.*/m) }
      end
      results.report "two" do
        N.times { y.pos = 4; y.rest; y.terminate }
      end
    end
  end

  INDENT = /^(?:\t| {4})/

  # two about 60% faster
  def test_string_gsub
    y = "    this is some string\n    with some data\n    that continues here"
    Benchmark.bm 20 do |results|
      results.report 'one' do
        N.times { y.gsub(/\n( {0,3}\S)/, ' \\1').gsub!(INDENT, '') }
      end
      results.report "two" do
        N.times { x = y; x.gsub!(/\n( {0,3}\S)/, ' \\1'); x.gsub!(INDENT, '') }
      end
    end
  end

  # two about 35% faster (using ! methods and using normal methods)
  def test_string_gsub_vs_tr
    y = "123. hallo ich habe! <span>hiere</span>"
    Benchmark.bm 20 do |results|
      results.report 'one' do
        N.times { x = y.dup; x.gsub!(/^[^a-zA-Z]+|[^a-zA-Z0-9 -]+/, ''); x.gsub!(' ', '-') }
      end
      results.report "two" do
        N.times { x = y.dup; x.gsub!(/^[^a-zA-Z]+/, ''); x.tr!('^a-zA-Z0-9 -', ''); x.tr!(' ', '-')}
      end
    end
  end

  def invoke_me
  end

  # two about 50% faster (using either hash line)
  def test_invoke_method
    me = :me
    hash = Hash.new {|h,k| h[k] = "invoke_#{k}"}
    #hash = {:me => "invoke_me"}
    Benchmark.bm 20 do |results|
      results.report 'one' do
        N.times { send("invoke_#{me}") }
      end
      results.report "two" do
        N.times { send(hash[me]) }
      end
    end
  end

  # similar runtimes
  def test_string_times
    Benchmark.bm 20 do |results|
      results.report 'one' do
        N.times { indent = 2; indent += 2; ' '*indent }
      end
      results.report "two" do
        N.times { indent = '  '; indent += indent; indent }
      end
    end
  end

  # runtimes are equal
  def test_string_concat2
    Benchmark.bm 20 do |results|
      x = 'my'
      results.report 'one' do
        N.times { "data#{x}>#{x}\n" }
      end
      results.report "two" do
        N.times { "data" << x << '>' << x << "\n" }
      end
    end
  end

  # simliar runtimes
  def test_regexp_match
    Benchmark.bm 20 do |results|
      x = "my some thing is\nasdfasd fsad fasdf adsf \ndsaf adfadsfsa\n"
      results.report 'one' do
        N.times { x =~ /\n\Z/ }
      end
      results.report "two" do
        N.times { x[-1,1] == "\n" }
      end
    end
  end

  # two 50% faster
  def test_equal_vs_regexp_match
    Benchmark.bm 20 do |results|
      x = "script"
      results.report 'one' do
        N.times { x =~ /^script$/ }
      end
      results.report "two" do
        N.times { x == 'script' }
      end
    end
  end

  # two 50% faster
  def test_equal_vs_regexp_match2
    Benchmark.bm 20 do |results|
      x = "script"
      re = /^script$/
      results.report 'one' do
        N.times { x =~ re }
      end
      results.report "two" do
        N.times { x == 'script' }
      end
    end
  end

  attr_accessor :accessor_test_1
  def accessor_test_2
    @accessor_test_2
  end

  # one 33% faster on Ruby 1.8.7, 6% on 1.9.2
  def test_accessors
    @accessor_test_1 = 1
    @accessor_test_2 = 1
    Benchmark.bm do |results|
      results.report 'one' do
        N.times { accessor_test_1 }
      end
      results.report "two" do
        N.times { accessor_test_2 }
      end
    end
  end


  attr_accessor :assign_test_1
  def assign_test_3
    @assign_test_1 ||= []
  end
  def assign_test_2
    @assign_test_2 ||= []
    #only useful when done on few objects on methods that are accessed often
    class << self; attr_accessor :assign_test_2; end
  end

  # one 40% faster when two=assign_test_3, equal when two=assign_test_2
  def test_accessors
    @assign_test_1 = []
    Benchmark.bm do |results|
      results.report 'one' do
        N.times { assign_test_1 }
      end
      results.report "two" do
        N.times { assign_test_2 }
      end
    end
  end


  # ary.select {|d| }.length vs ary.count
  def test_select_length_vs_count
    ary = []
    1.upto(1000) {|i| ary << rand(100)}
    Benchmark.bm do |results|
      results.report 'one' do
        N.times { ary.count {|c| c > 50} }
      end
      results.report "two" do
        N.times { ary.select {|c| c > 50}.length }
      end
    end
  end


  # 
  def test_unpack_vs_ord
    string = "abcd".force_encoding('ASCII-8BIT')
    x = nil
    Benchmark.bm do |results|
      results.report 'one' do
        N.times { x = string.unpack('C4'); (x[0] << 21) + (x[1] << 14) + (x[2] << 7) + x[3] }
      end
      results.report "two" do
        N.times { (string[0].ord << 21) + (string[1].ord << 14) + (string[2].ord << 7) + string[3].ord }
      end
    end
  end

  def test_camelize
    s = "my_underscore"
    Benchmark.bm do |results|
      re1 = /^(\w)|_(\w)/
      results.report 'one' do
        N.times { x = s.dup; x.gsub!(re1) { ($1 || $2).upcase } }
      end
      results.report "two" do
        N.times { x = s.dup; x.split('_').inject(''){ |s,x| s << x[0..0].upcase + x[1..-1] } }
      end
      re2 = /_/
      results.report "three" do
        N.times { x = s.dup; x.split(re2).inject(''){ |s,x| s << x[0..0].upcase + x[1..-1] } }
      end
    end
  end

  # two about 20% faster on 1.8.7, 8% faster on 1.9.3
  def test_regexp_creation
    Benchmark.bm 20 do |results|
      x = "script"
      re = /^script$/
      results.report 'one' do
        N.times { x =~ re }
      end
      results.report "two" do
        N.times { x =~ /^script$/ }
      end
    end
  end

end

# Change this to run a benchmark
Test.new.test_regexp_creation