benchmark results

Warming up --------------------------------------
      functional_xor    16.702k i/100ms
        iterator_xor    17.805k i/100ms
            pack_xor    18.711k i/100ms
          .each_byte     3.232k i/100ms
              .bytes    16.976k i/100ms
            .getbyte    23.730k i/100ms
          .byteslice    17.928k i/100ms
          .getbyte 8    28.353k i/100ms
        .byteslice 8    19.803k i/100ms
     .getbyte + pack    32.979k i/100ms
                xor5    49.542k i/100ms
                xor6    18.426k i/100ms
          8byte hack    48.279k i/100ms
Calculating -------------------------------------
      functional_xor    193.317k (± 8.0%) i/s -    968.716k
        iterator_xor    208.020k (± 5.6%) i/s -      1.050M
            pack_xor    225.964k (± 8.5%) i/s -      1.123M
          .each_byte     36.867k (± 6.0%) i/s -    184.224k
              .bytes    215.284k (± 3.9%) i/s -      1.086M
            .getbyte    333.548k (± 4.5%) i/s -      1.685M
          .byteslice    221.040k (± 4.9%) i/s -      1.112M
          .getbyte 8    334.545k (± 4.8%) i/s -      1.673M
        .byteslice 8    221.638k (± 4.7%) i/s -      1.109M
     .getbyte + pack    400.701k (± 5.1%) i/s -      2.012M
                xor5    714.254k (± 5.5%) i/s -      3.567M
                xor6    235.222k (± 4.5%) i/s -      1.179M
          8byte hack    842.431k (± 4.7%) i/s -      4.249M

Comparison:
          8byte hack:   842430.8 i/s
                xor5:   714253.6 i/s - 1.18x slower
     .getbyte + pack:   400701.3 i/s - 2.10x slower
          .getbyte 8:   334545.4 i/s - 2.52x slower
            .getbyte:   333547.6 i/s - 2.53x slower
                xor6:   235221.8 i/s - 3.58x slower
            pack_xor:   225963.6 i/s - 3.73x slower
        .byteslice 8:   221637.5 i/s - 3.80x slower
          .byteslice:   221039.5 i/s - 3.81x slower
              .bytes:   215284.4 i/s - 3.91x slower
        iterator_xor:   208020.0 i/s - 4.05x slower
      functional_xor:   193316.5 i/s - 4.36x slower
          .each_byte:    36866.7 i/s - 22.85x slower

xor_bench.rb

require 'benchmark/ips'

STR1 = 'qwertyui'.freeze
STR2 = 'zxcvbnm,'.freeze


def functional_xor(str1, str2)
  str1.bytes.zip(str2.bytes).map { |byte1, byte2| (byte1 ^ byte2).chr }.join
end

def iterator_xor(str1, str2)
  result = "\x00" * str1.size

  str1_bytes = str1.bytes
  str2_bytes = str2.bytes

  str1_bytes.each_with_index do |byte, index|
    result[index] = (byte ^ str2_bytes[index]).chr
  end

  result
end

def pack_xor(str1, str2)
  str1.bytes.zip(str2.bytes).map { |byte1, byte2| byte1 ^ byte2 }.pack('C*')
end


Benchmark.ips do |x|
  # Configure the number of seconds used during
  # the warmup phase (default 2) and calculation phase (default 5)

  x.report('functional_xor') do
    functional_xor(STR1, STR2)
  end

  x.report('iterator_xor') do
    iterator_xor(STR1, STR2)
  end

  x.report('pack_xor') do
    pack_xor(STR1, STR2)
  end

  x.report('.each_byte') { STR1.each_byte.zip(STR2.each_byte).map { |byte1, byte2| (byte1 ^ byte2).chr }.join }
  x.report('.bytes') { STR1.bytes.zip(STR2.bytes).map { |b1, b2| (b1 ^ b2).chr }.join }
  x.report('.getbyte') { Array.new(STR1.bytesize) { |i| (STR1.getbyte(i) ^ STR2.getbyte(i)).chr }.join }
  x.report('.byteslice') { Array.new(STR1.bytesize) { |i| (STR1.byteslice(i).ord ^ STR2.byteslice(i).ord).chr }.join }
  x.report('.getbyte 8') { Array.new(8) { |i| (STR1.getbyte(i) ^ STR2.getbyte(i)).chr }.join }
  x.report('.byteslice 8') { Array.new(8) { |i| (STR1.byteslice(i).ord ^ STR2.byteslice(i).ord).chr }.join }

  x.report('.getbyte + pack') { Array.new(STR1.bytesize) { |i| STR1.getbyte(i) ^ STR2.getbyte(i) }.pack('C*') }

  x.report('xor5') do
    s = []
    STR1.unpack('Q*').zip(STR2.unpack('Q*')) {|a,b| s.push( (a||0) ^ (b||0) ) }
    s.pack('Q*')
  end

  x.report('xor6') do
    s = []
    STR1.unpack('C*').zip(STR2.unpack('C*')) {|a,b| s.push( (a||0) ^ (b||0) ) }
    s.pack('C*')
  end

  x.report('8byte hack') do
    [STR1.unpack('Q').first ^ STR2.unpack('Q').first].pack('Q')
  end

  x.compare!
end