InsecureRandom benchmarks

insecurerandom.rb

# I wanted to make InsecureRandom.uuid to speed up specs, but

require 'securerandom'
require 'benchmark/ips'

Benchmark.ips do |x|
  x.report("sec") { SecureRandom.random_bytes(16) }
  x.report("rand") { Random::DEFAULT.bytes(16) }
end if ARGV[0] == '1'

# non secure is faster, which makes sense, so we should be able to use that to make InsecureRandom.uuid

#  sec    725.230k (± 9.6%) i/s -      3.636M in   5.068545s
# rand      5.470M (±12.0%) i/s -     27.096M in   5.036877s


# SecureRandom.uuid is implemented like this
# File securerandom.rb, line 246
# def self.uuid
#   ary = self.random_bytes(16).unpack("NnnnnN")
#   ary[2] = (ary[2] & 0x0fff) | 0x4000
#   ary[3] = (ary[3] & 0x3fff) | 0x8000
#   "%08x-%04x-%04x-%04x-%04x%08x" % ary
# end


module InsecureRandom
  def self.uuid
    ary = Random::DEFAULT.bytes(16).unpack("NnnnnN")
    ary[2] = (ary[2] & 0x0fff) | 0x4000
    ary[3] = (ary[3] & 0x3fff) | 0x8000
    "%08x-%04x-%04x-%04x-%04x%08x" % ary
  end
end

Benchmark.ips do |x|
  x.report("insecure") { InsecureRandom.uuid }
  x.report("  secure") {   SecureRandom.uuid }
end if ARGV[0] = '2'

# insecure    184.782k (±32.6%) i/s -    795.504k in   5.015430s
#   secure    193.009k (±10.9%) i/s -    961.128k in   5.042140s

# but it isn't actually any faster. Is either unpack or printf actually that
# slow that it dominates the time?

try

module InsecureRandom
  FMT = "%08x-%04x-%04x-%04x-%04x%08x".freeze
  UP = "NnnnnN".freeze
  def self.uuid
    ary = Random::DEFAULT.bytes(16).unpack(UP)
    ary[2] = (ary[2] & 0x0fff) | 0x4000
    ary[3] = (ary[3] & 0x3fff) | 0x8000
    FMT % ary
  end
end

granted, SecureRandom should just implement that same trick.