How to easily get consistent object hash?

16

I also managed to try https://github.com/ysbaddaden/siphash.cr and it’s working better than FNV on big strings. I’ve made a comparison of these three: OpenSSL::SHA1, FNV and SipHash on 10, 100, 500 and 10k-sized strings. I’ve made my conclusions and I’m gonna give the developer a choice on what algorithm to use for a job.

Benchmark code 
require "openssl"
require "./fnv1a"
require "siphash"
require "benchmark"
require "random/secure"

payload_10 = ("a" * 10).to_slice
payload_100 = ("a" * 100).to_slice
payload_500 = ("a" * 500).to_slice
payload_10000 = ("a" * 10000).to_slice

sha_1digest = OpenSSL::Digest.new("SHA1")
siphash_key = StaticArray(UInt8, 16).new(0)

Benchmark.ips do |x|
  x.report "sha1 10" do
    hash = sha_1digest.update(payload_10).to_s
  end

  x.report "sha1 100" do
    hash = sha_1digest.update(payload_100).to_s
  end

  x.report "sha1 500" do
    hash = sha_1digest.update(payload_500).to_s
  end

  x.report "sha1 10000" do
    hash = sha_1digest.update(payload_10000).to_s
  end

  x.report "fnv1a 10" do
    hash = FNV.fnv1a_32(payload_10).to_s
  end

  x.report "fnv1a 100" do
    hash = FNV.fnv1a_32(payload_100).to_s
  end

  x.report "fnv1a 500" do
    hash = FNV.fnv1a_32(payload_500).to_s
  end

  x.report "fnv1a 10000" do
    hash = FNV.fnv1a_32(payload_10000).to_s
  end

  x.report "siphash 10" do
    hash = SipHash(1, 3).siphash(payload_10, siphash_key).to_s
  end

  x.report "siphash 100" do
    hash = SipHash(1, 3).siphash(payload_100, siphash_key).to_s
  end

  x.report "siphash 500" do
    hash = SipHash(1, 3).siphash(payload_500, siphash_key).to_s
  end

  x.report "siphash 10000" do
    hash = SipHash(1, 3).siphash(payload_10000, siphash_key).to_s
  end
end

Results:

      sha1 10 854.76k (  1.17µs) (± 0.82%)  368 B/op   17.50× slower
     sha1 100 710.62k (  1.41µs) (± 1.20%)  368 B/op   21.05× slower
     sha1 500 468.16k (  2.14µs) (± 0.96%)  368 B/op   31.95× slower
   sha1 10000  54.48k ( 18.36µs) (± 4.26%)  368 B/op  274.55× slower
     fnv1a 10  14.96M ( 66.86ns) (± 1.15%)   32 B/op         fastest
    fnv1a 100   4.04M (247.47ns) (± 1.57%)   32 B/op    3.70× slower
    fnv1a 500 971.51k (  1.03µs) (± 2.13%)   32 B/op   15.40× slower
  fnv1a 10000  53.39k ( 18.73µs) (± 2.13%)   32 B/op  280.18× slower
   siphash 10   8.74M (114.47ns) (± 0.86%)   32 B/op    1.71× slower
  siphash 100   5.23M (191.16ns) (± 0.81%)   48 B/op    2.86× slower
  siphash 500   2.24M (445.82ns) (± 0.91%)   48 B/op    6.67× slower
siphash 10000 161.62k (  6.19µs) (± 2.34%)   48 B/op   92.55× slower