Consistent String#hash based only on the string's content

Question

GOAL: Map every URL handled by a server to 0, 1, 2, or 3, distributing as uniformly as possible.

While the documentation for ruby\'s String#hash met

Answer 1

There is tiny library xxHash:

XXhash.xxh32('qwe') #=> 2396643526
XXhash.xxh64('qwe') #=> 9343136760830690622

Maybe it will have more collisions but it is 10x faster than SHA1:

Benchmark.bm do |x|
  n = 100_000
  str = 'qweqweqwe'
  x.report('xxhash32') { n.times { XXhash.xxh32(str) } }
  x.report('xxhash64') { n.times { XXhash.xxh64(str) } }
  x.report('hexadigest') { n.times { Digest::SHA1.hexdigest(str) } }
end;1

#       user     system      total        real
# xxhash32  0.020000   0.000000   0.020000 (  0.021948)
# xxhash64  0.040000   0.000000   0.040000 (  0.036340)
# hexadigest  0.240000   0.030000   0.270000 (  0.276443)