sharding_example.py

import random
import hashlib

_generated = set()


def rand_ip_part():
    return random.randint(0, 255)


def gen_ip():
    r = rand_ip_part
    return "%d.%d.%d.%d" % (r(), r(), r(), r())


def gen_uniq_ip():
    global _generated
    while True:
        ip = gen_ip()
        if ip not in _generated:
            _generated.add(ip)
            return ip


def should_redirect(ip):
    return int(hashlib.sha256(ip).hexdigest(), 16) % 100 >= 5


def main():
    yes = 0
    no = 0
    for x in xrange(0, 10000, 1):
        if should_redirect(gen_uniq_ip()):
            yes += 1
        else:
            no += 1
    print "YES:", yes, "NO:", no

if __name__ == '__main__':
    main()