Time based uuid

gen.py

import random
from datetime import datetime, timezone

BASE62 = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
def encode(num, alphabet=BASE62):
    """Encode a positive number in Base X

    Arguments:
    - `num`: The number to encode
    - `alphabet`: The alphabet to use for encoding
    """
    base = len(alphabet)
    if num < base:
        return alphabet[num]
    arr = []
    while num:
        num, rem = divmod(num, base)
        arr.append(alphabet[rem])
    arr.reverse()
    return ''.join(arr)

epoch_bits = 33 # 2 ** 33 seconds == 272 years
fill_bits = 64 - epoch_bits
def guid():
    # epoch = datetime.utcfromtimestamp(1559355764)
    epoch = datetime(2017, 9, 9, tzinfo=timezone.utc)
    now = datetime.fromtimestamp(datetime.utcnow().timestamp(), tz=timezone.utc)
    rand_timestamp = f'{int((now - epoch).total_seconds() * 1000):b}'.zfill(epoch_bits)[:epoch_bits]
    # print(rand_timestamp)
    rand_bits = f'{random.getrandbits(fill_bits):b}'
    zfill = rand_bits.zfill(fill_bits)
    sixty_four = rand_timestamp + zfill
    return encode(int(sixty_four, 2))

loops = 0
avg = 0
while True:
    uniq = set()
    count = 0
    while len(uniq) == count:
        count += 1
        # uniq.add(random.getrandbits(23))
        g = guid()
        uniq.add(g)
        # print(g)

    loops += 1

    print(count)
    avg += count
    print(avg / loops)