Customizable and portable Snowflake generator

snowflake.py

import os
import time
from math import floor


class SnowflakeGenerator:
    def __init__(self, mid=None, time_start=1288834974657):
        self.time_start = time_start
        self.mid = mid if mid else os.getpid()

        self.seq = 0
        self.last_msec = 0

    def get(self):
        now = floor(time.time() * 1000)

        if now - self.time_start > (2**41 - 1):
            raise ValueError("Time larger than 2^41! The end is near...")

        if now < self.last_msec:
            wait = (self.last_msec - now) / 1000
            time.sleep(wait)
            now = floor(time.time() * 1000)

        if self.seq == 4096:
            if self.last_msec == now:
                wait = (now + 1 - time.time() * 1000) / 1000
                time.sleep(wait)
                now = floor(time.time() * 1000)
            self.seq = 0

        snowflake = self._construct(now - self.time_start, self.mid, self.seq)

        self.seq += 1
        self.last_msec = now

        return snowflake

    def parse(self, snowflake):
        seq = snowflake & (2**12 - 1)
        mid = (snowflake >> 12) & (2**10 - 1)
        time_ms = (snowflake >> 22) & (2**41 - 1)
        timestamp = (time_ms + self.time_start) / 1000

        return timestamp, mid, seq

    def _construct(self, now, mid, seq):
        snowflake = 0
        snowflake += now << 22
        snowflake += mid << 12
        snowflake += seq

        return snowflake