py3 snowflake脚本

Snowflake是一种用于生成唯一ID的算法，可以保证在分布式系统中每个节点生成的ID不会重复。以下是一个基于Python 3的Snowflake脚本示例：

import time

class Snowflake:
    def __init__(self, worker_id, data_center_id, sequence=0):
        self.worker_id = worker_id
        self.data_center_id = data_center_id
        self.sequence = sequence
        self.epoch = 1585644267000  # 2020-03-31 16:17:47

    def get_timestamp(self):
        return int(time.time() * 1000)

    def next_id(self):
        timestamp = self.get_timestamp()
        if timestamp < self.last_timestamp:
            raise Exception('Clock moved backwards, waiting for a new timestamp')
        if timestamp == self.last_timestamp:
            self.sequence = (self.sequence + 1) & 4095
            if self.sequence == 0:
                timestamp = self.wait_for_next_millis()
        else:
            self.sequence = 0
        self.last_timestamp = timestamp
        return ((timestamp - self.epoch) << 22) | (self.data_center_id << 17) | (self.worker_id << 12) | self.sequence

    def wait_for_next_millis(self):
        timestamp = self.get_timestamp()
        while timestamp <= self.last_timestamp:
            timestamp = self.get_timestamp()
        return timestamp

if __name__ == '__main__':
    worker_id = 1
    data_center_id = 1
    snowflake = Snowflake(worker_id, data_center_id)
    print(snowflake.next_id())

这个脚本定义了一个Snowflake类，该类接受3个参数：worker_id，data_center_id和sequence。其中，worker_id和data_center_id用于标识不同的节点，sequence用于在相同的毫秒内生成新的ID。脚本使用time模块获取当前时间戳，并将其转换为毫秒级别。在生成ID时，脚本会先检查时间戳是否向后移动，然后根据当前时间戳、worker_id、data_center_id和sequence计算出一个唯一的ID。如果在相同的毫秒内生成新的ID，则会增加sequence的值，如果sequence的值达到了最大值（4095），则需要等待下一个毫秒再生成ID。