# Twitter's Snowflake algorithm implementation which is used to generate distributed IDs.
# https://github.com/twitter-archive/snowflake/blob/snowflake-2010/src/main/scala/com/twitter/service/snowflake/IdWorker.scalaimport time
import loggingclass InvalidSystemClock(Exception):"""时钟回拨异常"""pass# 64位ID的划分
WORKER_ID_BITS = 5
DATACENTER_ID_BITS = 5
SEQUENCE_BITS = 12# 最大取值计算
MAX_WORKER_ID = -1 ^ (-1 << WORKER_ID_BITS)  # 2**5-1 0b11111
MAX_DATACENTER_ID = -1 ^ (-1 << DATACENTER_ID_BITS)# 移位偏移计算
WOKER_ID_SHIFT = SEQUENCE_BITS
DATACENTER_ID_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS
TIMESTAMP_LEFT_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS + DATACENTER_ID_BITS# 序号循环掩码
SEQUENCE_MASK = -1 ^ (-1 << SEQUENCE_BITS)# Twitter元年时间戳
TWEPOCH = 1288834974657logger = logging.getLogger('flask.app')class IdWorker(object):"""用于生成IDs"""def __init__(self, datacenter_id, worker_id, sequence=0):"""初始化:param datacenter_id: 数据中心（机器区域）ID:param worker_id: 机器ID:param sequence: 其实序号"""# sanity checkif worker_id > MAX_WORKER_ID or worker_id < 0:raise ValueError('worker_id值越界')if datacenter_id > MAX_DATACENTER_ID or datacenter_id < 0:raise ValueError('datacenter_id值越界')self.worker_id = worker_idself.datacenter_id = datacenter_idself.sequence = sequenceself.last_timestamp = -1  # 上次计算的时间戳def _gen_timestamp(self):"""生成整数时间戳:return:int timestamp"""return int(time.time() * 1000)def get_id(self):"""获取新ID:return:"""timestamp = self._gen_timestamp()# 时钟回拨if timestamp < self.last_timestamp:logging.error('clock is moving backwards. Rejecting requests until {}'.format(self.last_timestamp))raise InvalidSystemClockif timestamp == self.last_timestamp:self.sequence = (self.sequence + 1) & SEQUENCE_MASKif self.sequence == 0:timestamp = self._til_next_millis(self.last_timestamp)else:self.sequence = 0self.last_timestamp = timestampnew_id = ((timestamp - TWEPOCH) << TIMESTAMP_LEFT_SHIFT) | (self.datacenter_id << DATACENTER_ID_SHIFT) | \(self.worker_id << WOKER_ID_SHIFT) | self.sequencereturn new_iddef _til_next_millis(self, last_timestamp):"""等到下一毫秒"""timestamp = self._gen_timestamp()while timestamp <= last_timestamp:timestamp = self._gen_timestamp()return timestampif __name__ == '__main__':worker = IdWorker(1, 2, 0)print(worker.get_id())