83 lines
2.5 KiB
Python
83 lines
2.5 KiB
Python
# -*- coding: utf-8 -*-
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"""
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@author: cxyfreedom
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@desc: 基于 snowflake 生成分布式ID
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"""
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import time
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# 每一部分占用的位数
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TIMESTAMP_BIT = 41 # 时间戳占用位数
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MACHINE_BIT = 5 # 机器标识占用的位数
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DATACENTER_BIT = 5 # 数据中心占用的位数
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SEQUENCE_BIT = 12 # 序列号占用的位数
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# 每一部分的最大值
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MAX_DATACENTER_NUM = -1 ^ (-1 << DATACENTER_BIT)
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MAX_MACHINE_NUM = -1 ^ (-1 << MACHINE_BIT)
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MAX_SEQUENCE = -1 ^ (-1 << SEQUENCE_BIT)
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# 每一部分向左的位移
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MACHINE_LEFT = SEQUENCE_BIT
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DATACENTER_LEFT = MACHINE_BIT + SEQUENCE_BIT
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TIMESTAMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT
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class SnowFlake:
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class OverflowError(TypeError):
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"""
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分布式ID生成算法占位符溢出异常，会导致生成ID为负数
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"""
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pass
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class RuntimeError(TypeError):
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"""
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运行时间错误，在此项目中当前运行时间小于上一次运行时间。
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"""
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pass
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def __init__(self):
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if TIMESTAMP_BIT + SEQUENCE_BIT + MACHINE_BIT + DATACENTER_BIT != 63:
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raise self.OverflowError(
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"TIMESTAMP_BIT + SEQUENCE_BIT + MACHINE_BIT + DATACENTER_BIT not equal to 63bit")
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self.datacenter_id = 0 # 数据中心编号
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self.machineId = 0 # 机器标识编号
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self.sequence = 0 # 序列号
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self.last_stamp = -1 # 上一次时间戳
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def nextId(self):
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"""生成下一个ID"""
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cur_stamp = self.get_new_stamp()
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if cur_stamp < self.last_stamp:
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raise self.RuntimeError(
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"Clock moved backwards. Refusing to generate id")
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if cur_stamp == self.last_stamp:
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# 相同毫秒内，序列号自增
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self.sequence = (self.sequence + 1) & MAX_SEQUENCE
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# 同一秒的序列数已经达到最大
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if self.sequence == 0:
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cur_stamp = self.get_next_mill()
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else:
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# 不同秒内，序列号为0
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self.sequence = 0
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self.last_stamp = cur_stamp
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return (cur_stamp << TIMESTAMP_LEFT) | (
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self.datacenter_id << DATACENTER_LEFT) | (
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self.machineId << MACHINE_LEFT) | self.sequence
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def get_next_mill(self):
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mill = self.get_new_stamp()
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while mill <= self.last_stamp:
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mill = self.get_new_stamp()
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return mill
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@staticmethod
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def get_new_stamp():
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now = lambda: int(time.time() * 1000)
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return now()
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if __name__ == "__main__":
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print(SnowFlake().nextId())
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