55 lines
1.8 KiB
Python
55 lines
1.8 KiB
Python
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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import time
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class SnowflakeManager(object):
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"""
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Twitter的雪花算法实现
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"""
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def __init__(self, start_time=1420041600000):
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self.start_time = start_time / 1000 # 以秒为单位
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self.last_timestamp = -1
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# 41 bits时间戳
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self.timestamp_shift = 22
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# 10 bits机器编号
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self.machine_id_shift = 12
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# 12 bits序列号
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self.sequence_shift = 0
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# 41 bits可以表示的最大值，2^41 - 1
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self.max_timestamp = -1 ^ (-1 << self.timestamp_shift)
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# 10 bits可以表示的最大值，2^10 - 1
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self.max_machine_id = -1 ^ (-1 << self.machine_id_shift)
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# 12 bits可以表示的最大值，2^12 - 1
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self.max_sequence = -1 ^ (-1 << self.sequence_shift)
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# 机器编号和序列号暂时不使用，可以通过参数传入
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self.machine_id = 0
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self.sequence = 0
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def next_id(self):
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timestamp = int(time.time())
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if timestamp < self.last_timestamp:
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raise ValueError('Current timestamp is less than last timestamp.')
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if timestamp == self.last_timestamp:
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self.sequence = (self.sequence + 1) & self.max_sequence
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if self.sequence == 0:
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timestamp = self.til_next_millis(self.last_timestamp)
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else:
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self.sequence = 0
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self.last_timestamp = timestamp
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return ((timestamp - int(self.start_time)) << self.timestamp_shift) | (
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self.machine_id << self.machine_id_shift) | self.sequence
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def til_next_millis(self, last_timestamp):
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timestamp = int(time.time())
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while timestamp <= last_timestamp:
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timestamp = int(time.time())
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return timestamp
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