71 lines
2.4 KiB
Python
71 lines
2.4 KiB
Python
import threading
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import time
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class SnowflakeIDGenerator:
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# 目标：总比特数约40位，十进制最多12位（2^40 ≈ 1.1e12）
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# 时间戳用28位（可覆盖约8.5年），机器ID用6位（64台），序列号用6位（每毫秒64个）
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TIMESTAMP_BITS = 28
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WORKER_ID_BITS = 6
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SEQUENCE_BITS = 6
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# 起始时间戳（2025-01-01 00:00:00 UTC），单位毫秒
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CUSTOM_EPOCH = 1735689600000
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MAX_WORKER_ID = -1 ^ (-1 << WORKER_ID_BITS)
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MAX_SEQUENCE = -1 ^ (-1 << SEQUENCE_BITS)
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# 移位计算
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WORKER_ID_SHIFT = SEQUENCE_BITS
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TIMESTAMP_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS
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def __init__(self, worker_id, sequence=0):
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if worker_id > self.MAX_WORKER_ID or worker_id < 0:
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raise ValueError(f"Worker ID must be between 0 and {self.MAX_WORKER_ID}")
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self.worker_id = worker_id
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self.sequence = sequence
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self.last_timestamp = -1
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self.lock = threading.Lock()
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def _wait_next_ms(self, last_ts):
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ts = self._now()
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while ts <= last_ts:
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ts = self._now()
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return ts
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def _now(self):
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return int(time.time() * 1000)
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def generate_id(self):
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with self.lock:
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ts = self._now()
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if ts < self.last_timestamp:
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raise Exception("Clock moved backwards")
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if ts == 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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ts = self._wait_next_ms(self.last_timestamp)
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else:
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self.sequence = 0
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self.last_timestamp = ts
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# 相对时间（毫秒），只取低TIMESTAMP_BITS位
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relative_ts = (ts - self.CUSTOM_EPOCH) & ((1 << self.TIMESTAMP_BITS) - 1)
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new_id = (relative_ts << self.TIMESTAMP_SHIFT) | \
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(self.worker_id << self.WORKER_ID_SHIFT) | \
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self.sequence
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return new_id
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def generate_str(self):
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return str(self.generate_id())
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# 全局生成器实例 (worker_id和datacenter_id需在分布式环境中保证唯一)
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# 单机开发环境可暂时固定，生产环境建议通过配置中心或启动参数传入
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generator = SnowflakeIDGenerator(worker_id=1)
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if __name__ == "__main__":
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print(generator.generate_id())
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print(type(generator.generate_id()))
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print(generator.generate_str())
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