pysnowflake

from datetime import datetime
import threading

tlock = threading.Lock()

machineId = 0 #机器ID
datacenterId = 0 # 数据ID

sequence = 0 # 计数从零开始

twepoch = 687888001020 # 唯一时间随机量

machineIdBits = 5 # 机器码位数  
datacenterIdBits = 5 # 数据位数  
maxMachineId = -1 ^ -1 << machineIdBits # 最大机器ID  
maxDatacenterId = -1 ^ (-1 << datacenterIdBits) # 最大数据ID  

sequenceBits = 12 # 计数器位数，12个位用来保存计数码          
machineIdShift = sequenceBits # 机器码数据左移位数，就是后面计数器占用的位数  
datacenterIdShift = sequenceBits + machineIdBits
timestampLeftShift = sequenceBits + machineIdBits + datacenterIdBits # 时间戳左移动位数就是机器码+计数器总位数+数据位数  
sequenceMask = -1 ^ -1 << sequenceBits # 一微秒内可以产生计数，如果达到该值则等到下一微妙在进行生成  

lastTimestamp = -1 # 最后时间戳  



def getTimestamp():
    return int(datetime.now().timestamp() * 1000)


def getNextTimestamp(lastTimestamp):
    timestamp = getTimestamp()
    while timestamp <= lastTimestamp:
        timestamp = getTimestamp()
    return timestamp



def getId():
    '''
    线程安全的
    '''
    # plock.acquire()
    with tlock:
        global lastTimestamp, sequence
        timestamp = getTimestamp()
        if lastTimestamp == timestamp:
            # 同一微妙中生成ID  
            sequence = (sequence + 1) & sequenceMask # 用&运算计算该微秒内产生的计数是否已经到达上限
            if sequence == 0: 
                # 一微妙内产生的ID计数已达上限，等待下一微妙  
                timestamp = getNextTimestamp(lastTimestamp)
        else:
            #不同微秒生成ID  
            sequence = 0
        
        if timestamp < lastTimestamp:
            raise Exception("时间戳比上一次生成ID时时间戳还小，故异常")
        lastTimestamp = timestamp # 把当前时间戳保存为最后生成ID的时间戳  
        # print(((timestamp - twepoch) << timestampLeftShift), sequence)#, file=open('t.txt', 'a'))
        Id = ((timestamp - twepoch) << timestampLeftShift)\
            | (datacenterId << datacenterIdShift)\
            | (machineId << machineIdShift)\
            | sequence
        # tlock.release()
        # plock.release()
        return Id

from pysnowflake import getId
import threading

def getIds(l):
    l.extend([getId() for i in range(10)])


if __name__ == '__main__':
    l = []
    ts = []
    for i in range(10):
        ts.append(threading.Thread(target=getIds, args=(l,)))
    for t in ts:
        t.start()
        t.join()
    assert len(l) == 100, 'Error'