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62 lines
1.4 KiB
62 lines
1.4 KiB
package helper
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import (
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"sync"
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"time"
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)
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// Snowflake 结构体
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type Snowflake struct {
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mu sync.Mutex
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startTime int64 // 起始时间戳，可以根据实际需求设置
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machineID int64 // 机器ID
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sequenceNum int64 // 序列号
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}
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// NewSnowflake 创建一个Snowflake实例
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func NewSnowflake(machineID int64) *Snowflake {
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return &Snowflake{
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startTime: getTimeStamp(),
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machineID: machineID,
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sequenceNum: 0,
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}
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}
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// Generate 生成一个唯一ID
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func (s *Snowflake) Generate() int64 {
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s.mu.Lock()
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defer s.mu.Unlock()
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currentTime := getTimeStamp()
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// 如果当前时间小于上一次生成ID的时间，说明时钟回拨，需要等待
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if currentTime < s.startTime {
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time.Sleep(time.Duration(s.startTime - currentTime))
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currentTime = getTimeStamp()
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}
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// 如果是同一毫秒内生成的ID，需要增加序列号
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if currentTime == s.startTime {
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s.sequenceNum++
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} else {
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s.sequenceNum = 0
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s.startTime = currentTime
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}
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// 如果序列号超过了12位的最大值，等待下一毫秒再生成ID
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if s.sequenceNum >= 1<<12 {
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time.Sleep(time.Millisecond)
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s.startTime = getTimeStamp()
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s.sequenceNum = 0
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}
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// 生成ID
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id := (currentTime-s.startTime)<<22 | (s.machineID << 12) | s.sequenceNum
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return id
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}
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// 获取当前时间戳（毫秒级）
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func getTimeStamp() int64 {
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return time.Now().UnixNano() / int64(time.Millisecond)
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}
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