全局唯一id生成snowflake算法golang实现

snowflake.go

package snowflake
import (
 "fmt"
 "time"
 "errors"
)
/*
组成:0(1 bit) | timestamp in milli second (41 bit) | machine id (10 bit) | index (12 bit)
每毫秒最多生成4096个id,集群机器最多1024台
*/
type Snowflake struct {
 lastTimestamp int64
 index int16
 machId int16
}
func (s *Snowflake)Init(id int16) error {
 if id > 0xff {
 return errors.New("illegal machine id")
 }
 s.machId = id
 s.lastTimestamp = time.Now().UnixNano()/1e6
 s.index = 0
 return nil
}
func (s *Snowflake)GetId() (int64, error) {
 curTimestamp := time.Now().UnixNano()/1e6
 if (curTimestamp == s.lastTimestamp) {
 s.index++
 if(s.index>0xfff) {
 s.index = 0xfff
 return -1,errors.New("out of range")
 }
 } else {
 //fmt.Printf("id/ms:%d -- %d\n", s.lastTimestamp, s.index)
 s.index = 0
 s.lastTimestamp = curTimestamp
 }
 return int64((0x1ffffffffff & s.lastTimestamp) << 22) + int64(0xff << 10) + int64(0xfff & s.index),nil
}
var UUID Snowflake

单元测试
snowflake_test.go

package snowflake
import (
 "github.com/deckarep/golang-set"
 "testing"
)
// 生成1亿个ID看有没有重复
func TestSnowFlake( t *testing.T ) {
 UUID.Init(1024)
 s := mapset.NewSet()
 for i:=0;i<1e9;i++ {
 id,err := UUID.GetId()
 if err!= nil {
 t.FailNow()
 }
 if(s.Add(id) == false) {
 t.FailNow()
 }
 }
}

把代码都放到同一个文件夹下,运行

go test -v snowflake_test.go snowflake.go

本文来自:简书

感谢作者:小怪兽狂殴奥特曼

查看原文:全局唯一id生成snowflake算法golang实现

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