标准 snowflake

github.com/bwmarrin/snowflake 是一个相当轻量化的 snowflake 的 Go 实现。其文档对各位使用的定义如下图所示：

此库和标准的 snowflake 实现方式全完一致，使用也比较简单：

package main

import (
    // 示例代码只导入提供核心功能的package，其他内置package自行导入，下同
    "github.com/bwmarrin/snowflake"
)

func main() {
    node, err := snowflake.NewNode(1)
    if err != nil {
        println(err.Error())
        os.Exit(1)
    }

    for i := 0; i < 20; i++ {
        id := node.Generate()

        fmt.Printf("Int64  ID: %d\n", id)
        fmt.Printf("String ID: %s\n", id)
        fmt.Printf("Base2  ID: %s\n", id.Base2())
        fmt.Printf("Base64 ID: %s\n", id.Base64())

        fmt.Printf("ID Time  : %d\n", id.Time())

        fmt.Printf("ID Node  : %d\n", id.Node())

        fmt.Printf("ID Step  : %d\n", id.Step())

        fmt.Println("---------------------------------------------")
    }

}

这个库因为是单文件，所以也方便定制，其源码本身就预留了一些可定制字段：

var (
    // Epoch is set to the twitter snowflake epoch of Nov 04 2010 01:42:54 UTC in milliseconds
    // You may customize this to set a different epoch for your application.
    Epoch int64 = 1288834974657

    // NodeBits holds the number of bits to use for Node
    // Remember, you have a total 22 bits to share between Node/Step
    NodeBits uint8 = 10

    // StepBits holds the number of bits to use for Step
    // Remember, you have a total 22 bits to share between Node/Step
    StepBits uint8 = 12
)

Epoch为起始时间，NodeBits是实例id的位长，StepBits是自增id的位长。