go语言生成雪花算法代码

下面是一个简单的 Go 代码示例，用于生成雪花算法的 ID：

package main

import (
    "fmt"
    "sync"
    "time"
)

const (
    workerBits uint8 = 10
    sequenceBits uint8 = 12
    maxWorkerID int64 = -1 ^ (-1 << workerBits)
    maxSequence int64 = -1 ^ (-1 << sequenceBits)
    epoch int64 = 1600000000000 // 2020-09-13 00:00:00 UTC
)

type Snowflake struct {
    mutex sync.Mutex
    lastTimestamp int64
    workerID int64
    sequence int64
}

func NewSnowflake(workerID int64) *Snowflake {
    if workerID < 0 || workerID > maxWorkerID {
        panic(fmt.Sprintf("worker ID must be between 0 and %d", maxWorkerID))
    }
    return &Snowflake{
        lastTimestamp: 0,
        workerID: workerID,
        sequence: 0,
    }
}

func (sf *Snowflake) NextID() int64 {
    sf.mutex.Lock()
    defer sf.mutex.Unlock()

    now := time.Now().UnixNano() / 1000000 // convert to milliseconds
    if now < sf.lastTimestamp {
        panic(fmt.Sprintf("clock moved backwards, refusing to generate ID for %d milliseconds", sf.lastTimestamp-now))
    }

    if now == sf.lastTimestamp {
        sf.sequence = (sf.sequence + 1) & maxSequence
        if sf.sequence == 0 {
            now = sf.waitNextMillisecond(now)
        }
    } else {
        sf.sequence = 0
    }

    sf.lastTimestamp = now
    return (now-epoch) << (workerBits+sequenceBits) | sf.workerID << sequenceBits | sf.sequence
}

func (sf *Snowflake) waitNextMillisecond(currentTimestamp int64) int64 {
    for {
        now := time.Now().UnixNano() / 1000000
        if now > currentTimestamp {
            return now
        }
    }
}

func main() {
    sf := NewSnowflake(1)
    for i := 0; i < 10; i++ {
        fmt.Println(sf.NextID())
    }
}

该代码使用了互斥锁来防止多个 Goroutine 同时生成相同的 ID。它还实现了一个等待下一个毫秒的函数，以防止在同一毫秒内生成多个 ID。您可以根据自己的需求调整 workerBits 和 sequenceBits 变量的值。