From 814bdf7d293b16c07d0206fd6682fc7a9d725b3f Mon Sep 17 00:00:00 2001
From: guzeng <guzeng@tetele.net>
Date: Mon, 4 Sep 2023 10:20:25 +0800
Subject: [PATCH] =?UTF-8?q?=E5=A2=9E=E5=8A=A0=E9=9B=AA=E8=8A=B1=E7=AE=97?=
 =?UTF-8?q?=E6=B3=95=E5=AE=9E=E7=8E=B0=E6=96=B9=E6=B3=95?=
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---
 snowflake.go      | 62 +++++++++++++++++++++++++++++++++++++++++++++++
 snowflake_test.go | 16 ++++++++++++
 2 files changed, 78 insertions(+)
 create mode 100644 snowflake.go
 create mode 100644 snowflake_test.go

diff --git a/snowflake.go b/snowflake.go
new file mode 100644
index 0000000..eecb0ed
--- /dev/null
+++ b/snowflake.go
@@ -0,0 +1,62 @@
+package helper
+
+import (
+	"sync"
+	"time"
+)
+
+// Snowflake 结构体
+type Snowflake struct {
+	mu          sync.Mutex
+	startTime   int64 // 起始时间戳，可以根据实际需求设置
+	machineID   int64 // 机器ID
+	sequenceNum int64 // 序列号
+}
+
+// NewSnowflake 创建一个Snowflake实例
+func NewSnowflake(machineID int64) *Snowflake {
+	return &Snowflake{
+		startTime:   getTimeStamp(),
+		machineID:   machineID,
+		sequenceNum: 0,
+	}
+}
+
+// Generate 生成一个唯一ID
+func (s *Snowflake) Generate() int64 {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	currentTime := getTimeStamp()
+
+	// 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
+	if currentTime < s.startTime {
+		time.Sleep(time.Duration(s.startTime - currentTime))
+		currentTime = getTimeStamp()
+	}
+
+	// 如果是同一毫秒内生成的ID，需要增加序列号
+	if currentTime == s.startTime {
+		s.sequenceNum++
+	} else {
+		s.sequenceNum = 0
+		s.startTime = currentTime
+	}
+
+	// 如果序列号超过了12位的最大值，等待下一毫秒再生成ID
+	if s.sequenceNum >= 1<<12 {
+		time.Sleep(time.Millisecond)
+		s.startTime = getTimeStamp()
+		s.sequenceNum = 0
+	}
+
+	// 生成ID
+	id := (currentTime-s.startTime)<<22 | (s.machineID << 12) | s.sequenceNum
+
+	return id
+}
+
+// 获取当前时间戳（毫秒级）
+func getTimeStamp() int64 {
+	return time.Now().UnixNano() / int64(time.Millisecond)
+}
diff --git a/snowflake_test.go b/snowflake_test.go
new file mode 100644
index 0000000..4e3375e
--- /dev/null
+++ b/snowflake_test.go
@@ -0,0 +1,16 @@
+package helper
+
+import (
+	"testing"
+)
+
+func Test_snowflake(t *testing.T) {
+
+	// 创建一个Snowflake实例
+	snowflake := NewSnowflake(169379266710)
+	// 生成10个唯一ID并输出
+	for i := 0; i < 10; i++ {
+		id := snowflake.Generate()
+		t.Log(id)
+	}
+}