From 37e9cabde8ebe6c499e3e3af8e743d8d7726e6b3 Mon Sep 17 00:00:00 2001
From: charlie <3140647@qq.com>
Date: Mon, 25 Jul 2022 14:51:16 +0800
Subject: [PATCH] snow flake

---
 snow_flake/snow_flake.go      | 52 +++++++++++++++++++++------------
 snow_flake/snow_flake_test.go | 54 ++++++++++++++++++++++++++++++++++-
 2 files changed, 87 insertions(+), 19 deletions(-)

diff --git a/snow_flake/snow_flake.go b/snow_flake/snow_flake.go
index 18a3649..e381598 100644
--- a/snow_flake/snow_flake.go
+++ b/snow_flake/snow_flake.go
@@ -1,20 +1,22 @@
 package snowflake
 
 import (
+	"fmt"
+	"log"
 	"sync"
 	"time"
 )
 
-// 雪花算法默认起始时间 2020-01-01
-const defaultStarTimestamp = 1579536000
+// 雪花算法默认起始时间 2022-01-01
+const defaultStarTimestamp = 1640966400000
 
 const (
-	MachineIdBits = uint(8)  //机器id所占的位数
-	SequenceBits  = uint(12) //序列所占的位数
-	//MachineIdMax   = int64(-1 ^ (-1 << MachineIdBits)) //支持的最大机器id数量
-	SequenceMask   = int64(-1 ^ (-1 << SequenceBits)) //
-	MachineIdShift = SequenceBits                     //机器id左移位数
-	TimestampShift = SequenceBits + MachineIdBits     //时间戳左移位数
+	MachineIdBits  = uint(8)                           //机器id所占的位数
+	SequenceBits   = uint(12)                          //序列所占的位数
+	MachineIdMax   = int64(-1 ^ (-1 << MachineIdBits)) //支持的最大机器id数量
+	SequenceMask   = int64(-1 ^ (-1 << SequenceBits))  //
+	MachineIdShift = SequenceBits                      //机器id左移位数
+	TimestampShift = SequenceBits + MachineIdBits      //时间戳左移位数
 )
 
 type SnowFlake interface {
@@ -30,28 +32,42 @@ type snowflake struct {
 }
 
 func CreateSnowflake(machineId int64) SnowFlake {
+	timeBits := 63 - MachineIdBits - SequenceBits
+	maxTime := time.UnixMilli(defaultStarTimestamp + (int64(-1 ^ (-1 << timeBits))))
+	log.Println("最大可用时间:", maxTime)
+
 	return &snowflake{
 		startTimeStamp: defaultStarTimestamp,
-		machineId:      machineId,
+		machineId:      machineId & MachineIdMax,
 	}
 }
 
+// 组织方式   时间戳-机器码-序列号
 func (s *snowflake) GetId() int64 {
+
+	// 生成序列号规则
+	// 检查当前生成时间与上次生成时间对比
+	// 如等于上次生成时间，检查是否已经达到序列号的最大值，如已达到等待下一个时间点并且设置序列号为零。
+	// 如不相等则序列号自增
 	s.Lock()
 	defer s.Unlock()
 
-	now := time.Now().UnixNano() / 1e6
-	if s.timestamp == now {
-		s.sequence = (s.sequence + 1) & SequenceMask
-		if s.sequence == 0 {
-			for now <= s.timestamp {
-				now = time.Now().UnixNano() / 1e6
-			}
+	now := time.Now().UnixMilli()
+	if s.timestamp == now && s.sequence == 0 {
+		fmt.Println(time.Now().Format("2006-01-02 15:04:05.000"), "下一个时间点")
+		for now <= s.timestamp {
+			now = time.Now().UnixMilli()
 		}
-	} else {
-		s.sequence = 0
 	}
+
 	s.timestamp = now
+	s.sequence = (s.sequence + 1) & SequenceMask
+
+	log.Println("时间戳:", now-s.startTimeStamp)
+
+	log.Println("时间差:", time.Now().Sub(time.UnixMilli(defaultStarTimestamp)))
+
 	r := (now-s.startTimeStamp)<<TimestampShift | (s.machineId << MachineIdShift) | (s.sequence)
+
 	return r
 }
diff --git a/snow_flake/snow_flake_test.go b/snow_flake/snow_flake_test.go
index 4366d7f..e5bf90d 100644
--- a/snow_flake/snow_flake_test.go
+++ b/snow_flake/snow_flake_test.go
@@ -1,6 +1,15 @@
 package snowflake
 
-import "testing"
+import (
+	"testing"
+
+	"github.com/charlienet/go-mixed/sets"
+)
+
+func TestGet(t *testing.T) {
+	s := CreateSnowflake(2)
+	t.Log(s.GetId())
+}
 
 func TestGetId(t *testing.T) {
 	s := CreateSnowflake(22)
@@ -8,3 +17,46 @@ func TestGetId(t *testing.T) {
 		t.Log(s.GetId())
 	}
 }
+
+func TestMutiGetId(t *testing.T) {
+	s := CreateSnowflake(11)
+	for i := 0; i < 100000; i++ {
+		s.GetId()
+	}
+}
+
+func TestMutiConflict(t *testing.T) {
+	set := sets.NewHashSet[int64]()
+	s := CreateSnowflake(11)
+	for i := 0; i < 10000000; i++ {
+		id := s.GetId()
+		if set.Contains(id) {
+			t.Fatal("失败，生成重复数据")
+		}
+
+		set.Add(id)
+	}
+}
+
+func BenchmarkGetId(b *testing.B) {
+	s := CreateSnowflake(11)
+	for i := 0; i < b.N; i++ {
+		s.GetId()
+	}
+}
+
+func BenchmarkMutiGetId(b *testing.B) {
+	s := CreateSnowflake(11)
+	set := sets.NewHashSet[int64]().WithSync()
+	b.RunParallel(func(p *testing.PB) {
+		for i := 0; p.Next(); i++ {
+			id := s.GetId()
+
+			if set.Contains(id) {
+				b.Fatal("标识重复", id)
+			}
+
+			set.Add(id)
+		}
+	})
+}