在游戏中排行榜是很常见的需求，之前一直使用的是redis的sortedset，刚好看到一个lua的实现，于是就移植到golang版本，github地址：https://github.com/Skycrab/go-zset，使用方法和redis 的cli命令基本一致。

使用了cgo封装，skiplist的实现基本和redis的一致，虽然cgo用起来很方便，但涉及到C中回调go时比较费事，

感觉还不如lua来得清爽。

go-zet并没有提供持久化的方法，我在https://github.com/Skycrab/cham/blob/master/lib/zset/zset.go中提供了持久化。主要是没有好的持久化方案，不像redis使用rdb格式。在cham中，和redis一样，fork后写文件，

只不过我使用的是json格式。

//use fork snapshot to save
func (z *zset) BgStore(name string) error {
	f,err := helper.LockFile(name,true)
	if err != nil {
		return err
	}
	pid,errno := helper.Fork()
	if errno != 0 {
		return errors.New("fork error," + errno.Error())
	}
	//child
	if pid == 0 {
		buf := bufio.NewWriter(f)
		encoder := json.NewEncoder(buf)
		encoder.Encode(z.tbl)
		buf.Flush()
		f.Close()
		os.Exit(0)
	}

	return nil

}

helper代码如下：

package helper

import (
	"os"
	"runtime"
	"syscall"
)

func Fork() (int,syscall.Errno) {
	r1,r2,err := syscall.RawSyscall(syscall.SYS_FORK,0)
	if err != 0 {
		return 0,err
	}
	if runtime.GOOS == "darwin" && r2 == 1 {
		r1 = 1
	}
	return int(r1),0
}

// referer http://ikarishinjieva.github.io/blog/blog/2014/03/20/go-file-lock/
func LockFile(name string,truncate bool) (*os.File,error) {
	flag := os.O_RDWR | os.O_CREATE
	if truncate {
		flag |= os.O_TRUNC
	}
	f,err := os.OpenFile(name,flag,0666)
	if err != nil {
		return nil,err
	}
	if err := syscall.Flock(int(f.Fd()),syscall.LOCK_EX|syscall.LOCK_NB); err != nil {
		f.Close()
		return nil,err
	}
	return f,nil
}

看看test基本就知道用法了

package zset

import (
	"fmt"
	"testing"
	"time"
)

func equal(a []string,b []string) bool {
	if len(a) != len(b) {
		return false
	}
	for i := 0; i < len(a); i++ {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}

func assert(t *testing.T,ok bool,s string) {
	if !ok {
		t.Error(s)
	}
}

func TestBase(t *testing.T) {
	z := New()
	assert(t,z.Count() == 0,"empty Count error")
	z.Add(1,"12")
	z.Add(1,"32")
	assert(t,z.Count() == 2,"not empty Count error")
	var score float64
	var ex bool
	score,ex = z.score("12")
	assert(t,score == 1,"score error")
	z.Add(2,"12")
	assert(t,"after add duplicate Count error")
	score,score == 2,"after add score error")
	z.Rem("12")
	assert(t,z.Count() == 1,"after rem Count error")
	score,ex == false,"not exist score error")
	fmt.Println("")
}

func TestRangeByscore(t *testing.T) {
	z := New()
	z.Add(2,"22")
	z.Add(1,"11")
	z.Add(3,"33")
	s := "TestRangeByscore error"
	assert(t,equal(z.RangeByscore(2,3),[]string{"22","33"}),s)
	assert(t,equal(z.RangeByscore(0,5),[]string{"11","22",equal(z.RangeByscore(10,[]string{}),0),[]string{"33","11"}),s)
}

func TestRange(t *testing.T) {
	z := New()
	z.Add(100.1,"1")
	z.Add(100.9,"9")
	z.Add(100.5,"5")
	assert(t,equal(z.Range(1,[]string{"1","5","9"}),"Range1 error")
	assert(t,equal(z.Range(3,1),[]string{"9","1"}),"Range2 error")
	assert(t,equal(z.RevRange(1,2),"5"}),"RevRange1 error")
	assert(t,equal(z.RevRange(3,"RevRange2 error")

}

func TestRank(t *testing.T) {
	z := New()
	assert(t,z.Rank("kehan") == 0,"Rank empty error")
	z.Add(1111.1111,"kehan")
	assert(t,z.Rank("kehan") == 1,"Rank error")
	z.Add(222.2222,"lwy")
	assert(t,z.Rank("kehan") == 2,"Rank 2 error")
	assert(t,z.RevRank("kehan") == 1,"RevRank error")
}

func TestLimit(t *testing.T) {
	z := New()
	z.Add(1,"1")
	z.Add(2,"2")
	z.Add(3,"3")
	z.Limit(1)
	assert(t,"Limit error")
	assert(t,z.Rank("3") == 0,"Limit Rank error")
	z.Add(4.4,"4")
	z.Add(5.5,"5")
	z.Add(0.5,"0.5")
	z.Dump()
	assert(t,z.RevLimit(4) == 0,"RevLimit error")
	assert(t,z.RevLimit(0) == 4,"RevLimit2 error")
}

func TestStore(t *testing.T) {
	z := New()
	z.Add(1,"3")
	z.BgStore("zdb.json")
	go func() {
		time.Sleep(time.Second * 2)
		fmt.Println("continue add")
		z.Add(4,"4")
		z.Add(5,"5")
	}()

}

func TestReStore(t *testing.T) {
	z := New()
	assert(t,len(z.tbl) == 0,"restore error")
	z.ReStore("zdb.json")
	fmt.Println(z.tbl)
	assert(t,len(z.tbl) != 0,"restore2 error")
	assert(t,z.Count() == len(z.tbl),"restore3 error")
}