update:Use the official sync.OnceFunc (#4840)

core/service/servicegroup.go

@@ -1,9 +1,10 @@
 package service
 
 import (
+	"sync"
+
 	"github.com/zeromicro/go-zero/core/logx"
 	"github.com/zeromicro/go-zero/core/proc"
-	"github.com/zeromicro/go-zero/core/syncx"
 	"github.com/zeromicro/go-zero/core/threading"
 )
 
@@ -35,7 +36,7 @@ type (
 // NewServiceGroup returns a ServiceGroup.
 func NewServiceGroup() *ServiceGroup {
 	sg := new(ServiceGroup)
-	sg.stopOnce = syncx.Once(sg.doStop)
+	sg.stopOnce = sync.OnceFunc(sg.doStop)
 	return sg
 }
 

core/syncx/once.go

@@ -1,11 +0,0 @@
-package syncx
-
-import "sync"
-
-// Once returns a func that guarantees fn can only called once.
-func Once(fn func()) func() {
-	once := new(sync.Once)
-	return func() {
-		once.Do(fn)
-	}
-}

core/syncx/once_test.go

@@ -1,33 +0,0 @@
-package syncx
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-func TestOnce(t *testing.T) {
-	var v int
-	add := Once(func() {
-		v++
-	})
-
-	for i := 0; i < 5; i++ {
-		add()
-	}
-
-	assert.Equal(t, 1, v)
-}
-
-func BenchmarkOnce(b *testing.B) {
-	var v int
-	add := Once(func() {
-		v++
-	})
-
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		add()
-	}
-	assert.Equal(b, 1, v)
-}