Fix the issue of incorrect values notified in the configuration center (#5348)

core/configcenter/subscriber/etcd.go

@@ -3,6 +3,8 @@ package subscriber
 import (
 	"github.com/zeromicro/go-zero/core/discov"
 	"github.com/zeromicro/go-zero/core/logx"
+	"sync"
+	"sync/atomic"
 )
 
 type (
@@ -37,6 +39,7 @@ func NewEtcdSubscriber(conf EtcdConf) (Subscriber, error) {
 func buildSubOptions(conf EtcdConf) []discov.SubOption {
 	opts := []discov.SubOption{
 		discov.WithExactMatch(),
+		discov.WithContainer(newConfigCenterContainer()),
 	}
 
 	if len(conf.User) > 0 {
@@ -65,3 +68,47 @@ func (s *etcdSubscriber) Value() (string, error) {
 
 	return "", nil
 }
+
+type configCenterContainer struct {
+	value     atomic.Value
+	lock      sync.Mutex
+	listeners []func()
+}
+
+func newConfigCenterContainer() *configCenterContainer {
+	return &configCenterContainer{}
+}
+
+func (c *configCenterContainer) OnAdd(kv discov.KV) {
+	c.value.Store([]string{kv.Val})
+	c.notifyChange()
+}
+
+func (c *configCenterContainer) OnDelete(_ discov.KV) {
+	c.value.Store([]string(nil))
+	c.notifyChange()
+}
+
+func (c *configCenterContainer) AddListener(listener func()) {
+	c.lock.Lock()
+	c.listeners = append(c.listeners, listener)
+	c.lock.Unlock()
+}
+
+func (c *configCenterContainer) GetValues() []string {
+	vals, ok := c.value.Load().([]string)
+	if !ok {
+		return []string(nil)
+	}
+	return vals
+}
+
+func (c *configCenterContainer) notifyChange() {
+	c.lock.Lock()
+	listeners := append(([]func())(nil), c.listeners...)
+	c.lock.Unlock()
+
+	for _, listener := range listeners {
+		listener()
+	}
+}

core/configcenter/subscriber/etcd_test.go

@@ -0,0 +1,186 @@
+package subscriber
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/zeromicro/go-zero/core/discov"
+)
+
+const (
+	actionAdd = iota
+	actionDel
+)
+
+func TestConfigCenterContainer(t *testing.T) {
+	type action struct {
+		act int
+		key string
+		val string
+	}
+	tests := []struct {
+		name   string
+		do     []action
+		expect []string
+	}{
+		{
+			name: "add one",
+			do: []action{
+				{
+					act: actionAdd,
+					key: "first",
+					val: "a",
+				},
+			},
+			expect: []string{
+				"a",
+			},
+		},
+		{
+			name: "add two",
+			do: []action{
+				{
+					act: actionAdd,
+					key: "first",
+					val: "a",
+				},
+				{
+					act: actionAdd,
+					key: "second",
+					val: "b",
+				},
+			},
+			expect: []string{
+				"b",
+			},
+		},
+		{
+			name: "add two, delete one",
+			do: []action{
+				{
+					act: actionAdd,
+					key: "first",
+					val: "a",
+				},
+				{
+					act: actionAdd,
+					key: "second",
+					val: "b",
+				},
+				{
+					act: actionDel,
+					key: "first",
+				},
+			},
+			expect: []string(nil),
+		},
+		{
+			name: "add two, delete two",
+			do: []action{
+				{
+					act: actionAdd,
+					key: "first",
+					val: "a",
+				},
+				{
+					act: actionAdd,
+					key: "second",
+					val: "b",
+				},
+				{
+					act: actionDel,
+					key: "first",
+				},
+				{
+					act: actionDel,
+					key: "second",
+				},
+			},
+			expect: []string(nil),
+		},
+		{
+			name: "add two, dup values",
+			do: []action{
+				{
+					act: actionAdd,
+					key: "first",
+					val: "a",
+				},
+				{
+					act: actionAdd,
+					key: "second",
+					val: "b",
+				},
+				{
+					act: actionAdd,
+					key: "third",
+					val: "a",
+				},
+			},
+			expect: []string{"a"},
+		},
+		{
+			name: "add three, dup values, delete two, add one",
+			do: []action{
+				{
+					act: actionAdd,
+					key: "first",
+					val: "a",
+				},
+				{
+					act: actionAdd,
+					key: "second",
+					val: "b",
+				},
+				{
+					act: actionAdd,
+					key: "third",
+					val: "a",
+				},
+				{
+					act: actionDel,
+					key: "first",
+				},
+				{
+					act: actionDel,
+					key: "second",
+				},
+				{
+					act: actionAdd,
+					key: "forth",
+					val: "c",
+				},
+			},
+			expect: []string{"c"},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			var changed bool
+			c := newConfigCenterContainer()
+			c.AddListener(func() {
+				changed = true
+			})
+			assert.Nil(t, c.GetValues())
+			assert.False(t, changed)
+
+			for _, order := range test.do {
+				if order.act == actionAdd {
+					c.OnAdd(discov.KV{
+						Key: order.key,
+						Val: order.val,
+					})
+				} else {
+					c.OnDelete(discov.KV{
+						Key: order.key,
+						Val: order.val,
+					})
+				}
+			}
+
+			assert.True(t, changed)
+			assert.ElementsMatch(t, test.expect, c.GetValues())
+		})
+	}
+}