[1.2-dev] fix: respsect filterFn in pluginRouter (#16689)

pkg/proxy/plugin.go

@@ -42,7 +42,7 @@ func newPluginRouter(r Router, p Plugin) *pluginRouter {
 
 // Route implements Router.Route.
 func (r *pluginRouter) Route(
-	ctx context.Context, ci clientInfo, filter func(uuid string) bool,
+	ctx context.Context, ci clientInfo, filter func(prevAddr string) bool,
 ) (*CNServer, error) {
 	re, err := r.plugin.RecommendCN(ctx, ci)
 	if err != nil {
@@ -59,6 +59,10 @@ func (r *pluginRouter) Route(
 		if re.CN == nil {
 			return nil, moerr.NewInternalErrorNoCtx("no CN server selected")
 		}
+		// selected CN should be filtered out, fall back to the delegated router
+		if filter != nil && filter(re.CN.SQLAddress) {
+			return r.Router.Route(ctx, ci, filter)
+		}
 		hash, err := ci.labelInfo.getHash()
 		if err != nil {
 			return nil, err

pkg/proxy/plugin_test.go

@@ -80,6 +80,7 @@ func TestPluginRouter_Route(t *testing.T) {
 		expectErr         bool
 		expectUUID        string
 		expectRefresh     int
+		filter            func(prevAddr string) bool
 	}{{
 		name: "recommend select CN",
 		mockRecommendCNFn: func(ctx context.Context, ci clientInfo) (*plugin.Recommendation, error) {
@@ -149,20 +150,40 @@ func TestPluginRouter_Route(t *testing.T) {
 		},
 		expectUUID:    "cn0",
 		expectRefresh: 1,
+	}, {
+		name: "filter out current CN",
+		mockRecommendCNFn: func(ctx context.Context, ci clientInfo) (*plugin.Recommendation, error) {
+			return &plugin.Recommendation{
+				Action: plugin.Select,
+				CN: &metadata.CNService{
+					ServiceID:  "cn0",
+					SQLAddress: "8.8.8.8:6001",
+				},
+				Updated: true,
+			}, nil
+		},
+		mockRouteFn: func(ctx context.Context, ci clientInfo) (*CNServer, error) {
+			return &CNServer{uuid: "cn1"}, nil
+		},
+		expectRefresh: 1,
+		expectUUID:    "cn1",
+		filter: func(addr string) bool {
+			return addr == "8.8.8.8:6001"
+		},
 	}}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			p := &mockPlugin{mockRecommendCNFn: tt.mockRecommendCNFn}
 			r := &mockRouter{mockRouteFn: tt.mockRouteFn}
 			pr := newPluginRouter(r, p)
-			cn, err := pr.Route(context.TODO(), clientInfo{}, nil)
+			cn, err := pr.Route(context.TODO(), clientInfo{}, tt.filter)
 			if tt.expectErr {
 				require.Error(t, err)
 				require.Nil(t, cn)
 			} else {
 				require.NotNil(t, cn)
-				require.Equal(t, cn.uuid, tt.expectUUID)
+				require.Equal(t, tt.expectUUID, cn.uuid)
 			}
 			require.Equal(t, r.refreshCount, tt.expectRefresh)
 		})