channelz: implement GetServer

Author: kazegusuri

Diff for: channelz/service/service.go

@@ -337,5 +337,10 @@ func (s *serverImpl) GetSocket(ctx context.Context, req *channelzpb.GetSocketReq
 }
 
 func (s *serverImpl) GetServer(ctx context.Context, req *channelzpb.GetServerRequest) (*channelzpb.GetServerResponse, error) {
-	return nil, status.Error(codes.Unimplemented, "GetServer not implemented")
+	var metric *channelz.ServerMetric
+	if metric = channelz.GetServer(req.GetServerId()); metric == nil {
+		return nil, status.Errorf(codes.NotFound, "requested server %d not found", req.GetServerId())
+	}
+	resp := &channelzpb.GetServerResponse{Server: serverMetricToProto(metric)}
+	return resp, nil
 }

Diff for: internal/channelz/funcs.go

@@ -155,6 +155,15 @@ func GetSocket(id int64) *SocketMetric {
 	return db.get().GetSocket(id)
 }
 
+// GetServer returns the ServerMetric for the server (identified by id).
+func GetServer(id int64) *ServerMetric {
+	metrics, _ := db.get().GetServers(id, 1)
+	if len(metrics) == 1 && metrics[0].ID == id {
+		return metrics[0]
+	}
+	return nil
+}
+
 // RegisterChannel registers the given channel c in channelz database with ref
 // as its reference name, and add it to the child list of its parent (identified
 // by pid). pid = 0 means no parent. It returns the unique channelz tracking id

Diff for: test/channelz_test.go

@@ -102,6 +102,43 @@ func TestCZServerRegistrationAndDeletion(t *testing.T) {
 	}
 }
 
+func TestCZGetServer(t *testing.T) {
+	defer leakcheck.Check(t)
+
+	channelz.NewChannelzStorage()
+	e := tcpClearRREnv
+	te := newTest(t, e)
+	te.startServer(&testServer{security: e.security})
+	defer te.tearDown()
+
+	ss, _ := channelz.GetServers(0, 0)
+	if len(ss) != 1 {
+		t.Fatalf("there should only be one servers, not %d", len(ss))
+	}
+
+	serverID := ss[0].ID
+	srv := channelz.GetServer(serverID)
+	if srv == nil {
+		t.Fatalf("server %d does not exist", serverID)
+	}
+	if srv.ID != serverID {
+		t.Fatalf("server want id %d, but got %d", serverID, srv.ID)
+	}
+
+	te.tearDown()
+
+	if err := verifyResultWithDelay(func() (bool, error) {
+		srv := channelz.GetServer(serverID)
+		if srv != nil {
+			return false, fmt.Errorf("server %d does not exist", serverID)
+		}
+
+		return true, nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestCZTopChannelRegistrationAndDeletion(t *testing.T) {
 	defer leakcheck.Check(t)
 	testcases := []struct {
@@ -379,6 +416,9 @@ func TestCZServerListenSocketDeletion(t *testing.T) {
 		if len(ss) != 1 {
 			return false, fmt.Errorf("there should be 1 server, not %d", len(ss))
 		}
+		if len(ss[0].ListenSockets) != 0 {
+			return false, fmt.Errorf("there should only be %d server listen socket, not %d", 0, len(ss[0].ListenSockets))
+		}
 		return true, nil
 	}); err != nil {
 		t.Fatal(err)