refine defer deleting pvc codes

pkg/manager/member/pd_scaler.go

@@ -45,7 +45,7 @@ func (psd *pdScaler) ScaleOut(tc *v1alpha1.TidbCluster, oldSet *apps.StatefulSet
 		return nil
 	}
 
-	err := psd.deleteAllDeferDeletingPVC(tc, oldSet.GetName(), v1alpha1.PDMemberType, *oldSet.Spec.Replicas, *newSet.Spec.Replicas)
+	_, err := psd.deleteAllDeferDeletingPVC(tc, oldSet.GetName(), v1alpha1.PDMemberType, *oldSet.Spec.Replicas, *newSet.Spec.Replicas)
 	if err != nil {
 		resetReplicas(newSet, oldSet)
 		return err

pkg/manager/member/scaler.go

@@ -15,18 +15,21 @@ package member
 
 import (
 	"fmt"
-	"time"
 
-	"github.com/golang/glog"
 	"github.com/pingcap/tidb-operator/pkg/apis/pingcap.com/v1alpha1"
 	"github.com/pingcap/tidb-operator/pkg/controller"
 	"github.com/pingcap/tidb-operator/pkg/label"
 	apps "k8s.io/api/apps/v1beta1"
 	"k8s.io/apimachinery/pkg/api/errors"
-	"k8s.io/apimachinery/pkg/util/wait"
 	corelisters "k8s.io/client-go/listers/core/v1"
 )
 
+const (
+	skipReasonPVCNotFound             = "pvc is not found"
+	skipReasonAnnIsNil                = "pvc annotations is nil"
+	skipReasonAnnDeferDeletingIsEmpty = "pvc annotations defer deleting is empty"
+)
+
 // Scaler implements the logic for scaling out or scaling in the cluster.
 type Scaler interface {
 	// ScaleOut scales out the cluster
@@ -42,46 +45,38 @@ type generalScaler struct {
 }
 
 func (gs *generalScaler) deleteAllDeferDeletingPVC(tc *v1alpha1.TidbCluster,
-	setName string, memberType v1alpha1.MemberType, from, to int32) error {
+	setName string, memberType v1alpha1.MemberType, from, to int32) (map[int32]string, error) {
 	ns := tc.GetNamespace()
+	// for unit test
+	skipReason := map[int32]string{}
 
 	for i := from; i < to; i++ {
 		pvcName := ordinalPVCName(memberType, setName, i)
 		pvc, err := gs.pvcLister.PersistentVolumeClaims(ns).Get(pvcName)
 		if errors.IsNotFound(err) {
+			skipReason[i] = skipReasonPVCNotFound
 			continue
 		}
 		if err != nil {
-			return err
+			return skipReason, err
 		}
 
 		if pvc.Annotations == nil {
+			skipReason[i] = skipReasonAnnIsNil
 			continue
 		}
 		if _, ok := pvc.Annotations[label.AnnPVCDeferDeleting]; !ok {
+			skipReason[i] = skipReasonAnnDeferDeletingIsEmpty
 			continue
 		}
 
 		err = gs.pvcControl.DeletePVC(tc, pvc)
 		if err != nil {
-			return err
-		}
-
-		err = wait.Poll(1*time.Second, 30*time.Second, func() (done bool, err error) {
-			_, err = gs.pvcLister.PersistentVolumeClaims(ns).Get(pvcName)
-			if errors.IsNotFound(err) {
-				return true, nil
-			}
-
-			glog.V(4).Infof("waiting for PVC: %s/%s deleting", ns, pvcName)
-			return false, nil
-		})
-		if err != nil {
-			return err
+			return skipReason, err
 		}
 	}
 
-	return nil
+	return skipReason, nil
 }
 
 func resetReplicas(newSet *apps.StatefulSet, oldSet *apps.StatefulSet) {