allow deleting only older empty dir without recursion (#4430)

weed/pb/filer_pb/filer_pb_helper.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"os"
 	"strings"
+	"time"
 
 	"github.com/seaweedfs/seaweedfs/weed/glog"
 	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
@@ -13,6 +14,8 @@ import (
 	"google.golang.org/protobuf/proto"
 )
 
+const cutoffTimeNewEmptyDir = 3
+
 func (entry *Entry) IsInRemoteOnly() bool {
 	return len(entry.GetChunks()) == 0 && entry.RemoteEntry != nil && entry.RemoteEntry.RemoteSize > 0
 }
@@ -28,6 +31,10 @@ func (entry *Entry) FileMode() (fileMode os.FileMode) {
 	return
 }
 
+func (entry *Entry) IsOlderDir() bool {
+	return entry.IsDirectory && entry.Attributes != nil && entry.Attributes.Mime == "" && entry.Attributes.GetCrtime() <= time.Now().Unix()-cutoffTimeNewEmptyDir
+}
+
 func ToFileIdObject(fileIdStr string) (*FileId, error) {
 	t, err := needle.ParseFileIdFromString(fileIdStr)
 	if err != nil {
@@ -143,18 +150,22 @@ var ErrNotFound = errors.New("filer: no entry is found in filer store")
 func IsEmpty(event *SubscribeMetadataResponse) bool {
 	return event.EventNotification.NewEntry == nil && event.EventNotification.OldEntry == nil
 }
+
 func IsCreate(event *SubscribeMetadataResponse) bool {
 	return event.EventNotification.NewEntry != nil && event.EventNotification.OldEntry == nil
 }
+
 func IsUpdate(event *SubscribeMetadataResponse) bool {
 	return event.EventNotification.NewEntry != nil &&
 		event.EventNotification.OldEntry != nil &&
 		event.Directory == event.EventNotification.NewParentPath &&
 		event.EventNotification.NewEntry.Name == event.EventNotification.OldEntry.Name
 }
+
 func IsDelete(event *SubscribeMetadataResponse) bool {
 	return event.EventNotification.NewEntry == nil && event.EventNotification.OldEntry != nil
 }
+
 func IsRename(event *SubscribeMetadataResponse) bool {
 	return event.EventNotification.NewEntry != nil &&
 		event.EventNotification.OldEntry != nil &&