refactor client subscribe metadata

weed/command/filer_meta_backup.go

@@ -7,7 +7,6 @@ import (
 	"github.com/chrislusf/seaweedfs/weed/glog"
 	"github.com/spf13/viper"
 	"google.golang.org/grpc"
-	"io"
 	"reflect"
 	"time"
 
@@ -190,48 +189,15 @@ func (metaBackup *FilerMetaBackupOptions) streamMetadataBackup() error {
 		return nil
 	}
 
-	tailErr := pb.WithFilerClient(*metaBackup.filerAddress, metaBackup.grpcDialOption, func(client filer_pb.SeaweedFilerClient) error {
-
-		ctx, cancel := context.WithCancel(context.Background())
-		defer cancel()
-
-		stream, err := client.SubscribeMetadata(ctx, &filer_pb.SubscribeMetadataRequest{
-			ClientName: "meta_backup",
-			PathPrefix: *metaBackup.filerDirectory,
-			SinceNs:    startTime.UnixNano(),
-		})
-		if err != nil {
-			return fmt.Errorf("listen: %v", err)
-		}
-
-		var counter int64
-		var lastWriteTime time.Time
-		for {
-			resp, listenErr := stream.Recv()
-			if listenErr == io.EOF {
-				return nil
-			}
-			if listenErr != nil {
-				return listenErr
-			}
-			if err = eachEntryFunc(resp); err != nil {
-				return err
-			}
-
-			counter++
-			if lastWriteTime.Add(3 * time.Second).Before(time.Now()) {
-				glog.V(0).Infof("meta backup %s progressed to %v %0.2f/sec", *metaBackup.filerAddress, time.Unix(0, resp.TsNs), float64(counter)/float64(3))
-				counter = 0
-				lastWriteTime = time.Now()
-				if err2 := metaBackup.setOffset(lastWriteTime); err2 != nil {
-					return err2
-				}
-			}
-
-		}
-
+	processEventFnWithOffset := pb.AddOffsetFunc(eachEntryFunc, 3 * time.Second, func(counter int64, lastTsNs int64) error {
+		lastTime := time.Unix(0, lastTsNs)
+		glog.V(0).Infof("meta backup %s progressed to %v %0.2f/sec", *metaBackup.filerAddress, lastTime, float64(counter)/float64(3))
+		return metaBackup.setOffset(lastTime)
 	})
-	return tailErr
+
+	return pb.FollowMetadata(*metaBackup.filerAddress, metaBackup.grpcDialOption, "meta_backup",
+		*metaBackup.filerDirectory, startTime.UnixNano(), 0, processEventFnWithOffset, false)
+
 }
 
 func (metaBackup *FilerMetaBackupOptions) getOffset() (lastWriteTime time.Time, err error) {