feat(filer.sync): add offset to path.

weed/command/filer_sync.go

@@ -182,7 +182,7 @@ func doSubscribeFilerMetaChanges(clientId int32, grpcDialOption grpc.DialOption,
 
 	// if first time, start from now
 	// if has previously synced, resume from that point of time
-	sourceFilerOffsetTsNs, err := getOffset(grpcDialOption, targetFiler, SyncKeyPrefix, sourceFilerSignature)
+	sourceFilerOffsetTsNs, err := getOffset(grpcDialOption, targetFiler, getSignaturePrefixByPath(sourcePath), sourceFilerSignature)
 	if err != nil {
 		return err
 	}
@@ -214,7 +214,7 @@ func doSubscribeFilerMetaChanges(clientId int32, grpcDialOption grpc.DialOption,
 		now := time.Now().Nanosecond()
 		glog.V(0).Infof("sync %s to %s progressed to %v %0.2f/sec", sourceFiler, targetFiler, time.Unix(0, lastTsNs), float64(counter)/(float64(now-lastLogTsNs)/1e9))
 		lastLogTsNs = now
-		return setOffset(grpcDialOption, targetFiler, SyncKeyPrefix, sourceFilerSignature, lastTsNs)
+		return setOffset(grpcDialOption, targetFiler, getSignaturePrefixByPath(sourcePath), sourceFilerSignature, lastTsNs)
 	})
 
 	return pb.FollowMetadata(sourceFiler, grpcDialOption, "syncTo_"+string(targetFiler), clientId,
@@ -226,6 +226,16 @@ const (
 	SyncKeyPrefix = "sync."
 )
 
+// When each business is distinguished according to path, and offsets need to be maintained separately.
+func getSignaturePrefixByPath(path string) string {
+	// compatible historical version
+	if path == "/" {
+		return SyncKeyPrefix
+	} else {
+		return SyncKeyPrefix + path
+	}
+}
+
 func getOffset(grpcDialOption grpc.DialOption, filer pb.ServerAddress, signaturePrefix string, signature int32) (lastOffsetTsNs int64, readErr error) {
 
 	readErr = pb.WithFilerClient(false, filer, grpcDialOption, func(client filer_pb.SeaweedFilerClient) error {