| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| |
| package org.apache.iotdb.db.engine.version; |
| |
| /** |
| * VersionController manages the version(a monotonically increasing long) of a storage group. We |
| * define that each memtable flush, data deletion, or data update will generate a new version of |
| * dataset. So upon the above actions are performed, a new version number is generated and assigned |
| * to such actions. Additionally, we also assign versions to TsFiles in their file names, so |
| * hopefully we will compare files directly across IoTDB replicas. NOTICE: Thread-safety should be |
| * guaranteed by the caller. |
| */ |
| public interface VersionController { |
| /** |
| * Get the next version number. |
| * |
| * @return the next version number. |
| */ |
| long nextVersion(); |
| |
| /** |
| * Get the current version number. |
| * |
| * @return the current version number. |
| */ |
| long currVersion(); |
| } |