content: /*
   * 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.bifromq.basekv.localengine;
  
  import java.util.Map;
  
  /**
   * The interface of kv engine.
   *
   * @param <T> the type of kv space created by the engine
   */
  public interface IKVEngine<T extends IKVSpace> {
  
      String DEFAULT_NS = "default";
  
      /**
       * The unique identifier of the engine.
       *
       * @return id
       */
      String id();
  
      /**
       * Find all currently available kv spaces.
       *
       * @return the kv space list
       */
      Map<String, T> spaces();
  
      /**
       * Create a new key range with specified spaceId and boundary or get existing key range.
       *
       * @param spaceId the space id
       * @return the key range created
       */
      T createIfMissing(String spaceId);
  
      /**
       * Start the kv engine and specifying additional tags for generated metrics.
       *
       * @param metricTags the additional metric tags
       */
      void start(String... metricTags);
  
      /**
       * Stop the engine.
       */
      void stop();
  }
  