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.kafka.raft;
  
  import org.apache.kafka.server.common.KRaftVersion;
  
  import java.nio.file.Path;
  import java.util.Optional;
  
  /**
   *  Maintain the save and retrieval of quorum state information, so far only supports
   *  read and write of election states.
   */
  public interface QuorumStateStore {
      /**
       * Read the latest election state.
       *
       * @return the latest written election state or {@code Optional.empty()} if there is none
       */
      Optional<ElectionState> readElectionState();
  
      /**
       * Persist the updated election state.
       *
       * This must be atomic, both writing the full updated state and replacing the old state.
       *
       * @param latest the latest election state
       * @param kraftVersion the finalized kraft.version
       */
      void writeElectionState(ElectionState latest, KRaftVersion kraftVersion);
  
      /**
       * Path to the quorum state store
       */
      Path path();
  
      /**
       * Clear any state associated to the store for a fresh start
       */
      void clear();
  }
  