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 java.io.Closeable;
  import java.util.Optional;
  
  public interface EpochState extends Closeable {
  
      default Optional<LogOffsetMetadata> highWatermark() {
          return Optional.empty();
      }
  
      /**
       * Decide whether to grant a vote to a replica.
       *
       * It is the responsibility of the caller to invoke
       * {@link QuorumState#unattachedAddVotedState(int, ReplicaKey)} if a standard vote is granted.
       *
       * @param replicaKey the id and directory of the replica requesting the vote
       * @param isLogUpToDate whether the replica's log is at least as up-to-date as receiver’s log
       * @param isPreVote whether the vote request is a PreVote (non-binding) or standard vote
       * @return true if it can grant the vote, false otherwise
       */
      boolean canGrantVote(ReplicaKey replicaKey, boolean isLogUpToDate, boolean isPreVote);
  
      /**
       * Get the current election state, which is guaranteed to be immutable.
       */
      ElectionState election();
  
      /**
       * Get the current (immutable) epoch.
       */
      int epoch();
  
      /**
       * Returns the known endpoints for the leader.
       *
       * If the leader is not known then {@code Endpoints.empty()} is returned.
       */
      Endpoints leaderEndpoints();
  
      /**
       * User-friendly description of the state
       */
      String name();
  }
  