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.store.wal;
  
  import org.apache.bifromq.basekv.proto.KVRangeSnapshot;
  import org.apache.bifromq.basekv.raft.proto.LogEntry;
  import java.util.concurrent.CompletableFuture;
  
  public interface IKVRangeWALSubscriber {
      default void onSubscribe(IKVRangeWALSubscription subscription) {
  
      }
  
      CompletableFuture<Void> apply(LogEntry log);
  
      /**
       * Callback after snapshot restored.
       */
      interface IAfterRestoredCallback {
          CompletableFuture<Void> call(KVRangeSnapshot snapshot, Throwable ex);
      }
  
      /**
       * Install snapshot to kv range asynchronously and the returned snapshot will be used for WAL compaction.
       *
       * @param requested the snapshot requested to be installed
       * @param leader    the leader
       * @param callback  the callback to notify the result of snapshot installation
       */
      CompletableFuture<Void> restore(KVRangeSnapshot requested, String leader, IAfterRestoredCallback callback);
  }
  