code: /*
   * Copyright 2012-2018 Chronicle Map Contributors
   *
   * Licensed 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 net.openhft.chronicle.map.replication;
  
  import net.openhft.chronicle.hash.Data;
  import net.openhft.chronicle.hash.replication.RemoteOperationContext;
  import net.openhft.chronicle.hash.serialization.SizeMarshaller;
  import net.openhft.chronicle.map.ChronicleMap;
  import net.openhft.chronicle.map.ChronicleMapBuilder;
  import net.openhft.chronicle.map.MapEntryOperations;
  import net.openhft.chronicle.map.MapQueryContext;
  import org.jetbrains.annotations.Nullable;
  
  /**
   * Context of remote {@link ChronicleMap} queries and internal replication operations.
   *
   * @param <K> the map key type
   * @param <V> the map value type
   * @param <R> the return type of {@link MapEntryOperations} specified for the queried map
   * @see MapRemoteOperations
   */
  public interface MapRemoteQueryContext<K, V, R> extends MapQueryContext<K, V, R>,
          RemoteOperationContext<K> {
      @Nullable
      @Override
      MapReplicableEntry<K, V> entry();
  
      /**
       * The value used as a tombstone, for removed entries, to save space. This value has {@linkplain
       * SizeMarshaller#minStorableSize()} minimum possible size} for {@linkplain
       * ChronicleMapBuilder#valueSizeMarshaller(SizeMarshaller) the configured value size
       * marshaller}.
       * <p>
       * <p>The returned value doesn't have object form (i. e. it's {@link Data#get()} and {@link
       * Data#getUsing(Object)} methods throw {@code UnsupportedOperationException}), it has only
       * bytes form, of all zero bytes.
       *
       * @return dummy value of all zeros, of the minimum possible size.
       */
      Data<V> dummyZeroValue();
  }
  