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.impl.stage.data;
  
  import net.openhft.chronicle.bytes.Bytes;
  import net.openhft.chronicle.bytes.RandomDataInput;
  import net.openhft.chronicle.hash.AbstractData;
  import net.openhft.chronicle.hash.impl.stage.hash.CheckOnEachPublicOperation;
  import net.openhft.chronicle.map.impl.VanillaChronicleMapHolder;
  import net.openhft.chronicle.map.impl.stage.map.ValueBytesInterop;
  import net.openhft.sg.StageRef;
  import net.openhft.sg.Staged;
  
  @Staged
  public class DummyValueZeroData<V> extends AbstractData<V> {
  
      private final Bytes zeroBytes = ZeroBytesStore.INSTANCE.bytesForRead();
      @StageRef
      VanillaChronicleMapHolder<?, ?, ?> mh;
      @StageRef
      ValueBytesInterop<V> vi;
      @StageRef
      CheckOnEachPublicOperation checkOnEachPublicOperation;
  
      @Override
      public RandomDataInput bytes() {
          checkOnEachPublicOperation.checkOnEachPublicOperation();
          return ZeroBytesStore.INSTANCE;
      }
  
      @Override
      public long offset() {
          checkOnEachPublicOperation.checkOnEachPublicOperation();
          return 0;
      }
  
      @Override
      public long size() {
          checkOnEachPublicOperation.checkOnEachPublicOperation();
          return Math.max(0, mh.m().valueSizeMarshaller.minStorableSize());
      }
  
      @Override
      public V get() {
          checkOnEachPublicOperation.checkOnEachPublicOperation();
          // Not optimized and creates garbage, because this isn't the primary
          // use case. Zero data should only be used in bytes form
          return getUsing(null);
      }
  
      @Override
      public V getUsing(V using) {
          checkOnEachPublicOperation.checkOnEachPublicOperation();
          zeroBytes.readPosition(0);
          try {
              return vi.valueReader.read(zeroBytes, size(), using);
          } catch (Exception e) {
              throw zeroReadException(e);
          }
      }
  
      private IllegalStateException zeroReadException(Exception cause) {
          return new IllegalStateException(mh.h().toIdentityString() +
                  ": Most probable cause of this exception - zero bytes of\n" +
                  "the minimum positive encoding length, supported by the specified or default\n" +
                  "valueSizeMarshaller() is not correct serialized form of any value. You should\n" +
                  "configure defaultValueProvider() in ChronicleMapBuilder", cause);
      }
  }
  