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.hash.serialization.impl;
  
  import net.openhft.chronicle.bytes.Bytes;
  import net.openhft.chronicle.bytes.RandomDataInput;
  import net.openhft.chronicle.hash.AbstractData;
  import net.openhft.chronicle.hash.Data;
  import net.openhft.chronicle.hash.serialization.DataAccess;
  import net.openhft.chronicle.wire.WireIn;
  import net.openhft.chronicle.wire.WireOut;
  import org.jetbrains.annotations.NotNull;
  import org.jetbrains.annotations.Nullable;
  
  import java.io.*;
  
  import static net.openhft.chronicle.hash.serialization.impl.DefaultElasticBytes.DEFAULT_BYTES_CAPACITY;
  
  public class SerializableDataAccess<T extends Serializable> extends AbstractData<T>
          implements DataAccess<T> {
  
      // Cache fields
      transient Bytes bytes;
      transient OutputStream out;
      transient InputStream in;
  
      /**
       * State field
       */
      transient T instance;
  
      public SerializableDataAccess() {
          this(DEFAULT_BYTES_CAPACITY);
      }
  
      SerializableDataAccess(long bytesCapacity) {
          initTransients(bytesCapacity);
      }
  
      void initTransients(long bytesCapacity) {
          bytes = DefaultElasticBytes.allocateDefaultElasticBytes(bytesCapacity);
          out = bytes.outputStream();
          in = bytes.inputStream();
      }
  
      @Override
      public RandomDataInput bytes() {
          return bytes.bytesStore();
      }
  
      @Override
      public long offset() {
          return 0;
      }
  
      @Override
      public long size() {
          return bytes.readRemaining();
      }
  
      @Override
      public T get() {
          return instance;
      }
  
      // TODO reuse using object
      @Override
      public T getUsing(@Nullable T using) {
          try {
              T result = (T) new ObjectInputStream(in).readObject();
              bytes.readPosition(0);
              return result;
          } catch (IOException | ClassNotFoundException e) {
              throw new RuntimeException(e);
          }
      }
  
      @Override
      public Data<T> getData(@NotNull T instance) {
          this.instance = instance;
          bytes.clear();
          try {
              ObjectOutputStream out = new ObjectOutputStream(this.out);
              out.writeObject(instance);
              out.flush();
              return this;
          } catch (IOException e) {
              throw new RuntimeException(e);
          }
      }
  
      @Override
      public void uninit() {
          instance = null;
      }
  
      @Override
      public DataAccess<T> copy() {
          return new SerializableDataAccess<>(bytes.realCapacity());
      }
  
      @Override
      public void readMarshallable(@NotNull WireIn wireIn) {
          // no fields to read
          initTransients(DEFAULT_BYTES_CAPACITY);
      }
  
      @Override
      public void writeMarshallable(@NotNull WireOut wireOut) {
          // no fields to write
      }
  }
  