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.BytesStore;
  import net.openhft.chronicle.bytes.RandomDataInput;
  import net.openhft.chronicle.bytes.VanillaBytes;
  import net.openhft.chronicle.bytes.internal.NativeBytesStore;
  import net.openhft.chronicle.core.io.ReferenceOwner;
  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.nio.ByteBuffer;
  
  public class ByteBufferDataAccess extends AbstractData<ByteBuffer>
          implements DataAccess<ByteBuffer> {
  
      // Cache fields
      private transient VanillaBytes<Void> bytes;
  
      // State fields
      private transient ByteBuffer bb;
      private transient BytesStore bytesStore;
  
      public ByteBufferDataAccess() {
          initTransients();
      }
  
      private void initTransients() {
          bytes = VanillaBytes.vanillaBytes();
      }
  
      @Override
      public RandomDataInput bytes() {
          return bytesStore;
      }
  
      @Override
      public long offset() {
          return bb.position();
      }
  
      @Override
      public long size() {
          return bb.remaining();
      }
  
      @Override
      public ByteBuffer get() {
          return bb;
      }
  
      @Override
      public ByteBuffer getUsing(@Nullable ByteBuffer using) {
          if (using == null || using.capacity() < bb.remaining()) {
              using = ByteBuffer.allocate(bb.remaining());
          } else {
              using.position(0);
              using.limit(bb.remaining());
          }
          bytes.bytesStore(bytesStore, bb.position(), bb.remaining());
          bytes.read(using);
          using.flip();
          return using;
      }
  
      @Override
      public Data<ByteBuffer> getData(@NotNull ByteBuffer instance) {
          bb = instance;
          bytesStore = BytesStore.follow(instance);
          return this;
      }
  
      @Override
      public void uninit() {
          bb = null;
          bytesStore.release(ReferenceOwner.INIT);
          bytesStore = null;
      }
  
      @Override
      public DataAccess<ByteBuffer> copy() {
          return new ByteBufferDataAccess();
      }
  
      @Override
      public void readMarshallable(@NotNull WireIn wireIn) {
          // no fields to read
          initTransients();
      }
  
      @Override
      public void writeMarshallable(@NotNull WireOut wireOut) {
          // no fields to write
      }
  }
  