content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.network.protocol.databuffer;
  
  import alluxio.util.io.BufferUtils;
  
  import com.google.common.base.Preconditions;
  import io.netty.buffer.Unpooled;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  
  /**
   * A DataBuffer with the underlying data being a {@link ByteBuffer}. If the backing ByteBuffer is
   * a direct ByteBuffer, {@link #release()} should only be called when all references to the
   * object are finished with it. For this reason, it is not recommended to share objects of this
   * class unless reference counting is implemented by the users of this class.
   */
  public class NioDataBuffer implements DataBuffer {
    protected final ByteBuffer mBuffer;
    protected final long mLength;
  
    /**
     * @param buffer The ByteBuffer representing the data
     * @param length The length of the ByteBuffer
     */
    public NioDataBuffer(ByteBuffer buffer, long length) {
      mBuffer = Preconditions.checkNotNull(buffer, "buffer");
      Preconditions.checkArgument(mBuffer.remaining() == length, "length of buffer content mismatch");
      mLength = length;
    }
  
    @Override
    public Object getNettyOutput() {
      return Unpooled.wrappedBuffer(mBuffer);
    }
  
    @Override
    public long getLength() {
      return mLength;
    }
  
    @Override
    public ByteBuffer getReadOnlyByteBuffer() {
      ByteBuffer buffer = mBuffer.asReadOnlyBuffer();
      buffer.position(0);
      return buffer;
    }
  
    @Override
    public void readBytes(byte[] dst, int dstIndex, int length) {
      mBuffer.get(dst, dstIndex, length);
    }
  
    @Override
    public void readBytes(OutputStream outputStream, int length) throws IOException {
      Unpooled.wrappedBuffer(mBuffer).readBytes(outputStream, length).release();
    }
  
    @Override
    public void readBytes(ByteBuffer outputBuf) {
      if (mBuffer.remaining() <= outputBuf.remaining()) {
        outputBuf.put(mBuffer);
      } else {
        int oldLimit = mBuffer.limit();
        mBuffer.limit(mBuffer.position() + outputBuf.remaining());
        outputBuf.put(mBuffer);
        mBuffer.limit(oldLimit);
      }
    }
  
    @Override
    public int readableBytes() {
      return mBuffer.remaining();
    }
  
    @Override
    public void release() {
      if (mBuffer.isDirect()) {
        BufferUtils.cleanDirectBuffer(mBuffer);
      }
    }
  }
  