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.file;
  
  import alluxio.annotation.SuppressFBWarnings;
  import alluxio.util.io.ChannelAdapters;
  
  import io.netty.buffer.ByteBuf;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.RandomAccessFile;
  import java.nio.ByteBuffer;
  import java.nio.channels.WritableByteChannel;
  
  /**
   * Target buffer backed by bytes array for zero-copy read from page store.
   */
  @SuppressFBWarnings(
      value = "EI_EXPOSE_REP2",
      justification = "The target byte array is exposed as we expect.")
  public class ByteArrayTargetBuffer implements ReadTargetBuffer {
    private final byte[] mTarget;
    private int mOffset;
  
    /**
     * Constructor.
     * @param target
     * @param offset
     */
    public ByteArrayTargetBuffer(byte[] target, int offset) {
      mTarget = target;
      mOffset = offset;
    }
  
    @Override
    public byte[] byteArray() {
      return mTarget;
    }
  
    @Override
    public ByteBuffer byteBuffer() {
      return ByteBuffer.wrap(mTarget);
    }
  
    @Override
    public int offset() {
      return mOffset;
    }
  
    @Override
    public void offset(int newOffset) {
      mOffset = newOffset;
    }
  
    @Override
    public long remaining() {
      return mTarget.length - mOffset;
    }
  
    @Override
    public void writeBytes(byte[] srcArray, int srcOffset, int length) {
      System.arraycopy(srcArray, srcOffset, mTarget, mOffset, length);
      mOffset += length;
    }
  
    @Override
    public void writeBytes(ByteBuf buf) {
      int bytesToRead = Math.min(buf.readableBytes(), mTarget.length - mOffset);
      buf.readBytes(mTarget, mOffset, bytesToRead);
      mOffset += bytesToRead;
    }
  
    @Override
    public int readFromFile(RandomAccessFile file, int length) throws IOException {
      int bytesRead = file.read(mTarget, mOffset, length);
      if (bytesRead != -1) {
        mOffset += bytesRead;
      }
      return bytesRead;
    }
  
    @Override
    public int readFromInputStream(InputStream is, int length) throws IOException {
      int bytesRead = is.read(mTarget, mOffset, length);
      if (bytesRead != -1) {
        mOffset += bytesRead;
      }
      return bytesRead;
    }
  
    @Override
    public WritableByteChannel byteChannel() {
      return ChannelAdapters.intoByteArray(mTarget, mOffset, mTarget.length - mOffset);
    }
  }
  