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.worker.block.io;
  
  import alluxio.network.protocol.databuffer.DataBuffer;
  
  import io.netty.buffer.ByteBuf;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.channels.WritableByteChannel;
  
  /**
   * An abstract writer class to write or update a block stored in managed storage.
   * <p>
   * This class does not provide thread-safety.
   */
  public abstract class BlockWriter extends BlockClient {
  
    /**
     * Default constructor for the abstract writer implementations.
     */
    public BlockWriter() {
      super(Type.WRITER);
    }
  
    /**
     * Appends data to the end of a block from an input {@link ByteBuffer}.
     *
     * @param inputBuf {@link ByteBuffer} that input data is stored in
     * @return the size of data that was appended in bytes
     */
    public abstract long append(ByteBuffer inputBuf);
  
    /**
     * Appends buf.readableBytes() bytes to the end of this block writer from the given buf.
     *
     * @param buf the byte buffer that holds the data
     * @return the size of data that was appended in bytes
     */
    public abstract long append(ByteBuf buf) throws IOException;
  
    /**
     * Appends buffer.readableBytes() bytes to the end of this block writer from the given buffer.
     *
     * @param buffer the byte buffer that holds the data
     * @return the size of data that was appended in bytes
     */
    public abstract long append(DataBuffer buffer) throws IOException;
  
    /**
     * @return the current write position (same as the number of bytes written)
     */
    public abstract long getPosition();
  
    /**
     * @return a writeable byte channel of the block
     */
    public abstract WritableByteChannel getChannel();
  }
  