content: /**
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 com.alibaba.wasp.util;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.util.LinkedList;
  import java.util.List;
  
  /**
   * Utility to collect data written to an {@link java.io.OutputStream} in
   * {@link java.nio.ByteBuffer}s. Copied from avro.
   */
  public class ByteBufferOutputStream extends OutputStream {
    public static final int BUFFER_SIZE = 8192;
  
    private List<ByteBuffer> buffers;
  
    public ByteBufferOutputStream() {
      reset();
    }
  
    /** Returns all data written and resets the stream to be empty. */
    public List<ByteBuffer> getBufferList() {
      List<ByteBuffer> result = buffers;
      reset();
      for (ByteBuffer buffer : result)
        buffer.flip();
      return result;
    }
  
    /** Prepend a list of ByteBuffers to this stream. */
    public void prepend(List<ByteBuffer> lists) {
      for (ByteBuffer buffer : lists) {
        buffer.position(buffer.limit());
      }
      buffers.addAll(0, lists);
    }
  
    /** Append a list of ByteBuffers to this stream. */
    public void append(List<ByteBuffer> lists) {
      for (ByteBuffer buffer : lists) {
        buffer.position(buffer.limit());
      }
      buffers.addAll(lists);
    }
  
    public void reset() {
      buffers = new LinkedList<ByteBuffer>();
      buffers.add(ByteBuffer.allocate(BUFFER_SIZE));
    }
  
    public void write(ByteBuffer buffer) {
      buffers.add(buffer);
    }
  
    @Override
    public void write(int b) {
      ByteBuffer buffer = buffers.get(buffers.size() - 1);
      if (buffer.remaining() < 1) {
        buffer = ByteBuffer.allocate(BUFFER_SIZE);
        buffers.add(buffer);
      }
      buffer.put((byte) b);
    }
  
    @Override
    public void write(byte[] b, int off, int len) {
      ByteBuffer buffer = buffers.get(buffers.size() - 1);
      int remaining = buffer.remaining();
      while (len > remaining) {
        buffer.put(b, off, remaining);
        len -= remaining;
        off += remaining;
        buffer = ByteBuffer.allocate(BUFFER_SIZE);
        buffers.add(buffer);
        remaining = buffer.remaining();
      }
      buffer.put(b, off, len);
    }
  
    /** Add a buffer to the output without copying, if possible. */
    public void writeBuffer(ByteBuffer buffer) throws IOException {
      if (buffer.remaining() < BUFFER_SIZE) {
        write(buffer.array(), buffer.position(), buffer.remaining());
      } else { // append w/o copying bytes
        ByteBuffer dup = buffer.duplicate();
        dup.position(buffer.limit()); // ready for flip
        buffers.add(dup);
      }
    }
  }
  