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 org.apache.cassandra.io.util;
  
  import java.nio.ByteBuffer;
  import java.nio.FloatBuffer;
  import java.nio.IntBuffer;
  
  /**
   * Rebufferer for reading data by a RandomAccessReader.
   */
  public interface Rebufferer extends ReaderFileProxy
  {
      /**
       * Rebuffer (move on or seek to) a given position, and return a buffer that can be used there.
       * The only guarantee about the size of the returned data is that unless rebuffering at the end of the file,
       * the buffer will not be empty and will contain the requested position, i.e.
       * {@code offset <= position < offset + bh.buffer().limit()}, but the buffer will not be positioned there.
       */
      BufferHolder rebuffer(long position);
  
      /**
       * Called when a reader is closed. Should clean up reader-specific data.
       */
      void closeReader();
  
      interface BufferHolder
      {
          /**
           * Returns a useable buffer (i.e. one whose position and limit can be freely modified). Its limit will be set
           * to the size of the available data in the buffer.
           * The buffer must be treated as read-only.
           */
          ByteBuffer buffer();
  
          default FloatBuffer floatBuffer()
          {
              throw new UnsupportedOperationException();
          }
  
          default IntBuffer intBuffer()
          {
              throw new UnsupportedOperationException();
          }
  
          /**
           * Position in the file of the start of the buffer.
           */
          long offset();
  
          /**
           * To be called when this buffer is no longer in use. Must be called for all BufferHolders, or ChunkCache
           * will not be able to free blocks.
           */
          void release();
      }
  
      BufferHolder EMPTY = new BufferHolder()
      {
          final ByteBuffer EMPTY_BUFFER = ByteBuffer.allocate(0);
  
          @Override
          public ByteBuffer buffer()
          {
              return EMPTY_BUFFER;
          }
  
          @Override
          public long offset()
          {
              return 0;
          }
  
          @Override
          public void release()
          {
              // nothing to do
          }
      };
  }
  