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.index.sai.disk.io;
  
  
  import java.io.IOException;
  
  import org.apache.cassandra.io.util.FileHandle;
  import org.apache.cassandra.io.util.RandomAccessReader;
  import org.apache.lucene.store.DataInput;
  import org.apache.lucene.store.IndexInput;
  
  /**
   * This is a wrapper over a Cassandra {@link RandomAccessReader} that provides an {@link IndexInput}
   * interface for Lucene classes that need {@link IndexInput}. This is an optimisation because the
   * Lucene {@link DataInput} reads bytes one at a time whereas the {@link RandomAccessReader} is
   * optimised to read multibyte objects faster.
   */
  public class IndexInputReader extends IndexInput
  {
      /**
       * the byte order of `input`'s native readX operations doesn't matter,
       * because we only use `readFully` and `readByte` methods. IndexInput calls these
       * (via DataInput) with methods that enforce LittleEndian-ness.
      */
      private final RandomAccessReader input;
      private final Runnable doOnClose;
  
      private IndexInputReader(RandomAccessReader input, Runnable doOnClose)
      {
          super(input.getPath());
          this.input = input;
          this.doOnClose = doOnClose;
      }
  
      public static IndexInputReader create(RandomAccessReader input)
      {
          return new IndexInputReader(input, () -> {});
      }
  
      public static IndexInputReader create(RandomAccessReader input, Runnable doOnClose)
      {
          return new IndexInputReader(input, doOnClose);
      }
  
      public static IndexInputReader create(FileHandle handle)
      {
          RandomAccessReader reader = handle.createReader();
          return new IndexInputReader(reader, () -> {});
      }
  
      @Override
      public byte readByte() throws IOException
      {
          return input.readByte();
      }
  
      @Override
      public void readBytes(byte[] bytes, int off, int len) throws IOException
      {
          input.readFully(bytes, off, len);
      }
  
      @Override
      public void close()
      {
          try
          {
              input.close();
          }
          finally
          {
              doOnClose.run();
          }
      }
  
      @Override
      public long getFilePointer()
      {
          return input.getFilePointer();
      }
  
      @Override
      public void seek(long position)
      {
          input.seek(position);
      }
  
      @Override
      public long length()
      {
          return input.length();
      }
  
      @Override
      public IndexInput slice(String sliceDescription, long offset, long length)
      {
          throw new UnsupportedOperationException("Slice operations are not supported");
      }
  }
  