Package com.caucho.db.blob

Source Code of com.caucho.db.blob.InodeBlobInputStream

/*
* Copyright (c) 1998-2011 Caucho Technology -- all rights reserved
*
* This file is part of Resin(R) Open Source
*
* Each copy or derived work must preserve the copyright notice and this
* notice unmodified.
*
* Resin Open Source is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Resin Open Source is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
* of NON-INFRINGEMENT.  See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with Resin Open Source; if not, write to the
*   Free SoftwareFoundation, Inc.
*   59 Temple Place, Suite 330
*   Boston, MA 02111-1307  USA
*
* @author Scott Ferguson
*/

package com.caucho.db.blob;

import java.io.IOException;
import java.io.InputStream;

import com.caucho.db.block.Block;
import com.caucho.db.block.BlockStore;

/**
* Directly reading the blob from the inode.
*/
public class InodeBlobInputStream extends InputStream {
  private static final int INODE_DIRECT_BLOCKS = 14;
   
  private BlockStore _store;

  private long _length;
  private long _offset;

  private byte []_inode;
  private int _inodeOffset;

  private Block _block;
  private byte []_buffer;
  private int _bufferOffset;
  private int _bufferEnd;
 
  /**
   * Creates a blob output stream.
   *
   * @param store the output store
   */
  public InodeBlobInputStream(BlockStore store, byte []inode, int inodeOffset)
  {
    init(store, inode, inodeOffset);
  }
 
  /**
   * Creates a blob output stream.
   *
   * @param store the output store
   */
  public InodeBlobInputStream(Inode inode)
  {
    init(inode.getStore(), inode.getBuffer(), 0);
  }

  /**
   * Initialize the output stream.
   */
  public void init(BlockStore store, byte []inode, int inodeOffset)
  {
    if (store == null)
      throw new NullPointerException();
   
    _store = store;

    _inode = inode;
    _inodeOffset = inodeOffset;

    _length = readLong(inode, inodeOffset);
    _offset = 0;
   
    _block = null;

    if (_length <= Inode.INLINE_BLOB_SIZE) {
      _buffer = inode;
      _bufferOffset = inodeOffset + 8;
      _bufferEnd = (int) (_bufferOffset + _length);
    }
    else {
      _buffer = null;
      _bufferOffset = 0;
      _bufferEnd = 0;
    }
  }

  /**
   * Reads a byte.
   */
  public int read()
    throws IOException
  {
    if (_length <= _offset)
      return -1;

    if (_bufferEnd <= _bufferOffset)
      readBlock();

    _offset++;

    return _buffer[_bufferOffset++] & 0xff;
  }

  /**
   * Reads a buffer.
   */
  public int read(byte []buf, int offset, int length)
    throws IOException
  {
    if (_length <= _offset)
      return -1;

    if (_bufferEnd <= _bufferOffset)
      readBlock();

    int sublen = _bufferEnd - _bufferOffset;
    if (length < sublen)
      sublen = length;

    _offset += sublen;

    System.arraycopy(_buffer, _bufferOffset, buf, offset, sublen);

    _bufferOffset += sublen;

    return sublen;
  }

  /**
   * Closes the buffer.
   */
  public void close()
  {
    if (_block != null) {
      Block block = _block;
      _block = null;
      block.free();
    }
  }

  /**
   * Updates the buffer.
   */
  public void readBlock()
    throws IOException
  {
    if (_block != null) {
      Block block = _block;
      _block = null;
      block.free();
    }

    long addr;

    int blockCount = (int) (_offset / BlockStore.BLOCK_SIZE);
     
    if (blockCount < INODE_DIRECT_BLOCKS) {
      addr = readLong(_inode, _inodeOffset + 8 * (blockCount + 1));
    }
    else {
      long ptrAddr = readLong(_inode,
                              _inodeOffset + 8 * (INODE_DIRECT_BLOCKS + 1));

      Block ptr = _store.readBlock(_store.addressToBlockId(ptrAddr));

      addr = readLong(ptr.getBuffer(), 8 * (blockCount - INODE_DIRECT_BLOCKS));

      ptr.free();
    }

    _block = _store.readBlock(_store.addressToBlockId(addr));
    _buffer = _block.getBuffer();

    int offset = (int) (addr & BlockStore.BLOCK_OFFSET_MASK);

    if (offset > 0) {
      _bufferOffset = readShort(_buffer, offset);
      _bufferEnd = _bufferOffset + readShort(_buffer, offset + 2);
    }
    else {
      _bufferOffset = 0;
      _bufferEnd = _buffer.length;
    }
  }

  /**
   * Writes the long.
   */
  public static long readLong(byte []buffer, int offset)
  {
    return (((buffer[offset + 0] & 0xffL) << 56) +
            ((buffer[offset + 1] & 0xffL) << 48) +
            ((buffer[offset + 2] & 0xffL) << 40) +
            ((buffer[offset + 3] & 0xffL) << 32) +
            ((buffer[offset + 4] & 0xffL) << 24) +
            ((buffer[offset + 5] & 0xffL) << 16) +
            ((buffer[offset + 6] & 0xffL) << 8) +
            ((buffer[offset + 7] & 0xffL)));
  }

  /**
   * Writes the short.
   */
  private static int readShort(byte []buffer, int offset)
  {
    return (((buffer[offset + 0] & 0xff) << 8) +
            ((buffer[offset + 1] & 0xff)));
  }
}
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