jdbm.recman.FileHeader Maven / Gradle / Ivy
/**
* JDBM LICENSE v1.00
*
* Redistribution and use of this software and associated documentation
* ("Software"), with or without modification, are permitted provided
* that the following conditions are met:
*
* 1. Redistributions of source code must retain copyright
* statements and notices. Redistributions must also contain a
* copy of this document.
*
* 2. Redistributions in binary form must reproduce the
* above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* 3. The name "JDBM" must not be used to endorse or promote
* products derived from this Software without prior written
* permission of Cees de Groot. For written permission,
* please contact [email protected].
*
* 4. Products derived from this Software may not be called "JDBM"
* nor may "JDBM" appear in their names without prior written
* permission of Cees de Groot.
*
* 5. Due credit should be given to the JDBM Project
* (http://jdbm.sourceforge.net/).
*
* THIS SOFTWARE IS PROVIDED BY THE JDBM PROJECT AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
* NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* CEES DE GROOT OR ANY CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Copyright 2000 (C) Cees de Groot. All Rights Reserved.
* Contributions are Copyright (C) 2000 by their associated contributors.
*
* $Id: FileHeader.java,v 1.3 2005/06/25 23:12:32 doomdark Exp $
*/
package jdbm.recman;
import java.io.IOException;
import org.apache.directory.server.i18n.I18n;
/**
* This class represents a file header. It is a 1:1 representation of
* the data that appears in block 0 of a file.
* The FileHeader is stored into a BlockIo.
* The BlockIo will always contain the following bytes :
*
* - [0..3] 0x1350 : a marker for a FILE_HEADER
* - [4..11] : The BlockIo reference to the first FREE_PAGE ID
* - [12..19] : The BlockIo reference to the last FREE_PAGE ID
* - [20..27] : The BlockIo reference to the first USED_PAGE ID
* - [28..35] : The BlockIo reference to the last USED_PAGE ID
* - [36..43] : The BlockIo reference to the first TRANSLATION_PAGE ID
* - [44..51] : The BlockIo reference to the last TRANSLATION_PAGE ID
* - [52..59] : The BlockIo reference to the first FREELOGIDS_PAGE ID
* - [60..67] : The BlockIo reference to the last FREELOGIDS_PAGE ID
* - [68..71] : The BlockIo reference to the first FREEPHYSIDS_PAGE ID
* - [72..79] : The BlockIo reference to the last FREEPHYSIDS_PAGE ID
* - [80..87]* : The reference to the BlockIo which is the root for the data contained in this File.
* We may have more than one, but no more than 1014, if the BLOCK_SIZE is 8192
*
*/
class FileHeader implements BlockView
{
/** Position of the Magic number for FileHeader */
private static final short O_MAGIC = 0; // short magic
/** Position of the Lists in the blockIo */
private static final short O_LISTS = Magic.SZ_SHORT; // long[2*NLISTS]
/** Position of the ROOTs in the blockIo */
private static final int O_ROOTS = O_LISTS + ( Magic.NLISTS * 2 * Magic.SZ_LONG );
/** The BlockIo used to store the FileHeader */
private BlockIo block;
/** The number of "root" rowids available in the file. */
static final int NROOTS = ( RecordFile.BLOCK_SIZE - O_ROOTS ) / Magic.SZ_LONG;
/**
* Constructs a FileHeader object from a block.
*
* @param block The block that contains the file header
* @param isNew If true, the file header is for a new file.
* @throws IOException if the block is too short to keep the file
* header.
*/
FileHeader( BlockIo block, boolean isNew )
{
this.block = block;
if ( isNew )
{
block.writeShort( O_MAGIC, Magic.FILE_HEADER );
}
else if ( block.readShort( O_MAGIC ) != Magic.FILE_HEADER )
{
throw new Error( I18n.err( I18n.ERR_544, block.readShort( O_MAGIC ) ) );
}
}
/**
* Returns the offset of the "first" block of the indicated list
*/
private short offsetOfFirst( int list )
{
return ( short ) ( O_LISTS + ( 2 * Magic.SZ_LONG * list ) );
}
/**
* Returns the offset of the "last" block of the indicated list
*/
private short offsetOfLast( int list )
{
return ( short ) ( offsetOfFirst( list ) + Magic.SZ_LONG );
}
/**
* Returns the offset of the indicated root
*/
private short offsetOfRoot( int root )
{
return ( short ) ( O_ROOTS + ( root * Magic.SZ_LONG ) );
}
/**
* Returns the first block of the indicated list
*/
long getFirstOf( int list )
{
return block.readLong( offsetOfFirst( list ) );
}
/**
* Sets the first block of the indicated list
*/
void setFirstOf( int list, long value )
{
block.writeLong( offsetOfFirst( list ), value );
}
/**
* Returns the last block of the indicated list
*/
long getLastOf( int list )
{
return block.readLong( offsetOfLast( list ) );
}
/**
* Sets the last block of the indicated list
*/
void setLastOf( int list, long value )
{
block.writeLong( offsetOfLast( list ), value );
}
/**
* Returns the indicated root rowid. A root rowid is a special rowid
* that needs to be kept between sessions. It could conceivably be
* stored in a special file, but as a large amount of space in the
* block header is wasted anyway, it's more useful to store it where
* it belongs.
*
* @see #NROOTS
*/
long getRoot( int root )
{
return block.readLong( offsetOfRoot( root ) );
}
/**
* Sets the indicated root rowid.
*
* @see #getRoot
* @see #NROOTS
*/
void setRoot( int root, long rowid )
{
block.writeLong( offsetOfRoot( root ), rowid );
}
/**
* {@inheritDoc}
*/
public String toString()
{
StringBuilder sb = new StringBuilder();
sb.append( "FileHeader ( " );
// The blockIO
sb.append( block ).append( ", " );
// The free pages
sb.append( "free[" );
sb.append( block.readLong( ( short ) ( 2 + ( 2 * Magic.SZ_LONG * Magic.FREE_PAGE ) ) ) );
sb.append( ", " );
sb.append( block.readLong( ( short ) ( 2 + ( 2 * Magic.SZ_LONG * Magic.FREE_PAGE ) + Magic.SZ_LONG ) ) );
sb.append( "], " );
// The used pages
sb.append( "used[" );
sb.append( block.readLong( ( short ) ( 2 + ( 2 * Magic.SZ_LONG * Magic.USED_PAGE ) ) ) );
sb.append( ", " );
sb.append( block.readLong( ( short ) ( 2 + ( 2 * Magic.SZ_LONG * Magic.USED_PAGE ) + Magic.SZ_LONG ) ) );
sb.append( "], " );
// The translation pages
sb.append( "translation[" );
sb.append( block.readLong( ( short ) ( 2 + ( 2 * Magic.SZ_LONG * Magic.TRANSLATION_PAGE ) ) ) );
sb.append( ", " );
sb.append( block.readLong( ( short ) ( 2 + ( 2 * Magic.SZ_LONG * Magic.TRANSLATION_PAGE ) + Magic.SZ_LONG ) ) );
sb.append( "], " );
// The freeLogIds pages
sb.append( "freeLogIds[" );
sb.append( block.readLong( ( short ) ( 2 + ( 2 * Magic.SZ_LONG * Magic.FREELOGIDS_PAGE ) ) ) );
sb.append( ", " );
sb.append( block.readLong( ( short ) ( 2 + ( 2 * Magic.SZ_LONG * Magic.FREELOGIDS_PAGE ) + Magic.SZ_LONG ) ) );
sb.append( "], " );
// The freePhysIds pages
sb.append( "freePhysIds[" );
sb.append( block.readLong( ( short ) ( 2 + ( 2 * Magic.SZ_LONG * Magic.FREEPHYSIDS_PAGE ) ) ) );
sb.append( ", " );
sb.append( block.readLong( ( short ) ( 2 + ( 2 * Magic.SZ_LONG * Magic.FREEPHYSIDS_PAGE ) + Magic.SZ_LONG ) ) );
sb.append( "]" );
sb.append( " )" );
return sb.toString();
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy