org.crosswire.jsword.book.sword
Class ZVerseBackend

java.lang.Object
  org.crosswire.jsword.book.sword.AbstractBackend
      org.crosswire.jsword.book.sword.ZVerseBackend

All Implemented Interfaces:

Activatable

public class ZVerseBackend
extends AbstractBackend

A backend to read compressed data verse based files. While the text file contains data compressed with ZIP or LZSS, it cannot be uncompressed using a stand alone zip utility, such as WinZip or gzip. The reason for this is that the data file is a concatenation of blocks of compressed data.

The blocks can either be "b", book (aka testament); "c", chapter or "v", verse. The choice is a matter of trade offs. The program needs to uncompress a block into memory. Having it at the book level is very memory expensive. Having it at the verse level is very disk expensive, but takes the least amount of memory. The most common is chapter.

In order to find the data in the text file, we need to find the block. The first index (comp) is used for this. Each verse is indexed to a tuple (block number, verse start, verse size). This data allows us to find the correct block, and to extract the verse from the uncompressed block, but it does not help us uncompress the block.

Once the block is known, then the next index (idx) gives the location of the compressed block, its compressed size and its uncompressed size.

There are 3 files for each testament, 2 (comp and idx) are indexes into the third (text) which contains the data. The key into each index is the verse index within that testament, which is determined by book, chapter and verse of that key.

All numbers are stored 2-complement, little endian.

Then proceed as follows, at all times working on the set of files for the testament in question:

 in the comp file, seek to the index * 10
 read 10 bytes.
 the block-index is the first 4 bytes (32-bit number)
 the next bytes are the verse offset and length of the uncompressed block.
 in the idx file seek to block-index * 12
 read 12 bytes
 the text-block-index is the first 4 bytes
 the data-size is the next 4 bytes
 the uncompressed-size is the next 4 bytes
 in the text file seek to the text-block-index
 read data-size bytes
 decipher them if they are encrypted
 unGZIP them into a byte uncompressed-size
 

Author:

Joe Walker [joe at eireneh dot com]

See Also:

for license details.
The copyright to this program is held by it's authors.

Field Summary

private boolean	active Are we active
private BlockType	blockType Whether the book is blocked by Book, Chapter or Verse.
private static int	COMP_ENTRY_SIZE How many bytes in the comp index?
private static int	IDX_ENTRY_SIZE How many bytes in the idx index?
private long	lastBlockNum
private Testament	lastTestament
private byte[]	lastUncompressed
private static Logger	log The log stream
private File	ntCompFile
private RandomAccessFile	ntCompRaf
private File	ntIdxFile
private RandomAccessFile	ntIdxRaf
private File	ntTextFile
private RandomAccessFile	ntTextRaf
private File	otCompFile The compressed random access files
private RandomAccessFile	otCompRaf The compressed random access files
private File	otIdxFile The index random access files
private RandomAccessFile	otIdxRaf The index random access files
private File	otTextFile The data random access files
private RandomAccessFile	otTextRaf The data random access files
private static String	SUFFIX_COMP
private static String	SUFFIX_INDEX
private static String	SUFFIX_PART1
private static String	SUFFIX_TEXT

Constructor Summary

ZVerseBackend(SwordBookMetaData sbmd, BlockType blockType)
Simple ctor

Method Summary

void	activate(Lock lock) Called to indicate that the Book should initialize itself, and consume whatever system resources it needs to be able to respond to other queries.
protected void	checkActive() Helper method so we can quickly activate ourselves on access
boolean	contains(Key key) Determine whether this Book contains the key in question
void	deactivate(Lock lock) Called to indicate that the Book should release whatever system resources it can to make way for other uses.
String	getRawText(Key key) Get the text allotted for the given entry
void	setAliasKey(Key alias, Key source) Sets alias for a comment on a verse range I.e.
void	setRawText(Key key, String text) Set the text allotted for the given verse

Methods inherited from class org.crosswire.jsword.book.sword.AbstractBackend

create, decipher, encipher, getBookMetaData, getExpandedDataPath, isSupported, isWritable, readIndex

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SUFFIX_COMP

private static final String SUFFIX_COMP

See Also:

Constant Field Values

SUFFIX_INDEX

private static final String SUFFIX_INDEX

See Also:

Constant Field Values

SUFFIX_PART1

private static final String SUFFIX_PART1

See Also:

Constant Field Values

SUFFIX_TEXT

private static final String SUFFIX_TEXT

See Also:

Constant Field Values

blockType

private BlockType blockType

Whether the book is blocked by Book, Chapter or Verse.

lastTestament

private Testament lastTestament

lastBlockNum

private long lastBlockNum

lastUncompressed

private byte[] lastUncompressed

active

private boolean active

Are we active

otIdxRaf

private RandomAccessFile otIdxRaf

The index random access files

ntIdxRaf

private RandomAccessFile ntIdxRaf

otTextRaf

private RandomAccessFile otTextRaf

The data random access files

ntTextRaf

private RandomAccessFile ntTextRaf

otCompRaf

private RandomAccessFile otCompRaf

The compressed random access files

ntCompRaf

private RandomAccessFile ntCompRaf

otIdxFile

private File otIdxFile

The index random access files

ntIdxFile

private File ntIdxFile

otTextFile

private File otTextFile

The data random access files

ntTextFile

private File ntTextFile

otCompFile

private File otCompFile

The compressed random access files

ntCompFile

private File ntCompFile

COMP_ENTRY_SIZE

private static final int COMP_ENTRY_SIZE

How many bytes in the comp index?

See Also:

Constant Field Values

IDX_ENTRY_SIZE

private static final int IDX_ENTRY_SIZE

How many bytes in the idx index?

See Also:

Constant Field Values

log

private static final Logger log

The log stream

Constructor Detail

ZVerseBackend

public ZVerseBackend(SwordBookMetaData sbmd,
                     BlockType blockType)

Simple ctor

Method Detail

activate

public final void activate(Lock lock)

Description copied from interface: Activatable

Called to indicate that the Book should initialize itself, and consume whatever system resources it needs to be able to respond to other queries.

Parameters:

lock - An attempt to ensure that only the Activator calls this method

deactivate

public final void deactivate(Lock lock)

Description copied from interface: Activatable

Called to indicate that the Book should release whatever system resources it can to make way for other uses.

Parameters:

lock - An attempt to ensure that only the Activator calls this method

contains

public boolean contains(Key key)

Description copied from class: AbstractBackend

Determine whether this Book contains the key in question

Specified by:

contains in class AbstractBackend

Parameters:

key - The key whose presence is desired.

Returns:

true if the Book contains the key

getRawText

public String getRawText(Key key)
                  throws BookException

Description copied from class: AbstractBackend

Get the text allotted for the given entry

Specified by:

getRawText in class AbstractBackend

Parameters:

key - The key to fetch

Returns:

String The data for the verse in question

Throws:

BookException - If the data can not be read.

setAliasKey

public void setAliasKey(Key alias,
                        Key source)
                 throws IOException

Description copied from class: AbstractBackend

Sets alias for a comment on a verse range I.e. setRawText() was for verse range Gen.1.1-3 then setAliasKey should be called for Gen.1.1.2 and Gen.1.1.3

Specified by:

setAliasKey in class AbstractBackend

Parameters:

alias - Alias Key

source - Source Key

Throws:

IOException - Exception when anything goes wrong on writing the alias

setRawText

public void setRawText(Key key,
                       String text)
                throws BookException,
                       IOException

Description copied from class: AbstractBackend

Set the text allotted for the given verse

Specified by:

setRawText in class AbstractBackend

Parameters:

key - The key to set text to

text - The text to be set for key

Throws:

BookException - If the data can not be set.

IOException - If the module data path could not be created.

checkActive

protected final void checkActive()

Helper method so we can quickly activate ourselves on access