org.apache.xindice.core.filer
Class Paged

java.lang.Object
  |
  +--org.apache.xindice.core.filer.Paged

All Implemented Interfaces:

Configurable, DBObject

Direct Known Subclasses:

BTree, HashFiler

public abstract class Paged

extends Object

implements DBObject, Configurable

Paged is a paged file implementation that is foundation for both the BTree class and the HashFiler. It provides flexible paged I/O and page caching functionality.
Paged has folowing configuration attributes:

• pagesize: Size of the page used by the paged file. Default page size is 4096 bytes. This parameter can be set only before paged file is created. Once it is created, this parameter can not be changed.
• pagecount: Number of pages filer will be created with.
• maxkeysize: Maximum allowed size of the key. Default maximum key size is 256 bytes.
• max-descriptors: Defines maximum amount of simultaneously opened file descriptors this paged file can have. Several descriptors are needed to provide multithreaded access to the underlying file. Too large number will limit amount of collections you can open. Default value is 16 (DEFAULT_DESCRIPTORS_MAX).

FIXME: Currently it seems that maxkeysize is not used anywhere.
TODO: Introduce Paged interface, implementations.

Version:

$Revision: 533253 $, $Date: 2007-04-27 19:12:12 -0400 (Fri, 27 Apr 2007) $

Inner Class Summary

protected class	Paged.FileHeader Paged file's header
protected class	Paged.Page Paged file's page
protected static class	Paged.PageHeader Paged file page's header
protected static class	Paged.PageKey The object wrapping page number.

Field Summary

protected static String	CONFIG_DESCRIPTORS_MAX Name of the configuration attribute "max-descriptors"
protected static String	CONFIG_KEYSIZE_MAX Name of the configuration attribute "maxkeysize"
protected static String	CONFIG_PAGECOUNT Name of the configuration attribute "pagecount"
protected static String	CONFIG_PAGESIZE Name of the configuration attribute "pagesize"
protected static byte	DELETED Deleted page status
protected static int	NO_PAGE Page ID of non-existent page
protected static byte	OVERFLOW Overflow page status
protected static byte	UNUSED Unused page status

Constructor Summary

Paged()

Paged(File file)

Method Summary

protected void	checkOpened()
boolean	close() close closes the DBObject
protected void	closeDescriptor(RandomAccessFile raf) Closes a RandomAccessFile ('descriptor') and removes it from the pool.
boolean	create() create creates a new DBObject and any associated resources for the new DBObject, such as disk files, etc.
protected abstract Paged.FileHeader	createFileHeader() createFileHeader must be implemented by a Paged implementation in order to create an appropriate subclass instance of a FileHeader.
protected abstract Paged.PageHeader	createPageHeader() createPageHeader must be implemented by a Paged implementation in order to create an appropriate subclass instance of a PageHeader.
static int[]	deleteArrayInt(int[] vals, int idx)
static long[]	deleteArrayLong(long[] vals, int idx)
static short[]	deleteArrayShort(short[] vals, int idx)
static Value[]	deleteArrayValue(Value[] vals, int idx)
boolean	drop() drop instructs the DBObjectimplementation to remove itself from existence.
boolean	exists() exists returns whether or not a physical representation of this DBObject actually exists.
void	flush()
Configuration	getConfig() getConfig retrieves the configuration information for the Configurable object instance.
protected RandomAccessFile	getDescriptor() Obtain RandomAccessFile ('descriptor') object out of the pool.
protected File	getFile() getFile returns the file object for this Paged.
protected Paged.FileHeader	getFileHeader() getFileHeader returns the FileHeader
protected Paged.Page	getFreePage() getFreePage returns the first free Page from secondary storage.
protected Paged.Page	getPage(long pageNum) getPage returns the page specified by pageNum.
static int[]	insertArrayInt(int[] vals, int val, int idx)
static long[]	insertArrayLong(long[] vals, long val, int idx)
static short[]	insertArrayShort(short[] vals, short val, int idx)
static Value[]	insertArrayValue(Value[] vals, Value val, int idx)
boolean	isOpened() isOpened returns whether or not the DBObject is opened for business.
boolean	open() open opens the DBObject
protected void	putDescriptor(RandomAccessFile raf) Puts a RandomAccessFile ('descriptor') back into the descriptor pool.
protected Value	readValue(long page) readValue reads the multi-Paged Value starting at the specified page number.
protected Value	readValue(Paged.Page page) readValue reads the multi-Paged Value starting at the specified Page.
void	setConfig(Configuration config) setConfig sets the configuration information for the Configurable object instance.
protected void	setFile(File file) setFile sets the file object for this Paged.
protected void	unlinkPages(long pageNum) unlinkPages unlinks a set of pages starting at the specified page number.
protected void	unlinkPages(Paged.Page page) unlinkPages unlinks a set of pages starting at the specified Page.
protected void	writeValue(long page, Value value) writeValue writes the multi-Paged Value starting at the specified page number.
protected void	writeValue(Paged.Page page, Value value) writeValue writes the multi-Paged Value starting at the specified Page.

Methods inherited from class java.lang.Object

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

Field Detail

CONFIG_PAGESIZE

protected static final String CONFIG_PAGESIZE

Name of the configuration attribute "pagesize"

CONFIG_PAGECOUNT

protected static final String CONFIG_PAGECOUNT

Name of the configuration attribute "pagecount"

CONFIG_KEYSIZE_MAX

protected static final String CONFIG_KEYSIZE_MAX

Name of the configuration attribute "maxkeysize"

CONFIG_DESCRIPTORS_MAX

protected static final String CONFIG_DESCRIPTORS_MAX

Name of the configuration attribute "max-descriptors"

UNUSED

protected static final byte UNUSED

Unused page status

OVERFLOW

protected static final byte OVERFLOW

Overflow page status

DELETED

protected static final byte DELETED

Deleted page status

NO_PAGE

protected static final int NO_PAGE

Page ID of non-existent page

Constructor Detail

Paged

public Paged()

Paged

public Paged(File file)

Method Detail

setConfig

public void setConfig(Configuration config)

Description copied from interface: Configurable

setConfig sets the configuration information for the Configurable object instance.

Specified by:

setConfig in interface Configurable

Following copied from interface: org.apache.xindice.util.Configurable

Parameters:

config - The configuration Node

getConfig

public Configuration getConfig()

Description copied from interface: Configurable

getConfig retrieves the configuration information for the Configurable object instance.

Specified by:

getConfig in interface Configurable

Following copied from interface: org.apache.xindice.util.Configurable

Returns:

The configuration Node

setFile

protected final void setFile(File file)

setFile sets the file object for this Paged.

Parameters:

file - The File

getFile

protected final File getFile()

getFile returns the file object for this Paged.

Returns:

The File

getDescriptor

protected final RandomAccessFile getDescriptor()
                                        throws IOException

Obtain RandomAccessFile ('descriptor') object out of the pool. If no descriptors available, and maximum amount already allocated, the call will block.

putDescriptor

protected final void putDescriptor(RandomAccessFile raf)

Puts a RandomAccessFile ('descriptor') back into the descriptor pool.

closeDescriptor

protected final void closeDescriptor(RandomAccessFile raf)

Closes a RandomAccessFile ('descriptor') and removes it from the pool.

getPage

protected final Paged.Page getPage(long pageNum)
                            throws IOException

getPage returns the page specified by pageNum.

Parameters:

pageNum - The Page number

Returns:

The requested Page

Throws:

IOException - if an Exception occurs

readValue

protected final Value readValue(Paged.Page page)
                         throws IOException

readValue reads the multi-Paged Value starting at the specified Page.

Parameters:

page - The starting Page

Returns:

The Value

Throws:

IOException - if an Exception occurs

readValue

protected final Value readValue(long page)
                         throws IOException

readValue reads the multi-Paged Value starting at the specified page number.

Parameters:

page - The starting page number

Returns:

The Value

Throws:

IOException - if an Exception occurs

writeValue

protected final void writeValue(Paged.Page page,
                                Value value)
                         throws IOException

writeValue writes the multi-Paged Value starting at the specified Page.

Parameters:

page - The starting Page

value - The Value to write

Throws:

IOException - if an Exception occurs

writeValue

protected final void writeValue(long page,
                                Value value)
                         throws IOException

writeValue writes the multi-Paged Value starting at the specified page number.

Parameters:

page - The starting page number

value - The Value to write

Throws:

IOException - if an Exception occurs

unlinkPages

protected void unlinkPages(Paged.Page page)
                    throws IOException

unlinkPages unlinks a set of pages starting at the specified Page.

Parameters:

page - The starting Page to unlink

Throws:

IOException - if an Exception occurs

unlinkPages

protected final void unlinkPages(long pageNum)
                          throws IOException

unlinkPages unlinks a set of pages starting at the specified page number.

Parameters:

pageNum - The starting page number to unlink

Throws:

IOException - if an Exception occurs

getFreePage

protected final Paged.Page getFreePage()
                                throws IOException

getFreePage returns the first free Page from secondary storage. If no Pages are available, the file is grown as appropriate.

Returns:

The next free Page

Throws:

IOException - if an Exception occurs

checkOpened

protected final void checkOpened()
                          throws DBException

Throws:

DBException - COL_COLLECTION_CLOSED if paged file is closed

getFileHeader

protected Paged.FileHeader getFileHeader()

getFileHeader returns the FileHeader

Returns:

The FileHeader

exists

public boolean exists()

Description copied from interface: DBObject

exists returns whether or not a physical representation of this DBObject actually exists. In the case of a HashFiler, this would check for the file, and in the case of an FTPFiler, it might perform a connection check.

Specified by:

exists in interface DBObject

Returns:

True if this paged file exists

create

public boolean create()
               throws DBException

Description copied from interface: DBObject

create creates a new DBObject and any associated resources for the new DBObject, such as disk files, etc.

Specified by:

create in interface DBObject

Following copied from interface: org.apache.xindice.core.DBObject

Returns:

Whether or not the DBObject was created

open

public boolean open()
             throws DBException

Description copied from interface: DBObject

open opens the DBObject

Specified by:

open in interface DBObject

Following copied from interface: org.apache.xindice.core.DBObject

Returns:

Whether or not the DBObject was opened

close

public boolean close()
              throws DBException

Description copied from interface: DBObject

close closes the DBObject

Specified by:

close in interface DBObject

Following copied from interface: org.apache.xindice.core.DBObject

Returns:

Whether or not the DBObject was closed

isOpened

public boolean isOpened()

Description copied from interface: DBObject

isOpened returns whether or not the DBObject is opened for business.

Specified by:

isOpened in interface DBObject

Following copied from interface: org.apache.xindice.core.DBObject

Returns:

The open status of the DBObject

drop

public boolean drop()
             throws DBException

Description copied from interface: DBObject

drop instructs the DBObjectimplementation to remove itself from existence. The DBObject's parent is responsible for removing any references to the DBObject in its own context.

Specified by:

drop in interface DBObject

Following copied from interface: org.apache.xindice.core.DBObject

Returns:

Whether or not the DBObject was dropped

flush

public void flush()
           throws DBException

createFileHeader

protected abstract Paged.FileHeader createFileHeader()

createFileHeader must be implemented by a Paged implementation in order to create an appropriate subclass instance of a FileHeader.

Returns:

a new FileHeader

createPageHeader

protected abstract Paged.PageHeader createPageHeader()

createPageHeader must be implemented by a Paged implementation in order to create an appropriate subclass instance of a PageHeader.

Returns:

a new PageHeader

insertArrayValue

public static Value[] insertArrayValue(Value[] vals,
                                       Value val,
                                       int idx)

deleteArrayValue

public static Value[] deleteArrayValue(Value[] vals,
                                       int idx)

insertArrayLong

public static long[] insertArrayLong(long[] vals,
                                     long val,
                                     int idx)

deleteArrayLong

public static long[] deleteArrayLong(long[] vals,
                                     int idx)

insertArrayInt

public static int[] insertArrayInt(int[] vals,
                                   int val,
                                   int idx)

deleteArrayInt

public static int[] deleteArrayInt(int[] vals,
                                   int idx)

insertArrayShort

public static short[] insertArrayShort(short[] vals,
                                       short val,
                                       int idx)

deleteArrayShort

public static short[] deleteArrayShort(short[] vals,
                                       int idx)