com.healthmarketscience.jackcess.impl

Class TempPageHolder

java.lang.Object

com.healthmarketscience.jackcess.impl.TempPageHolder

public final class TempPageHolder
extends java.lang.Object

Manages a reference to a page buffer.

Field Summary

Fields

Modifier and Type	Field and Description
private TempBufferHolder	_buffer
private int	_bufferModCount the last "modification" count of the buffer that this holder observed.
private int	_pageNumber

Constructor Summary

Constructors

Modifier	Constructor and Description
private	TempPageHolder(TempBufferHolder.Type type)

Method Summary

Modifier and Type	Method and Description
void	clear() Forces any current page data to be disregarded (any getPage/setPage call must reload page data) and releases any referenced memory.
java.nio.ByteBuffer	getPage(PageChannel pageChannel)
int	getPageNumber()
void	invalidate() Forces any current page data to be disregarded (any getPage/setPage call must reload page data).
static TempPageHolder	newHolder(TempBufferHolder.Type type) Creates a new TempPageHolder.
void	possiblyInvalidate(int modifiedPageNumber, java.nio.ByteBuffer modifiedBuffer) Forces any current page data to be disregarded if it matches the given page number (any getPage/setPage call must reload page data) and is not the given buffer.
java.nio.ByteBuffer	setNewPage(PageChannel pageChannel) Allocates a new buffer in the database (with undefined data) and returns a new empty buffer.
java.nio.ByteBuffer	setPage(PageChannel pageChannel, int pageNumber) Sets the current page number and returns that page
private java.nio.ByteBuffer	setPage(PageChannel pageChannel, int pageNumber, boolean rewind)

Methods inherited from class java.lang.Object

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

Field Detail

_pageNumber

private int _pageNumber

_buffer

private final TempBufferHolder _buffer

_bufferModCount

private int _bufferModCount

the last "modification" count of the buffer that this holder observed. this is tracked so that the page data can be re-read if the underlying buffer has been discarded since the last page read

Constructor Detail

TempPageHolder

private TempPageHolder(TempBufferHolder.Type type)

Method Detail

newHolder

public static TempPageHolder newHolder(TempBufferHolder.Type type)

Creates a new TempPageHolder.

Parameters:

type - the type of reference desired for any create page buffers

getPageNumber

public int getPageNumber()

Returns:

the currently set page number

getPage

public java.nio.ByteBuffer getPage(PageChannel pageChannel)
                            throws java.io.IOException

Returns:

the page for the current page number, reading as necessary, position and limit are unchanged

Throws:

java.io.IOException

setPage

public java.nio.ByteBuffer setPage(PageChannel pageChannel,
                                   int pageNumber)
                            throws java.io.IOException

Sets the current page number and returns that page

Returns:

the page for the new page number, reading as necessary, resets position

Throws:

java.io.IOException

setPage

private java.nio.ByteBuffer setPage(PageChannel pageChannel,
                                    int pageNumber,
                                    boolean rewind)
                             throws java.io.IOException

Throws:

java.io.IOException

setNewPage

public java.nio.ByteBuffer setNewPage(PageChannel pageChannel)
                               throws java.io.IOException

Allocates a new buffer in the database (with undefined data) and returns a new empty buffer.

Throws:

java.io.IOException

invalidate

public void invalidate()

Forces any current page data to be disregarded (any getPage/setPage call must reload page data). Does not necessarily release any memory.

possiblyInvalidate

public void possiblyInvalidate(int modifiedPageNumber,
                               java.nio.ByteBuffer modifiedBuffer)

Forces any current page data to be disregarded if it matches the given page number (any getPage/setPage call must reload page data) and is not the given buffer. Does not necessarily release any memory.

clear

public void clear()

Forces any current page data to be disregarded (any getPage/setPage call must reload page data) and releases any referenced memory.