com.healthmarketscience.jackcess
Class PageChannel

java.lang.Object
  com.healthmarketscience.jackcess.PageChannel

All Implemented Interfaces:

java.io.Closeable, java.io.Flushable, java.nio.channels.Channel

public class PageChannel
extends java.lang.Object
implements java.nio.channels.Channel, java.io.Flushable

Reads and writes individual pages in a database file

Author:

Tim McCune

Constructor Summary

PageChannel(java.nio.channels.FileChannel channel, JetFormat format, boolean autoSync)

Method Summary

int	allocateNewPage() Allocates a new page in the database.
void	close()
java.nio.ByteBuffer	createBuffer(int size)
java.nio.ByteBuffer	createBuffer(int size, java.nio.ByteOrder order)
java.nio.ByteBuffer	createPageBuffer()
void	deallocatePage(int pageNumber) Deallocate a previously used page in the database.
void	flush()
JetFormat	getFormat()
void	initialize(Database database) Does second-stage initialization, must be called after construction.
boolean	isOpen()
static java.nio.ByteBuffer	narrowBuffer(java.nio.ByteBuffer buffer, int position, int limit)
void	readPage(java.nio.ByteBuffer buffer, int pageNumber)
int	writeNewPage(java.nio.ByteBuffer page) Write a page to disk as a new page, appending it to the database
void	writePage(java.nio.ByteBuffer page, int pageNumber) Write a page to disk
void	writePage(java.nio.ByteBuffer page, int pageNumber, int pageOffset) Write a page (or part of a page) to disk

Methods inherited from class java.lang.Object

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

Constructor Detail

PageChannel

public PageChannel(java.nio.channels.FileChannel channel,
                   JetFormat format,
                   boolean autoSync)
            throws java.io.IOException

Parameters:

channel - Channel containing the database

format - Format of the database in the channel

Throws:

java.io.IOException

Method Detail

initialize

public void initialize(Database database)
                throws java.io.IOException

Does second-stage initialization, must be called after construction.

Throws:

java.io.IOException

getFormat

public JetFormat getFormat()

readPage

public void readPage(java.nio.ByteBuffer buffer,
                     int pageNumber)
              throws java.io.IOException

Parameters:

buffer - Buffer to read the page into

pageNumber - Number of the page to read in (starting at 0)

Throws:

java.io.IOException

writePage

public void writePage(java.nio.ByteBuffer page,
                      int pageNumber)
               throws java.io.IOException

Write a page to disk

Parameters:

page - Page to write

pageNumber - Page number to write the page to

Throws:

java.io.IOException

writePage

public void writePage(java.nio.ByteBuffer page,
                      int pageNumber,
                      int pageOffset)
               throws java.io.IOException

Write a page (or part of a page) to disk

Parameters:

page - Page to write

pageNumber - Page number to write the page to

pageOffset - offset within the page at which to start writing the page data

Throws:

java.io.IOException

writeNewPage

public int writeNewPage(java.nio.ByteBuffer page)
                 throws java.io.IOException

Write a page to disk as a new page, appending it to the database

Parameters:

page - Page to write

Returns:

Page number at which the page was written

Throws:

java.io.IOException

allocateNewPage

public int allocateNewPage()
                    throws java.io.IOException

Allocates a new page in the database. Data in the page is undefined until it is written in a call to writePage(ByteBuffer,int).

Throws:

java.io.IOException

deallocatePage

public void deallocatePage(int pageNumber)
                    throws java.io.IOException

Deallocate a previously used page in the database.

Throws:

java.io.IOException

createPageBuffer

public java.nio.ByteBuffer createPageBuffer()

Returns:

A newly-allocated buffer that can be passed to readPage

createBuffer

public java.nio.ByteBuffer createBuffer(int size)

Returns:

A newly-allocated buffer of the given size and LITTLE_ENDIAN byte order

createBuffer

public java.nio.ByteBuffer createBuffer(int size,
                                        java.nio.ByteOrder order)

Returns:

A newly-allocated buffer of the given size and byte order

flush

public void flush()
           throws java.io.IOException

Specified by:

flush in interface java.io.Flushable

Throws:

java.io.IOException

close

public void close()
           throws java.io.IOException

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.nio.channels.Channel

Throws:

java.io.IOException

isOpen

public boolean isOpen()

Specified by:

isOpen in interface java.nio.channels.Channel

narrowBuffer

public static java.nio.ByteBuffer narrowBuffer(java.nio.ByteBuffer buffer,
                                               int position,
                                               int limit)

Returns:

a duplicate of the current buffer narrowed to the given position and limit. mark will be set at the current position.