net.metanotion.io.block

Class FreeListBlock

java.lang.Object

net.metanotion.io.block.FreeListBlock

class FreeListBlock
extends Object

Manages free pages in a block file.

Tracks available pages for allocation using a linked list of blocks. Each block contains multiple free page references and fits on a single disk page.

On-disk format:

    Magic number (long)
    next freelist block page (unsigned int)
    size (unsigned int)
    that many free pages (unsigned ints)
 

Free page format:

    Magic number (long)
 

Field Summary

Fields

Modifier and Type	Field and Description
int	page

Constructor Summary

Constructors

Constructor and Description
FreeListBlock(RandomAccessInterface file, int startPage)

Method Summary

Modifier and Type	Method and Description
void	addPage(int freePage) Adds free page and writes new len to disk
boolean	flbck(boolean fix) Recursive.
int	getNextPage()
static void	initPage(RandomAccessInterface file, int page)
boolean	isEmpty()
boolean	isFull()
void	setNextPage(int nxt) Set and write the next page only
int	takePage() Takes next page and writes new len to disk
String	toString()
void	writeBlock()

Methods inherited from class java.lang.Object

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

Field Detail

page

public final int page

Constructor Detail

FreeListBlock

public FreeListBlock(RandomAccessInterface file,
                     int startPage)
              throws IOException

Throws:

IOException

Method Detail

addPage

public void addPage(int freePage)
             throws IOException

Adds free page and writes new len to disk

Throws:

IllegalStateException - if full

IOException

flbck

public boolean flbck(boolean fix)
              throws IOException

Recursive.

Throws:

IOException

getNextPage

public int getNextPage()

initPage

public static void initPage(RandomAccessInterface file,
                            int page)
                     throws IOException

Throws:

IOException

isEmpty

public boolean isEmpty()

isFull

public boolean isFull()

setNextPage

public void setNextPage(int nxt)
                 throws IOException

Set and write the next page only

Throws:

IOException

takePage

public int takePage()
             throws IOException

Takes next page and writes new len to disk

Throws:

IllegalStateException - if empty

IOException

toString

public String toString()

Overrides:

toString in class Object

writeBlock

public void writeBlock()
                throws IOException

Throws:

IOException