de.lmu.ifi.dbs.elki.index.tree

Class TreeIndexHeader

java.lang.Object

de.lmu.ifi.dbs.elki.persistent.DefaultPageHeader

de.lmu.ifi.dbs.elki.index.tree.TreeIndexHeader

All Implemented Interfaces:

PageHeader

Direct Known Subclasses:

MkTreeHeader, RdKNNTreeHeader

public class TreeIndexHeader
extends DefaultPageHeader

Encapsulates the header information of a tree-like index structure. This information is needed for persistent storage.

Author:

Elke Achtert

Field Summary

Fields

Modifier and Type	Field and Description
(package private) int	dirCapacity The capacity of a directory node (= 1 + maximum number of entries in a directory node).
(package private) int	dirMinimum The minimum number of entries in a directory node.
private int	emptyPagesSize The number of bytes additionally needed for the listing of empty pages of the headed page file.
private int	largestPageID The largest ID used so far
(package private) int	leafCapacity The capacity of a leaf node (= 1 + maximum number of entries in a leaf node).
(package private) int	leafMinimum The minimum number of entries in a leaf node.
private static int	SIZE The size of this header in Bytes, which is 20 Bytes ( 4 Bytes for dirCapacity, leafCapacity, dirMinimum, leafMinimum, and emptyPagesSize).

Constructor Summary

Constructors

Constructor and Description
TreeIndexHeader() Empty constructor for serialization.
TreeIndexHeader(int pageSize, int dirCapacity, int leafCapacity, int dirMinimum, int leafMinimum) Creates a new header with the specified parameters.

Method Summary

Methods

Modifier and Type	Method and Description
int	getDirCapacity() Returns the capacity of a directory node (= 1 + maximum number of entries in a directory node).
int	getDirMinimum() Returns the minimum number of entries in a directory node.
int	getEmptyPagesSize()
int	getLargestPageID()
int	getLeafCapacity() Returns the capacity of a leaf node (= 1 + maximum number of entries in a leaf node).
int	getLeafMinimum() Returns the minimum number of entries in a leaf node.
Stack<Integer>	readEmptyPages(RandomAccessFile file) Read the empty pages from the end of file.
void	readHeader(RandomAccessFile file) Initializes this header from the specified file.
void	setEmptyPagesSize(int emptyPagesSize) Set the size required by the listing of empty pages.
void	setLargestPageID(int largestPageID)
int	size() Returns DefaultPageHeader.size() plus the value of SIZE).
void	writeEmptyPages(Stack<Integer> emptyPages, RandomAccessFile file) Write the indices of empty pages the the end of file.
void	writeHeader(RandomAccessFile file) Writes this header to the specified file.

Methods inherited from class de.lmu.ifi.dbs.elki.persistent.DefaultPageHeader

asByteArray, getPageSize, getReservedPages, readHeader

Methods inherited from class java.lang.Object

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

Field Detail

SIZE

private static int SIZE

The size of this header in Bytes, which is 20 Bytes ( 4 Bytes for dirCapacity, leafCapacity, dirMinimum, leafMinimum, and emptyPagesSize).

dirCapacity

int dirCapacity

The capacity of a directory node (= 1 + maximum number of entries in a directory node).

leafCapacity

int leafCapacity

The capacity of a leaf node (= 1 + maximum number of entries in a leaf node).

dirMinimum

int dirMinimum

The minimum number of entries in a directory node.

leafMinimum

int leafMinimum

The minimum number of entries in a leaf node.

emptyPagesSize

private int emptyPagesSize

The number of bytes additionally needed for the listing of empty pages of the headed page file.

largestPageID

private int largestPageID

The largest ID used so far

Constructor Detail

TreeIndexHeader

public TreeIndexHeader()

Empty constructor for serialization.

TreeIndexHeader

public TreeIndexHeader(int pageSize,
               int dirCapacity,
               int leafCapacity,
               int dirMinimum,
               int leafMinimum)

Creates a new header with the specified parameters.

Parameters:

pageSize - the size of a page in bytes

dirCapacity - the maximum number of entries in a directory node

leafCapacity - the maximum number of entries in a leaf node

dirMinimum - the minimum number of entries in a directory node

leafMinimum - the minimum number of entries in a leaf node

Method Detail

readHeader

public void readHeader(RandomAccessFile file)
                throws IOException

Initializes this header from the specified file. Calls DefaultPageHeader#readHeader(file) and reads the integer values of dirCapacity, leafCapacity, dirMinimum, leafMinimum and emptyPagesSize from the file.

Specified by:

readHeader in interface PageHeader

Overrides:

readHeader in class DefaultPageHeader

Parameters:

file - the file to which this header belongs

Throws:

IOException - if an I/O-error occurs during reading

writeHeader

public void writeHeader(RandomAccessFile file)
                 throws IOException

Writes this header to the specified file. Writes the integer values of dirCapacity, leafCapacity, dirMinimum, leafMinimum and emptyPagesSize to the file.

Specified by:

writeHeader in interface PageHeader

Overrides:

writeHeader in class DefaultPageHeader

Parameters:

file - the file to which this header belongs

Throws:

IOException - IOException if an I/O-error occurs during writing

getDirCapacity

public int getDirCapacity()

Returns the capacity of a directory node (= 1 + maximum number of entries in a directory node).

Returns:

the capacity of a directory node (= 1 + maximum number of entries in a directory node)

getLeafCapacity

public int getLeafCapacity()

Returns the capacity of a leaf node (= 1 + maximum number of entries in a leaf node).

Returns:

the capacity of a leaf node (= 1 + maximum number of entries in a leaf node)

getDirMinimum

public int getDirMinimum()

Returns the minimum number of entries in a directory node.

Returns:

the minimum number of entries in a directory node

getLeafMinimum

public int getLeafMinimum()

Returns the minimum number of entries in a leaf node.

Returns:

the minimum number of entries in a leaf node

getEmptyPagesSize

public int getEmptyPagesSize()

Returns:

the number of bytes needed for the listing of empty pages

setEmptyPagesSize

public void setEmptyPagesSize(int emptyPagesSize)

Set the size required by the listing of empty pages.

Parameters:

emptyPagesSize - the number of bytes needed for this listing of empty pages

getLargestPageID

public int getLargestPageID()

setLargestPageID

public void setLargestPageID(int largestPageID)

size

public int size()

Returns DefaultPageHeader.size() plus the value of SIZE). Note, this is only the base size and probably not the overall size of this header, as there may be empty pages to be maintained.

Specified by:

size in interface PageHeader

Overrides:

size in class DefaultPageHeader

Returns:

the size of this header in Bytes

writeEmptyPages

public void writeEmptyPages(Stack<Integer> emptyPages,
                   RandomAccessFile file)
                     throws IOException

Write the indices of empty pages the the end of file. Calling this method should be followed by a writeHeader(RandomAccessFile).

Parameters:

emptyPages - the stack of empty page ids which remain to be filled

file - File to work with

Throws:

IOException - thrown on IO errors

readEmptyPages

public Stack<Integer> readEmptyPages(RandomAccessFile file)
                              throws IOException,
                                     ClassNotFoundException

Read the empty pages from the end of file.

Parameters:

file - File to work with

Returns:

a stack of empty pages in file

Throws:

IOException - thrown on IO errors

ClassNotFoundException - if the stack of empty pages could not be correctly read from file