ru.biosoft.access
Class BTreeIndex

java.lang.Object
  java.util.AbstractMap
      ru.biosoft.access.BTreeIndex

All Implemented Interfaces:

Index, java.util.Map

Direct Known Subclasses:

BTreeRangeIndex

public class BTreeIndex

extends java.util.AbstractMap

implements Index

Maps keys to entries. A index cannot contain duplicate keys; each key can map to at most one entry.

Key and entries stored in file as Balanced Tree.

Keys are strings and entryes are Index.IndexEntry.

Since:

1.2

Version:

1.0

Author:

DevelopmentOnTheEdge

See Also:

Index.IndexEntry

To do:

Comment, Optimize for speed, Decrease size of index file when indexes removed., HIGH way for specify location for index (or create in temporary) - if dataFile on CD., Describe perfomance.

Nested Class Summary

protected class	BTreeIndex.Block One block of index file.
static class	BTreeIndex.IntKey
static class	BTreeIndex.NodeKey

Nested classes inherited from class ru.biosoft.access.Index

Index.IndexEntry, Index.StringIndexEntry

Nested classes inherited from class java.util.Map

java.util.Map.Entry

Field Summary

protected int	currSize Current size of index
static int	DEFAULT_BLOCK_SIZE Default file block size.
protected java.io.RandomAccessFile	indexFile Index file
protected BTreeIndex.Block	root Root
static int	ROOT_BLOCK_OFFSET Root block offset

Fields inherited from interface ru.biosoft.access.Index

DEFAULT_INDEX_NAME

Constructor Summary

BTreeIndex(java.io.File dataFile, java.lang.String indexName, java.lang.String indexPath)
Create index with DEFAULT_BLOCK_SIZE.

BTreeIndex(java.io.File dataFile, java.lang.String indexName, java.lang.String indexPath, int blockSize)
Construct index based on specified file.

Method Summary

void	clear() Removes all keys and entries from this index.
void	close() Close this index and releases resources (index file).
boolean	containsKey(java.lang.Object key) Returns true if this index contains entry for the specified key.
java.lang.Object	createNode(byte[] buffer, int pos)
java.lang.Object	createNode(byte[] buffer, int pos, java.lang.String key, Index.IndexEntry value)
java.util.Set	entrySet() Returns a set view of the mappings contained in this index.
protected void	finalize()
java.lang.Object	get(java.lang.Object key) Returns the entry to which this index maps the specified key.
protected BTreeIndex.Block	getBlock(int offset)
java.io.File	getIndexFile() Returns index file.
boolean	isValid() Check is index file is valid.
java.util.Iterator	keyIterator(Key key)
java.util.Iterator	nodeIterator(Key key)
java.lang.Object	put(java.lang.Object key, java.lang.Object entry) Associates the specified entry with the specified key in this index.
java.lang.Object	remove(java.lang.Object key) Removes the entry for this key from this index if present.
int	size() Returns the number of key-entry mappings in this index.

Methods inherited from class java.util.AbstractMap

clone, containsValue, equals, hashCode, isEmpty, keySet, putAll, toString, values

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map

containsValue, equals, hashCode, isEmpty, keySet, putAll, values

Field Detail

DEFAULT_BLOCK_SIZE

public static final int DEFAULT_BLOCK_SIZE

Default file block size.

See Also:

Constant Field Values

ROOT_BLOCK_OFFSET

public static final int ROOT_BLOCK_OFFSET

Root block offset

See Also:

Constant Field Values

indexFile

protected java.io.RandomAccessFile indexFile

Index file

currSize

protected int currSize

Current size of index

root

protected BTreeIndex.Block root

Root

Constructor Detail

BTreeIndex

public BTreeIndex(java.io.File dataFile,
                  java.lang.String indexName,
                  java.lang.String indexPath,
                  int blockSize)
           throws java.io.IOException

Construct index based on specified file. If index file already created and blockSize of file not equals specified blockSize, then all operations with index will be invalid and index file may be damaged.

Parameters:

dataFile - File for which index will be created. (or already created)

indexName - Name of the index. Will be added to index file name.

blockSize - Size of block for file operations.

Throws:

java.io.IOException - if an I/O error occurs.

To do:

Extended Comments needed.

BTreeIndex

public BTreeIndex(java.io.File dataFile,
                  java.lang.String indexName,
                  java.lang.String indexPath)
           throws java.io.IOException

Create index with DEFAULT_BLOCK_SIZE.

Parameters:

dataFile - File for which index will be created. (or already created)

indexName - Name of the index. Will be added to index file name.

Throws:

java.io.IOException - if an I/O error occurs.

See Also:

#BTreeIndex(File,String,int)

To do:

Extended Comments needed.

Method Detail

createNode

public java.lang.Object createNode(byte[] buffer,
                                   int pos,
                                   java.lang.String key,
                                   Index.IndexEntry value)

createNode

public java.lang.Object createNode(byte[] buffer,
                                   int pos)

keyIterator

public java.util.Iterator keyIterator(Key key)

nodeIterator

public java.util.Iterator nodeIterator(Key key)

Specified by:

nodeIterator in interface Index

isValid

public boolean isValid()

Check is index file is valid. Check existence and format of index file. If file corrupt you must clear index.

Specified by:

isValid in interface Index

Returns:

true if index valid, false otherwise.

See Also:

clear()

size

public int size()

Returns the number of key-entry mappings in this index. If the index contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

Specified by:

size in interface java.util.Map

Returns:

the number of key-entry mappings in this index.

entrySet

public java.util.Set entrySet()

Returns a set view of the mappings contained in this index. Each element in the returned set is a Map.Entry. The set is backed by the index, so changes to the index are reflected in the set, and vice-versa. If the index is modified while an iteration over the set is in progress, the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the index, via the Iterator.remove, Set.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

Specified by:

entrySet in interface java.util.Map

Returns:

a set view of the mappings contained in this index.

To do:

HIGH Test changes reflection!!!.

containsKey

public boolean containsKey(java.lang.Object key)

Returns true if this index contains entry for the specified key.

Specified by:

containsKey in interface java.util.Map

Parameters:

key - key whose presence in this index is to be tested.

Returns:

true if this index contains entry for the specified key.

Throws:

java.lang.ClassCastException - if the key is not of type String.

java.lang.NullPointerException - key is null and this index does not permit null keys.

ChainRuntimeException - if an I/O error occurs.

put

public java.lang.Object put(java.lang.Object key,
                            java.lang.Object entry)

Associates the specified entry with the specified key in this index. If the index previously contained entry for this key, the old entry is replaced.

Specified by:

put in interface java.util.Map

Parameters:

entry - entry to be associated with the specified key.

Returns:

previous entry associated with specified key, or null if there was no mapping for key.

Throws:

java.lang.ClassCastException - if the key is not of type String. or entry is not of type Index.IndexEntry.

java.lang.IllegalArgumentException - if some aspect of this key or entry prevents it from being stored in this index.

java.lang.NullPointerException - this index does not permit null keys or entries, and the specified key or entry is null.

ChainRuntimeException - if an I/O error occurs.

get

public java.lang.Object get(java.lang.Object key)

Returns the entry to which this index maps the specified key. Returns null if the index contains no entry for this key.

Specified by:

get in interface java.util.Map

Parameters:

key - key whose associated entry is to be returned.

Returns:

the entry to which this index maps the specified key, or null if the index not contains entry for this key.

Throws:

java.lang.ClassCastException - if the key is not of type String.

java.lang.NullPointerException - key is null and this index does not permit null keys.

ChainRuntimeException - if an I/O error occurs.

See Also:

Index.IndexEntry

remove

public java.lang.Object remove(java.lang.Object key)

Removes the entry for this key from this index if present.

Specified by:

remove in interface java.util.Map

Parameters:

key - key whose entry is to be removed from the index.

Returns:

previous entry associated with specified key, or null if there was no entry for key.

Throws:

java.lang.ClassCastException - if the key is not of type String.

ChainRuntimeException - if an I/O error occurs.

getIndexFile

public java.io.File getIndexFile()

Returns index file. This information is essential to remove index files.

Specified by:

getIndexFile in interface Index

Returns:

index file.

clear

public void clear()

Removes all keys and entries from this index. File stored key-entries recreates.

Specified by:

clear in interface java.util.Map

Throws:

ChainRuntimeException - if an I/O error occurs.

close

public void close()
           throws java.io.IOException

Close this index and releases resources (index file). A closed index cannot perform any operations and cannot be reopened.

Specified by:

close in interface Index

Throws:

java.io.IOException - if an I/O error occurs.

finalize

protected void finalize()
                 throws java.lang.Throwable

Throws:

java.lang.Throwable

getBlock

protected BTreeIndex.Block getBlock(int offset)
                             throws java.io.IOException

Throws:

java.io.IOException