ru.biosoft.access
Class BTreeIndex

java.lang.Object
  |
  +--java.util.AbstractMap
        |
        +--ru.biosoft.access.BTreeIndex

public class BTreeIndex

extends 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.

Version: 1.0

Since: 1.2

See Also: Index.IndexEntry

todo 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.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Field Detail

DEFAULT_BLOCK_SIZE

public final static int DEFAULT_BLOCK_SIZE

Default file block size.

public final static int ROOT_BLOCK_OFFSET

Root block offset

public BTreeIndex(File dataFile, String indexName, 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:

IOException - if an I/O error occurs.

todo Extended Comments needed.

public BTreeIndex(File dataFile, String indexName, 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:

IOException - if an I/O error occurs.

See Also:

#BTreeIndex(File, String, int)

todo Extended Comments needed.

public void clear()

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

Throws:

ChainRuntimeException - if an I/O error occurs.

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.

Throws:

IOException - if an I/O error occurs.

public boolean containsKey(Object key)

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

Parameters:

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

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

Throws:

ClassCastException - if the key is not of type String.

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

ChainRuntimeException - if an I/O error occurs.

public 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.

Returns: a set view of the mappings contained in this index.

todo HIGH Test changes reflection!!!.

public Object get(Object key)

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

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:

ClassCastException - if the key is not of type String.

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

ChainRuntimeException - if an I/O error occurs.

See Also:

Index.IndexEntry

public boolean isValid()

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

See Also:

clear()

public Object put(Object key, 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.

Parameters:

_key - key with which the specified entry is to be associated.

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:

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

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

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.

public Object remove(Object key)

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

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:

ClassCastException - if the key is not of type String.

ChainRuntimeException - if an I/O error occurs.

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.

Returns: the number of key-entry mappings in this index.

Association Links

to Class ru.biosoft.access.BTreeIndex.NodeComparator

Comparator for compare keys of nodes.

to Class java.io.File

Name of index file

to Class java.io.RandomAccessFile

Index file

to Class ru.biosoft.access.BTreeIndex.Block

Root

to Class java.util.Map

Cache