Page

A page (a node or a leaf).

For b-tree nodes, the key at a given index is larger than the largest key of the child at the same index.

File format: page length (including length): int check value: short map id: varInt number of keys: varInt type: byte (0: leaf, 1: node; +2: compressed) compressed: bytes saved (varInt) keys leaf: values (one for each key) node: children (1 more than keys)

Methods
static Page	create(MVMap map, long version, Object[] keys, Object[] values, Page.PageReference[] children, long totalCount, int memory) Create a new page.
static Page	create(MVMap map, long version, Object[] keys, Object[] values, Page.PageReference[] children, long totalCount, int memory) Create a new page. The arrays are not cloned. Parameters: map - the map version - the version keys - the keys values - the values children - the child page positions totalCount - the total number of keys memory - the memory used in bytes Returns: the page
static Page	create(MVMap map, long version, Page source) Create a copy of a page.
static Page	create(MVMap map, long version, Page source) Create a copy of a page. Parameters: map - the map version - the version source - the source page Returns: the page
static Page	createEmpty(MVMap map, long version) Create a new, empty page.
static Page	createEmpty(MVMap map, long version) Create a new, empty page. Parameters: map - the map version - the version Returns: the new page
static Page	read(FileStore fileStore, long pos, MVMap map, long filePos, long maxPos) Read a page.
static Page	read(FileStore fileStore, long pos, MVMap map, long filePos, long maxPos) Read a page. Parameters: fileStore - the file store pos - the position map - the map filePos - the position in the file maxPos - the maximum position (the end of the chunk) Returns: the page
int	binarySearch(Object key) Search the key in this page using a binary search.
int	binarySearch(Object key) Search the key in this page using a binary search. Instead of always starting the search in the middle, the last found index is cached. If the key was found, the returned value is the index in the key array. If not found, the returned value is negative, where -1 means the provided key is smaller than any keys in this page. See also Arrays.binarySearch. Parameters: key - the key Returns: the value or null
Page	copy(long version) Create a copy of this page.
Page	copy(long version) Create a copy of this page. Parameters: version - the new version Returns: a page with the given version
boolean	equals(Object other)
boolean	equals(Object other)
Page	getChildPage(int index) Get the child page at the given index.
Page	getChildPage(int index) Get the child page at the given index. Parameters: index - the index Returns: the child page
long	getChildPagePos(int index) Get the position of the child.
long	getChildPagePos(int index) Get the position of the child. Parameters: index - the index Returns: the position
long	getCounts(int index) Get the descendant counts for the given child.
long	getCounts(int index) Get the descendant counts for the given child. Parameters: index - the child index Returns: the descendant count
Object	getKey(int index) Get the key at the given index.
Object	getKey(int index) Get the key at the given index. Parameters: index - the index Returns: the key
int	getKeyCount() Get the number of keys in this page.
int	getKeyCount() Get the number of keys in this page. Returns: the number of keys
int	getMemory()
int	getMemory()
long	getPos() Get the position of the page
long	getPos() Get the position of the page Returns: the position
int	getRawChildPageCount()
int	getRawChildPageCount()
long	getTotalCount() Get the total number of key-value pairs, including child pages.
long	getTotalCount() Get the total number of key-value pairs, including child pages. Returns: the number of key-value pairs
Object	getValue(int index) Get the value at the given index.
Object	getValue(int index) Get the value at the given index. Parameters: index - the index Returns: the value
long	getVersion()
long	getVersion()
int	hashCode()
int	hashCode()
void	insertLeaf(int index, Object key, Object value) Insert a key-value pair into this leaf.
void	insertLeaf(int index, Object key, Object value) Insert a key-value pair into this leaf. Parameters: index - the index key - the key value - the value
void	insertNode(int index, Object key, Page childPage) Insert a child page into this node.
void	insertNode(int index, Object key, Page childPage) Insert a child page into this node. Parameters: index - the index key - the key childPage - the child page
boolean	isLeaf() Check whether this is a leaf page.
boolean	isLeaf() Check whether this is a leaf page. Returns: true if it is a leaf
void	read(ByteBuffer buff, int chunkId, int offset, int maxLength) Read the page from the buffer.
void	read(ByteBuffer buff, int chunkId, int offset, int maxLength) Read the page from the buffer. Parameters: buff - the buffer chunkId - the chunk id offset - the offset within the chunk maxLength - the maximum length
void	remove(int index) Remove the key and value (or child) at the given index.
void	remove(int index) Remove the key and value (or child) at the given index. Parameters: index - the index
void	removeAllRecursive() Remove this page and all child pages.
void	removeAllRecursive() Remove this page and all child pages.
void	removePage() Remove the page.
void	removePage() Remove the page.
void	setChild(int index, Page c) Replace the child page.
void	setChild(int index, Page c) Replace the child page. Parameters: index - the index c - the new child page
void	setKey(int index, Object key) Replace the key at an index in this page.
void	setKey(int index, Object key) Replace the key at an index in this page. Parameters: index - the index key - the new key
Object	setValue(int index, Object value) Replace the value at an index in this page.
Object	setValue(int index, Object value) Replace the value at an index in this page. Parameters: index - the index value - the new value Returns: the old value
void	setVersion(long version)
void	setVersion(long version)
Page	split(int at) Split the page.
Page	split(int at) Split the page. This modifies the current page. Parameters: at - the split index Returns: the page with the entries after the split index
String	toString()
String	toString()
void	writeEnd() Unlink the children recursively after all data is written.
void	writeEnd() Unlink the children recursively after all data is written.
void	writeUnsavedRecursive(Chunk chunk, WriteBuffer buff) Store this page and all children that are changed, in reverse order, and update the position and the children.
void	writeUnsavedRecursive(Chunk chunk, WriteBuffer buff) Store this page and all children that are changed, in reverse order, and update the position and the children. Parameters: chunk - the chunk buff - the target buffer

Fields
static Object[]	EMPTY_OBJECT_ARRAY

EMPTY_OBJECT_ARRAY

An empty object array.