org.h2.mvstore
Class MVMap<K,V>

java.lang.Object
  java.util.AbstractMap<K,V>
      org.h2.mvstore.MVMap<K,V>

Type Parameters:

K - the key class

V - the value class

All Implemented Interfaces:

java.util.concurrent.ConcurrentMap<K,V>, java.util.Map<K,V>

Direct Known Subclasses:

MVRTreeMap, SequenceMap

public class MVMap<K,V>
extends java.util.AbstractMap<K,V>
implements java.util.concurrent.ConcurrentMap<K,V>

A stored map.

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

java.util.AbstractMap.SimpleEntry<K,V>, java.util.AbstractMap.SimpleImmutableEntry<K,V>

Nested classes/interfaces inherited from interface java.util.Map

java.util.Map.Entry<K,V>

Field Summary

protected Page	root The current root page (may not be null).
protected MVStore	store The store.

Constructor Summary

MVMap(DataType keyType, DataType valueType)

Method Summary

java.lang.String	asString() Get the map metadata as a string.
protected java.lang.Object	binarySearch(Page p, java.lang.Object key) Get the value for the given key, or null if not found.
protected Page	binarySearchPage(Page p, java.lang.Object key) Get the value for the given key, or null if not found.
K	ceilingKey(K key) Get the smallest key that is larger or equal to this key.
java.util.Iterator<K>	changeIterator(long version) Iterate over all keys in changed pages.
protected void	checkOpen() Check whether the map is open.
protected void	checkWrite() Check whether writing is allowed.
void	clear() Remove all entries.
void	close() Close the map, making it read only and release the memory.
boolean	containsKey(java.lang.Object key)
java.util.Set<java.util.Map.Entry<K,V>>	entrySet()
boolean	equals(java.lang.Object o)
K	firstKey() Get the first key, or null if the map is empty.
K	floorKey(K key) Get the largest key that is smaller or equal to this key.
V	get(java.lang.Object key) Get a value.
protected int	getChildPageCount(Page p) Get the child page count for this page.
K	getKey(long index) Get the key at the given index.
long	getKeyIndex(K key) Get the index of the given key in the map.
protected DataType	getKeyType() Get the key type.
protected Page	getPage(K key) Get the page for the given value.
Page	getRoot() Get the root page.
long	getSize()
java.lang.String	getType() Get the map type.
protected DataType	getValueType() Get the value type.
long	getVersion()
int	hashCode()
boolean	hasUnsavedChanges() Check whether this map has any unsaved changes.
K	higherKey(K key) Get the smallest key that is larger than the given key, or null if no such key exists.
boolean	isClosed()
boolean	isReadOnly()
Cursor<K>	keyIterator(K from) Iterate over all keys.
java.util.List<K>	keyList() Get the key list.
java.util.Set<K>	keySet()
K	lastKey() Get the last key, or null if the map is empty.
K	lowerKey(K key) Get the largest key that is smaller than the given key, or null if no such key exists.
protected void	newRoot(Page newRoot) Use the new root page from now on.
void	open(MVStore store, java.util.HashMap<java.lang.String,java.lang.String> config) Open this map with the given store and configuration.
protected MVMap<K,V>	openReadOnly() Open a copy of the map in read-only mode.
MVMap<K,V>	openVersion(long version) Open an old version for the given map.
V	put(K key, V value) Add or replace a key-value pair.
protected java.lang.Object	put(Page p, long writeVersion, java.lang.Object key, java.lang.Object value) Add or update a key-value pair.
V	putIfAbsent(K key, V value) Add a key-value pair if it does not yet exist.
V	remove(java.lang.Object key) Remove a key-value pair, if the key exists.
boolean	remove(java.lang.Object key, java.lang.Object value) Remove a key-value pair if the value matches the stored one.
protected java.lang.Object	remove(Page p, long writeVersion, java.lang.Object key) Remove a key-value pair.
void	removeMap() Remove all entries, and close the map.
protected void	removePage(Page p) Remove the given page (make the space available).
V	replace(K key, V value) Replace a value for an existing key.
boolean	replace(K key, V oldValue, V newValue) Replace a value for an existing key, if the value matches.
void	setReadOnly(boolean readOnly)
int	size()

Methods inherited from class java.util.AbstractMap

clone, containsValue, isEmpty, putAll, toString, values

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map

containsValue, isEmpty, putAll, values

Field Detail

store

protected MVStore store

The store.

root

protected volatile Page root

The current root page (may not be null).

Constructor Detail

MVMap

public MVMap(DataType keyType,
             DataType valueType)

Method Detail

open

public void open(MVStore store,
                 java.util.HashMap<java.lang.String,java.lang.String> config)

Open this map with the given store and configuration.

Parameters:

store - the store

config - the configuration

put

public V put(K key,
             V value)

Add or replace a key-value pair.

Specified by:

put in interface java.util.Map<K,V>

Overrides:

put in class java.util.AbstractMap<K,V>

Parameters:

key - the key (may not be null)

value - the value (may not be null)

Returns:

the old value if the key existed, or null otherwise

put

protected java.lang.Object put(Page p,
                               long writeVersion,
                               java.lang.Object key,
                               java.lang.Object value)

Add or update a key-value pair.

Parameters:

p - the page

writeVersion - the write version

key - the key (may not be null)

value - the value (may not be null)

Returns:

the old value, or null

firstKey

public K firstKey()

Get the first key, or null if the map is empty.

Returns:

the first key, or null

lastKey

public K lastKey()

Get the last key, or null if the map is empty.

Returns:

the last key, or null

getKey

public K getKey(long index)

Get the key at the given index.

This is a O(log(size)) operation.

Parameters:

index - the index

Returns:

the key

keyList

public java.util.List<K> keyList()

Get the key list. The list is a read-only representation of all keys.

The get and indexOf methods are O(log(size)) operations. The result of indexOf is cast to an int.

Returns:

the key list

getKeyIndex

public long getKeyIndex(K key)

Get the index of the given key in the map.

This is a O(log(size)) operation.

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. See also Arrays.binarySearch.

Parameters:

key - the key

Returns:

the index

higherKey

public K higherKey(K key)

Get the smallest key that is larger than the given key, or null if no such key exists.

Parameters:

key - the key (may not be null)

Returns:

the result

ceilingKey

public K ceilingKey(K key)

Get the smallest key that is larger or equal to this key.

Parameters:

key - the key (may not be null)

Returns:

the result

floorKey

public K floorKey(K key)

Get the largest key that is smaller or equal to this key.

Parameters:

key - the key (may not be null)

Returns:

the result

lowerKey

public K lowerKey(K key)

Get the largest key that is smaller than the given key, or null if no such key exists.

Parameters:

key - the key (may not be null)

Returns:

the result

get

public V get(java.lang.Object key)

Get a value.

Specified by:

get in interface java.util.Map<K,V>

Overrides:

get in class java.util.AbstractMap<K,V>

Parameters:

key - the key

Returns:

the value, or null if not found

binarySearch

protected java.lang.Object binarySearch(Page p,
                                        java.lang.Object key)

Get the value for the given key, or null if not found.

Parameters:

p - the page

key - the key

Returns:

the value or null

containsKey

public boolean containsKey(java.lang.Object key)

Specified by:

containsKey in interface java.util.Map<K,V>

Overrides:

containsKey in class java.util.AbstractMap<K,V>

getPage

protected Page getPage(K key)

Get the page for the given value.

Parameters:

key - the key

Returns:

the value, or null if not found

binarySearchPage

protected Page binarySearchPage(Page p,
                                java.lang.Object key)

Get the value for the given key, or null if not found.

Parameters:

p - the parent page

key - the key

Returns:

the page or null

clear

public void clear()

Remove all entries.

Specified by:

clear in interface java.util.Map<K,V>

Overrides:

clear in class java.util.AbstractMap<K,V>

removeMap

public void removeMap()

Remove all entries, and close the map.

close

public void close()

Close the map, making it read only and release the memory.

isClosed

public boolean isClosed()

remove

public V remove(java.lang.Object key)

Remove a key-value pair, if the key exists.

Specified by:

remove in interface java.util.Map<K,V>

Overrides:

remove in class java.util.AbstractMap<K,V>

Parameters:

key - the key (may not be null)

Returns:

the old value if the key existed, or null otherwise

putIfAbsent

public V putIfAbsent(K key,
                     V value)

Add a key-value pair if it does not yet exist.

Specified by:

putIfAbsent in interface java.util.concurrent.ConcurrentMap<K,V>

Parameters:

key - the key (may not be null)

value - the new value

Returns:

the old value if the key existed, or null otherwise

remove

public boolean remove(java.lang.Object key,
                      java.lang.Object value)

Remove a key-value pair if the value matches the stored one.

Specified by:

remove in interface java.util.concurrent.ConcurrentMap<K,V>

Parameters:

key - the key (may not be null)

value - the expected value

Returns:

true if the item was removed

replace

public boolean replace(K key,
                       V oldValue,
                       V newValue)

Replace a value for an existing key, if the value matches.

Specified by:

replace in interface java.util.concurrent.ConcurrentMap<K,V>

Parameters:

key - the key (may not be null)

oldValue - the expected value

newValue - the new value

Returns:

true if the value was replaced

replace

public V replace(K key,
                 V value)

Replace a value for an existing key.

Specified by:

replace in interface java.util.concurrent.ConcurrentMap<K,V>

Parameters:

key - the key (may not be null)

value - the new value

Returns:

true if the value was replaced

remove

protected java.lang.Object remove(Page p,
                                  long writeVersion,
                                  java.lang.Object key)

Remove a key-value pair.

Parameters:

p - the page (may not be null)

writeVersion - the write version

key - the key

Returns:

the old value, or null if the key did not exist

newRoot

protected void newRoot(Page newRoot)

Use the new root page from now on.

Parameters:

newRoot - the new root page

hasUnsavedChanges

public boolean hasUnsavedChanges()

Check whether this map has any unsaved changes.

Returns:

true if there are unsaved changes.

getKeyType

protected DataType getKeyType()

Get the key type.

Returns:

the key type

getValueType

protected DataType getValueType()

Get the value type.

Returns:

the value type

keyIterator

public Cursor<K> keyIterator(K from)

Iterate over all keys.

Parameters:

from - the first key to return

Returns:

the iterator

changeIterator

public java.util.Iterator<K> changeIterator(long version)

Iterate over all keys in changed pages.

Parameters:

version - the old version

Returns:

the iterator

entrySet

public java.util.Set<java.util.Map.Entry<K,V>> entrySet()

Specified by:

entrySet in interface java.util.Map<K,V>

Specified by:

entrySet in class java.util.AbstractMap<K,V>

keySet

public java.util.Set<K> keySet()

Specified by:

keySet in interface java.util.Map<K,V>

Overrides:

keySet in class java.util.AbstractMap<K,V>

getRoot

public Page getRoot()

Get the root page.

Returns:

the root page

setReadOnly

public void setReadOnly(boolean readOnly)

isReadOnly

public boolean isReadOnly()

checkOpen

protected void checkOpen()

Check whether the map is open.

Throws:

java.lang.IllegalStateException - if the map is closed

checkWrite

protected void checkWrite()

Check whether writing is allowed.

Throws:

java.lang.IllegalStateException - if the map is read-only

hashCode

public int hashCode()

Specified by:

hashCode in interface java.util.Map<K,V>

Overrides:

hashCode in class java.util.AbstractMap<K,V>

equals

public boolean equals(java.lang.Object o)

Specified by:

equals in interface java.util.Map<K,V>

Overrides:

equals in class java.util.AbstractMap<K,V>

size

public int size()

Specified by:

size in interface java.util.Map<K,V>

Overrides:

size in class java.util.AbstractMap<K,V>

getSize

public long getSize()

removePage

protected void removePage(Page p)

Remove the given page (make the space available).

Parameters:

p - the page

openVersion

public MVMap<K,V> openVersion(long version)

Open an old version for the given map.

Parameters:

version - the version

Returns:

the map

openReadOnly

protected MVMap<K,V> openReadOnly()

Open a copy of the map in read-only mode.

Returns:

the opened map

getVersion

public long getVersion()

getChildPageCount

protected int getChildPageCount(Page p)

Get the child page count for this page. This is to allow another map implementation to override the default, in case the last child is not to be used.

Parameters:

p - the page

Returns:

the number of direct children

getType

public java.lang.String getType()

Get the map type. When opening an existing map, the map type must match.

Returns:

the map type

asString

public java.lang.String asString()

Get the map metadata as a string.

Returns:

the string