Package 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.

All read and write operations can happen concurrently with all other operations, without risk of corruption.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	MVMap.BasicBuilder<M extends MVMap<K,V>,K,V>	A builder for this class.
static class	MVMap.Builder<K,V>	A builder for this class.
static class	MVMap.Decision	The decision on what to do on an update.
static class	MVMap.DecisionMaker<V>	Class DecisionMaker provides callback interface (and should become a such in Java 8) for MVMap.operate() method.
static interface	MVMap.MapBuilder<M extends MVMap<K,V>,K,V>	A builder for maps.

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

java.util.AbstractMap.SimpleEntry<K extends java.lang.Object,V extends java.lang.Object>, java.util.AbstractMap.SimpleImmutableEntry<K extends java.lang.Object,V extends java.lang.Object>

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

java.util.Map.Entry<K extends java.lang.Object,V extends java.lang.Object>

Field Summary

Fields

Modifier and Type	Field	Description
MVStore	store	The store.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	MVMap(java.util.Map<java.lang.String,java.lang.Object> config, DataType<K> keyType, DataType<V> valueType)
protected	MVMap(MVMap<K,V> source)

Method Summary

Modifier and Type	Method	Description
void	append(K key, V value)	Appends entry to this map.
protected java.lang.String	asString(java.lang.String name)	Get the map metadata as a string.
protected void	beforeWrite()	This method is called before writing to the map.
K	ceilingKey(K key)	Get the smallest key that is larger or equal to this key.
void	clear()	Remove all entries.
protected MVMap<K,V>	cloneIt()	Clone the current map.
boolean	containsKey(java.lang.Object key)
protected Page<K,V>	createEmptyLeaf()	Create empty leaf node page.
protected Page<K,V>	createEmptyNode()	Create empty internal node page.
Cursor<K,V>	cursor(K from)	Get a cursor to iterate over a number of keys and values in the latest version of this map.
Cursor<K,V>	cursor(K from, K to, boolean reverse)	Get a cursor to iterate over a number of keys and values in the latest version of this map.
Cursor<K,V>	cursor(RootReference<K,V> rootReference, K from, K to, boolean reverse)	Get a cursor to iterate over a number of keys and values.
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.
RootReference<K,V>	flushAndGetRoot()	Get the root reference, flushing any current append buffer.
V	get(java.lang.Object key)	Get the value for the given key, or null if not found.
V	get(Page<K,V> p, K key)	Get the value for the given key from a snapshot, or null if not found.
protected int	getChildPageCount(Page<K,V> p)	Get the child page count for this page.
int	getId()	Get the map id.
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.
DataType<K>	getKeyType()	Get the key type.
java.lang.String	getName()	Get the map name.
RootReference<K,V>	getRoot()
Page<K,V>	getRootPage()	The current root page (may not be null).
MVStore	getStore()
java.lang.String	getType()	Get the map type.
DataType<V>	getValueType()	Get the value type.
long	getVersion()	Get version of the map, which is the version of the store, at the moment when map was modified last time.
int	hashCode()
K	higherKey(K key)	Get the smallest key that is larger than the given key (next key in ascending order), or null if no such key exists.
K	higherKey(RootReference<K,V> rootRef, K key)	Get the smallest key that is larger than the given key, for the given root page, or null if no such key exists.
boolean	isClosed()
boolean	isEmpty()
protected boolean	isPersistent()
boolean	isReadOnly()
boolean	isVolatile()	Whether this is volatile map, meaning that changes are not persisted.
java.util.Iterator<K>	keyIterator(K from)	Iterate over a number of keys.
java.util.Iterator<K>	keyIteratorReverse(K from)	Iterate over a number of keys in reverse order
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.
K	lowerKey(RootReference<K,V> rootRef, K key)	Get the largest key that is smaller than the given key, for the given root page, or null if no such key exists.
MVMap<K,V>	openVersion(long version)	Open an old version for the given map.
V	operate(K key, V value, MVMap.DecisionMaker<V> decisionMaker)	Add, replace or remove a key-value pair.
V	put(K key, V value)	Add or replace a key-value pair.
V	putIfAbsent(K key, V value)	Add a key-value pair if it does not yet exist.
protected void	registerUnsavedMemory(int memory)
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.
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	setVolatile(boolean isVolatile)	Set the volatile flag of the map.
int	size()	Get the number of entries, as integer.
long	sizeAsLong()	Get the number of entries, as a long.
java.lang.String	toString()
void	trimLast()	Removes last entry from this map.
protected RootReference<K,V>	tryLock(RootReference<K,V> rootReference, int attempt)	Try to lock the root.
protected void	unlockRoot(Page<K,V> newRootPage)	Unlock the root page.
protected static <K,V> boolean	updateRoot(RootReference<K,V> expectedRootReference, Page<K,V> newRootPage, int attemptUpdateCounter)	Use the new root page from now on.

Methods inherited from class java.util.AbstractMap

clone, containsValue, putAll, values

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.concurrent.ConcurrentMap

compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, replaceAll

Methods inherited from interface java.util.Map

containsValue, putAll, values

Field Detail

store

public final MVStore store

The store.

Constructor Detail

MVMap

protected MVMap(java.util.Map<java.lang.String,java.lang.Object> config,
                DataType<K> keyType,
                DataType<V> valueType)

MVMap

protected MVMap(MVMap<K,V> source)

Method Detail

cloneIt

protected MVMap<K,V> cloneIt()

Clone the current map.

Returns:

clone of this.

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

firstKey

public final K firstKey()

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

Returns:

the first key, or null

lastKey

public final K lastKey()

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

Returns:

the last key, or null

getKey

public final 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 final 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 final 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 final K higherKey(K key)

Get the smallest key that is larger than the given key (next key in ascending order), or null if no such key exists.

Parameters:

key - the key

Returns:

the result

higherKey

public final K higherKey(RootReference<K,V> rootRef,
                         K key)

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

Parameters:

rootRef - the root reference of the map

key - to start from

Returns:

the result

ceilingKey

public final K ceilingKey(K key)

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

Parameters:

key - the key

Returns:

the result

floorKey

public final K floorKey(K key)

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

Parameters:

key - the key

Returns:

the result

lowerKey

public final 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

Returns:

the result

lowerKey

public final K lowerKey(RootReference<K,V> rootRef,
                        K key)

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

Parameters:

rootRef - the root page

key - the key

Returns:

the result

get

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

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

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

Throws:

java.lang.ClassCastException - if type of the specified key is not compatible with this map

get

public V get(Page<K,V> p,
             K key)

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

Parameters:

p - the root of a snapshot

key - the key

Returns:

the value, or null if not found

Throws:

java.lang.ClassCastException - if type of the specified key is not compatible with this map

containsKey

public final 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>

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>

registerUnsavedMemory

protected final void registerUnsavedMemory(int memory)

isClosed

public final 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

Throws:

java.lang.ClassCastException - if type of the specified key is not compatible with this map

putIfAbsent

public final 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>

Specified by:

putIfAbsent in interface java.util.Map<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>

Specified by:

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

Parameters:

key - the key (may not be null)

value - the expected value

Returns:

true if the item was removed

replace

public final 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>

Specified by:

replace in interface java.util.Map<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 final V replace(K key,
                       V value)

Replace a value for an existing key.

Specified by:

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

Specified by:

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

Parameters:

key - the key (may not be null)

value - the new value

Returns:

the old value, if the value was replaced, or null

getKeyType

public final DataType<K> getKeyType()

Get the key type.

Returns:

the key type

getValueType

public final DataType<V> getValueType()

Get the value type.

Returns:

the value type

keyIterator

public final java.util.Iterator<K> keyIterator(K from)

Iterate over a number of keys.

Parameters:

from - the first key to return

Returns:

the iterator

keyIteratorReverse

public final java.util.Iterator<K> keyIteratorReverse(K from)

Iterate over a number of keys in reverse order

Parameters:

from - the first key to return

Returns:

the iterator

cursor

public final Cursor<K,V> cursor(K from)

Get a cursor to iterate over a number of keys and values in the latest version of this map.

Parameters:

from - the first key to return

Returns:

the cursor

cursor

public final Cursor<K,V> cursor(K from,
                                      K to,
                                      boolean reverse)

Get a cursor to iterate over a number of keys and values in the latest version of this map.

Parameters:

from - the first key to return

to - the last key to return

reverse - if true, iterate in reverse (descending) order

Returns:

the cursor

cursor

public Cursor<K,V> cursor(RootReference<K,V> rootReference,
                                K from,
                                K to,
                                boolean reverse)

Get a cursor to iterate over a number of keys and values.

Parameters:

rootReference - of this map's version to iterate over

from - the first key to return

to - the last key to return

reverse - if true, iterate in reverse (descending) order

Returns:

the cursor

entrySet

public final 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>

getName

public final java.lang.String getName()

Get the map name.

Returns:

the name

getStore

public final MVStore getStore()

isPersistent

protected final boolean isPersistent()

getId

public final int getId()

Get the map id. Please note the map id may be different after compacting a store.

Returns:

the map id

getRootPage

public final Page<K,V> getRootPage()

The current root page (may not be null).

Returns:

the root page

getRoot

public RootReference<K,V> getRoot()

flushAndGetRoot

public RootReference<K,V> flushAndGetRoot()

Get the root reference, flushing any current append buffer.

Returns:

current root reference

updateRoot

protected static <K,V> boolean updateRoot(RootReference<K,V> expectedRootReference,
                                                Page<K,V> newRootPage,
                                                int attemptUpdateCounter)

Use the new root page from now on.

Type Parameters:

K - the key class

V - the value class

Parameters:

expectedRootReference - expected current root reference

newRootPage - the new root page

attemptUpdateCounter - how many attempt (including current) were made to update root

Returns:

new RootReference or null if update failed

isReadOnly

public final boolean isReadOnly()

setVolatile

public final void setVolatile(boolean isVolatile)

Set the volatile flag of the map.

Parameters:

isVolatile - the volatile flag

isVolatile

public final boolean isVolatile()

Whether this is volatile map, meaning that changes are not persisted. By default, even if the store is not persisted, maps are not volatile.

Returns:

whether this map is volatile

beforeWrite

protected final void beforeWrite()

This method is called before writing to the map. The default implementation checks whether writing is allowed, and tries to detect concurrent modification.

Throws:

java.lang.UnsupportedOperationException - if the map is read-only, or if another thread is concurrently writing

hashCode

public final int hashCode()

Specified by:

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

Overrides:

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

equals

public final 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 final int size()

Get the number of entries, as integer. Integer.MAX_VALUE is returned if there are more entries than it can hold.

Specified by:

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

Overrides:

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

Returns:

the number of entries, as an integer

See Also:

sizeAsLong()

sizeAsLong

public final long sizeAsLong()

Get the number of entries, as a long.

Returns:

the number of entries

isEmpty

public boolean isEmpty()

Specified by:

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

Overrides:

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

openVersion

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

Open an old version for the given map. It will restore map at last known state of the version specified. (at the point right before the commit() call, which advanced map to the next version) Map is opened in read-only mode.

Parameters:

version - the version

Returns:

the map

getVersion

public final long getVersion()

Get version of the map, which is the version of the store, at the moment when map was modified last time.

Returns:

version

getChildPageCount

protected int getChildPageCount(Page<K,V> 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

protected java.lang.String asString(java.lang.String name)

Get the map metadata as a string.

Parameters:

name - the map name (or null)

Returns:

the string

createEmptyLeaf

protected Page<K,V> createEmptyLeaf()

Create empty leaf node page.

Returns:

new page

createEmptyNode

protected Page<K,V> createEmptyNode()

Create empty internal node page.

Returns:

new page

append

public void append(K key,
                   V value)

Appends entry to this map. this method is NOT thread safe and can not be used neither concurrently, nor in combination with any method that updates this map. Non-updating method may be used concurrently, but latest appended values are not guaranteed to be visible.

Parameters:

key - should be higher in map's order than any existing key

value - to be appended

trimLast

public void trimLast()

Removes last entry from this map. this method is NOT thread safe and can not be used neither concurrently, nor in combination with any method that updates this map. Non-updating method may be used concurrently, but latest removal may not be visible.

toString

public final java.lang.String toString()

Overrides:

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

operate

public V operate(K key,
                 V value,
                 MVMap.DecisionMaker<V> decisionMaker)

Add, replace or remove a key-value pair.

Parameters:

key - the key (may not be null)

value - new value, it may be null when removal is intended

decisionMaker - command object to make choices during transaction.

Returns:

previous value, if mapping for that key existed, or null otherwise

tryLock

protected RootReference<K,V> tryLock(RootReference<K,V> rootReference,
                                           int attempt)

Try to lock the root.

Parameters:

rootReference - the old root reference

attempt - the number of attempts so far

Returns:

the new root reference

unlockRoot

protected void unlockRoot(Page<K,V> newRootPage)

Unlock the root page.

Parameters:

newRootPage - the new root