org.apache.drill.common.collections

Class MapWithOrdinal<K,V>

java.lang.Object

org.apache.drill.common.collections.MapWithOrdinal<K,V>

Type Parameters:

K - key type

V - value type

All Implemented Interfaces:

Map<K,V>

public class MapWithOrdinal<K,V>
extends Object
implements Map<K,V>

An implementation of map that supports constant time look-up by a generic key or an ordinal. This class extends the functionality a regular Map with ordinal lookup support. Upon insertion an unused ordinal is assigned to the inserted (key, value) tuple. Upon update the same ordinal id is re-used while value is replaced. Upon deletion of an existing item, its corresponding ordinal is recycled and could be used by another item. For any instance with N items, this implementation guarantees that ordinals are in the range of [0, N). However, the ordinal assignment is dynamic and may change after an insertion or deletion. Consumers of this class are responsible for explicitly checking the ordinal corresponding to a key via getOrdinal(Object) before attempting to execute a lookup with an ordinal.

Nested Class Summary

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

Map.Entry<K,V>

Constructor Summary

Constructors

Constructor and Description
MapWithOrdinal()

Method Summary

Modifier and Type	Method and Description
void	clear()
boolean	containsKey(Object key)
boolean	containsValue(Object value)
Set<Map.Entry<K,V>>	entrySet()
V	get(Object key)
V	getByOrdinal(int id) Returns the value corresponding to the given ordinal
int	getOrdinal(K key) Returns the ordinal corresponding to the given key.
boolean	isEmpty()
Set<K>	keySet()
V	put(K key, V value) Inserts the tuple (key, value) into the map extending the semantics of Map.put(K, V) with automatic ordinal assignment.
void	putAll(Map<? extends K,? extends V> m)
V	remove(Object key) Removes the element corresponding to the key if exists extending the semantics of Map.remove(java.lang.Object) with ordinal re-cycling.
int	size()
Collection<V>	values()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, merge, putIfAbsent, remove, replace, replace, replaceAll

Constructor Detail

MapWithOrdinal

public MapWithOrdinal()

Method Detail

getByOrdinal

public V getByOrdinal(int id)

Returns the value corresponding to the given ordinal

Parameters:

id - ordinal value for lookup

Returns:

an instance of V

getOrdinal

public int getOrdinal(K key)

Returns the ordinal corresponding to the given key.

Parameters:

key - key for ordinal lookup

Returns:

ordinal value corresponding to key if it exists or -1

size

public int size()

Specified by:

size in interface Map<K,V>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<K,V>

get

public V get(Object key)

Specified by:

get in interface Map<K,V>

put

public V put(K key,
             V value)

Inserts the tuple (key, value) into the map extending the semantics of Map.put(K, V) with automatic ordinal assignment. A new ordinal is assigned if key does not exists. Otherwise the same ordinal is re-used but the value is replaced. Map.put(K, V)

Specified by:

put in interface Map<K,V>

values

public Collection<V> values()

Specified by:

values in interface Map<K,V>

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map<K,V>

containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Map<K,V>

remove

public V remove(Object key)

Removes the element corresponding to the key if exists extending the semantics of Map.remove(java.lang.Object) with ordinal re-cycling. The ordinal corresponding to the given key may be re-assigned to another tuple. It is important that consumer checks the ordinal value via getOrdinal(Object) before attempting to look-up by ordinal. Map.remove(java.lang.Object)

Specified by:

remove in interface Map<K,V>

putAll

public void putAll(Map<? extends K,? extends V> m)

Specified by:

putAll in interface Map<K,V>

clear

public void clear()

Specified by:

clear in interface Map<K,V>

keySet

public Set<K> keySet()

Specified by:

keySet in interface Map<K,V>

entrySet

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

Specified by:

entrySet in interface Map<K,V>