org.apache.druid.query.extraction

Class MapLookupExtractor

java.lang.Object

org.apache.druid.query.lookup.LookupExtractor

org.apache.druid.query.extraction.MapLookupExtractor

public class MapLookupExtractor
extends LookupExtractor

Constructor Summary

Constructors

Constructor and Description
MapLookupExtractor(Map<String,String> map, boolean isOneToOne)

Method Summary

Modifier and Type	Method and Description
String	apply(String key) Apply a particular lookup methodology to the input string
boolean	canGetKeySet() Returns true if this lookup extractor's LookupExtractor.keySet() method will return a valid set.
boolean	canIterate() Returns true if this lookup extractor's LookupExtractor.iterable() method will return a valid iterator.
boolean	equals(Object o)
long	estimateHeapFootprint() Estimated heap footprint of this object.
static <K,V> long	estimateHeapFootprint(Map<K,V> map) Estimate the heap footprint of a Map.
byte[]	getCacheKey() Create a cache key for use in results caching
Map<String,String>	getMap()
int	hashCode()
boolean	isOneToOne()
Iterable<Map.Entry<String,String>>	iterable() Returns an Iterable that iterates over the keys and values in this lookup extractor.
Set<String>	keySet() Returns a Set of all keys in this lookup extractor.
List<String>	unapply(String value) Provide the reverse mapping from a given value to a list of keys

Methods inherited from class org.apache.druid.query.lookup.LookupExtractor

applyAll, unapplyAll

Methods inherited from class java.lang.Object

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

Constructor Detail

MapLookupExtractor

public MapLookupExtractor(Map<String,String> map,
                          boolean isOneToOne)

Method Detail

estimateHeapFootprint

public static <K,V> long estimateHeapFootprint(@Nullable
                                               Map<K,V> map)

Estimate the heap footprint of a Map. Important note: the implementation accepts any kind of Map, but estimates zero footprint for keys and values of types other than String.

getMap

public Map<String,String> getMap()

apply

@Nullable
public String apply(@Nullable
                              String key)

Description copied from class: LookupExtractor

Apply a particular lookup methodology to the input string

Specified by:

apply in class LookupExtractor

Parameters:

key - The value to apply the lookup to.

Returns:

The lookup, or null when key is `null` or cannot have the lookup applied to it and should be treated as missing.

unapply

public List<String> unapply(@Nullable
                            String value)

Description copied from class: LookupExtractor

Provide the reverse mapping from a given value to a list of keys

Specified by:

unapply in class LookupExtractor

Parameters:

value - the value to apply the reverse lookup

Returns:

the list of keys that maps to value or empty list. Note that for the case of a none existing value in the lookup we have to cases either return an empty list OR list with null element. returning an empty list implies that user want to ignore such a lookup value. In the other hand returning a list with the null element implies user want to map the none existing value to the key null. Null value maps to empty list.

isOneToOne

public boolean isOneToOne()

Overrides:

isOneToOne in class LookupExtractor

getCacheKey

public byte[] getCacheKey()

Description copied from class: LookupExtractor

Create a cache key for use in results caching

Specified by:

getCacheKey in class LookupExtractor

Returns:

A byte array that can be used to uniquely identify if results of a prior lookup can use the cached values

canIterate

public boolean canIterate()

Description copied from class: LookupExtractor

Returns true if this lookup extractor's LookupExtractor.iterable() method will return a valid iterator.

Specified by:

canIterate in class LookupExtractor

canGetKeySet

public boolean canGetKeySet()

Description copied from class: LookupExtractor

Returns true if this lookup extractor's LookupExtractor.keySet() method will return a valid set.

Specified by:

canGetKeySet in class LookupExtractor

iterable

public Iterable<Map.Entry<String,String>> iterable()

Description copied from class: LookupExtractor

Returns an Iterable that iterates over the keys and values in this lookup extractor.

Specified by:

iterable in class LookupExtractor

keySet

public Set<String> keySet()

Description copied from class: LookupExtractor

Returns a Set of all keys in this lookup extractor. The returned Set will not change.

Specified by:

keySet in class LookupExtractor

estimateHeapFootprint

public long estimateHeapFootprint()

Description copied from class: LookupExtractor

Estimated heap footprint of this object. Not guaranteed to be accurate. For example, some implementations return zero even though they do use on-heap structures. However, the most common class, MapLookupExtractor, does have a reasonable implementation. This API is provided for best-effort memory management and monitoring.

Overrides:

estimateHeapFootprint in class LookupExtractor

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object