CompactLabelToOrdinal (The Adobe Experience Manager SDK 2022.11.9850.20221116T162329Z-220900)

java.lang.Object
- org.apache.lucene.facet.taxonomy.writercache.LabelToOrdinal
- - org.apache.lucene.facet.taxonomy.writercache.CompactLabelToOrdinal

```
public class CompactLabelToOrdinal
extends LabelToOrdinal
```
This is a very efficient LabelToOrdinal implementation that uses a CharBlockArray to store all labels and a configurable number of HashArrays to reference the labels.
Since the HashArrays don't handle collisions, a CollisionMap is used to store the colliding labels.
This data structure grows by adding a new HashArray whenever the number of collisions in the CollisionMap exceeds loadFactor * LabelToOrdinal.getMaxOrdinal(). Growing also includes reinserting all colliding labels into the HashArrays to possibly reduce the number of collisions. For setting the loadFactor see CompactLabelToOrdinal(int, float, int).
This data structure has a much lower memory footprint (~30%) compared to a Java HashMap<String, Integer>. It also only uses a small fraction of objects a HashMap would use, thus limiting the GC overhead. Ingestion speed was also ~50% faster compared to a HashMap for 3M unique labels.

Field Summary

Fields
Modifier and Type Field Description

static float DefaultLoadFactor
Default maximum load factor.
- Fields inherited from class org.apache.lucene.facet.taxonomy.writercache.LabelToOrdinal
  INVALID_ORDINAL

Constructor Summary

Constructors
Constructor Description

CompactLabelToOrdinal(int initialCapacity, float loadFactor, int numHashArrays)
Sole constructor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`addLabel(FacetLabel label, int ordinal)`	Adds a new label if its not yet in the table.
`int`	`getOrdinal(FacetLabel label)`	Returns the ordinal assigned to the given label, or `LabelToOrdinal.INVALID_ORDINAL` if the label cannot be found in this table.
`int`	`sizeOfMap()`	How many labels.

Methods inherited from class org.apache.lucene.facet.taxonomy.writercache.LabelToOrdinal
getMaxOrdinal, getNextOrdinal

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - DefaultLoadFactor
```
public static final float DefaultLoadFactor
```
    Default maximum load factor.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - CompactLabelToOrdinal
```
public CompactLabelToOrdinal(int initialCapacity,
                             float loadFactor,
                             int numHashArrays)
```
    Sole constructor.
- Method Detail
  - sizeOfMap
```
public int sizeOfMap()
```
    How many labels.
  - addLabel
```
public void addLabel(FacetLabel label,
                     int ordinal)
```
    Description copied from class: LabelToOrdinal
    
    Adds a new label if its not yet in the table. Throws an IllegalArgumentException if the same label with a different ordinal was previoulsy added to this table.
    
    Specified by:
    
    addLabel in class LabelToOrdinal
  - getOrdinal
```
public int getOrdinal(FacetLabel label)
```
    Description copied from class: LabelToOrdinal
    
    Returns the ordinal assigned to the given label, or LabelToOrdinal.INVALID_ORDINAL if the label cannot be found in this table.
    
    Specified by:
    
    getOrdinal in class LabelToOrdinal