co.cask.cdap.data2.dataset2.lib.timeseries

Class EntityTable

java.lang.Object

co.cask.cdap.data2.dataset2.lib.timeseries.EntityTable

All Implemented Interfaces:

Closeable, AutoCloseable

public final class EntityTable
extends Object
implements Closeable

This class handle assignment of unique ID to entity name, persisted by a OVCTable. Entity table is for storing mapping between name to unique ID. There are two set of rows in this table, one is for generating the next sequence ID using increment, the other stores the actual mappings.

Generator rows

Row key is formated as [type].maxId and there is only one column "maxId" which stores the last ID being generated. Each time when a new ID is needed for a given type, and increment and get on the corresponding row would be called.

Entity mapping rows

Each entity would have two rows. One is keyed by [type].[entityName] and have one "id" column which stores the unique ID. The other is a reverse map from [type].id to entity name in "name" column.

Constructor Summary

Constructors

Constructor and Description
EntityTable(MetricsTable table) Creates an EntityTable with max id = 16777215.

Method Summary

Methods

Modifier and Type	Method and Description
void	close()
long	getId(String type, String name) Returns an unique id for the given name.
int	getIdSize() Returns number of bytes for ID represented by this table.
String	getName(long id, String type) Returns the entity name for the given id and type.

Methods inherited from class java.lang.Object

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

Constructor Detail

EntityTable

public EntityTable(MetricsTable table)

Creates an EntityTable with max id = 16777215. See EntityTable(MetricsTable, long).

Method Detail

getId

public long getId(String type,
         @Nullable
         String name)

Returns an unique id for the given name.

Parameters:

name - The EntityName to lookup. Can be null, which is treated as a normal value.

Returns:

Unique ID, it is guaranteed to be smaller than the maxId passed in constructor.

getName

@Nullable
public String getName(long id,
                      String type)

Returns the entity name for the given id and type.

Parameters:

id - The id to lookup

type - The type of the entity.

Returns:

The entity name with the given id assigned to or null if given id is an encoded null value

Throws:

IllegalArgumentException - if the given ID does not map to any name.

getIdSize

public int getIdSize()

Returns number of bytes for ID represented by this table.

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException