org.tentackle.persist

Class ObjectSequenceId

java.lang.Object

org.tentackle.persist.AbstractIdSource

org.tentackle.persist.ObjectSequenceId

All Implemented Interfaces:

IdSource

public class ObjectSequenceId
extends AbstractIdSource

An IdSource to create unique object IDs from a database sequence.

To reduce the number of roundtrips the sequence is multiplied by a sequence-multiplier and a counter just incremented within that range.

The creation of the sequence is backend-specific. For example, postgres expects:

 CREATE SEQUENCE object_sequence_id;
 

Author:

harald

Field Summary

Fields

Modifier and Type	Field and Description
static int	GLOBAL_MULTIPLIER Default global multiplier to allow application-specific offsets.
static int	SEQUENCE_MULTIPLIER Default sequence multiplier.

Method Summary

Modifier and Type	Method and Description
static ObjectSequenceId	get(String name) Gets a sequence id source. Id sources are unique by name.
static ObjectSequenceId	get(String name, int sequenceMultiplier, int globalMultiplier) Gets a sequence id source. Id sources are unique by name.
boolean	isLockFree() Returns whether retrieving an id is a lock-free operation.
long	nextId(Db db) Get the next unique ID.

Methods inherited from class org.tentackle.persist.AbstractIdSource

assertDbNotRemote, assertOneRowAffected, getName, toString

Methods inherited from class java.lang.Object

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

Field Detail

GLOBAL_MULTIPLIER

public static final int GLOBAL_MULTIPLIER

Default global multiplier to allow application-specific offsets.

See Also:

Constant Field Values

SEQUENCE_MULTIPLIER

public static final int SEQUENCE_MULTIPLIER

Default sequence multiplier.

See Also:

Constant Field Values

Method Detail

get

public static ObjectSequenceId get(String name,
                                   int sequenceMultiplier,
                                   int globalMultiplier)

Gets a sequence id source.
Id sources are unique by name.

Parameters:

name - the unique sequence name

sequenceMultiplier - the sequence multiplier

globalMultiplier - the global multiplier

Returns:

the ID source

get

public static ObjectSequenceId get(String name)

Gets a sequence id source.
Id sources are unique by name.

Parameters:

name - the unique sequence name

Returns:

the ID source

isLockFree

public boolean isLockFree()

Description copied from interface: IdSource

Returns whether retrieving an id is a lock-free operation.

Returns:

true if lockfree

nextId

public long nextId(Db db)

Description copied from interface: IdSource

Get the next unique ID.

Parameters:

db - the current db connection to be checked against getDb()

Returns:

a free ID.