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.

Constructor Summary

Constructors

Constructor and Description
ObjectSequenceId(String name) Creates a sequence id with default multipliers.
ObjectSequenceId(String name, int sequenceMultiplier, int globalMultiplier) Creates a sequence id source.

Method Summary

Modifier and Type	Method and Description
protected long	addGlobalOffset(long nextId) Adds some global offset to the id.
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

Constructor Detail

ObjectSequenceId

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

Creates a sequence id source.

Parameters:

name - the source and sequence name

sequenceMultiplier - the sequence multiplier

globalMultiplier - the global multiplier

ObjectSequenceId

public ObjectSequenceId(String name)

Creates a sequence id with default multipliers.

Parameters:

name - the source name

Method Detail

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.

addGlobalOffset

protected long addGlobalOffset(long nextId)

Adds some global offset to the id.

Parameters:

nextId - the computed new id

Returns:

the id plus offset