com.goldencode.p2j.persist.id

Class SequenceIdentityManager

java.lang.Object

com.goldencode.p2j.persist.id.SequenceIdentityManager

All Implemented Interfaces:

IdentityManager, IdentityPoolManager

public final class SequenceIdentityManager
extends java.lang.Object
implements IdentityPoolManager

Implementation of the IdentityManager interface which uses a sequence (global to a specific database) to produce 64-bit integer IDs which are unique across all records in that database.

Current limitations:

• Wrapping to a negative number after we increment beyond Long.MAX_VALUE is not handled at this time.
• Does not detect/repair fragmentation of the primary key address space for a table; existing gaps in primary keys are never plugged. Note that a solution for this item may preclude having to address the previous item.

Field Summary

Fields

Modifier and Type	Field and Description
private IdentityPool	identityPool Identity pool used by this identity manager.
private static CentralLogger	LOG Logger
private java.lang.String	nextKeySQL SQL statement used to get next sequence value
private Persistence	persistence Persistence service object associated with this identity manager
private static java.lang.Integer[]	PREFETCH_ARGS Range arguments passed to prefetch SQL statement
private java.util.Queue<java.lang.Long>	prefetched Queue of prefetched results
private java.lang.String	prefetchKeySQL SQL statement used to prefetch multiple sequence values at once

Constructor Summary

Constructors

Constructor and Description
SequenceIdentityManager() Default constructor.

Method Summary

Modifier and Type	Method and Description
java.lang.Long	nextPrimaryKey(java.lang.String table) Return the next primary key for the specified table.
void	reclaimKeys(java.lang.Long[] keys) Inform the identity manager that the given primary keys can be reused.
void	setIdentityPool(IdentityPool identityPool) Sets identity pool which can be used by this identity manager.
void	setPersistence(Persistence persistence) Specify the database for the identity manager.

Methods inherited from class java.lang.Object

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

Field Detail

LOG

private static final CentralLogger LOG

Logger

PREFETCH_ARGS

private static final java.lang.Integer[] PREFETCH_ARGS

Range arguments passed to prefetch SQL statement

prefetched

private java.util.Queue<java.lang.Long> prefetched

Queue of prefetched results

identityPool

private IdentityPool identityPool

Identity pool used by this identity manager.

persistence

private Persistence persistence

Persistence service object associated with this identity manager

prefetchKeySQL

private java.lang.String prefetchKeySQL

SQL statement used to prefetch multiple sequence values at once

nextKeySQL

private java.lang.String nextKeySQL

SQL statement used to get next sequence value

Constructor Detail

SequenceIdentityManager

public SequenceIdentityManager()

Default constructor.

Method Detail

setPersistence

public void setPersistence(Persistence persistence)

Specify the database for the identity manager. DefaultIdentityManager is initialized here - current maximum IDs for each table are retrieved.

Specified by:

setPersistence in interface IdentityManager

Parameters:

persistence - Persistence service object associated with identity manager.

nextPrimaryKey

public java.lang.Long nextPrimaryKey(java.lang.String table)
                              throws PersistenceException

Return the next primary key for the specified table. The pool of reclaimed IDs is checked first. If no reclaimed ID is available, a new ID is generated from the sequence.

Specified by:

nextPrimaryKey in interface IdentityManager

Parameters:

table - Table for which the next primary key will be returned.

Returns:

The next primary key for the given table.

Throws:

PersistenceException - if there is an error determining the next primary key ID.

reclaimKeys

public void reclaimKeys(java.lang.Long[] keys)

Inform the identity manager that the given primary keys can be reused.

Specified by:

reclaimKeys in interface IdentityManager

Parameters:

keys - Keys for reuse.

setIdentityPool

public void setIdentityPool(IdentityPool identityPool)

Sets identity pool which can be used by this identity manager.

Specified by:

setIdentityPool in interface IdentityPoolManager

Parameters:

identityPool - Identity pool for use.