org.datanucleus.store.valuegenerator

Class AbstractGenerator<T>

java.lang.Object

org.datanucleus.store.valuegenerator.AbstractGenerator<T>

All Implemented Interfaces:

ValueGenerator<T>

Direct Known Subclasses:

AbstractDatastoreGenerator, AbstractUIDGenerator, TimestampGenerator, TimestampValueGenerator

public abstract class AbstractGenerator<T>
extends Object
implements ValueGenerator<T>

Abstract value generator.

Field Summary

Fields

Modifier and Type	Field and Description
protected int	allocationSize Allocation size
protected ValueGenerationBlock<T>	block The current block of values that have been reserved.
protected int	initialValue Initial value (of the first id).
protected String	name Symbolic name for the sequence.
protected Properties	properties Properties controlling the generator behaviour.
protected boolean	repositoryExists Flag for whether we know that the repository exists.

Constructor Summary

Constructors

Constructor and Description
AbstractGenerator(String name, Properties props) Constructor.

Method Summary

Modifier and Type	Method and Description
void	allocate(int additional) Method to allocate a number of values into the block.
protected boolean	createRepository() Method to create any needed repository for the values.
T	current() Accessor for the current value allocated.
long	currentValue() Accessor for the current element in the sequence as a long.
String	getName() Accessor for the symbolic name for this generator.
T	next() Get next value from the reserved block of values.
long	nextValue() Accessor for the next element in the sequence as a long.
protected ValueGenerationBlock<T>	obtainGenerationBlock() Get a new block with the default number of ids.
protected ValueGenerationBlock<T>	obtainGenerationBlock(int number) Get a new block with the specified number of ids.
protected boolean	repositoryExists() Method to return if the repository already exists.
protected boolean	requiresRepository() Indicator for whether the generator requires its own repository.
protected ValueGenerationBlock<T>	reserveBlock() Method to reserve a default sized block of values.
protected abstract ValueGenerationBlock<T>	reserveBlock(long size) Method to reserve a block of "size" values.

Methods inherited from class java.lang.Object

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

Field Detail

name

protected String name

Symbolic name for the sequence.

properties

protected Properties properties

Properties controlling the generator behaviour.

allocationSize

protected int allocationSize

Allocation size

initialValue

protected int initialValue

Initial value (of the first id).

block

protected ValueGenerationBlock<T> block

The current block of values that have been reserved.

repositoryExists

protected boolean repositoryExists

Flag for whether we know that the repository exists. Only applies if repository is required.

Constructor Detail

AbstractGenerator

public AbstractGenerator(String name,
                         Properties props)

Constructor. Will receive the following properties (as a minimum) through this constructor.

• class-name : Name of the class whose object is being inserted.
• root-class-name : Name of the root class in this inheritance tree
• field-name : Name of the field with the strategy (unless datastore identity field)
• catalog-name : Catalog of the table (if specified)
• schema-name : Schema of the table (if specified)
• table-name : Name of the root table for this inheritance tree (containing the field).
• column-name : Name of the column in the table (for the field)
• sequence-name : Name of the sequence (if specified in MetaData as "sequence)

Parameters:

name - Symbolic name for this generator

props - Properties controlling the behaviour of the generator (or null if not required).

Method Detail

getName

public String getName()

Accessor for the symbolic name for this generator.

Specified by:

getName in interface ValueGenerator<T>

Returns:

Symbolic name for the generator.

next

public T next()

Get next value from the reserved block of values.

Specified by:

next in interface ValueGenerator<T>

Returns:

The next value

current

public T current()

Accessor for the current value allocated. Returns null if none are allocated

Specified by:

current in interface ValueGenerator<T>

Returns:

The current value

nextValue

public long nextValue()

Accessor for the next element in the sequence as a long.

Specified by:

nextValue in interface ValueGenerator<T>

Returns:

The next element

Throws:

NucleusDataStoreException - Thrown if not numeric

currentValue

public long currentValue()

Accessor for the current element in the sequence as a long.

Specified by:

currentValue in interface ValueGenerator<T>

Returns:

The current element

Throws:

NucleusDataStoreException - Thrown if not numeric

allocate

public void allocate(int additional)

Method to allocate a number of values into the block. If the block already exists and has remaining values, the additional values are added to the block.

Specified by:

allocate in interface ValueGenerator<T>

Parameters:

additional - The number to allocate

obtainGenerationBlock

protected ValueGenerationBlock<T> obtainGenerationBlock()

Get a new block with the default number of ids.

Returns:

the block

obtainGenerationBlock

protected ValueGenerationBlock<T> obtainGenerationBlock(int number)

Get a new block with the specified number of ids.

Parameters:

number - The number of additional ids required

Returns:

the block

reserveBlock

protected ValueGenerationBlock<T> reserveBlock()

Method to reserve a default sized block of values.

Returns:

The reserved block

reserveBlock

protected abstract ValueGenerationBlock<T> reserveBlock(long size)

Method to reserve a block of "size" values.

Parameters:

size - Number of values to reserve

Returns:

The allocated block

requiresRepository

protected boolean requiresRepository()

Indicator for whether the generator requires its own repository. AbstractValueGenerator returns false and this should be overridden by all generators requiring a repository.

Returns:

Whether a repository is required.

repositoryExists

protected boolean repositoryExists()

Method to return if the repository already exists.

Returns:

Whether the repository exists

createRepository

protected boolean createRepository()

Method to create any needed repository for the values. AbstractValueGenerator just returns true and should be overridden by any implementing generator requiring its own repository.

Returns:

If all is ready for use