org.datanucleus.store.valuegenerator

Class ValueGenerationManagerImpl

java.lang.Object

org.datanucleus.store.valuegenerator.ValueGenerationManagerImpl

All Implemented Interfaces:

ValueGenerationManager

public class ValueGenerationManagerImpl
extends Object
implements ValueGenerationManager

Manager for the creation of ValueGenerators. ValueGenerators are of two primary types.

• unique : apply to any datastore, and generate unique values. For example, UUID, which generates the values in Java space.
• datastore : apply to a particular datastore, and member. For example, an RDBMS SEQUENCE.

Any unique generators are loaded at initialisation. Any datastore generators are loaded when required. All generators are cached once created, and can be looked up by the member "key" that they are for.

Member Key

The member "key" is either the fully-qualified member name (e.g "mydomain.MyClass.myField") that is having its values generated, or is for a (surrogate) datastore id member (e.g "mydomain.MyClass (datastore-id)"). All unique generators can also be looked up by the strategy name (since there is one instance of that generator per strategy.

Field Summary

Fields

Modifier and Type	Field and Description
protected Map<String,ValueGenerator>	generatorsByMemberKey Map of ValueGenerators, keyed by the member key ("{class}.{field}", or "{class} + (datastore-id)").
protected StoreManager	storeMgr
protected Map<String,ValueGenerator>	uniqueGeneratorsByName Map of "unique" ValueGenerators, keyed by their strategy name.

Constructor Summary

Constructors

Constructor and Description
ValueGenerationManagerImpl(StoreManager storeMgr) Constructor.

Method Summary

Modifier and Type	Method and Description
void	clear() Method to clear out the generators managed by this manager.
ValueGenerator	createAndRegisterValueGenerator(String memberKey, String strategyName, Properties props) Method to create and register a generator of the specified strategy, for the specified memberKey.
ValueGenerator	createValueGenerator(String strategyName, String seqName, Properties props, ValueGenerationConnectionProvider connectionProvider) Method to create a ValueGenerator when the generator is datastore based.
String	getMemberKey(AbstractClassMetaData cmd, int fieldNumber) Simple way of generating a member "key" for use in lookups.
Class	getTypeForValueGeneratorForMember(String strategyName, String memberKey) Accessor for the type of value that is generated by the ValueGenerator for the specified strategy, for the member "key".
ValueGenerator	getUniqueValueGeneratorByName(String name) Accessor for the "unique" ValueGenerator for the specified name (if any).
ValueGenerator	getValueGeneratorForMemberKey(String memberKey) Method to access the currently defined ValueGenerator for the specified member "key" (if any).
void	registerValueGeneratorForMemberKey(String memberKey, ValueGenerator generator) Method to store a ValueGenerator for the specified member "key".
boolean	supportsStrategy(String strategy) Convenience accessor for whether the specified strategy is supported for this datastore.

Methods inherited from class java.lang.Object

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

Field Detail

storeMgr

protected final StoreManager storeMgr

generatorsByMemberKey

protected Map<String,ValueGenerator> generatorsByMemberKey

Map of ValueGenerators, keyed by the member key ("{class}.{field}", or "{class} + (datastore-id)").

uniqueGeneratorsByName

protected Map<String,ValueGenerator> uniqueGeneratorsByName

Map of "unique" ValueGenerators, keyed by their strategy name.

Constructor Detail

ValueGenerationManagerImpl

public ValueGenerationManagerImpl(StoreManager storeMgr)

Constructor.

Parameters:

storeMgr - Store Manager

Method Detail

clear

public void clear()

Description copied from interface: ValueGenerationManager

Method to clear out the generators managed by this manager.

Specified by:

clear in interface ValueGenerationManager

getValueGeneratorForMemberKey

public ValueGenerator getValueGeneratorForMemberKey(String memberKey)

Description copied from interface: ValueGenerationManager

Method to access the currently defined ValueGenerator for the specified member "key" (if any).

Specified by:

getValueGeneratorForMemberKey in interface ValueGenerationManager

Parameters:

memberKey - The member "key"

Returns:

Its ValueGenerator

registerValueGeneratorForMemberKey

public void registerValueGeneratorForMemberKey(String memberKey,
                                               ValueGenerator generator)

Description copied from interface: ValueGenerationManager

Method to store a ValueGenerator for the specified member "key".

Specified by:

registerValueGeneratorForMemberKey in interface ValueGenerationManager

Parameters:

memberKey - The member "key"

generator - The ValueGenerator to use for that member key

getUniqueValueGeneratorByName

public ValueGenerator getUniqueValueGeneratorByName(String name)

Description copied from interface: ValueGenerationManager

Accessor for the "unique" ValueGenerator for the specified name (if any).

Specified by:

getUniqueValueGeneratorByName in interface ValueGenerationManager

Parameters:

name - The (strategy) name.

Returns:

The ValueGenerator for that name

getMemberKey

public String getMemberKey(AbstractClassMetaData cmd,
                           int fieldNumber)

Description copied from interface: ValueGenerationManager

Simple way of generating a member "key" for use in lookups.

Specified by:

getMemberKey in interface ValueGenerationManager

Parameters:

cmd - Metadata for the class

fieldNumber - The field number (absolute). -1 if datastore-id surrogate member.

Returns:

The member "key" to use

getTypeForValueGeneratorForMember

public Class getTypeForValueGeneratorForMember(String strategyName,
                                               String memberKey)

Description copied from interface: ValueGenerationManager

Accessor for the type of value that is generated by the ValueGenerator for the specified strategy, for the member "key".

Specified by:

getTypeForValueGeneratorForMember in interface ValueGenerationManager

Parameters:

strategyName - The value generation strategy

memberKey - The member "key"

Returns:

The type of value generated

createAndRegisterValueGenerator

public ValueGenerator createAndRegisterValueGenerator(String memberKey,
                                                      String strategyName,
                                                      Properties props)

Description copied from interface: ValueGenerationManager

Method to create and register a generator of the specified strategy, for the specified memberKey.

Specified by:

createAndRegisterValueGenerator in interface ValueGenerationManager

Parameters:

memberKey - The member key

strategyName - Strategy for the generator

props - The properties to use

Returns:

The ValueGenerator

supportsStrategy

public boolean supportsStrategy(String strategy)

Description copied from interface: ValueGenerationManager

Convenience accessor for whether the specified strategy is supported for this datastore.

Specified by:

supportsStrategy in interface ValueGenerationManager

Parameters:

strategy - The strategy name

Returns:

Whether it is supported

createValueGenerator

public ValueGenerator createValueGenerator(String strategyName,
                                           String seqName,
                                           Properties props,
                                           ValueGenerationConnectionProvider connectionProvider)

Description copied from interface: ValueGenerationManager

Method to create a ValueGenerator when the generator is datastore based. This is used solely by the NucleusSequence API to create a generator, but not to register it here for further use.

Specified by:

createValueGenerator in interface ValueGenerationManager

Parameters:

strategyName - Strategy name

seqName - Symbolic name of the generator

props - Properties to control the generator

connectionProvider - Provider for connections

Returns:

The ValueGenerator