org.hibernate.ogm.datastore.neo4j.dialect.impl

Class Neo4jSequenceGenerator

java.lang.Object

org.hibernate.ogm.datastore.neo4j.dialect.impl.Neo4jSequenceGenerator

public class Neo4jSequenceGenerator
extends Object

Generates the next value of an id sequence as represented by IdSourceKey.

Both, IdSourceKeyMetadata.IdSourceType.TABLE and IdSourceKeyMetadata.IdSourceType.SEQUENCE are supported. For the table strategy, nodes in the following form are used (the exact property names and the label value can be configured using the options exposed by OgmTableGenerator):

 (:hibernate_sequences:TABLE_BASED_SEQUENCE { sequence_name = 'ExampleSequence', current_value : 3 })
 

For the sequence strategy, nodes in the following form are used (the sequence name can be configured using the option exposed by OgmSequenceGenerator):

 (:SEQUENCE { sequence_name = 'ExampleSequence', next_val : 3 })
 

Sequences are created at startup.

A write lock is acquired on the node every time the sequence needs to be updated.

Author:

Davide D'Alto <davide@hibernate.org>, Gunnar Morling

Constructor Summary

Constructors

Constructor and Description
Neo4jSequenceGenerator(org.neo4j.graphdb.GraphDatabaseService neo4jDb, int sequenceCacheMaxSize)

Method Summary

Methods

Modifier and Type	Method and Description
void	createSequences(Set<PersistentNoSqlIdentifierGenerator> identifierGenerators) Create the sequence nodes setting the initial value if the node does not exists already.
int	nextValue(IdSourceKey idSourceKey, int increment) Generate the next value in a sequence for a given RowKey.

Methods inherited from class java.lang.Object

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

Constructor Detail

Neo4jSequenceGenerator

public Neo4jSequenceGenerator(org.neo4j.graphdb.GraphDatabaseService neo4jDb,
                      int sequenceCacheMaxSize)

Method Detail

createSequences

public void createSequences(Set<PersistentNoSqlIdentifierGenerator> identifierGenerators)

Create the sequence nodes setting the initial value if the node does not exists already.

All nodes are created inside the same transaction

Parameters:

identifierGenerators - the generators representing the sequences

nextValue

public int nextValue(IdSourceKey idSourceKey,
            int increment)

Generate the next value in a sequence for a given RowKey.

Parameters:

idSourceKey - identifies the generator

increment - the difference between to consecutive values in the sequence

Returns:

the next value in a sequence