Package com.mckoi.database

Class SequenceManager

java.lang.Object

com.mckoi.database.SequenceManager

final class SequenceManager
extends java.lang.Object

An object that manages the creation and removal of sequence keys, and that offers access to the sequence values (possibly cached). When the sequence table is changed, this opens an optimized transaction on the database and manipulates the SequenceInfo table.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	SequenceManager.SequenceGenerator	An object that encapsulates information about the sequence key.
private static class	SequenceManager.SequenceInternalTableInfo	An object that models the list of sequences as table objects in a transaction.

Field Summary

Fields

Modifier and Type	Field	Description
private TableDataConglomerate	conglomerate	The TableDataConglomerate object.
private static TObject	ONE_VAL	A static TObject that represents numeric 1.
private java.util.HashMap	sequence_key_map	A hashmap that maps from the TableName of the sequence key to the object that manages this sequence (SequenceGenerator).
private static TObject	TRUE_VAL	A static TObject that represents boolean true.

Constructor Summary

Constructors

Constructor	Description
SequenceManager(TableDataConglomerate conglomerate)	Constructs the object.

Method Summary

Modifier and Type	Method	Description
(package private) static void	addNativeTableGenerator(Transaction transaction, TableName table_name)	Static convenience - adds an entry to the Sequence table for a native table in the database.
(package private) static InternalTableInfo	createInternalTableInfo(Transaction transaction)	Returns an InternalTableInfo object used to model the list of sequence generators that are accessible within the given Transaction object.
(package private) static void	createSequenceGenerator(Transaction transaction, TableName table_name, long start_value, long increment_by, long min_value, long max_value, long cache, boolean cycle)	Creates a new sequence generator with the given name and details.
(package private) long	curValue(SimpleTransaction transaction, TableName name)	Returns the current value from the sequence generator.
(package private) static void	dropSequenceGenerator(Transaction transaction, TableName table_name)
(package private) void	flushGenerator(TableName name)	Flushes a sequence generator from the cache.
private SequenceManager.SequenceGenerator	getGenerator(TableName name)	Returns a SequenceGenerator object representing the sequence generator with the given name.
private Transaction	getTransaction()	Returns a new Transaction object for manipulating and querying the system state.
(package private) long	nextValue(SimpleTransaction transaction, TableName name)	Returns the next value from the sequence generator.
(package private) static void	removeNativeTableGenerator(Transaction transaction, TableName table_name)	Static convenience - removes an entry in the Sequence table for a native table in the database.
(package private) void	setValue(SimpleTransaction transaction, TableName name, long value)	Sets the current value of the sequence generator.
private void	updateGeneratorState(SequenceManager.SequenceGenerator generator)	Updates the state of the sequence key in the sequence tables in the database.

Methods inherited from class java.lang.Object

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

Field Detail

conglomerate

private TableDataConglomerate conglomerate

The TableDataConglomerate object.

sequence_key_map

private java.util.HashMap sequence_key_map

A hashmap that maps from the TableName of the sequence key to the object that manages this sequence (SequenceGenerator). (TableName) -> (SequenceGenerator)

ONE_VAL

private static final TObject ONE_VAL

A static TObject that represents numeric 1.

TRUE_VAL

private static final TObject TRUE_VAL

A static TObject that represents boolean true.

Constructor Detail

SequenceManager

SequenceManager(TableDataConglomerate conglomerate)

Constructs the object.

Method Detail

getTransaction

private Transaction getTransaction()

Returns a new Transaction object for manipulating and querying the system state.

getGenerator

private SequenceManager.SequenceGenerator getGenerator(TableName name)

Returns a SequenceGenerator object representing the sequence generator with the given name.

updateGeneratorState

private void updateGeneratorState(SequenceManager.SequenceGenerator generator)

Updates the state of the sequence key in the sequence tables in the database. The update occurs on an independant transaction.

flushGenerator

void flushGenerator(TableName name)

Flushes a sequence generator from the cache. This should be used when a sequence generator is altered or dropped from the database.

addNativeTableGenerator

static void addNativeTableGenerator(Transaction transaction,
                                    TableName table_name)

Static convenience - adds an entry to the Sequence table for a native table in the database. This acts as a gateway between the native sequence table function and the custom sequence generator. Note that some of the system tables and all of the VIEW tables will not have native sequence generators and thus not have an entry in the sequence table.

removeNativeTableGenerator

static void removeNativeTableGenerator(Transaction transaction,
                                       TableName table_name)

Static convenience - removes an entry in the Sequence table for a native table in the database.

createSequenceGenerator

static void createSequenceGenerator(Transaction transaction,
                                    TableName table_name,
                                    long start_value,
                                    long increment_by,
                                    long min_value,
                                    long max_value,
                                    long cache,
                                    boolean cycle)

Creates a new sequence generator with the given name and details. Note that this method does not check if the generator name clashes with an existing database object.

dropSequenceGenerator

static void dropSequenceGenerator(Transaction transaction,
                                  TableName table_name)

nextValue

long nextValue(SimpleTransaction transaction,
               TableName name)

Returns the next value from the sequence generator. This will atomically increment the sequence counter.

curValue

long curValue(SimpleTransaction transaction,
              TableName name)

Returns the current value from the sequence generator.

setValue

void setValue(SimpleTransaction transaction,
              TableName name,
              long value)

Sets the current value of the sequence generator.

createInternalTableInfo

static InternalTableInfo createInternalTableInfo(Transaction transaction)

Returns an InternalTableInfo object used to model the list of sequence generators that are accessible within the given Transaction object. This is used to model all sequence generators that have been defined as tables.