org.apache.activemq.store.kahadb

Interface KahaDBMetaData<T>

All Known Implementing Classes:

AbstractKahaDBMetaData, JobSchedulerKahaDBMetaData

public interface KahaDBMetaData<T>

Interface for the store meta data used to hold the index value and other needed information to manage a KahaDB store instance.

Field Summary

Fields

Modifier and Type	Field and Description
static int	CLOSED_STATE Indicates that this meta data instance has been closed and is no longer active.
static int	OPEN_STATE Indicates that this meta data instance has been opened and is active.

Method Summary

Methods

Modifier and Type	Method and Description
Location	getLastUpdateLocation() Returns the Journal Location value that indicates that last recorded update that was successfully performed for this KahaDB store implementation.
Page<T>	getPage() Gets the Page in the store PageFile where the KahaDBMetaData instance is stored.
int	getState() Gets the state flag of this meta data instance.
void	initialize(Transaction tx) For a newly created KahaDBMetaData instance this method is called to allow the instance to create all of it's internal indices and other state data.
void	load(Transaction tx) Instructs this object to load its internal data structures from the KahaDB PageFile and prepare itself for use.
void	read(DataInput in) Reads the serialized for of this object from the KadaDB PageFile and prepares it for use.
void	setLastUpdateLocation(Location location) Updates the value of the last successful update.
void	setPage(Page<T> page) Sets the Page instance used to load and store the KahaDBMetaData instance.
void	setState(int value) Sets the current value of the state flag.
void	write(DataOutput out) Writes the object into a serialized form which can be read back in again using the read method.

Field Detail

OPEN_STATE

static final int OPEN_STATE

Indicates that this meta data instance has been opened and is active.

See Also:

Constant Field Values

CLOSED_STATE

static final int CLOSED_STATE

Indicates that this meta data instance has been closed and is no longer active.

See Also:

Constant Field Values

Method Detail

getPage

Page<T> getPage()

Gets the Page in the store PageFile where the KahaDBMetaData instance is stored.

Returns:

the Page to use to start access the KahaDBMetaData instance.

setPage

void setPage(Page<T> page)

Sets the Page instance used to load and store the KahaDBMetaData instance.

Parameters:

page - the new Page value to use.

getState

int getState()

Gets the state flag of this meta data instance.

Returns:

the current state value for this instance.

setState

void setState(int value)

Sets the current value of the state flag.

Parameters:

value - the new value to assign to the state flag.

getLastUpdateLocation

Location getLastUpdateLocation()

Returns the Journal Location value that indicates that last recorded update that was successfully performed for this KahaDB store implementation.

Returns:

the location of the last successful update location.

setLastUpdateLocation

void setLastUpdateLocation(Location location)

Updates the value of the last successful update.

Parameters:

location - the new value to assign the last update location field.

initialize

void initialize(Transaction tx)
                throws IOException

For a newly created KahaDBMetaData instance this method is called to allow the instance to create all of it's internal indices and other state data.

Parameters:

tx - the Transaction instance under which the operation is executed.

Throws:

IOException - if an error occurs while creating the meta data structures.

load

void load(Transaction tx)
          throws IOException

Instructs this object to load its internal data structures from the KahaDB PageFile and prepare itself for use.

Parameters:

tx - the Transaction instance under which the operation is executed.

Throws:

IOException - if an error occurs while creating the meta data structures.

read

void read(DataInput in)
          throws IOException

Reads the serialized for of this object from the KadaDB PageFile and prepares it for use. This method does not need to perform a full load of the meta data structures only read in the information necessary to load them from the PageFile on a call to the load method.

Parameters:

in - the DataInput instance used to read this objects serialized form.

Throws:

IOException - if an error occurs while reading the serialized form.

write

void write(DataOutput out)
           throws IOException

Writes the object into a serialized form which can be read back in again using the read method.

Parameters:

out - the DataOutput instance to use to write the current state to a serialized form.

Throws:

IOException - if an error occurs while serializing this instance.