org.apache.derby.impl.store.replication.slave

Class SlaveController

java.lang.Object

org.apache.derby.impl.store.replication.slave.SlaveController

All Implemented Interfaces:

ModuleControl, ModuleSupportable, SlaveFactory

public class SlaveController
extends java.lang.Object
implements SlaveFactory, ModuleControl, ModuleSupportable

This is an implementation of the replication slave controller service. The service is booted when this instance of Derby will have the replication slave role for this database.

Note: The current version of the class is far from complete. Code to control the replication slave behavior will be added as more parts of the replication functionality is added to Derby.

See Also:

SlaveFactory

Field Summary

Fields inherited from interface org.apache.derby.iapi.store.replication.slave.SlaveFactory

MODULE, REPLICATION_MODE, SLAVE_DB, SLAVE_MODE, SLAVE_PRE_MODE

Constructor Summary

Constructors

Constructor and Description
SlaveController() Empty constructor required by Monitor.bootServiceModule

Method Summary

Modifier and Type	Method and Description
void	boot(boolean create, java.util.Properties properties) Used by Monitor.bootServiceModule to start the service.
boolean	canSupport(java.util.Properties startParams) Used by Monitor.bootServiceModule to check if this class is usable for replication.
void	failover() Used to turn this slave instance of the database into a normal instance that clients can connect to, assuming that the connection with the master is down.
boolean	isStarted() Check whether or not slave replication mode has been successfully started.
void	startSlave(RawStoreFactory rawStore, LogFactory logFac) Start slave replication.
void	stop() Will tear down the replication slave service.
void	stopSlave(boolean forcedStop) Stop replication slave mode.

Methods inherited from class java.lang.Object

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

Constructor Detail

SlaveController

public SlaveController()

Empty constructor required by Monitor.bootServiceModule

Method Detail

boot

public void boot(boolean create,
                 java.util.Properties properties)
          throws StandardException

Used by Monitor.bootServiceModule to start the service. It will set up basic variables

Specified by:

boot in interface ModuleControl

Parameters:

create - Currently ignored

properties - Properties used to start the service in the correct mode

Throws:

StandardException - Standard Derby exception policy, thrown on error.

See Also:

Monitor, ModuleFactory

stop

public void stop()

Will tear down the replication slave service.

Specified by:

stop in interface ModuleControl

See Also:

Monitor, ModuleFactory

canSupport

public boolean canSupport(java.util.Properties startParams)

Used by Monitor.bootServiceModule to check if this class is usable for replication. To be usable, we require that slave replication mode is specified in startParams by checking that a property with key SlaveFactory.REPLICATION_MODE has the value SlaveFactory.SLAVE_MODE.

Specified by:

canSupport in interface ModuleSupportable

Parameters:

startParams - The properties used to start replication

Returns:

true if slave repliation is specified, meaning that this MasterController is a suitable implementation for the SlaveFactory service. False otherwise.

See Also:

ModuleSupportable.canSupport(java.util.Properties)

startSlave

public void startSlave(RawStoreFactory rawStore,
                       LogFactory logFac)
                throws StandardException

Start slave replication. This method establishes a network connection with the associated replication master and starts a thread that applies operations received from the master (in the form of log records) to the local slave database.

Specified by:

startSlave in interface SlaveFactory

Parameters:

rawStore - The RawStoreFactory for the database

logFac - The LogFactory ensuring recoverability for this database

Throws:

StandardException - Thrown if the slave could not be started.

stopSlave

public void stopSlave(boolean forcedStop)
               throws StandardException

Description copied from interface: SlaveFactory

Stop replication slave mode. Causes the database to abort the boot process, and should only be used when shutting down this database. If forcedStop is false, the method will fail with an exception if connected with the master. If forcedStop is true, the slave will be shut down even if connected to the master. A forcedStop value of true should only be used by system shutdown.

Specified by:

stopSlave in interface SlaveFactory

Parameters:

forcedStop - Determines whether or not an exception should be thrown when this method is called while the network connection to the master is up.

Throws:

StandardException - Thrown if slave is connected with master and forcedStop is false.

See Also:

SlaveFactory.stopSlave(boolean)

failover

public void failover()
              throws StandardException

Description copied from interface: SlaveFactory

Used to turn this slave instance of the database into a normal instance that clients can connect to, assuming that the connection with the master is down. This is typically done in cases where a fatal error has happened on the master instance of the database, or when the master database is unreachable due to network problems.

By calling failover, this slave instance of the database will be recovered so that all committed operations that have been received from the master are reflected here. On the other hand, operations from transactions where the commit log record has not been received from the master will not be reflected.

Note that even though an operation has been executed (and even committed) on the master, it is not neccessarily reflected in the slave instance of the database. This depends on the replication strategy used by the MasterFactory.

Specified by:

failover in interface SlaveFactory

Throws:

StandardException - Thrown if slave is connected with master

See Also:

MasterFactory, MasterController.flushedTo(long)

isStarted

public boolean isStarted()

Description copied from interface: SlaveFactory

Check whether or not slave replication mode has been successfully started.

Specified by:

isStarted in interface SlaveFactory

Returns:

true if slave replication mode has started successfully, false if slave mode startup is not yet confirmed

See Also:

SlaveFactory.isStarted()