org.objectweb.cjdbc.controller.loadbalancer.singledb
Class SingleDB

java.lang.Object
  javax.management.StandardMBean
      org.objectweb.cjdbc.controller.jmx.AbstractStandardMBean
          org.objectweb.cjdbc.controller.loadbalancer.AbstractLoadBalancer
              org.objectweb.cjdbc.controller.loadbalancer.singledb.SingleDB

All Implemented Interfaces:

AbstractLoadBalancerMBean, javax.management.DynamicMBean, javax.management.NotificationBroadcaster, javax.management.NotificationEmitter, XmlComponent

public class SingleDB

extends AbstractLoadBalancer

Single Database request load balancer.

The requests coming from the request controller are directly forwarded to the single backend. This load balancer does not support multiple backends.

Version:

1.0

Author:

Emmanuel Cecchet , Vadim Kassin , Jaco Swart , Jean-Bernard van Zuylen

Nested Class Summary

Nested classes inherited from class javax.management.StandardMBean

Field Summary

private DatabaseBackend	backend
private static Trace	logger

Fields inherited from class org.objectweb.cjdbc.controller.loadbalancer.AbstractLoadBalancer

macroHandler, parsingGranularity, raidbLevel, totalOrderQueue, vdb

Fields inherited from class org.objectweb.cjdbc.controller.jmx.AbstractStandardMBean

Fields inherited from class javax.management.StandardMBean

Fields inherited from interface org.objectweb.cjdbc.common.xml.XmlComponent

DOCTYPE_CONTROLLER, DOCTYPE_DB, XML_VERSION

Constructor Summary

SingleDB(VirtualDatabase vdb)
Creates a new SingleDB instance.

Method Summary

void	begin(TransactionMarkerMetaData tm) Begins a new transaction.
void	commit(TransactionMarkerMetaData tm) Commits a transaction.
void	disableBackend(DatabaseBackend db) Disables a backend that was previously enabled.
void	enableBackend(DatabaseBackend db, boolean writeEnabled) Enables a backend that was previously disabled.
ControllerResultSet	execReadOnlyReadStoredProcedure(StoredProcedure proc, MetadataCache metadataCache) Call a read-only stored procedure that returns a ResultSet.
ControllerResultSet	execReadRequest(SelectRequest request, MetadataCache metadataCache) Performs a read request.
ControllerResultSet	execReadStoredProcedure(StoredProcedure proc, MetadataCache metadataCache) Call a stored procedure that returns a ResultSet.
int	execWriteRequest(AbstractWriteRequest request) Performs a write request on the backend.
ControllerResultSet	execWriteRequestWithKeys(AbstractWriteRequest request, MetadataCache metadataCache) Perform a write request and return a ResultSet containing the auto generated keys.
int	execWriteStoredProcedure(StoredProcedure proc) Call a stored procedure that performs an update.
java.lang.String	getInformation() Gets information about the request load balancer
int	getNumberOfEnabledBackends() Get the number of currently enabled backends. 0 means that no backend is available.
java.lang.String	getXmlImpl() Get information about the Request Load Balancer in xml
void	releaseSavepoint(TransactionMarkerMetaData tm, java.lang.String name) Release a savepoint from a transaction
void	rollback(TransactionMarkerMetaData tm) Rollbacks a transaction.
void	rollback(TransactionMarkerMetaData tm, java.lang.String savepointName) Rollback a transaction to a savepoint
void	setSavepoint(TransactionMarkerMetaData tm, java.lang.String name) Set a savepoint to a transaction.
void	setWeight(java.lang.String name, int w) Associate a weight to a backend identified by its logical name.

Methods inherited from class org.objectweb.cjdbc.controller.loadbalancer.AbstractLoadBalancer

executeReadStoredProcedureOnBackend, executeSelectRequestOnBackend, executeUpdateRequestOnBackend, executeUpdateRequestOnBackendWithKeys, executeWriteStoredProcedureOnBackend, getAssociatedString, getConnectionAndBeginTransaction, getParsingGranularity, getRAIDbLevel, getXml, handleMacros, removeHeadFromAndNotifyTotalOrderQueue, setMacroHandler, setParsingGranularity, setRAIDbLevel, waitForTotalOrder

Methods inherited from class org.objectweb.cjdbc.controller.jmx.AbstractStandardMBean

addNotificationListener, getDescription, getDescription, getDescription, getDescription, getDescription, getDescription, getNotificationInfo, getParameterName, getParameterName, removeNotificationListener, removeNotificationListener, sendNotification

Methods inherited from class javax.management.StandardMBean

cacheMBeanInfo, getAttribute, getAttributes, getCachedMBeanInfo, getClassName, getConstructors, getDescription, getImpact, getImplementation, getImplementationClass, getMBeanInfo, getMBeanInterface, invoke, setAttribute, setAttributes, setImplementation

Methods inherited from class java.lang.Object

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

Field Detail

backend

private DatabaseBackend backend

logger

private static Trace logger

Constructor Detail

SingleDB

public SingleDB(VirtualDatabase vdb)
         throws java.lang.Exception

Creates a new SingleDB instance.

Parameters:

vdb - the VirtualDatabase this load balancer belongs to

Throws:

java.lang.Exception - if there is not exactly one backend attached to the VirtualDatabase

Method Detail

execReadRequest

public ControllerResultSet execReadRequest(SelectRequest request,
                                           MetadataCache metadataCache)
                                    throws java.sql.SQLException

Performs a read request. It is up to the implementation to choose to which backend node(s) this request should be sent.

Specified by:

execReadRequest in class AbstractLoadBalancer

Parameters:

request - an SelectRequest

metadataCache - MetadataCache (null if none)

Returns:

the corresponding java.sql.ResultSet

Throws:

java.sql.SQLException - if an error occurs

execWriteRequest

public int execWriteRequest(AbstractWriteRequest request)
                     throws java.sql.SQLException

Performs a write request on the backend.

Specified by:

execWriteRequest in class AbstractLoadBalancer

Parameters:

request - an AbstractWriteRequest

Returns:

number of rows affected by the request

Throws:

java.sql.SQLException - if an error occurs

execWriteRequestWithKeys

public ControllerResultSet execWriteRequestWithKeys(AbstractWriteRequest request,
                                                    MetadataCache metadataCache)
                                             throws java.sql.SQLException

Description copied from class: AbstractLoadBalancer

Perform a write request and return a ResultSet containing the auto generated keys.

Specified by:

execWriteRequestWithKeys in class AbstractLoadBalancer

Parameters:

request - an AbstractWriteRequest

metadataCache - MetadataCache (null if none)

Returns:

auto generated keys

Throws:

java.sql.SQLException - if an error occurs

See Also:

AbstractLoadBalancer.execWriteRequestWithKeys(AbstractWriteRequest, MetadataCache)

execReadOnlyReadStoredProcedure

public ControllerResultSet execReadOnlyReadStoredProcedure(StoredProcedure proc,
                                                           MetadataCache metadataCache)
                                                    throws java.sql.SQLException

Description copied from class: AbstractLoadBalancer

Call a read-only stored procedure that returns a ResultSet. The stored procedure will be executed by one node only.

Specified by:

execReadOnlyReadStoredProcedure in class AbstractLoadBalancer

Parameters:

proc - the stored procedure call

metadataCache - MetadataCache (null if none)

Returns:

a ControllerResultSet value

Throws:

java.sql.SQLException - if an error occurs

See Also:

AbstractLoadBalancer.execReadOnlyReadStoredProcedure(StoredProcedure, MetadataCache)

execReadStoredProcedure

public ControllerResultSet execReadStoredProcedure(StoredProcedure proc,
                                                   MetadataCache metadataCache)
                                            throws java.sql.SQLException

Description copied from class: AbstractLoadBalancer

Call a stored procedure that returns a ResultSet. This stored procedure can possibly perform writes and will therefore be executed by all nodes.

Specified by:

execReadStoredProcedure in class AbstractLoadBalancer

Parameters:

proc - the stored procedure call

metadataCache - MetadataCache (null if none)

Returns:

a ControllerResultSet value

Throws:

java.sql.SQLException - if an error occurs

See Also:

AbstractLoadBalancer.execReadStoredProcedure(StoredProcedure, MetadataCache)

execWriteStoredProcedure

public int execWriteStoredProcedure(StoredProcedure proc)
                             throws java.sql.SQLException

Description copied from class: AbstractLoadBalancer

Call a stored procedure that performs an update.

Specified by:

execWriteStoredProcedure in class AbstractLoadBalancer

Parameters:

proc - the stored procedure call

Returns:

number of rows affected

Throws:

java.sql.SQLException - if an error occurs

See Also:

AbstractLoadBalancer.execWriteStoredProcedure(org.objectweb.cjdbc.common.sql.StoredProcedure)

begin

public void begin(TransactionMarkerMetaData tm)
           throws java.sql.SQLException

Begins a new transaction.

Specified by:

begin in class AbstractLoadBalancer

Parameters:

tm - the transaction marker metadata

Throws:

java.sql.SQLException - if an error occurs

commit

public void commit(TransactionMarkerMetaData tm)
            throws java.sql.SQLException

Commits a transaction.

Specified by:

commit in class AbstractLoadBalancer

Parameters:

tm - the transaction marker metadata

Throws:

java.sql.SQLException - if an error occurs

rollback

public void rollback(TransactionMarkerMetaData tm)
              throws java.sql.SQLException

Rollbacks a transaction.

Specified by:

rollback in class AbstractLoadBalancer

Parameters:

tm - the transaction marker metadata

Throws:

java.sql.SQLException - if an error occurs

rollback

public void rollback(TransactionMarkerMetaData tm,
                     java.lang.String savepointName)
              throws java.sql.SQLException

Rollback a transaction to a savepoint

Specified by:

rollback in class AbstractLoadBalancer

Parameters:

tm - The transaction marker metadata

savepointName - The name of the savepoint

Throws:

java.sql.SQLException - if an error occurs

releaseSavepoint

public void releaseSavepoint(TransactionMarkerMetaData tm,
                             java.lang.String name)
                      throws java.sql.SQLException

Release a savepoint from a transaction

Specified by:

releaseSavepoint in class AbstractLoadBalancer

Parameters:

tm - The transaction marker metadata

name - The name of the savepoint ro release

Throws:

java.sql.SQLException - if an error occurs

setSavepoint

public void setSavepoint(TransactionMarkerMetaData tm,
                         java.lang.String name)
                  throws AllBackendsFailedException,
                         java.sql.SQLException

Set a savepoint to a transaction.

Specified by:

setSavepoint in class AbstractLoadBalancer

Parameters:

tm - The transaction marker metadata

name - The name of the new savepoint

Throws:

AllBackendsFailedException - if no backend succeeded in setting the savepoint.

java.sql.SQLException - if an error occurs

enableBackend

public void enableBackend(DatabaseBackend db,
                          boolean writeEnabled)
                   throws java.sql.SQLException

Enables a backend that was previously disabled. Asks the corresponding connection manager to initialize the connections if needed.

Specified by:

enableBackend in class AbstractLoadBalancer

Parameters:

db - the database backend to enable

writeEnabled - True if the backend must be enabled for writes

Throws:

java.sql.SQLException - if an error occurs

disableBackend

public void disableBackend(DatabaseBackend db)
                    throws java.sql.SQLException

Disables a backend that was previously enabled. Asks the corresponding connection manager to finalize the connections if needed.

Specified by:

disableBackend in class AbstractLoadBalancer

Parameters:

db - the database backend to disable

Throws:

java.sql.SQLException - if an error occurs

setWeight

public void setWeight(java.lang.String name,
                      int w)
               throws java.sql.SQLException

Description copied from class: AbstractLoadBalancer

Associate a weight to a backend identified by its logical name.

Specified by:

setWeight in interface AbstractLoadBalancerMBean

Overrides:

setWeight in class AbstractLoadBalancer

Parameters:

name - the backend name

w - the weight

Throws:

java.sql.SQLException - if an error occurs

See Also:

AbstractLoadBalancer.setWeight(String, int)

getNumberOfEnabledBackends

public int getNumberOfEnabledBackends()

Description copied from class: AbstractLoadBalancer

Get the number of currently enabled backends. 0 means that no backend is available.

Specified by:

getNumberOfEnabledBackends in class AbstractLoadBalancer

Returns:

number of currently enabled backends

See Also:

AbstractLoadBalancer.getNumberOfEnabledBackends()

getInformation

public java.lang.String getInformation()

Gets information about the request load balancer

Specified by:

getInformation in interface AbstractLoadBalancerMBean

Specified by:

getInformation in class AbstractLoadBalancer

Returns:

String containing information

getXmlImpl

public java.lang.String getXmlImpl()

Description copied from class: AbstractLoadBalancer

Get information about the Request Load Balancer in xml

Specified by:

getXmlImpl in class AbstractLoadBalancer

Returns:

String containing information, xml formatted

See Also:

AbstractLoadBalancer.getXmlImpl()