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

java.lang.Object
  org.objectweb.cjdbc.controller.loadbalancer.AbstractLoadBalancer
      org.objectweb.cjdbc.controller.loadbalancer.singledb.SingleDB

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

Field Summary

private DatabaseBackend	backend
private static Trace	logger

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

parsingGranularity, raidbLevel, vdb

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) Enables a backend that was previously disabled.
java.sql.ResultSet	execReadRequest(SelectRequest request) Performs a read request.
java.sql.ResultSet	execReadStoredProcedure(StoredProcedure proc) Call a stored procedure that returns a ResultSet.
int	execWriteRequest(AbstractWriteRequest request) Performs a write request on the backend.
java.sql.ResultSet	execWriteRequestWithKeys(AbstractWriteRequest request) 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
java.lang.String	getXmlInformation() Get information about the Request Load Balancer in xml
void	rollback(TransactionMarkerMetaData tm) Rollbacks 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

getParsingGranularity, getRAIDbLevel, setParsingGranularity, setRAIDbLevel

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.sql.SQLException

Creates a new SingleDB instance.

Parameters:

vdb - the VirtualDatabase this load balancer belongs to

Throws:

java.sql.SQLException - if there is not exactly one backend attached to the VirtualDatabase

Method Detail

execReadRequest

public java.sql.ResultSet execReadRequest(SelectRequest request)
                                   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

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 java.sql.ResultSet execWriteRequestWithKeys(AbstractWriteRequest request)
                                            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

Returns:

auto generated keys

Throws:

java.sql.SQLException - if an error occurs

See Also:

AbstractLoadBalancer.execWriteRequestWithKeys(AbstractWriteRequest)

execReadStoredProcedure

public java.sql.ResultSet execReadStoredProcedure(StoredProcedure proc)
                                           throws java.sql.SQLException

Description copied from class: AbstractLoadBalancer

Call a stored procedure that returns a ResultSet.

Specified by:

execReadStoredProcedure in class AbstractLoadBalancer

Parameters:

proc - the stored procedure call

Returns:

a java.sql.ResultSet value

Throws:

java.sql.SQLException - if an error occurs

See Also:

AbstractLoadBalancer.execReadStoredProcedure(org.objectweb.cjdbc.sql.StoredProcedure)

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.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

enableBackend

public void enableBackend(DatabaseBackend db)
                   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

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.

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)

getInformation

public java.lang.String getInformation()

Gets information about the request load balancer

Specified by:

getInformation in class AbstractLoadBalancer

Returns:

String containing information

getXmlInformation

public java.lang.String getXmlInformation()

Description copied from class: AbstractLoadBalancer

Get information about the Request Load Balancer in xml

Specified by:

getXmlInformation in class AbstractLoadBalancer

Returns:

String containing information, xml formatted

See Also:

AbstractLoadBalancer.getXmlInformation()