org.objectweb.cjdbc.controller.loadbalancer.raidb1
Class RAIDb1_WRR

java.lang.Object
  javax.management.StandardMBean
      org.objectweb.cjdbc.controller.jmx.AbstractStandardMBean
          org.objectweb.cjdbc.controller.loadbalancer.AbstractLoadBalancer
              org.objectweb.cjdbc.controller.loadbalancer.raidb1.RAIDb1
                  org.objectweb.cjdbc.controller.loadbalancer.raidb1.RAIDb1_WRR

All Implemented Interfaces:

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

public class RAIDb1_WRR

extends RAIDb1

RAIDb-1 Weighted Round Robin load balancer

The read requests coming from the request manager are sent to the backend nodes using a weighted round robin. Write requests are broadcasted to all backends.

Version:

1.0

Author:

Emmanuel Cecchet , Julie Marguerite , Nicolas Modrzyk

Nested Class Summary

Nested classes inherited from class javax.management.StandardMBean

Field Summary

private int	index
private java.util.HashMap	weights

Fields inherited from class org.objectweb.cjdbc.controller.loadbalancer.raidb1.RAIDb1

backendBlockingThreads, backendBlockingThreadsRWLock, backendNonBlockingThreads, backendNonBlockingThreadsRWLock, logger, waitForCompletionPolicy

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

RAIDb1_WRR(VirtualDatabase vdb, WaitForCompletionPolicy waitForCompletionPolicy)
Creates a new RAIDb-1 Weighted Round Robin request load balancer.

Method Summary

ControllerResultSet	execReadOnlyReadStoredProcedure(StoredProcedure proc, MetadataCache metadataCache) Selects the backend using a least pending request first policy.
ControllerResultSet	execReadRequest(SelectRequest request, MetadataCache metadataCache) Selects the backend using a weighted round-robin algorithm and executes the read request.
private ControllerResultSet	executeWRR(AbstractRequest request, boolean isSelect, java.lang.String errorMsgPrefix, MetadataCache metadataCache) Common code to execute a SelectRequest or a StoredProcedure on a backend chosen using a weighted round-robin algorithm.
java.lang.String	getInformation() Gets information about the request load balancer.
java.lang.String	getRaidb1Xml() Surrounding raidb1 tags can be treated by getXmlImpl above, but more detailed content have to be returned by the method getRaidb1Xml below.
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.raidb1.RAIDb1

begin, commit, disableBackend, enableBackend, execReadStoredProcedure, executeRequestOnBackend, executeStoredProcedureOnBackend, execWriteRequest, execWriteRequestWithKeys, execWriteStoredProcedure, getNumberOfEnabledBackends, getXmlImpl, releaseSavepoint, rollback, rollback, setSavepoint, waitForAllWritesToComplete, waitForAllWritesToComplete, waitForAllWritesToComplete

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

weights

private java.util.HashMap weights

index

private int index

Constructor Detail

RAIDb1_WRR

public RAIDb1_WRR(VirtualDatabase vdb,
                  WaitForCompletionPolicy waitForCompletionPolicy)
           throws java.lang.Exception

Creates a new RAIDb-1 Weighted Round Robin request load balancer.

Parameters:

vdb - the virtual database this load balancer belongs to.

waitForCompletionPolicy - How many backends must complete before returning the result?

Throws:

java.lang.Exception - if an error occurs

Method Detail

execReadRequest

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

Selects the backend using a weighted round-robin algorithm and executes the read request.

Specified by:

execReadRequest in class RAIDb1

Throws:

java.sql.SQLException

See Also:

RAIDb1.execReadRequest(SelectRequest, MetadataCache)

execReadOnlyReadStoredProcedure

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

Selects the backend using a least pending request first policy. The backend that has the shortest queue of currently executing queries is chosen to execute this stored procedure.

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)

executeWRR

private ControllerResultSet executeWRR(AbstractRequest request,
                                       boolean isSelect,
                                       java.lang.String errorMsgPrefix,
                                       MetadataCache metadataCache)
                                throws java.sql.SQLException

Common code to execute a SelectRequest or a StoredProcedure on a backend chosen using a weighted round-robin algorithm.

Parameters:

request - a SelectRequest or StoredProcedure

isSelect - true if it is a SelectRequest, false if it is a StoredProcedure

errorMsgPrefix - the error message prefix, usually "Request " or "Stored procedure " ... failed because ...

metadataCache - a metadataCache if any or null

Returns:

a ResultSet

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)

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

getRaidb1Xml

public java.lang.String getRaidb1Xml()

Description copied from class: RAIDb1

Surrounding raidb1 tags can be treated by getXmlImpl above, but more detailed content have to be returned by the method getRaidb1Xml below.

Specified by:

getRaidb1Xml in class RAIDb1

Returns:

content of Raidb1 xml

See Also:

RAIDb1.getRaidb1Xml()