org.apache.hadoop.conf

Class ReconfigurableBase

java.lang.Object

org.apache.hadoop.conf.Configured

org.apache.hadoop.conf.ReconfigurableBase

All Implemented Interfaces:

Configurable, Reconfigurable

public abstract class ReconfigurableBase
extends Configured
implements Reconfigurable

Utility base class for implementing the Reconfigurable interface. Subclasses should override reconfigurePropertyImpl to change individual properties and getReconfigurableProperties to get all properties that can be changed at run time.

Constructor Summary

Constructors

Constructor and Description
ReconfigurableBase() Construct a ReconfigurableBase.
ReconfigurableBase(Configuration conf) Construct a ReconfigurableBase with the Configuration conf.

Method Summary

Modifier and Type	Method and Description
Collection<ReconfigurationUtil.PropertyChange>	getChangedProperties(Configuration newConf, Configuration oldConf)
protected abstract Configuration	getNewConf() Create a new configuration.
abstract Collection<String>	getReconfigurableProperties() Return all the properties that can be changed at run time.
org.apache.hadoop.conf.ReconfigurationTaskStatus	getReconfigurationTaskStatus()
boolean	isPropertyReconfigurable(String property) Return whether a given property is changeable at run time.
void	reconfigureProperty(String property, String newVal) Change a configuration property on this object to the value specified.
protected abstract String	reconfigurePropertyImpl(String property, String newVal) Change a configuration property.
void	setReconfigurationUtil(ReconfigurationUtil ru)
void	shutdownReconfigurationTask()
void	startReconfigurationTask() Start a reconfiguration task to reload configuration in background.

Methods inherited from class org.apache.hadoop.conf.Configured

getConf, setConf

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.conf.Configurable

getConf, setConf

Constructor Detail

ReconfigurableBase

public ReconfigurableBase()

Construct a ReconfigurableBase.

ReconfigurableBase

public ReconfigurableBase(Configuration conf)

Construct a ReconfigurableBase with the Configuration conf.

Parameters:

conf - configuration.

Method Detail

setReconfigurationUtil

@VisibleForTesting
public void setReconfigurationUtil(ReconfigurationUtil ru)

getNewConf

protected abstract Configuration getNewConf()

Create a new configuration.

Returns:

configuration.

getChangedProperties

@VisibleForTesting
public Collection<ReconfigurationUtil.PropertyChange> getChangedProperties(Configuration newConf,
                                                                                              Configuration oldConf)

startReconfigurationTask

public void startReconfigurationTask()
                              throws IOException

Start a reconfiguration task to reload configuration in background.

Throws:

IOException - raised on errors performing I/O.

getReconfigurationTaskStatus

public org.apache.hadoop.conf.ReconfigurationTaskStatus getReconfigurationTaskStatus()

shutdownReconfigurationTask

public void shutdownReconfigurationTask()

reconfigureProperty

public final void reconfigureProperty(String property,
                                      String newVal)
                               throws ReconfigurationException

Change a configuration property on this object to the value specified. Change a configuration property on this object to the value specified and return the previous value that the configuration property was set to (or null if it was not previously set). If newVal is null, set the property to its default value; This method makes the change to this objects Configuration and calls reconfigurePropertyImpl to update internal data structures. This method cannot be overridden, subclasses should instead override reconfigurePropertyImpl.

Specified by:

reconfigureProperty in interface Reconfigurable

Parameters:

property - property name.

newVal - new value.

Throws:

ReconfigurationException - if there was an error applying newVal. If the property cannot be changed, throw a ReconfigurationException.

getReconfigurableProperties

public abstract Collection<String> getReconfigurableProperties()

Return all the properties that can be changed at run time. Subclasses must override this.

Specified by:

getReconfigurableProperties in interface Reconfigurable

Returns:

reconfigurable propertys.

isPropertyReconfigurable

public boolean isPropertyReconfigurable(String property)

Return whether a given property is changeable at run time. If isPropertyReconfigurable returns true for a property, then changeConf should not throw an exception when changing this property. Subclasses may wish to override this with a more efficient implementation.

Specified by:

isPropertyReconfigurable in interface Reconfigurable

Parameters:

property - property name.

Returns:

true if property reconfigurable; false if not.

reconfigurePropertyImpl

protected abstract String reconfigurePropertyImpl(String property,
                                                  String newVal)
                                           throws ReconfigurationException

Change a configuration property. Subclasses must override this. This method applies the change to all internal data structures derived from the configuration property that is being changed. If this object owns other Reconfigurable objects reconfigureProperty should be called recursively to make sure that the configuration of these objects are updated.

Parameters:

property - Name of the property that is being reconfigured.

newVal - Proposed new value of the property.

Returns:

Effective new value of the property. This may be different from newVal.

Throws:

ReconfigurationException - if there was an error applying newVal.