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

ReconfigurableBase()
Construct a ReconfigurableBase.

ReconfigurableBase(Configuration conf)
Construct a ReconfigurableBase with the Configuration conf.

Method Summary

abstract Collection<String>	getReconfigurableProperties() Return all the properties that can be changed at run time.
boolean	isPropertyReconfigurable(String property) Return whether a given property is changeable at run time.
String	reconfigureProperty(String property, String newVal) Change a configuration property on this object to the value specified.
protected abstract void	reconfigurePropertyImpl(String property, String newVal) Change a configuration property.

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.

Method Detail

reconfigureProperty

public final String 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; If the property cannot be changed, throw a ReconfigurationException. 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 reconfigureProperty.

Specified by:

reconfigureProperty in interface Reconfigurable

Throws:

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

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

reconfigurePropertyImpl

protected abstract void 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 to make sure that the configuration of these objects is updated.

Throws:

ReconfigurationException