org.apache.hadoop.net
Class ScriptBasedMapping

java.lang.Object
  org.apache.hadoop.net.AbstractDNSToSwitchMapping
      org.apache.hadoop.net.CachedDNSToSwitchMapping
          org.apache.hadoop.net.ScriptBasedMapping

All Implemented Interfaces:

Configurable, DNSToSwitchMapping

@InterfaceAudience.Public
@InterfaceStability.Evolving
public final class ScriptBasedMapping
extends CachedDNSToSwitchMapping

This class implements the DNSToSwitchMapping interface using a script configured via the CommonConfigurationKeysPublic.NET_TOPOLOGY_SCRIPT_FILE_NAME_KEY option.

It contains a static class RawScriptBasedMapping that performs the work: reading the configuration parameters, executing any defined script, handling errors and such like. The outer class extends CachedDNSToSwitchMapping to cache the delegated queries.

This DNS mapper's CachedDNSToSwitchMapping.isSingleSwitch() predicate returns true if and only if a script is defined.

Field Summary

static String

NO_SCRIPT Text used in the toString() method if there is no string "no script"

Fields inherited from class org.apache.hadoop.net.CachedDNSToSwitchMapping

rawMapping

Constructor Summary

ScriptBasedMapping()
Create an instance with the default configuration.

ScriptBasedMapping(Configuration conf)
Create an instance from the given configuration

Method Summary

Configuration	getConf() Return the configuration used by this object.
void	setConf(Configuration conf) Set the configuration to be used by this object.
String	toString()

Methods inherited from class org.apache.hadoop.net.CachedDNSToSwitchMapping

getSwitchMap, isSingleSwitch, reloadCachedMappings, reloadCachedMappings, resolve

Methods inherited from class org.apache.hadoop.net.AbstractDNSToSwitchMapping

dumpTopology, isMappingSingleSwitch, isSingleSwitchByScriptPolicy

Methods inherited from class java.lang.Object

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

Field Detail

NO_SCRIPT

public static final String NO_SCRIPT

Text used in the toString() method if there is no string "no script"

See Also:

Constant Field Values

Constructor Detail

ScriptBasedMapping

public ScriptBasedMapping()

Create an instance with the default configuration.

Calling setConf(Configuration) will trigger a re-evaluation of the configuration settings and so be used to set up the mapping script.

ScriptBasedMapping

public ScriptBasedMapping(Configuration conf)

Create an instance from the given configuration

Parameters:

conf - configuration

Method Detail

getConf

public Configuration getConf()

Description copied from interface: Configurable

Return the configuration used by this object.

Specified by:

getConf in interface Configurable

Overrides:

getConf in class AbstractDNSToSwitchMapping

toString

public String toString()

Overrides:

toString in class CachedDNSToSwitchMapping

setConf

public void setConf(Configuration conf)

Set the configuration to be used by this object.

This will get called in the superclass constructor, so a check is needed to ensure that the raw mapping is defined before trying to relaying a null configuration.

Specified by:

setConf in interface Configurable

Overrides:

setConf in class AbstractDNSToSwitchMapping

Parameters:

conf -