org.apache.hadoop.net

Class ScriptBasedMapping.RawScriptBasedMapping

java.lang.Object

org.apache.hadoop.net.AbstractDNSToSwitchMapping

org.apache.hadoop.net.ScriptBasedMapping.RawScriptBasedMapping

All Implemented Interfaces:

Configurable, DNSToSwitchMapping

Enclosing class:

ScriptBasedMapping

protected static class ScriptBasedMapping.RawScriptBasedMapping
extends AbstractDNSToSwitchMapping

This is the uncached script mapping that is fed into the cache managed by the superclass CachedDNSToSwitchMapping

Constructor Summary

Constructors

Constructor and Description
RawScriptBasedMapping() Constructor.

Method Summary

Modifier and Type	Method and Description
boolean	isSingleSwitch() Declare that the mapper is single-switched if a script was not named in the configuration.
void	reloadCachedMappings() Reload all of the cached mappings.
void	reloadCachedMappings(List<String> names) Reload cached mappings on specific nodes.
List<String>	resolve(List<String> names) Resolves a list of DNS-names/IP-addresses and returns back a list of switch information (network paths).
protected String	runResolveCommand(List<String> args, String commandScriptName) Build and execute the resolution command.
void	setConf(Configuration conf) Set the configuration and extract the configuration parameters of interest
String	toString()

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

dumpTopology, getConf, getSwitchMap, isMappingSingleSwitch, isSingleSwitchByScriptPolicy

Methods inherited from class java.lang.Object

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

Constructor Detail

RawScriptBasedMapping

public RawScriptBasedMapping()

Constructor. The mapping is not ready to use until setConf(Configuration) has been called

Method Detail

setConf

public void setConf(Configuration conf)

Set the configuration and extract the configuration parameters of interest

Specified by:

setConf in interface Configurable

Overrides:

setConf in class AbstractDNSToSwitchMapping

Parameters:

conf - the new configuration

resolve

public List<String> resolve(List<String> names)

Description copied from interface: DNSToSwitchMapping

Resolves a list of DNS-names/IP-addresses and returns back a list of switch information (network paths). One-to-one correspondence must be maintained between the elements in the lists. Consider an element in the argument list - x.y.com. The switch information that is returned must be a network path of the form /foo/rack, where / is the root, and 'foo' is the switch where 'rack' is connected. Note the hostname/ip-address is not part of the returned path. The network topology of the cluster would determine the number of components in the network path.

If a name cannot be resolved to a rack, the implementation should return NetworkTopology.DEFAULT_RACK. This is what the bundled implementations do, though it is not a formal requirement

Parameters:

names - the list of hosts to resolve (can be empty)

Returns:

list of resolved network paths. If names is empty, the returned list is also empty

runResolveCommand

protected String runResolveCommand(List<String> args,
                                   String commandScriptName)

Build and execute the resolution command. The command is executed in the directory specified by the system property "user.dir" if set; otherwise the current working directory is used

Parameters:

args - a list of arguments

Returns:

null if the number of arguments is out of range, or the output of the command.

isSingleSwitch

public boolean isSingleSwitch()

Declare that the mapper is single-switched if a script was not named in the configuration.

Overrides:

isSingleSwitch in class AbstractDNSToSwitchMapping

Returns:

true iff there is no script

toString

public String toString()

Overrides:

toString in class Object

reloadCachedMappings

public void reloadCachedMappings()

Description copied from interface: DNSToSwitchMapping

Reload all of the cached mappings. If there is a cache, this method will clear it, so that future accesses will get a chance to see the new data.

reloadCachedMappings

public void reloadCachedMappings(List<String> names)

Description copied from interface: DNSToSwitchMapping

Reload cached mappings on specific nodes. If there is a cache on these nodes, this method will clear it, so that future accesses will see updated data.