org.apache.hadoop.net

クラス AbstractDNSToSwitchMapping

java.lang.Object

org.apache.hadoop.net.AbstractDNSToSwitchMapping

すべての実装されたインタフェース:

Configurable, DNSToSwitchMapping

直系の既知のサブクラス:

CachedDNSToSwitchMapping

@InterfaceAudience.Public
 @InterfaceStability.Evolving
public abstract class AbstractDNSToSwitchMapping
extends Object
implements DNSToSwitchMapping, Configurable

This is a base class for DNS to Switch mappings.

It is not mandatory to derive DNSToSwitchMapping implementations from it, but it is strongly recommended, as it makes it easy for the Hadoop developers to add new methods to this base class that are automatically picked up by all implementations.

This class does not extend the Configured base class, and should not be changed to do so, as it causes problems for subclasses. The constructor of the Configured calls the setConf(Configuration) method, which will call into the subclasses before they have been fully constructed.

コンストラクタのサマリー

コンストラクタ

修飾子	コンストラクタと説明
protected	AbstractDNSToSwitchMapping() Create an unconfigured instance
protected	AbstractDNSToSwitchMapping(Configuration conf) Create an instance, caching the configuration file.

メソッドのサマリー

修飾子とタイプ	メソッドと説明
String	dumpTopology() Generate a string listing the switch mapping implementation, the mapping for every known node and the number of nodes and unique switches known about -each entry to a separate line.
Configuration	getConf() Return the configuration used by this object.
Map<String,String>	getSwitchMap() Get a copy of the map (for diagnostics)
static boolean	isMappingSingleSwitch(DNSToSwitchMapping mapping) Query for a DNSToSwitchMapping instance being on a single switch.
boolean	isSingleSwitch() Predicate that indicates that the switch mapping is known to be single-switch.
protected boolean	isSingleSwitchByScriptPolicy()
void	setConf(Configuration conf) Set the configuration to be used by this object.

クラスから継承されたメソッド java.lang.Object

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

インタフェースから継承されたメソッド org.apache.hadoop.net.DNSToSwitchMapping

reloadCachedMappings, reloadCachedMappings, resolve

コンストラクタの詳細

AbstractDNSToSwitchMapping

protected AbstractDNSToSwitchMapping()

Create an unconfigured instance

AbstractDNSToSwitchMapping

protected AbstractDNSToSwitchMapping(Configuration conf)

Create an instance, caching the configuration file. This constructor does not call setConf(Configuration); if a subclass extracts information in that method, it must call it explicitly.

パラメータ:

conf - the configuration

メソッドの詳細

getConf

public Configuration getConf()

インタフェースからコピーされた説明: Configurable

Return the configuration used by this object.

定義:

getConf インタフェース内 Configurable

setConf

public void setConf(Configuration conf)

インタフェースからコピーされた説明: Configurable

Set the configuration to be used by this object.

定義:

setConf インタフェース内 Configurable

isSingleSwitch

public boolean isSingleSwitch()

Predicate that indicates that the switch mapping is known to be single-switch. The base class returns false: it assumes all mappings are multi-rack. Subclasses may override this with methods that are more aware of their topologies.

This method is used when parts of Hadoop need know whether to apply single rack vs multi-rack policies, such as during block placement. Such algorithms behave differently if they are on multi-switch systems.

戻り値:

true if the mapping thinks that it is on a single switch

getSwitchMap

public Map<String,String> getSwitchMap()

Get a copy of the map (for diagnostics)

戻り値:

a clone of the map or null for none known

dumpTopology

public String dumpTopology()

Generate a string listing the switch mapping implementation, the mapping for every known node and the number of nodes and unique switches known about -each entry to a separate line.

戻り値:

a string that can be presented to the ops team or used in debug messages.

isSingleSwitchByScriptPolicy

protected boolean isSingleSwitchByScriptPolicy()

isMappingSingleSwitch

public static boolean isMappingSingleSwitch(DNSToSwitchMapping mapping)

Query for a DNSToSwitchMapping instance being on a single switch.

This predicate simply assumes that all mappings not derived from this class are multi-switch.

パラメータ:

mapping - the mapping to query

戻り値:

true if the base class says it is single switch, or the mapping is not derived from this class.