org.apache.hadoop.net
Class CachedDNSToSwitchMapping

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

All Implemented Interfaces:

DNSToSwitchMapping

Direct Known Subclasses:

ScriptBasedMapping

public class CachedDNSToSwitchMapping
extends java.lang.Object
implements DNSToSwitchMapping

A cached implementation of DNSToSwitchMapping that takes an raw DNSToSwitchMapping and stores the resolved network location in a cache. The following calls to a resolved network location will get its location from the cache.

Field Summary

protected DNSToSwitchMapping

rawMapping

Constructor Summary

CachedDNSToSwitchMapping(DNSToSwitchMapping rawMapping)

Method Summary

java.util.List<java.lang.String>

resolve(java.util.List<java.lang.String> names) Resolves a list of DNS-names/IP-addresses and returns back a list of switch information (network paths).

Methods inherited from class java.lang.Object

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

Field Detail

rawMapping

protected DNSToSwitchMapping rawMapping

Constructor Detail

CachedDNSToSwitchMapping

public CachedDNSToSwitchMapping(DNSToSwitchMapping rawMapping)

Method Detail

resolve

public java.util.List<java.lang.String> resolve(java.util.List<java.lang.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.

Specified by:

resolve in interface DNSToSwitchMapping

Returns:

list of resolved network paths