Package org.apache.hadoop.hdfs.server.federation.resolver.order

Class LocalResolver

java.lang.Object

org.apache.hadoop.hdfs.server.federation.resolver.order.RouterResolver<java.lang.String,java.lang.String>

org.apache.hadoop.hdfs.server.federation.resolver.order.LocalResolver

All Implemented Interfaces:

OrderedResolver

public class LocalResolver
extends RouterResolver<java.lang.String,java.lang.String>

The local subcluster (where the writer is) should be tried first. The writer is defined from the RPC query received in the RPC server.

Field Summary

Fields inherited from class org.apache.hadoop.hdfs.server.federation.resolver.order.RouterResolver

MIN_UPDATE_PERIOD_KEY

Constructor Summary

Constructors

Constructor	Description
LocalResolver(org.apache.hadoop.conf.Configuration conf, Router routerService)

Method Summary

Modifier and Type	Method	Description
protected java.lang.String	chooseFirstNamespace(java.lang.String path, PathLocation loc)	Get the local name space.
protected java.util.Map<java.lang.String,java.lang.String>	getSubclusterInfo(MembershipStore membershipStore)	Get the mapping from nodes to subcluster.

Methods inherited from class org.apache.hadoop.hdfs.server.federation.resolver.order.RouterResolver

getFirstNamespace, getMembershipStore, getRpcServer, getSubclusterMapping

Methods inherited from class java.lang.Object

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

Constructor Detail

LocalResolver

public LocalResolver(org.apache.hadoop.conf.Configuration conf,
                     Router routerService)

Method Detail

getSubclusterInfo

protected java.util.Map<java.lang.String,java.lang.String> getSubclusterInfo(MembershipStore membershipStore)

Get the mapping from nodes to subcluster. It gets this mapping from the subclusters through expensive calls (e.g., RPC) and uses caching to avoid too many calls. The cache might be updated asynchronously to reduce latency.

Specified by:

getSubclusterInfo in class RouterResolver<java.lang.String,java.lang.String>

Parameters:

membershipStore - Membership store the resolver queried from.

Returns:

Node IP to Subcluster.

chooseFirstNamespace

protected java.lang.String chooseFirstNamespace(java.lang.String path,
                                                PathLocation loc)

Get the local name space. This relies on the RPC Server to get the address from the client. TODO we only support DN and NN locations, we need to add others like Resource Managers.

Specified by:

chooseFirstNamespace in class RouterResolver<java.lang.String,java.lang.String>

Parameters:

path - Path ignored by this policy.

loc - Federated location with multiple destinations.

Returns:

Local name space. Null if we don't know about this machine.